,中国农业科学院郑州果树研究所,郑州 450009Progress on salt resistance in autopolyploid plants
Hongju Zhu, Wenge Liu,Zhengzhou Fruit Research Institute,Chinese Academy of Agriculture Sciences, Zhengzhou 450009, China通讯作者:
编委: 张根发
收稿日期:2017-09-14修回日期:2018-02-5网络出版日期:2018-04-20
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Received:2017-09-14Revised:2018-02-5Online:2018-04-20
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朱红菊,在读博士,研究方向：多倍体西瓜抗逆E-mail:
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朱红菊, 刘文革. 植物同源多倍体耐盐性研究进展. 遗传[J], 2018, 40(4): 315-326 doi:10.16288/j.yczz.17-305
Hongju Zhu, Wenge Liu.
多倍化是高等植物基因组进化的显著特征之一,大约有75%的被子植物和95%的蕨类植物在进化过程中发生过多倍化事件[1]。多倍体植物通常具有3套或者3套以上染色体组,按照染色体组的来源不同可分为由不同物种染色体组成的异源多倍体和由相同染色体组成的同源多倍体;根据形成方式的不同又分为自然形成的多倍体和人工诱导形成的多倍体。自然形成的多倍体主要是物种为了适应环境,经过长期自然选择进化而来;人工诱导的同源多倍体主要是通过秋水仙素等诱变剂抑制纺锤丝的形成达到染色体加倍的目的[2]。同源多倍体增大了植物基因组,大大提高了抗性基因的容量,丰富了抗性基因的遗传变异范围,增加了优良基因组合的概率,从而增强了植物对极端环境的适应性[3]。人工诱导的植物同源多倍体染色体组的增多可以提供其二倍体祖先所没有的新的特征,如孤雌生殖增加、组织器官增大、生物学产量提高、次生物质增加、抗逆性增强等,即多倍体优势[4]。同源多倍体因其独特的多倍体优势而被广泛地应用在农作物、园艺和药用植物领域。
土壤盐碱化一直威胁着人类赖以生存的有限土壤资源,成为日益严重的环境和生态问题之一[5]。据联合国教科文组织(UNCSCO)和粮农组织(FAO)不完全统计,在世界范围内,近1/3的灌溉土地受到盐分胁迫,并且降雨的缺乏加剧了盐渍化程度,使土壤盐渍化面积逐年增加,给农业生产造成重大损失[6]。因此在人口不断增加、耕地日趋减少和淡水资源不足的情况下,了解植物的耐盐机理、开发和利用耐盐植物资源、培育耐盐作物、有效控制和利用盐碱土,对农业发展、粮食安全、生态环境等具有重要意义。
大量研究发现,植物同源多倍体的耐盐能力超过了其同源二倍体(表1)。盐胁迫对植物的影响是多方面的,耐盐性是一种综合性状的表现,植物适应盐胁迫方式和耐盐机理与其组织或细胞的生理代谢和生化变化相关。因此,从与盐胁迫相关的耐盐性进化、生理生化水平、细胞结构和分子层面等多角度了解植物同源多倍体盐胁迫研究进展,有助于全面了解植物同源多倍体的耐盐机理。
Table 1
表1
表1 盐胁迫下人工诱导的同源多倍体植物抗性强弱比较
Table 1
| 植物 | 耐盐能力 | 参考文献 | 植物 | 耐盐能力 | 参考文献 |
|---|---|---|---|---|---|
| 水稻 (Oryza sativa L.) | 2x<4x | [7] | 冀橙 (Citrus macrophylla) | 2x<3x<4x | [12] |
| 大麦 (Hordeum bulbosum) | 2x<4x | [8] | 柑橘 (Citrus reticulata) | 2x<4x | [13] |
| 油菜 (Brassica rapa L.) | 2x<4x | [9] | 苹果 (Malus domestica) | 2x<4x | [14] |
| 西瓜 (Citrullus lanatus) | 3x<2x<4x | [10] | 刺槐 (Robinia pseudoacacia L. ) | 2x<4x | [15] |
| 白菜 (Brassica oleracea L.) | 2x<4x | [11] | 白花泡桐 (Paulownia fortunei) | 2x<4x | [16] |
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1 同源多倍体植物的进化
染色体加倍以后,同源多倍体植物在形态特征上表现出与其原始二倍体不同的特征。同源多倍体植物植株高大,茎粗叶厚,叶面积增加,种子变大。如四倍体荞麦(Fagopyrum esculentum)植株株高增加,茎秆粗壮[17];四倍体西瓜(Citrullus lanatus)叶片变厚,保卫细胞数目增多[18],种子变宽变厚[19];四倍体拟南芥(Arabidopsis thaliana)体细胞、根细胞都比其原始二倍体增大[20]。另外,次生代谢物质如萜类、酚类、黄酮类、生物碱类、花青素、苯丙脂类的含量和种类均被诱导增加[21]。植物同源多倍体在抗性方面也表现出很明显的优势,如耐盐[22]、抗病[23]、耐 冷[24]等。多倍化在生物演化历程中扮演了重要的角色,同源多倍体构成了基因的多次重复,提高了基因功能的保守性,显著降低了突变和隐性基因纯合表现的可能性,在严酷的自然条件下为其竞争提供了稳定的系统空间。研究表明,几乎所有的开花植物在历史的某个节点上都经历了全基因组的加倍事件,这种进化上的共性折射了多倍体进化与物种选择之间的紧密联系。多倍体能增加物种的多样性,新物种的基因组结构发生改变,包括重复基因的部分选择性丢失,同时也伴随着新功能基因的产生,极大地丰富了新的多倍体物种的遗传多样性。同时,基因组加倍也能增加多倍体物种在恶劣环境下的存活率。Fawcett等[25]研究发现,大多数的开花植物大约在6500万年前的中垩纪经历了一次全基因组加倍事件,一些全基因组加倍的开花植物被选择性存活下来,所以多倍化能增加新物种的生活力和适应性。Ellstrand等[26]对28个物种的生物入侵的成功率进行了分析,结果显示,多倍体物种更容易入侵新的生态环境。Chao等[20]对拟南芥同源四倍体的进化进行了研究,发现在四倍体拟南芥的分布区,其土壤中的钠离子含量要远远高于二倍体拟南芥的原生地,染色体倍性的增加有助于提高拟南芥高盐环境的适应性。多倍化是植物适应逆境而进化的一个重要特征,但是多倍体进化的过程是漫长的,因此可以通过人工诱导形成多倍体,这样将会加快物种进化的进程,使植物更能适应环境的剧烈变化。
2 盐胁迫对同源多倍体植物生理生化水平的影响
盐胁迫对植物造成的伤害首先表现为渗透胁迫,其次是离子转运不平衡而引起的缺素症和单盐毒害,最后细胞内稳态被破坏而导致质膜透性的改变、活性氧的积累和代谢的紊乱,进而影响植物正常的生长发育[27]。2.1 渗透胁迫
渗透胁迫是指盐胁迫后植物体内的渗透压低于环境渗透压,植物体不能吸水甚至失水,最终导致生理干旱或者死亡。渗透胁迫是一个快速过程,在盐处理的第1~2天发生[28]。研究发现,高盐浓度会对种子产生渗透抑制,只有胁迫减轻时才能消除这种抑制作用[29]。受渗透胁迫的影响,高盐浓度下植物种子发芽率降低,用150 mmol/L NaCl处理后,三倍体和四倍体蜜枚西瓜(Citrullus lanatus ‘Mimei’)种子的发芽率(分别为77.8%和63.4%)显著高于其同源二倍体西瓜种子(30.6%),而低盐浓度(30~90 mmol/L NaCl)下,不同倍性西瓜种子的发芽率没有显著差 异[30]。较高渗透调节能力是多倍体植物在盐胁迫初期耐盐的主要原因。2.2 离子胁迫
在盐胁迫环境下,植物选择性地对无机离子进行吸收,尤其是Na+和K+,平衡细胞内离子稳态,减少盐胁迫对植物的伤害。盐胁迫下大麦(Hordeum vulgare L.)、陆地棉(Gossypium hirsutum)、柑橘(Citrus reshni)的根系可截留大部分的Na+,地上部运输Na+离子少,减少了盐对叶片的伤害;然而在NaCl 胁迫下棉花体内95%以上的Na+积累在地上部,Na+在茎和叶柄中滞留和积累,根中的K+向地上部选择性运输,以维持叶片中较高的K+/Na+比[31,32,33]。因此,不同植物对Na+和K+的吸收不同。多倍体是如何通过Na+和K+的吸收来适应盐胁迫的?研究发现,四倍体拟南芥分布区Na+/K+远高于二倍体拟南芥分布区,染色体倍性的增加使拟南芥根细胞体积增大,细胞体积变化改变了根系K +含量,四倍体拟南芥通过根系聚集K +的方式达到其对高盐环境的适应[20]。朱红菊等[10]研究发现,盐胁迫下的四倍体西瓜叶片因为具有较高的K+和Ca2+含量而比其同源二倍体更耐盐。Zhu[34]研究认为,植物体细胞含有中央大液泡,能够鳌合大量的Na+,减少了细胞质中Na+质量分数,同时也缓解了细胞膜内外的渗透压。研究发现,四倍体油菜(Brassica rapa L.)细胞液泡螯合Na+的能力比二倍体强,从而比二倍体有更强的耐盐胁迫能 力[9]。盐胁迫后二倍体和四倍体刺槐(Robinia pseudoacacia L.)叶片中Cl-和Na+含量差异不大,但是四倍体刺槐叶片能积累更多的K+,四倍体刺槐依靠高的K+/Na+比值来维持高耐盐能力[15]。盐胁迫后四倍体柑橘根系中Na+含量显著高于二倍体,Na+向地上部分运输减少,从而减少了盐胁迫对地上部分的伤害[35]。因此,盐胁迫后,植物同源多倍体排出对本身伤害较大的Na+和吸收对本身有益的K+,通过叶片积累高K+类型、叶片中的液泡螯合Na+类型、根部积累Na+类型等实现其自身耐盐机理。2.3 氧化胁迫
在正常状态下,活性氧在植物体内的产生与清除处于平衡状态,植物生长不会受到影响。盐胁迫条件下,植物体内活性氧平衡被打破,细胞内开始积累自由基,各类生物膜选择透过性能力降低,最终导致代谢紊乱,植物体受到胁迫伤害。伴随植物体内活性氧的积累,丙二醛(malondialdehyde, MDA)含量增加,MDA是膜质过氧化的产物,其含量间接反应了细胞膜受伤害程度。盐胁迫后植物内部防御系统会产生相应的渗透调节物质和抗氧化保护系统来抵御胁迫伤害,如保护酶系统超氧化物歧化酶(superoxide dismutase, SOD)、过氧化物酶(peroxidase, POD)和抗坏血酸氧化酶(ascorbate oxidase, APX)、 谷胱甘肽还原酶(glutathion reductase, GR)的活性增 强等[36]。盐胁迫后,二倍体和四倍体刺槐的SOD均增加,但是四倍体增加程度大于二倍体;四倍体中POD、APX、GR活性在盐胁迫后增加,尤其是APX和GR活性增加的最多[15, 37],但是二倍体中几乎没有变化。研究发现,在相同的盐浓度下四倍体中游离的脯氨酸的含量比其同源二倍体显著增加,但是可溶性糖含量在两个倍性之间差异不显著,四倍体中MDA含量显著低于二倍体,因此四倍体水稻的耐盐能力强于其同源二倍体[38]。盐胁迫下四倍体费尔南德斯橙(Citrus sinensis L.)叶片中丙二醛含量显著低于二倍体,同时四倍体中SOD、POD活性高于二倍体,通过这些抗氧化保护酶类活性的增加,四倍体费尔南德斯橙表现出高的耐盐胁迫能力[39]。与二倍体砧木相比,四倍体砧木能增加金桔(Citrus reticulata)盐胁迫后叶片中SOD、POD酶活性,降低H2O2和O2-含量[13]。因此,在逆境胁迫下同源多倍体植物能够迅速提高细胞内的抗氧化保护酶的活性以及可溶性糖和脯氨酸含量以提高渗透势,增强保护酶活性以保持质膜的稳定性,同时减少对细胞有伤害的物质的积累,减少质膜透性。
2.4 内源激素
盐胁迫下,植物内源激素水平受到影响,如盐胁迫会引起生长素(auxin, IAA)、细胞分裂素等水平的减少,进而抑制植物生长;盐胁迫下脱落酸和乙烯等的合成增加,促进植物的衰老。豆峻岭等[40]研究不同倍性西瓜植株在生长过程中内源激素的变化,发现同一发育期不同倍性的西瓜植株内源激素差异不显著。但是在干旱胁迫后,以四倍体黎檬(Citrus limonia Osbeck)做砧木的甜橙(Citrus sinensis)叶片中脱落酸(abscisic acid, ABA)的含量显著高于以二倍体做砧木的植株[41]。二倍体和四倍体白花泡桐(Paulownia fortunei)经过盐处理后,其差异表达的蛋白主要参与了植物激素信号传导等途径[42]。孟华兵等[43]发现在盐胁迫后,二倍体和四倍体白菜型油菜(Brassica rapa)中参与调控ABA和乙烯的转录因子表达量差异显著。总之,针对同源多倍体盐胁迫后植物内源激素水平的研究相对较少,可能是因为植物内源激素对盐胁迫的响应不是直接的,而是间接地通过调控渗透调节、离子运输、光合作用和气孔开放等方式响应盐胁迫。2.5 光合作用
光合作用是植物最基本的生命活动,逆境条件下植物正常的光合作用会受到影响。盐胁迫后植物叶片光合参数、渗透势、水势、蒸腾速率以及相对含水量等会发生变化,同时与光合作用相关的酶、光合色素、类囊体膜蛋白及膜脂也都受到影响。NaCl胁迫后,比较不同倍性刺槐的光合作用相关指数发现,四倍体的净光合速率、气孔导度受盐胁迫影响较小,而二倍体的净光合速率、气孔导度盐胁迫前后变化较大。四倍体在盐胁迫后有高的水分利用率,以至于其在相对低含水量的情况下依然有相对稳定的光合作用能力[15]。盐胁迫后四倍体冀橙(Citrus macrophylla)叶片渗透势和蒸腾速率比二倍体低,气体交换相关参数比二倍体高,最终导致四倍体冀橙比二倍体耐盐[12]。六倍体小麦(Triticum aestivum L.)比四倍体小麦(Triticum turgidum L.)具有更高的净光合速率、气孔导度、淀粉含量、叶绿素含量和电解质渗出率[44]。在相同的盐浓度处理下,四倍体水稻(Oryza sativa L.)叶片中的叶绿素含量要显著高于其同源二倍体,四倍体中叶绿素a和叶绿素b的比值大于二倍体,四倍体的光合作用能力强于二倍体,四倍体水稻叶片的净光合速率也高于其同源二倍体[7]。因此可以得出结论,同源多倍体的高耐盐能力与其光合作用相关指标密切相关,植物同源多倍体叶片通过响应各种光合作用信号来响应盐胁迫,盐胁迫后四倍体植株中净光合速率、气孔导度、叶绿素含量高于二倍体,通过稳定光合系统实现耐盐能力。
3 盐胁迫对同源多倍体植物细胞结构和质膜透性的影响
盐胁迫影响植物的细胞结构,叶绿体是植物光合作用的场所,是对盐最敏感的一类细胞器,盐胁迫后植物的叶绿体会出现基粒片层紊乱、叶绿体肿胀、叶绿体膜破裂等现象[45]。细胞的受伤害程度是植物本身受伤害大小的直接反应,因此研究植物多倍体盐胁迫后的细胞结构变化,将有助于从细胞学水平解析多倍体抗逆性机理[46]。Dhar等[47]对酿酒酵母(Saccharomyces cerevisiae)的长期耐盐筛选表明,盐胁迫可以诱导细胞多倍体化。研究发现,植物染色体加倍以后经常产生新的表型,二倍体加倍后细胞体积增加了两倍,但是细胞表面积只增加了1.5倍,降低了植物的生长速率,改变了植物体的形态。研究发现,多倍体细胞体积的增大与耐盐相关[48]。盐胁迫导致活性氧物质如O2-和H2O2的积累,这些物质的积累会影响植物的细胞膜结构和核酸蛋白的稳定性[49]。盐胁迫后,植物叶片叶绿体肿胀变圆、内部的类囊体紊乱、淀粉粒大量积累,严重影响植物的光合作用。受盐胁迫影响,四倍体水稻、柑橘、刺槐、马铃薯(Solanum tuberosum)的细胞膜和叶绿体受伤害程度远远小于其同源二倍体细胞[48,12,50,51]。细胞是植物生活力反应的最直接的场所,细胞结构的完整性直接决定细胞行使自身功能的能力,多倍体植物在盐胁迫下细胞的结构能保持相对的完整,为植株的正常生长提供了相对稳定的场所,从细胞学层面上解释了植物多倍体耐盐的优势机理。
4 盐胁迫后同源多倍体植物在分子水平的变化
植物染色体同源加倍以后,在遗传水平上,多条同源染色体存在于同一细胞核中增加了染色体重组的概率,同时也可能诱导序列的消除。在表观遗传水平上,多倍体化之后植物基因组会发生转座子激活、DNA甲基化、组蛋白修饰、核仁显性和RNA干扰等。这些遗传和表观遗传因素,与基因的剂量效应和基因调控网络一起调节着多倍体化后植物基因的表达。植物多倍化后基因表达模式包括基因沉默、非加性表达、基因表达的基因组偏向性及组织特异性、基因激活等现象。转录组水平的变化影响蛋白质的翻译,植物同源加倍后的变化最终通过蛋白质的形式反应出来。盐胁迫后,对植物同源多倍体耐盐分子层面的研究主要集中在离子转运蛋白基因、渗透调节相关基因、信号传导相关基因、细胞抗氧化相关基因在表观遗传、转录组水平和蛋白水平的变化。4.1 DNA甲基化变化
表观遗传学是指不涉及DNA序列改变的基因或者蛋白表达的变化而引起的可遗传的表型改变。染色体加倍后,植物多倍体基因组结构未发生显著改变,但是表观遗传修饰发生了改变,全基因组加倍伴随胞嘧啶甲基化的增强[52],由此导致了多倍体植物基因表达的改变[53]。Zhang等[54]研究二倍体和四倍体水稻(Oryza sativa ssp. indica cv.)全基因组甲基化,分析发现,在转座元件附近DNA甲基化水平有很大的差异,这些甲基化水平的差异会影响相邻基因的表达。拟南芥染色体加倍以后原来在二倍体中表达的一些基因发生了沉默,但是用去甲基化物质aza-dC处理后,这些沉默的基因又重新恢复了活性[55]。盐胁迫下植物的基因组DNA甲基化水平上升被认为是植物抗盐的机理之一[56]。Fang等[57]研究认为,油菜(Brassica napus)在盐胁迫后通过甲基化水平变化影响其耐盐基因的表达。盐胁迫后四倍体甘蓝型油菜叶片中甲基化水平比其二倍体增加,同时甲基化率四倍体也高于二倍体[58]。朱红菊等[59]研究发现,NaCl处理西瓜幼苗后,在同一盐浓度下甲基化率二倍体大于四倍体,二倍体和四倍体西瓜甲基化水平与其受伤害程度呈正相关;DNA甲基化通过调控与盐胁迫相关的基因的表达参与植物的盐胁迫。盐胁迫下基因组DNA甲基化水平上升是植物耐盐的机理之一,因此对盐胁迫下DNA甲基化及其相关基因的研究是植物同源多倍体耐盐的表观遗传研究的重要方向。
