,1, 周浓,1, 曹鸣宇2Advance on the Methylglyoxal Metabolism in Plants Under Abiotic Stress
ZHAO JingJing,1, ZHOU Nong,1, CAO MingYu2通讯作者:
责任编辑: 杨鑫浩
收稿日期:2020-06-30接受日期:2020-08-17网络出版日期:2021-04-16
| 基金资助: |
Received:2020-06-30Accepted:2020-08-17Online:2021-04-16
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赵晶晶, 周浓, 曹鸣宇. 非生物胁迫下植物体内丙酮醛代谢的研究进展[J]. 中国农业科学, 2021, 54(8): 1627-1637 doi:10.3864/j.issn.0578-1752.2021.08.005
ZHAO JingJing, ZHOU Nong, CAO MingYu.
开放科学（资源服务）标识码（OSID）：
0 引言
植物由于固着性不能自行移动,决定了其不能像动物一样躲避逆境的威胁,因此经常暴露于一种或多种非生物胁迫下。非生物胁迫和植物之间的相互作用是复杂的,可以引起植物的多种形态、生理、生物化学和分子变化,如当植物处于非生物胁迫时,体内会产生大量的有害物质（如活性氧、活性氮和丙二醛等）,破坏细胞膜结构,产生脂质过氧化反应,致使细胞生理功能受损,最终使细胞死亡[1]。前人对于活性氧（ROS）[1,2,3]和活性氮[4,5]的产生和清除机制研究已经十分深入,而关于非生物胁迫对植物体内丙酮醛（methylglyoxal,MG）产生及清除机制的研究报道较少[6],故笔者着重且详细地介绍了非生物胁迫下植物体内丙酮醛的代谢过程。丙酮醛又称之为甲基乙二醛、2-氧代丙醛或α-氧代醛,常温下MG是一种黄色黏稠状液体,具有特殊的刺激性气味,其分子式为CH3COCHO,由其结构式可知（图1）,MG具有酮基和醛基2个功能基团,因此MG在生物体内既可以被氧化也可以被还原,一般情况下,醛基比酮基更具反应性[7]。目前,国内外测定MG含量的常用方法主要有高效液相分析法[8,9]、气相色谱法[10]和化学滴定法[11]等。
图1
新窗口打开|下载原图ZIP|生成PPT图1丙酮醛结构式
Fig. 1The structural formula of methylglyoxal
1 植物体内丙酮醛的形成过程
MG作为一种小分子的高活性二羰基复合物,广泛存在于植物体内的各种组织和细胞中,包括胞质溶胶、叶绿体和线粒体等,其产生的具体比率和位点取决于细胞或组织类型、植物器官以及整个植株的生理状态[12]。20世纪30年代中期MEYERHOF和LOHMANN首次报道了MG合成反应,但由于合成的MG仅仅是一种实验产物而被忽略[13],直至1993年RICHARD发现了从三糖磷酸盐中形成MG的机制,首次确定了这种反应的生理学意义[14]。如图2所示,植物体内的MG可来源于多条代谢通路,如氨基酸代谢、蛋白质代谢和糖酵解等过程[12,15-16]。其中,糖酵解途径是MG形成的最主要来源,由植物光合作用中间体三磷酸甘油醛（glyceraldehyde- 3-phosphate,G3P）和磷酸二羟丙酮（dihydroxyacetone phosphate,DHAP）裂解产生[17,18],这一形成途径既有非酶促反应也有酶促反应,如丙糖磷酸异构酶（TPI）催化G3P和DHAP的水解产物去磷酸化后形成MG属于酶促反应过程[19,20]。植物体内的MG也可以由蛋白质和氨基酸代谢过程产生,如糖基化蛋白质的降解以及苏氨酸代谢过程中氨基丙酮的氧化均会形成MG[21]。
图2
新窗口打开|下载原图ZIP|生成PPT图2植物体内丙酮醛形成过程
Fig. 2A diagrammatic representation of methylglyoxal (MG) synthesis in plants
2 植物体内丙酮醛的降解过程
植物体内可以分解MG的酶主要有乙二醛酶（glyoxalase,Gly）、丙酮醛脱氢酶、醛酮还原酶、甘油脱氢酶以及D-乳酸脱氢酶（图3）,此5种酶构成了5条分解代谢途径,即（1）依赖于还原型谷胱甘肽（GSH）的乙二醛酶Ⅰ（也称之为S-D-乳糖基谷胱甘肽裂解酶,glyoxalase I,GlyI）和乙二醛酶Ⅱ（也称之为S-2-羟酰基谷胱甘肽水解酶,glyoxalase II,GlyII）[12,16,18];（2）不依赖于谷胱甘肽的乙二醛酶Ⅲ（glyoxalase III,GlyIII）[22];（3）依赖于NADPH的丙酮醛还原酶;（4）依赖于NADPH的醛酮还原酶和甘油脱氢酶;（5）丙酮醛脱氢酶[22]。其中,依赖于GSH的GlyⅠ和GlyⅡ是MG降解的主要途径,MG能够与GSH经非酶促反应自发形成半缩醛后与GlyⅠ的2个活性位点结合,在Gly I的催化作用下转化成S-D-乳糖基谷胱甘肽（S-D-lactoylglutathione,SLG）,而细胞内SLG含量的增加不利于DNA的生物合成[23,24];继而在Gly II的作用下SLG被水解成D-乳酸[15,23-24],当细胞内的D-乳酸含量超过正常范围之后,其对细胞会产生毒害作用,故需D-乳酸脱氢酶进行及时分解生成丙酮酸,最后通过乙酰辅酶A催化进入三羧酸（TCA）循环（图2）,与此同时重新生成的GSH进入Gly I催化的第一步反应中被循环利用[12,15]。图3
新窗口打开|下载原图ZIP|生成PPT图3植物体内丙酮醛降解过程
Fig. 3A diagrammatic representation of methylglyoxal (MG) detoxification in plants
在植物细胞中,Gly途径存在于细胞质和细胞器中,在植物的叶绿体和线粒体中发现高水平的乙二醛酶活性,Gly I被认为是MG分解过程中的关键酶,其活性程度会直接影响MG浓度的高低[25]。GHOSH等[26]在植物中检测到一种新型乙二醛酶—Gly III,其发现为植物体内MG分解提供了更短的途径。常