4.2 耐盐相关基因表达
在正常生长的多倍体植物体内,大部分的基因表达量与二倍体相同,只有很少一部分基因的表达量存在差异。但是在盐胁迫条件下,多倍体为了适应环境,选择性地高表达一些盐胁迫相关基因,这些基因主要是一些与渗透调节、离子转运、抗氧化胁迫、信号转导的基因或是与这些途径相关的转录因子[60](表2)。Table 2
表2
表2 在多倍体植物中响应盐胁迫的部分基因及其功能
Table 2
| 物种名及倍性 | 基因名称 | 基因功能注释 | 参考文献 |
|---|---|---|---|
| 刺槐(4x) (Robinia pseudoacacia L.) | ASCF1 | ATP合酶 | [50] |
| FBA2 | 二磷酸果糖醛酸酶 | ||
| LADP | 叶绿素酶2 | ||
| HSP | 热激蛋白,蛋白稳定性 | ||
| 球茎大麦(4x) (Hordeum bulbosum) | ERF2 | 乙烯受体转录因子2 | [8] |
| PLDZ1 | 磷脂酶 | ||
| MZT1B | 纺锤丝组织 | ||
| RFA1C | DNA绑定 | ||
| 小麦(4x, 6x) (Triticum aestivum cv. Kharchia Local) | EMS62134 | 肌动蛋白1 | [60] |
| ABG75754.1 | 盐响应蛋白 | ||
| AAK76737.1 | Na+/H+转运 | ||
| EMS57734.1 | 磷酸酶类蛋白 | ||
| 白花泡桐(4x) (Paulownia fortunei) | DREB2A; | 转录因子 | [16] |
| GsWRKY20; | |||
| GAMYB | |||
| 拟南芥(4x) (Arabidopsis) | RC13 | 过氧化物酶 | [62] |
新窗口打开|下载CSV
四倍体拟南芥中的BrNaCIR9在盐胁迫后被诱导,该基因能产生盐胁迫蛋白,增强四倍体拟南芥的耐盐能力[61]。另外,小RNA也通过调控耐盐基因的表达参与了多倍体的耐盐机制。miR528b-3p通过调节四倍体球茎大麦(Hordeum bulbosum)耐盐基因的表达增加了其耐盐适应能力[8]。Fan等[16]研究在四倍体和二倍体泡桐幼苗盐胁迫后差异表达的miRNA的靶基因时发现,这些miRNA多与能量代谢、信号转导和转录调控相关的基因有关。拟南芥中与ABA信号转导有关的转录因子在盐胁迫后四倍体中的表达量高于了其二倍体植株[62]。二倍体和四倍体的刺槐的研究中也得到了一些差异的表达片段,这些差异表达片段的表达量在四倍体中高于二倍体,并且这些差异的表达片段经过测序后对应的基因分别与谷氧还蛋白、H-ATP酶、GTP结合蛋白、激素的信号传导等相关[15]。不同的盐胁迫相关基因在不同倍性植物之间的表达差异最终通过参与不同的代谢通路参与盐胁迫,研究盐胁迫下多倍体植物的耐盐机理,主要应该关注参与光合作用、离子运输、激素信号传导、能量合成、抗氧化酶活性等途径的基因在不同倍性植物之间的差异表达。
4.3 耐盐相关蛋白表达谱
利用蛋白质组学分析多个二倍体和四倍体物种的蛋白质谱,几乎没有在二倍体和四倍体之间发现较大的蛋白质水平差异[63]。对单倍体、二倍体和四倍体油菜(Brassica oleracea)的蛋白质组学研究发现,不同组织和基因型的差异是其蛋白质水平差异的唯一来源,而非倍性水平[11]。拟南芥中的二倍体和其同源四倍体蛋白质组的差异仅有6.8%。但是在生物和非生物逆境中拟南芥四倍体植株的功能蛋白质相对于其二倍体显著增加[64]。利用高通量蛋白质组学技术分析拟南芥、水稻等多种植物的盐胁迫应答蛋白质表达图谱,发现植物耐盐性受到多基因网络体系的调控,各种信号与代谢途径之间相互交错、彼此关联。高通量的植物盐胁迫应答蛋白质组学研究从整体上揭示了盐胁迫相关代谢和信号网络应答机制,并反映了植物类群、物种、组织器官、细胞和亚细胞结构应答盐胁迫的相似与特异机制。盐胁迫后,二倍体和四倍体刺槐叶片中共检测出62个差异显著的蛋白质位点[50]。磷酸核酮糖羧化酶(Rubisco)是叶片中丰度最高的蛋白,Rubisco相关的活化酶活性的增加会导致植物净光合速率的升 高[65,66],盐胁迫后四倍体刺槐中Rubisco蛋白大亚基的丰度显著高于其同源二倍体[50]。蛋白磷酸甘油酸激酶(phosphoglycerate kinase, PGK)在多种物种中被验证能够提高植物逆境适应能力,盐胁迫后四倍体刺槐叶片中PGK的活性上调表达,二倍体中则没有出现上调表达[15]。小麦中盐胁迫响应蛋白、锌指蛋白、离子转运受体蛋白、钙调蛋白等都均在二倍体和四倍体里存在显著差异[60]。赵婉[42]比较了盐胁迫后二倍体和四倍体白花泡桐蛋白质组学变化,共获得91个盐胁迫下的二倍体和四倍体泡桐的差异蛋白,其中34个是与倍性相关的盐应答蛋白,主要参与淀粉和蔗糖代谢、氨基酸和核苷酸糖代谢、光合作用、氧化磷酸化和核糖体的合成等通路。蛋白质是植物应对盐胁迫的最终产物,其丰度直接决定植物的耐盐能力。蛋白质表达谱响应不同倍性植物的盐胁迫,研究多倍体盐胁迫应该首先关注光合作用相关蛋白,其次是胁迫响应蛋白,之后是能量相关蛋白,通过对这几类蛋白质丰度的分析有助于了解植物同源多倍体耐盐机理。
5 同源多倍体耐盐性在育种中的应用
研究植物同源多倍体耐盐的机理主要目的是为了应用在生产中,随着对越来越多的多倍体植物的耐盐性进行研究,四倍体植物的耐盐能力已经得到了充分的证实。四倍体植物在遗传改良中具有重要的作用和价值,其本身既是优良的种质资源,又是三倍体和高倍性资源育种的基础[67]。近年来,四倍体植物因为较好的抗逆特性已经被应用到育种工作中,并作为重要的抗逆种质资源进行选育推广。四倍体的耐盐育种工作在柑橘类作物中开展的比较多,包括挖掘耐盐砧木[39]、筛选耐盐种质[12]、培育耐盐品种等[38]。目前四倍体柑橘类耐盐性品种已经广泛地应用到了柑橘产业中。在离体诱导多倍体西瓜过程中,利用不同倍性西瓜的耐盐性不同,只需对大批量的不定芽丛一次性地进行短时盐胁迫处理,就可以省掉独立的单株倍性鉴定过程,淘汰二倍体而筛选出四倍体[68]。刺槐是我国水土保持的重要树种,四倍体刺槐因其较强的耐盐碱能力目前已经成为了我国园林绿化的主要树种[50]。泡桐是我国林业生产中防风固沙和改善环境的主要树种,但是现有的品种不能在盐量大于0.05%的土壤上正常生长,邓敏捷等[69]创制四倍体泡桐新种质提高了泡桐的耐盐胁迫能力,在0.6%的NaCl胁迫下,四倍体泡桐的耐盐能力显著高于二倍体。人工诱导加倍的‘寒富’四倍体苹果耐盐能力较其同源二倍体显著提高[14,70],在提高抗逆性的同时丰富了苹果育种的种质资源,为培育优质抗逆苹果品种提供了有效途径。综合多倍体植物在育种中的应用,不难发现多倍体诱导已经成为创制植物种质资源的一个主要途径,由于多倍体植物在抗逆性方面的突出表现,通过染色体加倍途径而非转基因的途径培育出适合盐碱地栽培的品种变得更容易被人们接受。
6 结语与展望
植物同源多倍体因其独特的抗逆优势,已经越来越多地被应用到了育种工作中,人工诱导染色体加倍产生的新种质资源也逐渐增多,关于多倍体植物抗逆机制的研究工作有了深入进展。多倍体西瓜是人们对多倍体应用最成功的作物之一。多倍体西瓜具有许多二倍体亲本所没有的少籽(或无籽)、丰产、耐贮运、抗病抗逆性强、果实含糖量高等优良性状,尤其是抗逆适应性强。笔者所在研究团队长期从事多倍体西瓜研究,在基础研究以及多诱变和育种方面都做了较多工作。本研究团队已经诱变了300多份优质的四倍体西瓜种质资源,选育出30多个三倍体无籽西瓜品种,并在全国大面积推广[71]。在多倍体西瓜基础研究方面,本团队研究发现四倍体西瓜叶片[8]、花粉[72]、种子[9]均表现出多倍体植物器官的巨大性,三倍体和四倍体西瓜中的次生代谢物质如Vc[73]、番茄红素[40]、糖[74]等含量都比其同源二倍体高,而且四倍体西瓜与二倍体西瓜相比表现出较强的抗逆能力,如耐冷[23]、耐淹水[75]、抗枯萎病[76]、耐盐[10]等。关于多倍体西瓜的研究,Saminathan等[77]通过高通量测序研究二倍体和四倍体转录组水平上的差异,发现不同倍性的西瓜中与细胞分裂、光受体、离子储存、信号传导、淀粉和蔗糖的降解途径、精氨酸生物合成途径、乙烯合成等相关基因的表达差异显著。四倍体西瓜耐盐能力的增加具体与哪些基因有关尚未有研究报道,表观遗传学和基因剂量效应在多倍体西瓜耐盐性机理方面是通过哪些基因发挥作用的也不得而知。因此,今后的研究方向将是结合分子生物学和生理生化变化共同解释多倍体西瓜的耐盐机理。多倍体植物在育种中的应用除了抗逆优势之外,其结实率降低的性状也很关键。多倍体植物结实率降低既有优势又有劣势。同源多倍体结实率低的优势利用主要体现在多倍体西瓜育种中三倍体的无籽性和四倍体的少籽性利用[9];多倍体结实率低的劣势主要体现在育种中需要提高多倍体植物收获种子的产量,如三倍体无籽西瓜育种中,需要对其四倍体亲本进行孕性恢复,以提高采种量,降低育种成本[9]。当前研究的多倍体水稻育种,其关键在于选育出PMeS(polyploid meiosis stability)品系,突破多倍体育种结实率低的瓶颈[37,78~80]。提高多倍体植物的结实率是多倍体植物育种中需要解决的问题。
植物同源多倍体的耐盐性机理复杂,受多方面的影响,包括离子吸收、光合作用、渗透调节物质、细胞结构、基因表达、蛋白翻译等。同源多倍体植物与其耐盐性之间的关系仍有许多未解之谜,今后还需要深入研究。有研究发现,多倍体的耐盐性还与其保持染色体组的稳定性相关,稳定者抗性强,非稳定者抗性弱[81]。一个新形成的多倍体最显著的特征是基因组不稳定,并经历快速重构,以达到多个基因组在细胞核内的和谐共存[82,83]。人工合成的同源多倍体因为没有经历长期的自然进化,在形成初期会有一个基因组不稳定时期。因此,同源多倍体基因组的稳定性对其耐盐能力强弱的影响也是今后的研究中需要关注的热点。目前,该领域在以下3个方向尚需进一步研究：(1)多倍体耐盐性研究在表观遗传学层面的研究还比较薄弱,如DNA甲基化与耐盐基因的相关性,组蛋白修饰对耐盐性的影响等;(2)随着生物信息学的发展,基因组学、表观遗传组学、蛋白质组学、离子组学等的研究突飞猛进,多组学关联分析将是多倍体植物耐盐性研究的热点;(3)同源多倍体基因组的稳定性对其耐盐能力的影响非常重要,只有探究清楚其中原因,才能了解人工诱导的同源多倍体耐盐性的机理。
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URLPMID:15752992 [本文引用: 1]
Abstract Genome doubling (polyploidy) has been and continues to be a pervasive force in plant evolution. Modern plant genomes harbor evidence of multiple rounds of past polyploidization events, often followed by massive silencing and elimination of duplicated genes. Recent studies have refined our inferences of the number and timing of polyploidy events and the impact of these events on genome structure. Many polyploids experience extensive and rapid genomic alterations, some arising with the onset of polyploidy. Survivorship of duplicated genes are differential across gene classes, with some duplicate genes more prone to retention than others. Recent theory is now supported by evidence showing that genes that are retained in duplicate typically diversify in function or undergo subfunctionalization. Polyploidy has extensive effects on gene expression, with gene silencing accompanying polyploid formation and continuing over evolutionary time.
URLPMID:26715561 [本文引用: 1]
Abstract MAIN CONCLUSION: This article provides an up-to-date review concerning from basic issues of polyploidy to aspects regarding the relevance and role of both natural and artificial polyploids in plant breeding programs. Polyploidy is a major force in the evolution of both wild and cultivated plants. Polyploid organisms often exhibit increased vigor and, in some cases, outperform their diploid relatives in several aspects. This remarkable superiority of polyploids has been the target of many plant breeders in the last century, who have induced polyploidy and/or used natural polyploids in many ways to obtain increasingly improved plant cultivars. Some of the most important consequences of polyploidy for plant breeding are the increment in plant organs ("gigas" effect), buffering of deleterious mutations, increased heterozygosity, and heterosis (hybrid vigor). Regarding such features as tools, cultivars have been generated with higher yield levels, improving the product quality and increasing the tolerance to both biotic and abiotic stresses. In some cases, when the crossing between two species is not possible because of differences in ploidy level, polyploids can be used as a bridge for gene transferring between them. In addition, polyploidy often results in reduced fertility due to meiotic errors, allowing the production of seedless varieties. On the other hand, the genome doubling in a newly formed sterile hybrid allows the restoration of its fertility. Based on these aspects, the present review initially concerns the origin, frequency and classification of the polyploids, progressing to show the revolution promoted by the discovery of natural polyploids and polyploidization induction in the breeding program status of distinct crops.
URLPMID:22480430 [本文引用: 1]
Polyploidy, or whole genome duplication, is recognized as an important feature of eukaryotic genome evolution. Among eukaryotes, polyploidy has probably had the largest evolutionary impact on vascular plants where many contemporary species are of recent polyploid origin. Genomic analyses have uncovered evidence of at least one round of polyploidy in the ancestry of most plants, fueling speculation that genome duplications lead to increases in net diversity. In spite of the frequency of ancient polyploidy, recent analyses have found that recently formed polyploid species have higher extinction rates than their diploid relatives. These results suggest that despite leaving a substantial legacy in plant genomes, only rare polyploids survive over the long term and most are evolutionary dead-ends.
URLPMID:10860970 [本文引用: 1]
In 1950, G. Ledyard Stebbins devoted two chapters of his book Variation and Evolution in Plants (Columbia Univ. Press, New York) to polyploidy, one on occurrence and nature and one on distribution and significance. Fifty years later, many of the questions Stebbins posed have not been answered, and many new questions have arisen. In this paper, we review some of the genetic attributes of polyploids that have been suggested to account for the tremendous success of polyploid plants. Based on a limited number of studies, we conclude: (i) Polyploids, both individuals and populations, generally maintain higher levels of heterozygosity than do their diploid progenitors. (ii) Polyploids exhibit less inbreeding depression than do their diploid parents and can therefore tolerate higher levels of selfing; polyploid ferns indeed have higher levels of selfing than do their diploid parents, but polyploid angiosperms do not differ in outcrossing rates from their diploid parents. (iii) Most polyploid species are polyphyletic, having formed recurrently from genetically different diploid parents. This mode of formation incorporates genetic diversity from multiple progenitor populations into the polyploid "species"; thus, genetic diversity in polyploid species is much higher than expected by models of polyploid formation involving a single origin. (iv) Genome rearrangement may be a common attribute of polyploids, based on evidence from genome in situ hybridization (GISH), restriction fragment length polymorphism (RFLP) analysis, and chromosome mapping. (v) Several groups of plants may be ancient polyploids, with large regions of homologous DNA. These duplicated genes and genomes can undergo divergent evolution and evolve new functions. These genetic and genomic attributes of polyploids may have both biochemical and ecological benefits that contribute to the success of polyploids in nature.
[本文引用: 1]
URLPMID:4242248 [本文引用: 1]
Tolerance to high soil [Na62] involves processes in many different parts of the plant, and is manifested in a wide range of specializations at disparate levels of organization, such as gross morphology, membrane transport, biochemistry and gene transcription. Multiple adaptations to high [Na62] operate concurrently within a particular plant, and mechanisms of tolerance show large taxonomic variation. These mechanisms can occur in all cells within the plant, or can occur in specific cell types, reflecting adaptations at two major levels of organization: those that confer tolerance to individual cells, and those that contribute to tolerance not of cells per se, but of the whole plant. Salt-tolerant cells can contribute to salt tolerance of plants; but we suggest that equally important in a wide range of conditions are processes involving the management of Na62 movements within the plant. These require specific cell types in specific locations within the plant catalysing transport in a coordinated manner. For further understanding of whole plant tolerance, we require more knowledge of cell-specific transport processes and the consequences of manipulation of transporters and signalling elements in specific cell types.
URL [本文引用: 1]
The investigation was carried out to understand the salt tolerance mechanism of the halophytic tetraploid wild grass, Porteresia coarctata (Dhani grass: Syn. Oryza coarctata) compared with barley (Hordeum vulgare) and some salt sensitive and relatively salt tolerant rice (Oryza sativa L.) strains based on some physiological and biochemical parameters. K+ and Na+ accumulation in shoots of the ex...
[本文引用: 2]
URL [本文引用: 4]
Polyploidy is pursued in plant breeding programs due mainly to its ability to yield larger vegetative or reproductive organs. In controlled growth chamber experiments, a tetraploid turnip (cv. Aijiaohuang, 4n) and its diploid progenitor (cv. Aijiaohuang, 2n) were evaluated for their tolerance to salinity stress via investigations on a group of physiological parameters. The results indicate that the tetraploid turnip exhibit better adaptation to a high concentration salt medium (200 mmol L-1), as evidenced by a less-affected germination rate and a healthier morphological appearance at the seedling stage. Furthermore, an extension of salinity stress up to a certain period of time at the 5-7-leaf stage shows differences between the tetraploid turnip and its diploid progenitor. The former had a higher K+/Na+ ratio in the roots, higher glutathione concentration and antioxidant activities in the leaves, and smaller reductions in photosynthetic capacity in terms of leaf chlorophyll content. Studies on the differences between an autopolyploid and its respective relative, from which the autopolyploid originated, in terms of their tolerance to salinity and/or other abiotic stresses, have remained rather limited. The comparison is interesting due to a homogenous genetic background.
URL [本文引用: 2]
以黄枚西瓜同源二倍体(2x)、三倍体(3x)、四倍体(4x)为材料,分别用100、200、300、400mmol/L NaCl处理西瓜幼苗,鉴定不同浓度NaCl对不同倍性西瓜幼苗的伤害程度,采用微波消解-火焰原子吸收分光光度法测定NaCl胁迫8d后不同倍性西瓜幼苗叶片中的Na+、K+和Ca2+质量分数。结果表明,NaCl胁迫8d以后,随着NaCl浓度的增加,西瓜幼苗受害程度也随着加深,相同NaCl浓度下,不同倍性西瓜幼苗受伤害程度为2x3x4x;4x幼苗叶片中的Na+质量分数高于2x和3x。高NaCl浓度下,西瓜幼苗叶片内的K+质量分数为4x2x3x,Ca2+的质量分数为4x2x。NaCl胁迫后,耐NaCl胁迫能力表现为多倍体强于2x,4x的西瓜幼苗相对于2x具有较高的Na+、K+和Ca2+质量分数,与其表现的受伤害程度一致,3x的西瓜幼苗的受伤害程度与K+质量分数相关性最大,耐NaCl胁迫能力介于4x和2x间。2x的西瓜幼苗叶片受伤害程度与Na+、K+和Ca2+质量分数及K+/Na+比值、Na+/Ca2+比值的相关性较多倍体低。
URL [本文引用: 2]
以黄枚西瓜同源二倍体(2x)、三倍体(3x)、四倍体(4x)为材料,分别用100、200、300、400mmol/L NaCl处理西瓜幼苗,鉴定不同浓度NaCl对不同倍性西瓜幼苗的伤害程度,采用微波消解-火焰原子吸收分光光度法测定NaCl胁迫8d后不同倍性西瓜幼苗叶片中的Na+、K+和Ca2+质量分数。结果表明,NaCl胁迫8d以后,随着NaCl浓度的增加,西瓜幼苗受害程度也随着加深,相同NaCl浓度下,不同倍性西瓜幼苗受伤害程度为2x3x4x;4x幼苗叶片中的Na+质量分数高于2x和3x。高NaCl浓度下,西瓜幼苗叶片内的K+质量分数为4x2x3x,Ca2+的质量分数为4x2x。NaCl胁迫后,耐NaCl胁迫能力表现为多倍体强于2x,4x的西瓜幼苗相对于2x具有较高的Na+、K+和Ca2+质量分数,与其表现的受伤害程度一致,3x的西瓜幼苗的受伤害程度与K+质量分数相关性最大,耐NaCl胁迫能力介于4x和2x间。2x的西瓜幼苗叶片受伤害程度与Na+、K+和Ca2+质量分数及K+/Na+比值、Na+/Ca2+比值的相关性较多倍体低。
URLPMID:15852348 [本文引用: 1]
Polyploidization is a major evolutionary process in eukaryotes. In plants, genetic and epigenetic changes occur rapidly after formation of allopolyploids. Hybridization, rather than genome doubling itself, is considered as the main cause for the resulting differential gene expression. We studied the consequences of genome doubling alone in an autopolyploid model, by comparing two-dimensional gel electrophoresis (2-DE) gels of haploid, diploid, and tetraploid Brassica oleracea cabbages. Two fully homozygous lines, HDEM and RC, as well as two organs, leaf and stem, were studied. For the 558 common spots found present in all the 29 2-DE gels of the experiment, inter-organ and -genotype differences were the major sources of the variation in protein amounts: 41 and 10-13%, respectively. HDEM leaf and stem proteomes were not significantly affected by the ploidy level, since no qualitative variation was detected and since the number of quantitative variations could be due to chance. For RC, no qualitative variations were observed, but a few spots were significantly variable in protein amount. However, the number of inter-ploidy variations was of the same range as the number of intra-ploidy variations. In conclusion, whatever the ploidy level, leaf and stem proteomes remained globally unchanged in both cabbage lines.
[本文引用: 3]
URL [本文引用: 1]
Abstract This study compared the effects of chromium toxicity on the biomass, photosynthesis, antioxidants, reactive oxygen species, and nutrient concentration in Kinnow mandarin (Citrus nobilis Lour x Citrus deliciosa Ten) plants grafted on diploids (2x) and tetraploids (4x) of Poncirus trifoliata [L.], Citrus reshni, and Citrus limonia Osbeck. Plants were grown under controlled conditions and irrigated with complete nutrient solution supplemented with chromium (0.75 mM). After 120-d of growth under chromium stress, plant biomass, total chlorophyll concentrations, photosynthetic activity, stomatal conductance, transpiration rate, water use efficiency, H2O2 concentrations, rate of O2鈦 generation, lipid peroxidation, antioxidant activities (superoxide dismutase, peroxidase, catalase) and mineral nutrient concentration (Ca, Mg, K, P and Cr) were determined. Chromium inhibited plant growth, and decreased chlorophyll concentration, photosynthetic activity, stomatal conductance, transpiration rate, water use efficiency, and activities of antioxidant enzymes, but the rate of lipid peroxidation and formation of reactive oxygen species were increased. Chromium stress also caused alterations in nutrients concentration in roots and leaves. Nevertheless, it was observed that Kinnow mandarin plants grafted on the tetraploid rootstocks showed high tolerance to chromium toxicity as reported by maintaining greater biomass accumulation and less reduction in the attributes commented before. In addition, plants with 4 x rootstocks had higher Ca, Mg, K and P concentration in their roots and leaves in comparison to 2 x rootstocks. Plants grafted on 4 x rootstock presented higher quantity of chromium in roots than leaves, suggesting that the chromium tolerance of plants with tetraploid rootstocks may be attributed to chromium sequestration to roots with lower transfer to leaves; consequently avoiding oxidative damage to green pigments and the photosynthetic apparatus.
URLMagsci [本文引用: 1]
以含有200 mmol ? L-1 NaCl的1/2 Hoagland营养液处理‘寒富’二倍体苹果及其同源四倍体幼苗8 d，分别在处理0、2、4、6和8 d时进行叶片相关生理指标及水通道蛋白相关基因表达水平的测定，比较分析两者的耐盐性差异。结果表明：盐胁迫下四倍体的形态表现优于二倍体；四倍体和二倍体的叶片相对含水量一直在下降，二倍体下降幅度大于四倍体，丙二醛含量和脯氨酸的积累随胁迫时间的延长而增加，二倍体含量始终高于四倍体；NaCl处理8 d时，二倍体的叶片相对含水量比四倍体低8%，丙二醛含量比四倍体多4.466 nmol ? g-1FW，脯氨酸含量为四倍体的1.18倍；盐胁迫下两者叶片中水通道相关蛋白基因MdPIP1;1、MdPIP2;1、MdTIP1;1和MdTIP2;1的表达量均出现先下降后上升趋势，且四倍体均高于二倍体，尤其在处理24 h时差异最显著。四倍体比二倍体具有更强的耐盐性，可能与盐胁迫下四倍体相关水通道蛋白基因表达水平较高有关。
URLMagsci [本文引用: 1]
以含有200 mmol ? L-1 NaCl的1/2 Hoagland营养液处理‘寒富’二倍体苹果及其同源四倍体幼苗8 d，分别在处理0、2、4、6和8 d时进行叶片相关生理指标及水通道蛋白相关基因表达水平的测定，比较分析两者的耐盐性差异。结果表明：盐胁迫下四倍体的形态表现优于二倍体；四倍体和二倍体的叶片相对含水量一直在下降，二倍体下降幅度大于四倍体，丙二醛含量和脯氨酸的积累随胁迫时间的延长而增加，二倍体含量始终高于四倍体；NaCl处理8 d时，二倍体的叶片相对含水量比四倍体低8%，丙二醛含量比四倍体多4.466 nmol ? g-1FW，脯氨酸含量为四倍体的1.18倍；盐胁迫下两者叶片中水通道相关蛋白基因MdPIP1;1、MdPIP2;1、MdTIP1;1和MdTIP2;1的表达量均出现先下降后上升趋势，且四倍体均高于二倍体，尤其在处理24 h时差异最显著。四倍体比二倍体具有更强的耐盐性，可能与盐胁迫下四倍体相关水通道蛋白基因表达水平较高有关。
URLPMID:24129170 [本文引用: 5]
Tetraploid black locust (Robinia pseudoacacia L.) is adaptable to salt stress. Here, we compared morphological, physiological, ultrastructural, and proteomic traits of leaves in tetraploid black locust and its diploid relatives under salt stress. The results showed that diploid (2×) plants suffered from greater negative effects than those of tetraploid (4×) plants. After salt treatment, plant growth was inhibited, photosynthesis was reduced, reactive oxygen species, malondialdehyde content, and relative electrolyte leakage increased, and defense-related enzyme activities decreased in 2× compared to those in 4×. In addition, salt stress resulted in distorted chloroplasts, swollen thylakoid membranes, accumulation of plastoglobules, and increased starch grains in 2× compared to those in 4×. However, 4× developed diverse responses under salt stress. A comparative proteomic analysis revealed that 41 and 37 proteins were differentially expressed in 2× and 4×, respectively. These proteins were mainly involved in photosynthesis, stress and defense, energy, metabolism, transcription/translation, and transportation. Distinct patterns of protein changes between 2× and 4× were analyzed. Collectively, our results suggest that the plants showed significantly different responses to salt stress based on ploidy level of the plant. The 4× possessed a better salt protection mechanism than that of 2×, suggesting salt tolerance in the polyploid plant.
URLPMID:26894691 [本文引用: 1]
Abstract Salt stress is a global environmental problem that affects plant growth and development. Paulownia fortunei is an adaptable and fast-growing deciduous tree native to China that is environmentally and economically important. MicroRNAs (miRNAs) play important regulatory roles in growth, development, and stress responses in plants. MiRNAs that respond to biotic stresses have been identified; however, how miRNAs in P. fortunei respond to salt stress has not yet been reported. To identify salt-stress-responsive miRNAs and predict their target genes, four small RNA and four degradome libraries were constructed from NaCl-treated and NaCl-free leaves of P. fortunei seedlings. The results indicated that salt stress had different physiological effects on diploid and tetraploid P. fortunei. We detected 53 conserved miRNAs belonging to 17 miRNA families and 134 novel miRNAs in P. fortunei. Comparing their expression levels in diploid and tetraploid P. fortunei, we found 10 conserved and 10 novel miRNAs that were significantly differentially expressed under salt treatment, among them eight were identified as miRNAs probably associated with higher salt tolerance in tetraploid P. fortunei than in diploid P. fortunei. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathway analyses were performed to predict the functions of the target genes of the conserved and novel miRNAs. The expressions of 10 differentially expressed miRNAs were validated by quantitative real-time polymerase chain reaction (qRT-PCR). This is the first report on P. fortunei miRNAs and their target genes under salt stress. The results provided information at the physiological and molecular levels for further research into the response mechanisms of P. fortunei to salt stress.
URLPMID:16506063 [本文引用: 1]
Abstract Pot-culture experiments were carried out to estimate the role of non-hydraulic root signals (nHRS) and the relation of these signals to drought tolerance and grain yield formation under drought stress in six wheat varieties. These were two modern hexaploid wheat (Triticum aestivum L., AABBDD) Plateau602 and Longchun8139-2, two diploid wheat (Triticum monococcum L., AB) MO1 and MO4, and two tetraploid wheat (Triticum dicoccum Schuebl L., AABB) DM22 and DM31. In the two diploid relatives, the nHRS was switched on and off at a soil water content (SWC) of approximately 53-45% field water capacity (FWC). In contrast, in the modern hexaploid varieties, Longchun8139-2 and Plateau602 the nHRS occurred between a SWC of about 71 and 35% FWC, a much wider soil moisture range. The two tetraploid relatives, DM22 and DM31, were generally intermediate. The nHRS threshold range in SWC also narrowed as all six varieties went through successive developmental stages from shooting to grain filling. The two hexaploid wheat varieties had the longest duration of survival after the water supply ceased, and the best yield stability under drought stress, similar to with tetraploid wheat varieties; the diploid wheat varieties were least robust. These two parameters were both significantly correlated with the nHRS soil moisture threshold range (r=0.9456** and 0.8608*, respectively). Based on these patterns, we propose a "triple Z" model to describe the features of non-hydraulic stomatal sensitivity versus soil drought in wheat growth.
URL [本文引用: 1]
扫描电镜观察结果表明,随着西 瓜倍性的增加,叶片保卫细胞和表皮细胞增大,叶片单位面积上的气孔和表皮细胞的数目减少,细胞的大小与西瓜倍性呈正相关,单位面积上的细胞数目与西瓜倍性 呈负相关。通过FDA荧光记数法观察,4x、3x和2x的叶片保卫细胞中的叶绿体数目分别为19.9±3.4,15.9±2.2,11.5±1.5,其比 例约为4∶3∶2,与西瓜的倍性一致。根据此方法可以快速有效地对西瓜倍性进行早期鉴定。
URL [本文引用: 1]
扫描电镜观察结果表明,随着西 瓜倍性的增加,叶片保卫细胞和表皮细胞增大,叶片单位面积上的气孔和表皮细胞的数目减少,细胞的大小与西瓜倍性呈正相关,单位面积上的细胞数目与西瓜倍性 呈负相关。通过FDA荧光记数法观察,4x、3x和2x的叶片保卫细胞中的叶绿体数目分别为19.9±3.4,15.9±2.2,11.5±1.5,其比 例约为4∶3∶2,与西瓜的倍性一致。根据此方法可以快速有效地对西瓜倍性进行早期鉴定。
URL [本文引用: 1]
四倍体西瓜作为三倍体无籽西瓜的母本,其性状对三倍体西瓜组合选配起着重要作用,其中四倍体西瓜种子性状对三倍体西瓜品种的种子发芽率、成苗率、采种量起关键作用。为研究四倍体西瓜种子的性状变异,以41组秋水仙素诱导的T6同源四倍体西瓜为试验材料,以其诱导前的同源二倍体为对照,比较加倍后四倍体西瓜种子发芽率、单瓜种子数、百粒重和形态结构变异。结果表明,秋水仙素诱导加倍后,四倍体种子发芽率、单瓜种子数均低于其同源二倍体,但种子长度、宽度、厚度、喙宽、种皮厚度和百粒重均大于其二倍体。四倍体西瓜的单瓜种子数与其二倍体西瓜的种子数极显著相关,二倍体和四倍体西瓜的百粒重与其本身的长度和宽度极显著相关,四倍体西瓜种子种皮厚度与多个性状都显著相关,但四倍体种子的发芽率除与其种子的喙宽显著相关外,与其他性状都无显著相关性。本研究通过比较人工诱导的同源四倍体与其原始二倍体西瓜种子的差异,为诱导四倍体的选择及多倍体西瓜育种提供了一定的理论依据。
URL [本文引用: 1]
四倍体西瓜作为三倍体无籽西瓜的母本,其性状对三倍体西瓜组合选配起着重要作用,其中四倍体西瓜种子性状对三倍体西瓜品种的种子发芽率、成苗率、采种量起关键作用。为研究四倍体西瓜种子的性状变异,以41组秋水仙素诱导的T6同源四倍体西瓜为试验材料,以其诱导前的同源二倍体为对照,比较加倍后四倍体西瓜种子发芽率、单瓜种子数、百粒重和形态结构变异。结果表明,秋水仙素诱导加倍后,四倍体种子发芽率、单瓜种子数均低于其同源二倍体,但种子长度、宽度、厚度、喙宽、种皮厚度和百粒重均大于其二倍体。四倍体西瓜的单瓜种子数与其二倍体西瓜的种子数极显著相关,二倍体和四倍体西瓜的百粒重与其本身的长度和宽度极显著相关,四倍体西瓜种子种皮厚度与多个性状都显著相关,但四倍体种子的发芽率除与其种子的喙宽显著相关外,与其他性状都无显著相关性。本研究通过比较人工诱导的同源四倍体与其原始二倍体西瓜种子的差异,为诱导四倍体的选择及多倍体西瓜育种提供了一定的理论依据。
URLPMID:4018534 [本文引用: 3]
Genome duplication (or polyploidization) has occurred throughout plant evolutionary history and is thought to have driven the adaptive radiation of plants. We found that the cytotype of the root, and not the genotype, determined the majority of heritable natural variation in leaf potassium (K) concentration in Arabidopsis thaliana. Autopolyploidy also provided resistance to salinity and may represent an adaptive outcome of the enhanced K accumulation of plants with higher ploidy.
URL [本文引用: 1]
With the enrichment of metabolomic information in a diverse number of plants, the obtained datasets reflect on important aspects of...
URLPMID:5568289 [本文引用: 1]
Polyploidy is an important phenomenon in plants because of its roles in agricultural and forestry production as well as in plant tolerance to environmental stresses. Tetraploid black locust (Robinia pseudoacacia L.) is a polyploid plant and a pioneer tree species due to its wide ranging adaptability to adverse environments. To evaluate the ploidy-dependent differences in leaf mitochondria between diploid and tetraploid black locust under salinity stress, we conducted comparative proteomic, physiological, biochemical and ultrastructural profiling of mitochondria from leaves. Mitochondrial proteomic analysis was performed with 2-DE and MALDI-TOF-MS, and the ultrastructure of leaf mitochondria was observed by transmission electron microscopy. According to 2-DE analysis, 66 proteins that responded to salinity stress significantly were identified from diploid and/or tetraploid plants and classified into 9 functional categories. Assays of physiological characters indicated that tetraploids were more tolerant to salinity stress than diploids. The mitochondrial ultrastructure of diploids was damaged more severely under salinity stress than that of tetraploids. Tetraploid black locust possessed more tolerance of, and ability to acclimate to, salinity stress than diploids, which may be attributable to the ability to maintain mitochondrial structure and to trigger different expression patterns of mitochondrial proteins during salinity stress. The online version of this article (doi:10.1186/s12864-017-4038-2) contains supplementary material, which is available to authorized users.
URLPMID:79 [本文引用: 2]
All crop species are current or ancient polyploids. Following whole genome duplication, structural and functional modifications result in differential gene content or regulation in the duplicated regions, which can play a fundamental role in the diversification of genes underlying complex traits. We have investigated this issue in Brassica napus, a species with a highly duplicated genome, with the aim of studying the structural and functional organization of duplicated regions involved in quantitative resistance to stem canker, a disease caused by the fungal pathogen Leptosphaeria maculans. Genome-wide association analysis on two oilseed rape panels confirmed that duplicated regions of ancestral blocks E, J, R, U, and W were involved in resistance to stem canker. The structural analysis of the duplicated genomic regions showed a higher gene density on the A genome than on the C genome and a better collinearity between homoeologous regions than paralogous regions, as overall in the whole B. napus genome. The three ancestral sub-genomes were involved in the resistance to stem canker and the fractionation profile of the duplicated regions corresponded to what was expected from results on the B. napus progenitors. About 60% of the genes identified in these duplicated regions were single-copy genes while less than 5% were retained in all the duplicated copies of a given ancestral block. Genes retained in several copies were mainly involved in response to stress, signaling, or transcription regulation. Genes with resistance-associated markers were mainly retained in more than two copies. These results suggested that some genes underlying quantitative resistance to stem canker might be duplicated genes. Genes with a hydrolase activity that were retained in one copy or R-like genes might also account for resistance in some regions. Further analyses need to be conducted to indicate to what extent duplicated genes contribute to the expression of the resistance phenotype.
URL [本文引用: 1]
通过对蜜枚和JM的不同倍性西瓜品种的幼苗进行4 d、10℃的预冷处理,然后在5℃下低温胁迫8 d,结果表明:JM4x和M3x的耐低温能力得到提高,超过2x.冷锻炼诱导多倍体西瓜SOD、POD活性大幅度提高,降低四倍体MDA的含量,增强四倍 体西瓜的耐低温胁迫能力.
URL [本文引用: 1]
通过对蜜枚和JM的不同倍性西瓜品种的幼苗进行4 d、10℃的预冷处理,然后在5℃下低温胁迫8 d,结果表明:JM4x和M3x的耐低温能力得到提高,超过2x.冷锻炼诱导多倍体西瓜SOD、POD活性大幅度提高,降低四倍体MDA的含量,增强四倍 体西瓜的耐低温胁迫能力.
URLPMID:19325131 [本文引用: 1]
Abstract Most flowering plants have been shown to be ancient polyploids that have undergone one or more whole genome duplications early in their evolution. Furthermore, many different plant lineages seem to have experienced an additional, more recent genome duplication. Starting from paralogous genes lying in duplicated segments or identified in large expressed sequence tag collections, we dated these youngest duplication events through penalized likelihood phylogenetic tree inference. We show that a majority of these independent genome duplications are clustered in time and seem to coincide with the Cretaceous-Tertiary (KT) boundary. The KT extinction event is the most recent mass extinction caused by one or more catastrophic events such as a massive asteroid impact and/or increased volcanic activity. These events are believed to have generated global wildfires and dust clouds that cut off sunlight during long periods of time resulting in the extinction of approximately 60% of plant species, as well as a majority of animals, including dinosaurs. Recent studies suggest that polyploid species can have a higher adaptability and increased tolerance to different environmental conditions. We propose that polyploidization may have contributed to the survival and propagation of several plant lineages during or following the KT extinction event. Due to advantages such as altered gene expression leading to hybrid vigor and an increased set of genes and alleles available for selection, polyploid plants might have been better able to adapt to the drastically changed environment 65 million years ago.
URLPMID:10860969 [本文引用: 1]
Invasive species are of great interest to evolutionary biologists and ecologists because they represent historical examples of dramatic evolutionary and ecological change. Likewise, they are increasingly important economically and environmentally as pests. Obtaining generalizations about the tiny fraction of immigrant taxa that become successful invaders has been frustrated by two enigmatic phenomena. Many of those species that become successful only do so (i) after an unusually long lag time after initial arrival, and/or (ii) after multiple introductions. We propose an evolutionary mechanism that may account for these observations. Hybridization between species or between disparate source populations may serve as a stimulus for the evolution of invasiveness. We present and review a remarkable number of cases in which hybridization preceded the emergence of successful invasive populations. Progeny with a history of hybridization may enjoy one or more potential genetic benefits relative to their progenitors. The observed lag times and multiple introductions that seem a prerequisite for certain species to evolve invasiveness may be a correlate of the time necessary for previously isolated populations to come into contact and for hybridization to occur. Our examples demonstrate that invasiveness can evolve. Our model does not represent the only evolutionary pathway to invasiveness, but is clearly an underappreciated mechanism worthy of more consideration in explaining the evolution of invasiveness in plants.
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URLMagsci [本文引用: 1]
以4种不同基因型冬小麦为试验材料,利用分根法研究了盐胁迫对小麦的渗透胁迫和离子毒害的效应。结果表明,在盐胁迫下,小麦既受渗透胁迫,也受盐离子胁迫。渗透胁迫效应比较快,大约在处理后1-2d内发生;离子毒害效应比较缓慢,大约需3-4d时间。在一半盐胁迫(200mmol/L NaCl)和一半非盐胁迫的分根条件下,小麦没有明显的渗透胁迫效应,小麦植株地上部Na<sup>+ </sup>累积到毒性水平之前盐处理对小麦生长无抑制效应。小麦具有将Na<sup>+ </sup>从盐胁迫一侧转移非盐一侧的能力,说明小麦吸收的Na<sup>+ </sup>有一部分可以从地上部回流到根系中,回流率可达76%-89%。无水分胁迫(不加入PEG)的回流率大于水分胁迫(加入PEG)的回流率。不同基因型小麦在盐分吸收累积和回流,及渗透和离子胁迫的速度和程度等方面具有明显差异。NR 9405和小偃6号的Na<sup>+ </sup>累积速度要少于陕229和RB 6;NR 9405根系排Na<sup>+ </sup>能力强于陕229和RB 6。因此,NR 9405和小偃6号的耐盐性高于陕229和RB 6。
URLMagsci [本文引用: 1]
以4种不同基因型冬小麦为试验材料,利用分根法研究了盐胁迫对小麦的渗透胁迫和离子毒害的效应。结果表明,在盐胁迫下,小麦既受渗透胁迫,也受盐离子胁迫。渗透胁迫效应比较快,大约在处理后1-2d内发生;离子毒害效应比较缓慢,大约需3-4d时间。在一半盐胁迫(200mmol/L NaCl)和一半非盐胁迫的分根条件下,小麦没有明显的渗透胁迫效应,小麦植株地上部Na<sup>+ </sup>累积到毒性水平之前盐处理对小麦生长无抑制效应。小麦具有将Na<sup>+ </sup>从盐胁迫一侧转移非盐一侧的能力,说明小麦吸收的Na<sup>+ </sup>有一部分可以从地上部回流到根系中,回流率可达76%-89%。无水分胁迫(不加入PEG)的回流率大于水分胁迫(加入PEG)的回流率。不同基因型小麦在盐分吸收累积和回流,及渗透和离子胁迫的速度和程度等方面具有明显差异。NR 9405和小偃6号的Na<sup>+ </sup>累积速度要少于陕229和RB 6;NR 9405根系排Na<sup>+ </sup>能力强于陕229和RB 6。因此,NR 9405和小偃6号的耐盐性高于陕229和RB 6。
URL [本文引用: 1]
Salsola affinis is a dominant annual inhabiting saline deserts of Xinjiang, China. Experiments were conducted to determine the effects of temperature, winged perianths and NaCl on seed germination and on germination recovery from the effects of saline conditions after transfer to distilled water. Freshly harvested seeds could germinate equally well in light and darkness at 5-30 degrees C. Attached winged perianths significantly inhibited germination, removal enhanced germination. However, germination was not inhibited in the presence of detached winged perianths in any of the temperature treatments. We suggest that the winged perianth is a mechanical barrier for radicle emergence, not a barrier for water uptake; hence, it inhibited germination. Germination of seeds from which the perianth had been removed was not affected by NaCl at concentrations below 0.4 mol/l, but it was significantly decreased by NaCl at concentrations of 0.6-2.0 mol/l. No seeds germinated at 4.0 mol/l NaCl. Seeds incubated in NaCl at concentrations of 0.05-4.0 mol/l for 14 days recovered after being transferred to distilled water. However, germination was lower than that in the non-saline control, indicating that a portion of the NaCl-treated seeds may lose their ability to germinate. (C) 2008 Elsevier GmbH. All rights reserved.
URLMagsci [本文引用: 1]
用盐水浸种催芽方法，通过对蜜枚西瓜的二倍体、三倍体、四倍体在不同浓度NaCl胁迫下种子的发芽率、胚轴长度以及鲜重、发芽指数、活力指数等指标的测定，在30~90mmol/L低浓度下，倍性之间相对发芽率没有明显差异；在120 mmol/L以上浓度时，不同倍性之间差异明显，在150mmol/L NaCl胁迫下，其M4x、M3x、M2x相对发芽率分别为77.8%、63.4%、30.6%，180mmol/L时分别为37.8%、31.7%、0，在210mmol/L时，M4x和M3x仍然有种子萌发，耐盐性为M4x＞M3x＞M2x。
URLMagsci [本文引用: 1]
用盐水浸种催芽方法，通过对蜜枚西瓜的二倍体、三倍体、四倍体在不同浓度NaCl胁迫下种子的发芽率、胚轴长度以及鲜重、发芽指数、活力指数等指标的测定，在30~90mmol/L低浓度下，倍性之间相对发芽率没有明显差异；在120 mmol/L以上浓度时，不同倍性之间差异明显，在150mmol/L NaCl胁迫下，其M4x、M3x、M2x相对发芽率分别为77.8%、63.4%、30.6%，180mmol/L时分别为37.8%、31.7%、0，在210mmol/L时，M4x和M3x仍然有种子萌发，耐盐性为M4x＞M3x＞M2x。
URLPMID:2955754 [本文引用: 1]
Abstract Despite the fact that most plants accumulate both sodium (Na(+)) and chloride (Cl(-)) ions to high concentration in their shoot tissues when grown in saline soils, most research on salt tolerance in annual plants has focused on the toxic effects of Na(+) accumulation. There have also been some recent concerns about the ability of hydroponic systems to predict the responses of plants to salinity in soil. To address these two issues, an experiment was conducted to compare the responses to Na(+) and to Cl(-) separately in comparison with the response to NaCl in a soil-based system using two varieties of faba bean (Vicia faba), that differed in salinity tolerance. The variety Nura is a salt-sensitive variety that accumulates Na(+) and Cl(-) to high concentrations while the line 1487/7 is salt tolerant which accumulates lower concentrations of Na(+) and Cl(-). Soils were prepared which were treated with Na(+) or Cl(-) by using a combination of different Na(+) salts and Cl(-) salts, respectively, or with NaCl. While this method produced Na(+)-dominant and Cl(-)-dominant soils, it unavoidably led to changes in the availability of other anions and cations, but tissue analysis of the plants did not indicate any nutritional deficiencies or toxicities other than those targeted by the salt treatments. The growth, water use, ionic composition, photosynthesis, and chlorophyll fluorescence were measured. Both high Na(+) and high Cl(-) reduced growth of faba bean but plants were more sensitive to Cl(-) than to Na(+). The reductions in growth and photosynthesis were greater under NaCl stress and the effect was mainly additive. An important difference to previous hydroponic studies was that increasing the concentrations of NaCl in the soil increased the concentration of Cl(-) more than the concentration of Na(+). The data showed that salinity caused by high concentrations of NaCl can reduce growth by the accumulation of high concentrations of both Na(+) and Cl(-) simultaneously, but the effects of the two ions may differ. High Cl(-) concentration reduces the photosynthetic capacity and quantum yield due to chlorophyll degradation which may result from a structural impact of high Cl(-) concentration on PSII. High Na(+) interferes with K(+) and Ca(2+) nutrition and disturbs efficient stomatal regulation which results in a depression of photosynthesis and growth. These results suggest that the importance of Cl(-) toxicity as a cause of reductions in growth and yield under salinity stress may have been underestimated.
URLPMID:21361962 [本文引用: 1]
090004Polyploidy has occurred throughout plant evolution and can result in considerable changes to gene expression when it takes place and over evolutionary time. Little is known about the effects of abiotic stress conditions on duplicate gene expression patterns in polyploid plants.090004We examined the expression patterns of 60 duplicated genes in leaves, roots and cotyledons of allotetraploid Gossypium hirsutum in response to five abiotic stress treatments (heat, cold, drought, high salt and water submersion) using single-strand conformation polymorphism assays, and 20 genes in a synthetic allotetraploid.090004Over 70% of the genes showed stress-induced changes in the relative expression levels of the duplicates under one or more stress treatments with frequent variability among treatments. Twelve pairs showed opposite changes in expression levels in response to different abiotic stress treatments. Stress-induced expression changes occurred in the synthetic allopolyploid, but there was little correspondence in patterns between the natural and synthetic polyploids.090004Our results indicate that abiotic stress conditions can have considerable effects on duplicate gene expression in a polyploid, with the effects varying by gene, stress and organ type. Differential expression in response to environmental stresses may be a factor in the preservation of some duplicated genes in polyploids.
URLPMID:23608743 [本文引用: 1]
Abstract To understand the genotypic variation of citrus to mild salt stress, a proteomic approach has been carried out in parallel on two citrus genotypes ('Cleopatra' and 'Willow leaf' mandarins), which differ for Na(+) and Cl(-) accumulation, and their cognate autotetraploids (40103). Using two-dimensional electrophoresis approximately 910 protein spots were reproducibly detected in control and salt-stressed leaves of all genotypes. Among them, 44 protein spots showing significant variations at least in one genotype were subjected to mass spectrometry analysis for identification. Salt-responsive proteins were involved in several functions, including photosynthetic processes, ROS scavenging, stress defence, and signalling. Genotype factors affect the salt-responsive pattern, especially that of carbon metabolism. The no ion accumulator 'Cleopatra' mandarin genotype showed the highest number of salt-responsive proteins, and up-regulation of Calvin cycle-related proteins. Conversely the ion accumulator 'Willow leaf' mandarin showed high levels of several photorespiration-related enzymes. A common set of proteins (twelve spots) displayed higher levels in salt-stressed leaves of 20103 and 40103 'Cleopatra' and 40103 'Willow leaf' mandarin. Interestingly, antioxidant enzymes and heat shock proteins showed higher constitutive levels in 40103 'Cleopatra' mandarin and 40103 'Willow leaf' mandarin compared with the cognate 20103 genotype. This work provides for the first time information on the effect of 8 weeks of salt stress on citrus genotypes contrasting for ion accumulation and their cognate autotetraploids. Results underline that genetic factors have a predominant effect on the salt response, although a common stress response independent from genotype was also found. Copyright 0008 2013 Elsevier GmbH. All rights reserved.
URLPMID:12972044 [本文引用: 1]
Abstract When under salt stress, plants maintain a high concentration of K(+) and a low concentration of Na(+) in the cytosol. They do this by regulating the expression and activity of K(+) and Na(+) transporters and of H(+) pumps that generate the driving force for transport. Although salt-stress sensors remain elusive, some of the intermediary signaling components have been identified. Evidence suggests that a protein kinase complex consisting of the myristoylated calcium-binding protein SOS3 and the serine/threonine protein kinase SOS2 is activated by a salt-stress-elicited calcium signal. The protein kinase complex then phosphorylates and activates various ion transporters, such as the plasma membrane Na(+)/H(+) antiporter SOS1.
URLPMID:18722990 [本文引用: 1]
Les agrumes sont soumis à de nombreuses contraintes abiotiques telles que le stress salin. L'obtention de nouveaux porte-greffe plus tolérants est donc nécessaire. Dans cet article, nous avons comparé le comportement de tolérance au stress salin de trois porte-greffe tétraplo07des avec leurs diplo07des respectifs ( Poncirus trifoliata , citrange Carrizo, mandarinier Cléop09tre). La croissance des plantes, la chute des feuilles et le contenu en ions ont été étudiés. A la fin de l'expérimentation, une chute de feuilles a été observée uniquement pour les Poncirus trifoliata diplo07des, des sympt00mes de chloroses foliaires n'étant observés que pour les Poncirus trifoliata et Carrizo citrange diplo07des. La croissance des plants de mandariniers Cléop09tre diplo07des n'a pas été affectée par le stress et a même été augmentée pour les mandariniers Cléop09tre tétraplo07des. Les dosages ioniques ont montré que les porte-greffe tétraplo07des accumulaient moins des chlorures foliaires que les diplo07des. Nos résultats suggèrent que les porte-greffe d'agrumes tétraplo07des sont plus tolérants au stress salin que leurs diplo07des respectifs. Pour citer cet article : B. Saleh et al., C. R. Biologies 331 (2008).
URLPMID:15590011 [本文引用: 1]
Abstract Plants exposed to salt stress undergo changes in their environment. The ability of plants to tolerate salt is determined by multiple biochemical pathways that facilitate retention and/or acquisition of water, protect chloroplast functions, and maintain ion homeostasis. Essential pathways include those that lead to synthesis of osmotically active metabolites, specific proteins, and certain free radical scavenging enzymes that control ion and water flux and support scavenging of oxygen radicals or chaperones. The ability of plants to detoxify radicals under conditions of salt stress is probably the most critical requirement. Many salt-tolerant species accumulate methylated metabolites, which play crucial dual roles as osmoprotectants and as radical scavengers. Their synthesis is correlated with stress-induced enhancement of photorespiration. In this paper, plant responses to salinity stress are reviewed with emphasis on physiological, biochemical, and molecular mechanisms of salt tolerance. This review may help in interdisciplinary studies to assess the ecological significance of salt stress.
URL [本文引用: 2]
Methyl jasmonate (MeJA) is an essential and promising plant growth regulation factor that can improve plant development and growth. Here, we explored the mechanism by which MeJA regulates the tolerance of black locust (Robinia pseudoacacia L.) to salt stress. In this study, diploid and tetraploid R.pseudoacacia were subjected to three treatments: 50002mM NaCl; 10002μM MeJA; and 50002mM NaCl and 10002μM MeJA, and the changes in plant growth, endogenous MeJA levels and the anti-oxidative metabolism of leaves were investigated. The results showed that salt stress significantly inhibited plant growth and induced the accumulation of Na
URL [本文引用: 2]
Polyploidy was widely believed to facilitate increased plant adaptability to environmental extremes. Reports of the effect ofgenome duplication on rice development under salt stress are rare. In this study, tetraploid rice cultivars and the diploid ancestors were subjected to six levels of salinity, and the effects of genome duplication at seed germination and at the seedling growth stage were ...
URL [本文引用: 2]
Due to salt-sensitivity nature of citrus, it is imperative to provide rootstocks and cultivars that are tolerant to saline conditions. In this study, responses of tetraploid (4X) and its corresponding diploid (2X) Dez orange (Citrus sinensis (L.) Osb.) cultivar to different concentrations of NaCl (0, 20, 40 and 60 mM) were investigated using a randomized complete block design with four replicat...
URLMagsci [本文引用: 2]
以同基因型不同倍性（2x、3x、4x）的西瓜品种‘蜜枚’为材料，采用分光光度计法和酶联免疫法对西瓜果实发育过程中果肉番茄红素含量以及IAA、ABA、GA、ZR、BR等5种激素含量进行测定，以探究番茄红素积累与这5种激素之间的关系。结果显示：不同倍性的西瓜果实在授粉后25 ~ 30 d时都达到成熟果实的大小。不同倍性西瓜果实番茄红素含量在授粉后25 d时开始迅速增加，并且一直表现为三倍体 > 四倍体 > 二倍体；整个果实发育期，IAA的含量表现为多倍体大于二倍体，在授粉后15 d和25 d时，三倍体西瓜果实中IAA的含量远高于其它倍性；ABA的含量没有明显的规律，不同发育时期各个倍性中ABA的含量差异各不相同；不同倍性西瓜果实中GA的含量整体上表现为逐渐降低的趋势，均为发育前期最大；不同倍性西瓜果实中ZR的含量差异不明显，在授粉后25 d时有一个较小的峰值；不同倍性西瓜果实中BR的含量相对较少，整个发育时期都维持在5 ~ 15 ng ? g-1FW。不同倍性西瓜果实中番茄红素和GA的积累均呈负相关，其它激素和番茄红素的积累均无相关性。
URLMagsci [本文引用: 2]
以同基因型不同倍性（2x、3x、4x）的西瓜品种‘蜜枚’为材料，采用分光光度计法和酶联免疫法对西瓜果实发育过程中果肉番茄红素含量以及IAA、ABA、GA、ZR、BR等5种激素含量进行测定，以探究番茄红素积累与这5种激素之间的关系。结果显示：不同倍性的西瓜果实在授粉后25 ~ 30 d时都达到成熟果实的大小。不同倍性西瓜果实番茄红素含量在授粉后25 d时开始迅速增加，并且一直表现为三倍体 > 四倍体 > 二倍体；整个果实发育期，IAA的含量表现为多倍体大于二倍体，在授粉后15 d和25 d时，三倍体西瓜果实中IAA的含量远高于其它倍性；ABA的含量没有明显的规律，不同发育时期各个倍性中ABA的含量差异各不相同；不同倍性西瓜果实中GA的含量整体上表现为逐渐降低的趋势，均为发育前期最大；不同倍性西瓜果实中ZR的含量差异不明显，在授粉后25 d时有一个较小的峰值；不同倍性西瓜果实中BR的含量相对较少，整个发育时期都维持在5 ~ 15 ng ? g-1FW。不同倍性西瓜果实中番茄红素和GA的积累均呈负相关，其它激素和番茄红素的积累均无相关性。
URLPMID:23050986 [本文引用: 1]
ABSTRACT Whole-genome duplication, or polyploidy, is common in many plant species and often leads to better adaptation to adverse environmental condition. However, little is known about the physiological and molecular determinants underlying adaptation. We examined the drought tolerance in diploid (2x) and autotetraploid (4x) clones of Rangpur lime ( Citrus limonia ) rootstocks grafted with 2x Valencia Delta sweet orange ( Citrus sinensis ) scions, named V/2xRL and V/4xRL, respectively. Physiological experiments to study root鈥搒hoot communication associated with gene expression studies in roots and leaves were performed. V/4xRL was much more tolerant to water deficit than V/2xRL. Gene expression analysis in leaves and roots showed that more genes related to the response to water stress were differentially expressed in V/2xRL than in V/4xRL. Prior to the stress, when comparing V/4xRL to V/2xRL, V/4xRL leaves had lower stomatal conductance and greater abscisic acid (ABA) content. In roots, ABA content was higher in V/4xRL and was associated to a greater expression of drought responsive genes, including CsNCED1 , a pivotal regulatory gene of ABA biosynthesis. We conclude that tetraploidy modifies the expression of genes in Rangpur lime citrus roots to regulate long-distance ABA signalling and adaptation to stress.
[D].
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[D].
URL [本文引用: 1]
白菜型油菜(Brassica campestris L.)是油菜三大类型之一。中国又称小白菜、矮油菜、甜油菜等。白菜型油菜在既是油料作物,又是一种非常重要的蔬菜。“矮脚黄”白菜是长江流域的主栽品种,在浙江也有大面积种植。 多倍体与二倍体比拥有较大的营养器官和生殖器官,在生长过程中表现出一定的抗性优势,但以往的研究多集中在异源多倍体的抗性差异上,而对同源多倍体和二倍体的抗性差异研究甚少。本文采用同源四倍体“矮脚黄”白菜和二倍体“矮脚黄”白菜为材料,其中同源四倍体“矮脚黄”白菜是由二倍体“矮脚黄”白菜直接加倍而来。文章从生理生化、表观遗传、分子表达三个角度研究了二者在盐和镉逆境条件下的逆境差异机理,得到的主要结果如下： 1)同源四倍体在高盐胁迫下具有较快的发芽速度,较多的健康植株数；低浓度盐能够有效的刺激四倍体茎和根的生长。发芽7天后,四倍体和二倍体植株体内的钾钠钙离子在不同组织中的分布存在差异明显。四倍体在高盐浓度中具有一定的抗性优势,而Na+/Ca2+可以作为筛选白菜抗性品种的一个重要指标。 2)在5-7叶期间,四倍体叶绿素含量受到盐害的影响较二倍体小,四倍体体内的抗氧化还原剂GSH较二倍体含量高,四倍体白菜和二倍体白菜在盐胁迫下用不同的活性氧清除体系,四倍体的抗氧化酶体系更加稳定。盐处理后期,钾钠钙离子在地上组织和地下组织中的分布差异明显,二倍体的地上组织能够吸收更多的钠离子,四倍体能够在一定程度上阻止钠离子向地上部分运输；四倍体的地下组织吸收更高的钠离子含量以及保持高水平的钾离子水平。四倍体在根部能通过保持较高的K+／Na+比值,使其具有一定的抗盐优势。随着处理时间的增加,二倍体和四倍体的Na+/Ca2+比值差异越大,这些实验说明四倍体可以通过保持较低的Na+/Ca2+比值来缓解盐害。 3)发芽7天后发现在高浓度的镉处理中,四倍体在发芽率、根茎长以及健康植株数目指标上比二倍体具有明显的优势。随着处理浓度的增加,二倍体各组织中镉的含量逐渐增加。四倍体在高浓度的处理下发芽期可以通过限制镉的摄入来降低根部的镉浓度。 4)随着镉处理浓度和时间的增加,四倍体叶绿素和GSH含量比二倍体高,叶片内的MDA积累量要比二倍体低。四倍体白菜和二倍体白菜在镉胁迫下,抗氧化酶变化趋势存在着差异,四倍体的抗氧化酶的活性在镉环境中的缓冲力要强于二倍体。说明了四倍体在镉胁迫下其体内的活性氧、过氧化氢可以通过高含量的GSH以及稳定的抗氧化酶体系得到及时的清除,使得四倍体在镉胁迫下有一定的生长优势。镉进入四倍体根部后,有一部分运输至地上组织(叶片),减轻了镉对四倍体根部的毒害。 5)用MSAP分析四倍体和二倍体的逆境抗性的差异,56对引物共得到14382条扩增带,总甲基化条带共2924条。二倍体和四倍体在盐胁迫中,其总体甲基化水平都呈下降趋势。在镉胁迫环境中,两者的总体甲基化有上升的趋势。二倍体的甲基化水平下降了1.5个百分点,而四倍体下降了2.5个百分点,四倍体甲基化程度下降得更快；在镉处理中,二倍体的甲基化水平上升了2.7个百分点,四倍体上升了3.5个百分点,四倍体镉甲基化水平上升的程度更高。 6)二倍体和四倍体经过逆境条件下,其MSAP的甲基化模式发生了改变,四倍体在盐胁迫下与二倍体在盐胁迫下,有35%的甲基化模式发生了去甲基化(B类型)过程,20.0%发生过甲基化(C类型)转变；四倍体在镉胁迫下与二倍体在镉胁迫下,有24.8%的甲基化模式发生了去甲基化(B类型)过程,25.8%发生过甲基化(C类型)转变。盐胁迫下,四倍体发生去甲基化的位点数比二倍体多,而发生过甲基化位点数相差不大,暗示了去甲基化位点在四倍体白菜和二倍体白菜盐胁迫差异中启着重要的作用；镉胁迫下,四倍体发生过甲基化的位点数比二倍体多,而发生去甲基化位点数相差不大,说明了过甲基化位点在四倍体白菜和二倍体白菜的镉胁迫差异中启着关键性作用。 7) cDNA-AFLP实验结果表明与二倍体和四倍体各自在对照条件下相比,二者在盐和镉胁迫条件下的差异有扩大的趋势。在盐胁迫的差异片段中,二倍体基因表达被抑制的有14条(0.52%),四倍体基因表达被抑制的7条(0.26%);四倍体基因表达被诱导的差异基因有10条(0.37%),而二倍体被诱导的差异基因有5条(0.19%)。在镉胁迫的差异片断中,二倍体基因表达被抑制的有7条(0.26%),四倍体基因表达被抑制的为16条(0.60%)；四倍体基因表达被诱导的有5条(0.19%),二倍体基因表达被诱导的有12条(0.45%)。四倍体和二倍体在不同的逆境环境中基因表达的模式有很大的差异,在盐胁迫中,差异片段在二倍体中大部分被抑制,在四倍体中大部分被诱导；镉胁迫下,二倍体中大部分的基因表达差异体现为被诱导,而在四倍体中大部分的基因表达差异体现为被抑制。 8)对盐和镉的不同胁迫下,对二倍体和四倍体中的差异片段进行测序发现,盐胁迫导致的18条TDFs中有16条(88.9%)在现有数据库已有基因的功能(或者推测功能)的描述,两条TDFs中有1条其功能未知,另外一条和现有数据库中基因无任何同源性。16个TDFs按照功能可以分为三类：细胞代谢类、胁迫响应类、转录因子类。盐胁迫中的差异片段功能大部分参与了ABA信号合成及传递、过氧化物酶合成、醛脱氢酶合成、甜菜合成键酶的过程。在镉胁迫差异片段中,20条TDFs中有15条(75%)在现有数据库已有基因的功能(或者推测功能)的描述,有5条功能不明确,其中3条与数据库中的基因具有一定程度的同源性,另外2条在数据库找不到同源基因。在镉胁迫实验中,二倍体和四倍体有差异按照功能可以分为四类：细胞代谢类、胁迫响应类、转录因子类、光合作用类。镉胁迫中的差异片段所体现的基因,其功能大部分参与了蛋白激酶、热击蛋白、光合蛋白合成途径。
URL [本文引用: 1]
白菜型油菜(Brassica campestris L.)是油菜三大类型之一。中国又称小白菜、矮油菜、甜油菜等。白菜型油菜在既是油料作物,又是一种非常重要的蔬菜。“矮脚黄”白菜是长江流域的主栽品种,在浙江也有大面积种植。 多倍体与二倍体比拥有较大的营养器官和生殖器官,在生长过程中表现出一定的抗性优势,但以往的研究多集中在异源多倍体的抗性差异上,而对同源多倍体和二倍体的抗性差异研究甚少。本文采用同源四倍体“矮脚黄”白菜和二倍体“矮脚黄”白菜为材料,其中同源四倍体“矮脚黄”白菜是由二倍体“矮脚黄”白菜直接加倍而来。文章从生理生化、表观遗传、分子表达三个角度研究了二者在盐和镉逆境条件下的逆境差异机理,得到的主要结果如下： 1)同源四倍体在高盐胁迫下具有较快的发芽速度,较多的健康植株数；低浓度盐能够有效的刺激四倍体茎和根的生长。发芽7天后,四倍体和二倍体植株体内的钾钠钙离子在不同组织中的分布存在差异明显。四倍体在高盐浓度中具有一定的抗性优势,而Na+/Ca2+可以作为筛选白菜抗性品种的一个重要指标。 2)在5-7叶期间,四倍体叶绿素含量受到盐害的影响较二倍体小,四倍体体内的抗氧化还原剂GSH较二倍体含量高,四倍体白菜和二倍体白菜在盐胁迫下用不同的活性氧清除体系,四倍体的抗氧化酶体系更加稳定。盐处理后期,钾钠钙离子在地上组织和地下组织中的分布差异明显,二倍体的地上组织能够吸收更多的钠离子,四倍体能够在一定程度上阻止钠离子向地上部分运输；四倍体的地下组织吸收更高的钠离子含量以及保持高水平的钾离子水平。四倍体在根部能通过保持较高的K+／Na+比值,使其具有一定的抗盐优势。随着处理时间的增加,二倍体和四倍体的Na+/Ca2+比值差异越大,这些实验说明四倍体可以通过保持较低的Na+/Ca2+比值来缓解盐害。 3)发芽7天后发现在高浓度的镉处理中,四倍体在发芽率、根茎长以及健康植株数目指标上比二倍体具有明显的优势。随着处理浓度的增加,二倍体各组织中镉的含量逐渐增加。四倍体在高浓度的处理下发芽期可以通过限制镉的摄入来降低根部的镉浓度。 4)随着镉处理浓度和时间的增加,四倍体叶绿素和GSH含量比二倍体高,叶片内的MDA积累量要比二倍体低。四倍体白菜和二倍体白菜在镉胁迫下,抗氧化酶变化趋势存在着差异,四倍体的抗氧化酶的活性在镉环境中的缓冲力要强于二倍体。说明了四倍体在镉胁迫下其体内的活性氧、过氧化氢可以通过高含量的GSH以及稳定的抗氧化酶体系得到及时的清除,使得四倍体在镉胁迫下有一定的生长优势。镉进入四倍体根部后,有一部分运输至地上组织(叶片),减轻了镉对四倍体根部的毒害。 5)用MSAP分析四倍体和二倍体的逆境抗性的差异,56对引物共得到14382条扩增带,总甲基化条带共2924条。二倍体和四倍体在盐胁迫中,其总体甲基化水平都呈下降趋势。在镉胁迫环境中,两者的总体甲基化有上升的趋势。二倍体的甲基化水平下降了1.5个百分点,而四倍体下降了2.5个百分点,四倍体甲基化程度下降得更快；在镉处理中,二倍体的甲基化水平上升了2.7个百分点,四倍体上升了3.5个百分点,四倍体镉甲基化水平上升的程度更高。 6)二倍体和四倍体经过逆境条件下,其MSAP的甲基化模式发生了改变,四倍体在盐胁迫下与二倍体在盐胁迫下,有35%的甲基化模式发生了去甲基化(B类型)过程,20.0%发生过甲基化(C类型)转变；四倍体在镉胁迫下与二倍体在镉胁迫下,有24.8%的甲基化模式发生了去甲基化(B类型)过程,25.8%发生过甲基化(C类型)转变。盐胁迫下,四倍体发生去甲基化的位点数比二倍体多,而发生过甲基化位点数相差不大,暗示了去甲基化位点在四倍体白菜和二倍体白菜盐胁迫差异中启着重要的作用；镉胁迫下,四倍体发生过甲基化的位点数比二倍体多,而发生去甲基化位点数相差不大,说明了过甲基化位点在四倍体白菜和二倍体白菜的镉胁迫差异中启着关键性作用。 7) cDNA-AFLP实验结果表明与二倍体和四倍体各自在对照条件下相比,二者在盐和镉胁迫条件下的差异有扩大的趋势。在盐胁迫的差异片段中,二倍体基因表达被抑制的有14条(0.52%),四倍体基因表达被抑制的7条(0.26%);四倍体基因表达被诱导的差异基因有10条(0.37%),而二倍体被诱导的差异基因有5条(0.19%)。在镉胁迫的差异片断中,二倍体基因表达被抑制的有7条(0.26%),四倍体基因表达被抑制的为16条(0.60%)；四倍体基因表达被诱导的有5条(0.19%),二倍体基因表达被诱导的有12条(0.45%)。四倍体和二倍体在不同的逆境环境中基因表达的模式有很大的差异,在盐胁迫中,差异片段在二倍体中大部分被抑制,在四倍体中大部分被诱导；镉胁迫下,二倍体中大部分的基因表达差异体现为被诱导,而在四倍体中大部分的基因表达差异体现为被抑制。 8)对盐和镉的不同胁迫下,对二倍体和四倍体中的差异片段进行测序发现,盐胁迫导致的18条TDFs中有16条(88.9%)在现有数据库已有基因的功能(或者推测功能)的描述,两条TDFs中有1条其功能未知,另外一条和现有数据库中基因无任何同源性。16个TDFs按照功能可以分为三类：细胞代谢类、胁迫响应类、转录因子类。盐胁迫中的差异片段功能大部分参与了ABA信号合成及传递、过氧化物酶合成、醛脱氢酶合成、甜菜合成键酶的过程。在镉胁迫差异片段中,20条TDFs中有15条(75%)在现有数据库已有基因的功能(或者推测功能)的描述,有5条功能不明确,其中3条与数据库中的基因具有一定程度的同源性,另外2条在数据库找不到同源基因。在镉胁迫实验中,二倍体和四倍体有差异按照功能可以分为四类：细胞代谢类、胁迫响应类、转录因子类、光合作用类。镉胁迫中的差异片段所体现的基因,其功能大部分参与了蛋白激酶、热击蛋白、光合蛋白合成途径。
URLPMID:25074914 [本文引用: 1]
Hexaploid bread wheat (Triticum aestivum L., genome BBAADD) is generally more salt tolerant than its tetraploid wheat progenitor (Triticum turgidum L.). However, little is known about the physiological basis of this trait or about the relative contributions of allohexaploidization and subsequent evolutionary genetic changes on the trait development. Here, we compared the salt tolerance of a synthetic allohexaploid wheat (neo-6x) with its tetraploid (T. turgidum; BBAA) and diploid (Aegilops tauschii; DD) parents, as well as a natural hexaploid bread wheat (nat-6x). We studied 92 morphophysiological traits and analyzed homeologous gene expression of a major salt-tolerance gene High-Affinity K(+) Transporter 1;5 (HKT1;5). We observed that under salt stress, neo-6x exhibited higher fitness than both of its parental genotypes due to inheritance of favorable traits like higher germination rate from the 4x parent and the stronger root Na(+) retention capacity from the 2x parent. Moreover, expression of the D-subgenome HKT1;5 homeolog, which is responsible for Na(+) removal from the xylem vessels, showed an immediate transcriptional reprogramming following allohexaploidization, i.e., from constitutive high basal expression in Ae. tauschii (2x) to salt-induced expression in neo-6x. This phenomenon was also witnessed in the nat-6x. An integrated analysis of 92 traits showed that, under salt-stress conditions, neo-6x resembled more closely the 2x than the 4x parent, suggesting that the salt stress induces enhanced expressivity of the D-subgenome homeologs in the synthetic hexaploid wheat. Collectively, the results suggest that condition-dependent functionalization of the subgenomes might have contributed to the wide-ranging adaptability of natural hexaploid wheat.
URL [本文引用: 1]
Plant growth, photosynthetic parameters, chloroplast ultrastructure, and the ascorbate-glutathione cycle system in chloroplasts of self-grafted and rootstock-grafted cucumber leaves were investigated. Grafted plants were grown hydroponically and were exposed to 0, 50, and 10002mM NaCl concentrations for 1002days. Under NaCl stress, the hydrogen peroxide (H 2 O 2 ) content in cucumber chloroplasts increased, the chloroplast ultrastructure was damaged, and the gas stomatal conductance, intercellular CO 2 concentration, as well as shoot dry weight, plant height, stem diameter, leaf area, and leaf relative water content were inhibited, whereas these changes were less severe in rootstock-grafted plants. The activities of ascorbate peroxidase (APX; EC 1.11.1.11), glutathione reductase (GR; EC 1.6.4.2), and dehydroascorbate reductase (DHAR EC 1.8.5.1) were higher in the chloroplasts of rootstock-grafted plants compared with those of self-grafted plants under 50 and 10002mM NaCl. Similar trends were shown in leaf net CO 2 assimilation rate and transpiration rate, as well as reduced glutathione content under 10002mM NaCl. Results suggest that rootstock grafting enhances the H 2 O 2 -scavenging capacity of the ascorbate–glutathione cycle in cucumber chloroplasts under NaCl stress, thereby protecting the chloroplast structure and improving the photosynthetic performance of cucumber leaves. As a result, cucumber growth is promoted.
[本文引用: 1]
[本文引用: 1]
URL [本文引用: 2]
Although it is well established that many clades have polyploidization in their evolutionary history, the question of whether polyploidization is actually adaptive is far from resolved. It has been hypothesized that the evolutionary advantages of polyploidy are context-dependent, although we have yet to clearly identify the geographical or ecological contexts in which polyploids are more common. One reason why polyploidy may be displaying idiosyncratic ecological patterns is that previous comparative studies have often not separated polyploids into allopolyploids and autopolyploids, and we posit that there may be important differences in the origin and evolutionary success between the two types. Here, we examine the distribution of allopolyploid, autopolyploid, and diploid hybrid species along an elevation gradient from sea level to similar to 4500 m within British Columbia, Canada, and find that polyploids (especially those of hybrid origin) are disproportionately present at high elevations. These processes of hybridization and polyploidization may contribute to species richness patterns observed in British Columbia. We discuss whether the associations are more likely to be the result of differential ecological tolerance or differential origination rates of allopolyploids at higher elevations. These findings highlight the importance of studying both hybridization and polyploidy when considering the diversification process in plants.
[本文引用: 1]
URLPMID:26975701 [本文引用: 4]
Salinity is an important abiotic stressor that negatively affects plant growth. In this study, we investigated the physiological and molecular mechanisms underlying moderate and high salt tolerance in diploid (2×) and tetraploid (4×)Robinia pseudoacaciaL. Our results showed greater H2O2accumulation and higher levels of important antioxidative enzymes and non-enzymatic antioxidants in 4× plants compared with 2× plants under salt stress. In addition, 4× leaves maintained a relatively intact structure compared to 2× leaves under a corresponding condition. NaCl treatment didn’t significantly affect the photosynthetic rate, stomatal conductance or leaf intercellular CO2concentrations in 4× leaves. Moreover, proteins from control and salt treated 2× and 4× leaf chloroplast samples were extracted and separated by two-dimensional gel electrophoresis. A total of 61 spots in 2× (24) and 4× (27) leaves exhibited reproducible and significant changes under salt stress. In addition, 10 proteins overlapped between 2× and 4× plants under salt stress. These identified proteins were grouped into the following 7 functional categories: photosynthetic Calvin-Benson Cycle (26), photosynthetic electron transfer (7), regulation/defense (5), chaperone (3), energy and metabolism (12), redox homeostasis (1) and unknown function (8). This study provides important information of use in the improvement of salt tolerance in plants.
URLPMID:25184027 [本文引用: 1]
Salinity is a stressful environmental factor that limits the productivity of crop plants, and roots form the major interface between plants and various abiotic stresses. Rice is a salt-sensitive crop and its polyploid shows advantages in terms of stress resistance. The objective of this study was to investigate the effects of genome duplication on rice root resistance to salt stress. Both diploid rice (HN2026-2x and Nipponbare-2x) and their corresponding tetraploid rice (HN2026-4x and Nipponbare-4x) were cultured in half-strength Murashige and Skoog medium with 150 mM NaCl for 3 and 5 days. Accumulations of proline, soluble sugar, malondialdehyde (MDA), Na(+) content, H(+) (proton) flux at root tips, and the microstructure and ultrastructure in rice roots were examined. We found that tetraploid rice showed less root growth inhibition, accumulated higher proline content and lower MDA content, and exhibited a higher frequency of normal epidermal cells than diploid rice. In addition, a protective gap appeared between the cortex and pericycle cells in tetraploid rice. Next, ultrastructural analysis showed that genome duplication improved membrane, organelle, and nuclei stability. Furthermore, Na(+) in tetraploid rice roots significantly decreased while root tip H(+) efflux in tetraploid rice significantly increased. Our results suggest that genome duplication improves root resistance to salt stress, and that enhanced proton transport to the root surface may play a role in reducing Na(+) entrance into the roots.
URLPMID:22449082 [本文引用: 1]
Summary Top of page Summary Introduction Results Discussion Experimental Procedures Acknowledgements References Whole genome duplication leads to autopolyploidy and brings about an increase in cell size, concentration of secondary metabolites and enhanced cytosine methylation. The increased cell size offers a positive advantage to polyploids for cell-surface-related activities, but there is a differential response to change in body size across species and taxonomic groups. Although polyploidy has been very extensively studied, having genetic, ecological and evolutionary implications, there is no report that underscores the significance of native secondary metabolites vis-à-vis body size with ploidy change. To address this problem we targeted unique diploid–autotetraploid paired sets of eight diverse clones of six species of Cymbopogon – a species complex of aromatic grasses that accumulate qualitatively different monoterpene essential oils (secondary metabolite) in their vegetative biomass. Based on the qualitative composition of essential oils and the plant body size relationship between the diploid versus autotetraploid paired sets, we show that polyploidy brings about enhanced accumulation of secondary metabolites in all cases, but exerts differential effects on body size in various species. It is observed that the accumulation of alcohol-type metabolites (e.g. geraniol) does not inhibit increase in body size with ploidy change from 2× to 4× ( r = 0.854, P < 0.01), but aldehyde-type metabolites (e.g. citral) appear to drastically impede body development ( r =610.895). Such a differential response may be correlated to the metabolic steps involved in the synthesis of essential oil components. When changed to tetraploidy, the progenitor diploids requiring longer metabolic steps in production of their secondary metabolites are stressed, and those having shorter metabolite routes better utilize their resources for growth and vigour. In situ immunodetection of 5-methylcytosine sites reveals enhanced DNA methylation in autopolyploids. It is underpinned that the qualitative composition of secondary metabolites found in the vegetative biomass of the progenitor diploid has a decisive bearing on the body size of the derived autotetraploids and brings about an enhancement in genome-wide cytosine methylation.
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Polyploidy, the presence of more than two chromosome sets, is rare in animals, but is wide spread in plants. Polyploidy is believed to play an important role in speciation and diversification of plants. It is conjectured that almost all angiosperms are likely to be ancient polyploids i.e. palaeopolyploids that have undergone diploidization through differential mutation, elimination and inversion of duplicated chromosomes. Therefore, understanding of consequences of gene duplication on functional divergence, developmental behavior and genome stability is of utmost importance from utilitarian view point. Studies conducted by our group for over a quarter century on the cyotogenetics of polyploids on an array of medicinal and aromatic plants have enabled us to develop strategies to realize high fertility in the autotetraploids. It is surmised that pre-selection of diploid progenitor with low chiasmate association, preferably with distal chiasma localization facilitates high bivalent pairing and balanced meiotic segregation in the derived autotetraploid, and thereby promising high fertility. This has implications in ploidy mediated fixation of heterozygosity and genetic enhancement. However, the elevated ploidy level does not always bring about increase in body size. Both, increase or decrease in body size happen to occur consequent to genomic duplication, depending upon the species and composition of native secondary metabolites / cost of metabolic load. Of course, polyploidization does bring about increase in secondary metabolite concentration and DNA methylation. Further, the patterns of chromosome / ploidy variation encountered in callus cultures over passage of subcultures are indicative of variation happening over evolutionary timescale. The details concerning such issues are dealt in this article based on our own experimental observations and are discussed from utilitarian view point for further researches.
URLPMID:26621743 [本文引用: 1]
Abstract Polyploidy, or whole-genome duplication (WGD), serves as a key innovation in plant evolution and is an important genomic feature for all eukaryotes. Neopolyploids have to overcome difficulties in meiosis, genomic alterations, changes of gene expression, and epigenomic reorganization. However, the underlying mechanisms for these processes are poorly understood. One of the most interesting aspects is that genome doubling events increase the dosage of all genes. Unlike allopolyploids entangled by both hybridization and polyploidization, autopolyploids, especially artificial lines, in relatively uniform genetic background offer a model system to understand mechanisms of genome-dosage effects. To investigate DNA methylation effects in response to WGD rather than hybridization, we produced autotetraploid rice with its diploid donor, Oryza sativa ssp. indica cv. Aijiaonante, both of which were independently self-pollinated over 48 generations, and generated and compared their comprehensive transcriptomes, base pair-resolution methylomes, and siRNAomes. DNA methylation variation of transposable elements (TEs) was observed as widespread in autotetraploid rice, in which hypermethylation of class II DNA transposons was predominantly noted in CHG and CHH contexts. This was accompanied by changes of 24-nt siRNA abundance, indicating the role of the RNA-directed DNA methylation pathway. Our results showed that the increased methylation state of class II TEs may suppress the expression of neighboring genes in autotetraploid rice that has obtained double alleles, leading to no significant differences in transcriptome alterations for most genes from its diploid donor. Collectively, our findings suggest that chromosome doubling induces methylation variation in TEs that affect gene expression and may become a "genome shock" response factor to help neoautopolyploids adapt to genome-dosage effects.
URLPMID:17803908 [本文引用: 1]
Maintenance of CG methylation ((m)CG) patterns is essential for chromatin-mediated epigenetic regulation of transcription in plants and mammals. However, functional links between (m)CG and other epigenetic mechanisms in vivo remain obscure. Using successive generations of an Arabidopsis thaliana mutant deficient in maintaining (m)CG, we find that (m)CG loss triggers genome-wide activation of alternative epigenetic mechanisms. However, these mechanisms, which involve RNA-directed DNA methylation, inhibiting expression of DNA demethylases, and retargeting of histone H3K9 methylation, act in a stochastic and uncoordinated fashion. As a result, new and aberrant epigenetic patterns are progressively formed over several plant generations in the absence of (m)CG. Interestingly, the unconventional redistribution of epigenetic marks is necessary to "rescue" the loss of (m)CG, since mutant plants impaired in rescue activities are severely dwarfed and sterile. Our results provide evidence that (m)CG is a central coordinator of epigenetic memory that secures stable transgenerational inheritance in plants.
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Autotetraploid plants of apple ( Malus domestica ) cultivar ‘Hanfu’ and ‘Gala’ were induced from leaves by colchicine treatment. There were obvious morphological differences in the leaves of diploid and autotetraploid plants. We treated the diploid and autotetraploid apple seedlings with 20002mmol02L 611 NaCl for 802days in 0.5× Hoagland's nutrient solution and measured the physiological characters and the expression of aquaporin genes in leaves at different times during treatment. The results showed that the response of the autotetraploid to salt stress was better than that of the diploid; the relative water content (RWC) decreased in both over time, but the RWC was higher in the autotetraploid than in the diploid for the duration of the salt stress treatment. The proline content and the accumulation of malondialdehyde (MDA) were higher in the diploid than the autotetraploid, with both increasing over the course of the treatment. We also showed that the expression of aquaporin genes ( MdPIP1;1 , and MdTIP1;1 ) decreased initially before peaking at 2402h and then rapidly declining at 4802h and 9602h. The relative expression levels in the autotetraploid were higher than in the diploid at all sampling times, and were 4 to 10-fold higher at 2402h. Our results show that autotetraploid apple possesses better salt tolerance than diploid, which may be associated with the higher levels of expression of aquaporin genes in response to salt stress. The results of our study will make a practical and theoretical contribution to the breeding of polyploid apple cultivars.
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Salinity stress significantly affects plant growth and development because of osmotic stress, ion toxicity, and nutrient imbalance. Therefore, salinity stress becomes a serious threat to rapeseed prod
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[目的]研究二倍体和同源四倍体西瓜幼苗NaCl胁迫后形态学指 标差异和DNA甲基化变化情况,分析不同倍性西瓜幼苗之间耐盐差异,结合形态学指标从表观遗传学角度解释二倍体和四倍体抗逆性差异机制.[方法]以3组不 同倍性(二倍体、四倍体)西瓜幼苗为研究对象,待长至三叶一心时,用含有0、100、200、300和400mmol·L-1 NaCl的1/2 Hoagland营养液处理西瓜幼苗,NaCl处理8d之后,鉴定西瓜幼苗受到的盐害指数,并运用甲基化敏感扩增多态性(methylation sensitive amplified polymorphism,MSAP)技术,分析NaCl处理8d之后二倍体和四倍体西瓜幼苗叶片基因组DNA甲基化水平和模式的变化.[结果]NaCl 处理后,形态学指标比较发现,随着NaCl浓度的增加,三组西瓜幼苗的受伤害程度都随着增加,在不同的西瓜品种之间受伤害程度有差异,但是同一品种内同一 NaCl浓度下,西瓜幼苗受伤害程度二倍体大于四倍体;从甲基化水平看,西瓜幼苗基因组DNA全甲基化率、半甲基化率、总甲基化率都随着NaCl浓度的增 加而降低,同一NaCl浓度处理下甲基化率二倍体大于四倍体,二倍体和四倍体西瓜甲基化水平与其受伤害程度呈正相关;从甲基化模式来看,NaCl胁迫后 DNA的去甲基化比率降低,超甲基化比率升高,并且其变化幅度是四倍体大于二倍体,不同倍性西瓜幼苗的甲基化模式与其受伤害程度呈负相关.[结 论]NaCl胁迫后西瓜幼苗基因组DNA的甲基化状态发生了变化,并且这种变化与NaCl胁迫程度高度线性相关,西瓜幼苗通过降低甲基化率和降低去甲基化 比率来应对NaCl胁迫,四倍体较二倍体有更低的甲基化比率和去甲基化比率,抗逆性四倍体强于二倍体.
URL [本文引用: 1]
[目的]研究二倍体和同源四倍体西瓜幼苗NaCl胁迫后形态学指 标差异和DNA甲基化变化情况,分析不同倍性西瓜幼苗之间耐盐差异,结合形态学指标从表观遗传学角度解释二倍体和四倍体抗逆性差异机制.[方法]以3组不 同倍性(二倍体、四倍体)西瓜幼苗为研究对象,待长至三叶一心时,用含有0、100、200、300和400mmol·L-1 NaCl的1/2 Hoagland营养液处理西瓜幼苗,NaCl处理8d之后,鉴定西瓜幼苗受到的盐害指数,并运用甲基化敏感扩增多态性(methylation sensitive amplified polymorphism,MSAP)技术,分析NaCl处理8d之后二倍体和四倍体西瓜幼苗叶片基因组DNA甲基化水平和模式的变化.[结果]NaCl 处理后,形态学指标比较发现,随着NaCl浓度的增加,三组西瓜幼苗的受伤害程度都随着增加,在不同的西瓜品种之间受伤害程度有差异,但是同一品种内同一 NaCl浓度下,西瓜幼苗受伤害程度二倍体大于四倍体;从甲基化水平看,西瓜幼苗基因组DNA全甲基化率、半甲基化率、总甲基化率都随着NaCl浓度的增 加而降低,同一NaCl浓度处理下甲基化率二倍体大于四倍体,二倍体和四倍体西瓜甲基化水平与其受伤害程度呈正相关;从甲基化模式来看,NaCl胁迫后 DNA的去甲基化比率降低,超甲基化比率升高,并且其变化幅度是四倍体大于二倍体,不同倍性西瓜幼苗的甲基化模式与其受伤害程度呈负相关.[结 论]NaCl胁迫后西瓜幼苗基因组DNA的甲基化状态发生了变化,并且这种变化与NaCl胁迫程度高度线性相关,西瓜幼苗通过降低甲基化率和降低去甲基化 比率来应对NaCl胁迫,四倍体较二倍体有更低的甲基化比率和去甲基化比率,抗逆性四倍体强于二倍体.
URLPMID:27293111 [本文引用: 2]
Kharchia Local wheat variety is an Indian salt tolerant land race known for its tolerance to salinity. However, there is a lack of detailed information regarding molecular mechanism imparting tolerance to high salinity in this bread wheat. In the present study, differential root transcriptome analysis identifying salt stress responsive gene networks and functional annotation under salt stress in Kharchia Local was performed. A total of 453,882 reads were obtained after quality filtering, using Roche 454-GS FLX Titanium sequencing technology. From these reads 22,241 ESTs were generated out of which, 17,911 unigenes were obtained. A total of 14,898 unigenes were annotated against nr protein database. Seventy seven transcription factors families in 826 unigenes and 11,002 SSRs in 6,939 unigenes were identified. Kyoto Encyclopedia of Genes and Genomes database identified 310 metabolic pathways. The expression pattern of few selected genes was compared during the time course of salt stress treatment between salt-tolerant (Kharchia Local) and susceptible (HD2687). The transcriptome data is the first report, which offers an insight into the mechanisms and genes involved in salt tolerance. This information can be used to improve salt tolerance in elite wheat cultivars and to develop tolerant germplasm for other cereal crops.
URLPMID:18687588 [本文引用: 1]
The Arabidopsis thaliana sterol carrier protein-2 (AtSCP2) is a small, basic and peroxisomal protein that in vitro enhances the transfer of lipids between membranes. AtSCP2 and all other plant SCP-2 that have been identified are single-domain polypeptides, whereas in many other eukaryotes SCP-2 domains are expressed in the terminus of multidomain polypeptides. The AtSCP2 transcript is expressed in all analysed tissues and developmental stages, with the highest levels in floral tissues and in maturing seeds. The expression of AtSCP2 is highly correlated with the multifunctional protein-2 (MFP2) involved in o-oxidation. A. thaliana Atscp2-1 plants deficient in AtSCP2 show altered seed morphology, a delayed germination, and are dependent on an exogenous carbon source to avoid a delayed seedling establishment. Metabolomic investigations revealed 110 variables (putative metabolites) that differed in relative concentration between Atscp2-1 and normal A. thaliana wild-type seedlings. Microarray analysis revealed that many genes whose expression is altered in mutants with a deficiency in the glyoxylate pathway, also have a changed expression level in Atscp2-1.
URLPMID:12366797 [本文引用: 1]
Abstract A cDNA from Arabidopsis corresponding to a new cold-inducible gene, RCI3 (for Rare Cold Inducible gene 3), was isolated. Isoelectric focusing electrophoresis and staining of peroxidase activity demonstrated that RCI3 encodes an active cationic peroxidase. RNA-blot analysis revealed that RCI3 expression in response to low temperature is negatively regulated by light, as RCI3 transcripts were exclusively detected in etiolated seedlings and roots of adult plants. RCI3 expression was also induced in etiolated seedlings, but not in roots, exposed to dehydration, salt stress or ABA, indicating that it is subjected to a complex regulation through different signaling pathways. Analysis of transgenic plants containing RCI3::GUS fusions established that this regulation occurs at the transcriptional level during plant development, and that cold-induced RCI3 expression in roots is mainly restricted to the endodermis. Plants overexpressing RCI3 showed an increase in dehydration and salt tolerance, while antisense suppression of RCI3 expression gave dehydration- and salt-sensitive phenotypes. These results indicate that RCI3 is involved in the tolerance to both stresses in Arabidopsis, and illustrate that manipulation of RCI3 has a potential with regard to plant improvement of stress tolerance.
URLPMID:26993527 [本文引用: 1]
Although major advances have been made during the past 20聽years in our understanding of the genetic and genomic consequences of polyploidy, our knowledge of polyploidy and the proteome is in its infancy. One of our goals is to stimulate additional study, particularly broad-scale proteomic analyses of polyploids and their progenitors. Although it may be too early to generalize regarding the extent to which transcriptomic data are predictive of the proteome of polyploids, it is clear that the proteome does not always reflect the transcriptome. Despite limited data, important observations on the proteomes of polyploids are emerging. In some cases, proteomic profiles show qualitatively and/or quantitatively non-additive patterns, and proteomic novelty has been observed. Allopolyploids generally combine the parental contributions, but there is evidence of parental dominance of one contributing genome in some allopolyploids. Autopolyploids are typically qualitatively identical to but quantitatively different from their parents. There is also evidence of parental legacy at the proteomic level. Proteomes clearly provide insights into the consequences of genomic merger and doubling beyond what is obtained from genomic and/or transcriptomic data. Translating proteomic changes in polyploids to differences in morphology and physiology remains the holy grail of polyploidy 鈥 this daunting task of linking genotype to proteome to phenotype should emerge as a focus of polyploidy research in the next decade. This article is part of a Special Issue entitled: Plant Proteomics鈥 a bridge between fundamental processes and crop production, edited by Dr. Hans-Peter Mock.
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URLPMID:25595546 [本文引用: 1]
Effects of overexpression of high activity-type Rubisco small subunit (RbcS) from a cold-resistant plant, timothy ( Phleum pratense ), on kinetic properties of Rubisco were studied in rice ( Oryza sativa ). The full-length mRNA sequence of timothy RbcS ( PpRbcS1 ) was determined by 5鈥睷ACE and 3鈥睷ACE. The coding sequence of PpRbcS1 was fused to the chlorophyll a/b-binding protein promoter and introduced into rice. PpRbcS was highly expressed in leaf blade and accounted for approximately 30聽% of total RbcS in homozygous transgenic lines. However, the catalytic turnover rate and K m for CO 2 of Rubisco did not significantly change in these transgenic lines compared to non-transgenic rice, suggesting that PpRbcS1 is not effective for improvement of catalytic efficiency of rice Rubisco. The photosynthetic rate and growth were essentially unchanged, whereas the photosynthetic rate at low CO 2 condition was marginally increased in transgenic lines. Rubisco content was significantly increased, whereas soluble protein, nitrogen, and chlorophyll contents were unchanged in transgenic lines compared to non-transgenic rice. Because the kinetic properties were similar, observed slight increase in photosynthetic rate at low CO 2 is considered to be large due to increase in Rubisco content in transgenic lines. Introduction of foreign RbcS is an effective approach for the improvement of Rubisco kinetics and photosynthesis. However, in this study, it was suggested that RbcS of high activity-type Rubisco, even showing higher amino acid identity with rice RbcS, did not always enhance the catalytic turnover rate of Rubisco in rice. Thus, we should carefully select RbcS to be overexpressed before introduction.
URLPMID:4957745 [本文引用: 1]
Abstract Allotetraploid cotton species are a vital source of spinnable fiber for textiles. The polyploid nature of the cotton genome raises many evolutionary questions as to the relationships between duplicated genomes. We describe the evolution of the cotton genome (SNPs and structural variants) with the greatly improved resolution of 34 deeply re-sequenced genomes. We also explore the evolution of homoeologous regions in the AT- and DT-genomes and especially the phenomenon of conversion between genomes. We did not find any compelling evidence for homoeologous conversion between genomes. These findings are very different from other recent reports of frequent conversion events between genomes. We also identified several distinct regions of the genome that have been introgressed between G. hirsutum and G. barbadense, which presumably resulted from breeding efforts targeting associated beneficial alleles. Finally, the genotypic data resulting from this study provides access to a wealth of diversity sorely needed in the narrow germplasm of cotton cultivars.
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在不同Nacl浓度(0,0.2%,0.4%,0.6%)下研究二倍体毛泡桐(T2)和二倍体豫杂一号泡桐(TF2)及其四倍体泡桐T4和TF4的生理生态响应特征,并比较四倍体泡桐及其二倍体泡桐的耐盐性。结果表明:随着盐胁迫浓度的增加,2种四倍体泡桐与其二倍体泡桐的生理生化指标变化规律一致,叶片相对含水量和叶绿素含量随盐胁迫浓度的升高呈下降趋势,四倍体泡桐的叶片相对含水量和叶绿素含量均高于其二倍体;相对电导率和丙二醛含量随盐浓度增大呈升高趋势,四倍体泡桐的相对电导率和丙二醛含量均小于其二倍体;SOD活性和可溶性蛋白质含量随盐胁迫的加强先升高后下降;可溶性糖含量和脯氨酸含量随盐浓度的增大呈升高趋势,并且四倍体泡桐高于其二倍体泡桐;对0.6%盐浓度胁迫下四倍体泡桐及其二倍体泡桐的各项生理指标利用模糊隶属函数进行抗盐性评价,抗盐性从强到弱排列为TF4T4TF2T2。
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在不同Nacl浓度(0,0.2%,0.4%,0.6%)下研究二倍体毛泡桐(T2)和二倍体豫杂一号泡桐(TF2)及其四倍体泡桐T4和TF4的生理生态响应特征,并比较四倍体泡桐及其二倍体泡桐的耐盐性。结果表明:随着盐胁迫浓度的增加,2种四倍体泡桐与其二倍体泡桐的生理生化指标变化规律一致,叶片相对含水量和叶绿素含量随盐胁迫浓度的升高呈下降趋势,四倍体泡桐的叶片相对含水量和叶绿素含量均高于其二倍体;相对电导率和丙二醛含量随盐浓度增大呈升高趋势,四倍体泡桐的相对电导率和丙二醛含量均小于其二倍体;SOD活性和可溶性蛋白质含量随盐胁迫的加强先升高后下降;可溶性糖含量和脯氨酸含量随盐浓度的增大呈升高趋势,并且四倍体泡桐高于其二倍体泡桐;对0.6%盐浓度胁迫下四倍体泡桐及其二倍体泡桐的各项生理指标利用模糊隶属函数进行抗盐性评价,抗盐性从强到弱排列为TF4T4TF2T2。
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为建立寒富苹果高效的离体再生 体系和多倍体诱导体系,以试管苗叶片为外植体,研究了培养基中激素对寒富叶片再生芽的影响及适宜的四倍体诱导方法。结果表明,当培养基中BA质量浓度为 0.5mg/L时,再生频率最高达35.7%;当培养基中BA质量浓度为2.5mg/L时,再生频率超过90%,平均再生芽数在4以上。在培养基中附加 1.0mg/LTDZ,再生频率达100%,平均再生芽数达19.47。以附加15、30、60、120mg/L秋水仙素的液体再生培养基处理叶片5d, 各个质量浓度处理均诱导出四倍体植株,诱变率在5.3%～22.2%之间;寒富苹果叶片在附加50mg/L秋水仙素固体再生培养基上处理5d亦获得了四倍 体植株。研究结果表明寒富苹果叶片具有极强的不定芽再生能力,叶片再生过程中进行秋水仙素处理是获得其四倍体的一个有效途径。
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为建立寒富苹果高效的离体再生 体系和多倍体诱导体系,以试管苗叶片为外植体,研究了培养基中激素对寒富叶片再生芽的影响及适宜的四倍体诱导方法。结果表明,当培养基中BA质量浓度为 0.5mg/L时,再生频率最高达35.7%;当培养基中BA质量浓度为2.5mg/L时,再生频率超过90%,平均再生芽数在4以上。在培养基中附加 1.0mg/LTDZ,再生频率达100%,平均再生芽数达19.47。以附加15、30、60、120mg/L秋水仙素的液体再生培养基处理叶片5d, 各个质量浓度处理均诱导出四倍体植株,诱变率在5.3%～22.2%之间;寒富苹果叶片在附加50mg/L秋水仙素固体再生培养基上处理5d亦获得了四倍 体植株。研究结果表明寒富苹果叶片具有极强的不定芽再生能力,叶片再生过程中进行秋水仙素处理是获得其四倍体的一个有效途径。
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<FONT face=Verdana>采用扫描电子显微镜对不同倍性西瓜12个品种的花粉形态进行了系统观察，结果表明：二倍体花粉多为近长球形，极轴/赤道轴(P/E)值为1.283，具3孔沟，花粉整齐一致；四倍体花粉为圆球形,P/E值为1.111，有3孔沟，4孔沟，多孔沟，其中有异形花粉、粘连花粉和空瘪花粉等；三倍体花粉全部为空瘪花粉。从孢粉学角度阐述了四倍体花粉萌发率低，三倍体花粉不育的原因。</FONT>
URLMagsci [本文引用: 1]
<FONT face=Verdana>采用扫描电子显微镜对不同倍性西瓜12个品种的花粉形态进行了系统观察，结果表明：二倍体花粉多为近长球形，极轴/赤道轴(P/E)值为1.283，具3孔沟，花粉整齐一致；四倍体花粉为圆球形,P/E值为1.111，有3孔沟，4孔沟，多孔沟，其中有异形花粉、粘连花粉和空瘪花粉等；三倍体花粉全部为空瘪花粉。从孢粉学角度阐述了四倍体花粉萌发率低，三倍体花粉不育的原因。</FONT>
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为了研究西瓜植株在淹水情况下对淹水胁迫的响应,以蜜枚 (M2x)和京牟(JM2x)2个二倍体西瓜品种为试材,在盆栽条件下研究了淹水胁迫对西瓜叶片受害指数、生理生化特性的影响.结果表明,西瓜幼苗在淹水 胁迫下,真叶发黄失绿,随着淹水时间延长,茎开始腐烂,出现气生根,30 d后淹水解除,植株生长无法恢复.西瓜幼苗叶片SOD活性在淹水初期下降,随着西瓜幼苗对淹水胁迫的适应,SOD开始回升,在胁迫8 d后超出对照.淹水胁迫后西瓜幼苗叶片POD活性一直是上升趋势且高于对照.可溶性蛋白质含量受涝害后都比对照降低.随着淹水胁迫增加,PRO降低幅度加 大.MDA含量受淹水胁迫后都比对照上升,MDA含量先降,后升高,再降低,然后大幅度升高.根据试验结果推断西瓜叶片伤害顺序为,SOD活性受抑制→活 性氧增生→SOD、POD活性、PRO含量增加→清除活性氧→淹水胁迫加深→活性氧再增加→MDA积累→保护酶活性降低→质膜受损.京牟西瓜品种的耐淹水 能力强于蜜枚.
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为了研究西瓜植株在淹水情况下对淹水胁迫的响应,以蜜枚 (M2x)和京牟(JM2x)2个二倍体西瓜品种为试材,在盆栽条件下研究了淹水胁迫对西瓜叶片受害指数、生理生化特性的影响.结果表明,西瓜幼苗在淹水 胁迫下,真叶发黄失绿,随着淹水时间延长,茎开始腐烂,出现气生根,30 d后淹水解除,植株生长无法恢复.西瓜幼苗叶片SOD活性在淹水初期下降,随着西瓜幼苗对淹水胁迫的适应,SOD开始回升,在胁迫8 d后超出对照.淹水胁迫后西瓜幼苗叶片POD活性一直是上升趋势且高于对照.可溶性蛋白质含量受涝害后都比对照降低.随着淹水胁迫增加,PRO降低幅度加 大.MDA含量受淹水胁迫后都比对照上升,MDA含量先降,后升高,再降低,然后大幅度升高.根据试验结果推断西瓜叶片伤害顺序为,SOD活性受抑制→活 性氧增生→SOD、POD活性、PRO含量增加→清除活性氧→淹水胁迫加深→活性氧再增加→MDA积累→保护酶活性降低→质膜受损.京牟西瓜品种的耐淹水 能力强于蜜枚.
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URLPMID:25520388 [本文引用: 1]
Abstract The exploitation of synthetic polyploids for producing seedless fruits is well known in watermelon. Tetraploid progenitors of triploid watermelon plants, compared with their diploid counterparts, exhibit wide phenotypic differences. Although many factors modulate alternative splicing (AS) in plants, the effects of autopolyploidization on AS are still unknown. In this study, we used tissues of leaf, stem, and fruit of diploid and tetraploid sweet watermelon to understand changes in gene expression and the occurrence of AS. RNA-sequencing analysis was performed along with reverse transcription quantitative PCR and rapid amplification of cDNA ends (RACE)-PCR to demonstrate changes in expression and splicing. All vegetative tissues except fruit showed an increased level of AS in the tetraploid watermelon throughout the growth period. The ploidy levels of diploids and the tetraploid were confirmed using a ploidy analyser. We identified 5362 and 1288 genes that were up- and downregulated, respectively, in tetraploid as compared with diploid plants. We further confirmed that 22 genes underwent AS events across tissues, indicating possibilities of generating different protein isoforms with altered functions of important transcription factors and transporters. Arginine biosynthesis, chlorophyllide synthesis, GDP mannose biosynthesis, trehalose biosynthesis, and starch and sucrose degradation pathways were upregulated in autotetraploids. Phloem protein 2, chloroplastic PGR5-like protein, zinc-finger protein, fructokinase-like 2, MYB transcription factor, and nodulin MtN21 showed AS in fruit tissues. These results should help in developing high-quality seedless watermelon and provide additional transcriptomic information related to other cucurbits. 漏 The Author 2014. Published by Oxford University Press on behalf of the Society for Experimental Biology. All rights reserved. For permissions, please email: journals.permissions@oup.com.
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运用遗传育种、细胞工程及分子 生物学等技术手段对同源四倍体水稻开展了多方面的研究。取得成果如下:创制了同源四倍体水稻材料近1000份。选育出同源四倍体水稻雄性不育系6份、不育 系材料46份;保持系22份、保持系材料100多份;恢复系28份、恢复系材料500多份;成功地实现了四倍体水稻杂种优势利用三系配套。培育出 T462A×T4509等四倍体杂交稻新组合。三系及杂种的细胞学研究表明,其染色体数为48条,为二倍体水稻染色体数的2倍,证明是同源四倍体。并初步 开展了分子生物学的研究。
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运用遗传育种、细胞工程及分子 生物学等技术手段对同源四倍体水稻开展了多方面的研究。取得成果如下:创制了同源四倍体水稻材料近1000份。选育出同源四倍体水稻雄性不育系6份、不育 系材料46份;保持系22份、保持系材料100多份;恢复系28份、恢复系材料500多份;成功地实现了四倍体水稻杂种优势利用三系配套。培育出 T462A×T4509等四倍体杂交稻新组合。三系及杂种的细胞学研究表明,其染色体数为48条,为二倍体水稻染色体数的2倍,证明是同源四倍体。并初步 开展了分子生物学的研究。
URLMagsci
本文论述了远缘杂交和多倍体化结合利用基因组间和多倍体杂种优势，开创水稻育种新途径的策略。纵观水稻育种的历史，无论是常规杂交育种，还是杂交稻育种，其研究战略都是建立在有性生殖和二倍体基础上的，归根结底，都是利用栽培稻同一基因组（A基因组）内优良基因的重组以及从野生稻向栽培稻引入少数优良基因。从作物进化
URLMagsci
本文论述了远缘杂交和多倍体化结合利用基因组间和多倍体杂种优势，开创水稻育种新途径的策略。纵观水稻育种的历史，无论是常规杂交育种，还是杂交稻育种，其研究战略都是建立在有性生殖和二倍体基础上的，归根结底，都是利用栽培稻同一基因组（A基因组）内优良基因的重组以及从野生稻向栽培稻引入少数优良基因。从作物进化
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Autotetraploid rice is a special germplasm with four sets of genome that is derived from diploid rice treated by colchicine.Compared with its diploid progenitor,the chromosomes and genome of the autotetraploids are doubled,thus the phenotype or morphology of the autotetraploids,especially the reproductive traits,are obviously changed.When indica and japonica are respectively developed into autotetraploid by chromosome doubling and crossed with each other,the autotetraploid hybrid will have superior heterosis in growth and biological character compared with their parents and the diploid hybrid between indica and japonica.But low seed setting rate makes this intersubspecific autotetraploid hybrids cannot be used directly in rice breeding.Therefore,it is very important to study the mechanism of low seed setting rate in the autotetraploid hybrids.In the diploid hybrid between indica and japonica,it is known that the interaction of pollen sterility genes,such as S-a,S-b and S-c,causes the hybrids to be low fertility.However,it is little known how these pollen sterility genes work in the autotetraploid hybrid between indica and japonica.In this study,autotetraploid rice Taichung 65-4x and its near-isogenic lines with pollen sterile genes were used to develop the autotetraploid hybrids with interaction at different pollen sterility gene loci,i.e.S-a,S-b and S-c.The chromosome behaviors during the meiosis of PMC were studied by the technique of chromosome squash and showed that quadrivalents and bivalents coexisted in the diakinesis in the most of PMCs of autotetraploid parents and their hybrids.The chromosome association per PMC was 9.20Ⅳ+5.60Ⅱ in Taichung 65-4x,and 9.52Ⅳ+4.90Ⅱ in the hybrids on an average,showing no significant difference in the number of quadrivalent between the parents and the hybrids.Abnormal behaviors were found in the following process of meiosis,which included lagging chromosomes,chromosome fragments,micronuclei,the loss of synchronization in segregation of chromosomes and the formation of unreduced gametes(PlateⅡ).Pollen fertility,embryo sac fertility(PlateⅠ),which were observed by WCLSM,and seed setting rate in both the tetraploid parents and their hybrids were significantly lower than those in Taichung 65.The average of pollen fertility was 30.57% in the hybrids with the single-gene interaction at the locus of S-b,and 37.56%,26.53% in the hybrids with double-gene interactions of S-b and S-a,S-b and S-c,respectively.The pollen fertility in these hybrids was significantly lower than that in the autotetraploid parents,with 67.93% on an average.The hybrids with interactions at other loci were not significantly decreased in the pollen sterility compared with the autotetraploid parents,which were those with the single-gene interaction at the locus of S-a or S-c,and double-gene interactions of S-a and S-c etc.The seed setting rate was lower in all hybrids,which was from 0.90% to 22.75% on an average,than that in the autotetraploid parents(26.12%),and that in the hybrid with the interaction at the locus of S-b was the lowest,with 0.90% on an average.It concludes preliminarily that the interaction of pollen sterile genes at different loci has no obvious effect on the abnormal behaviors of chromosome in meiosis.However,the interaction by locus of S-b may decrease the fertility of hybrids,which may be caused together by abnormal behaviors of chromosome in meiosis because of four genomes in autotetraploid rice.
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URLPMID:10999418 [本文引用: 1]
Allopolyploid plants are hybrids that contain two copies of the genome from each parent. Whereas wild and cultivated allopolyploids are well adapted, man-made allopolyploids are typically unstable, displaying homeotic transformation and lethality as well as chromosomal rearrangements and changes in the number and distribution of repeated DNA sequences within heterochromatin. Large increases in the length of some chromosomes has been documented in allopolyploid hybrids and could be caused by the activation of dormant retrotransposons, as shown to be the case in marsupial hybrids. Synthetic (man-made) allotetraploids of Arabidopsis exhibit rapid changes in gene regulation, including gene silencing. These regulatory abnormalities could derive from ploidy changes and/or incompatible interactions between parental genomes, although comparison of auto- and allopolyploids suggests that intergenomic incompatibilities play the major role. Models to explain intergenomic incompatibilities incorporate both genetic and epigenetic mechanisms. In one model, the activation of heterochromatic transposons (McClintock's genomic shock) may lead to widespread perturbation of gene expression, perhaps by a silencing interaction between activated transposons and euchromatic genes. Qualitatively similar responses, of lesser intensity, may occur in intraspecific hybrids. Therefore, insight into genome function gained from the study of allopolyploidy may be applicable to hybrids of any type and may even elucidate positive interactions, such as those responsible for hybrid vigor.
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ABSTRACT Polyploidy is produced by multiplication of a single genome (autopolyploid) or combination of two or more divergent genomes (allopolyploid). The available data obtained from the study of synthetic (newly created or human-made) plant allopolyploids have documented dynamic and stochastic changes in genomic organization and gene expression, including sequence elimination, inter-chromosomal exchanges, cytosine methylation, gene repression, novel activation, genetic dominance, subfunctionalization and transposon activation. The underlying mechanisms for these alterations are poorly understood. To promote a better understanding of genomic and gene expression changes in polyploidy, we briefly review origins and forms of polyploidy and summarize what has been learned from genome-wide gene expression analyses in newly synthesized auto-and allopolyploids. We show transcriptome divergence between the progenitors and in the newly formed allopolyploids. We propose models for transcriptional regulation, chromatin modification and RNA-mediated pathways in establishing locus-specific expression of orthologous and homoeologous genes during allopolyploid formation and evolution.
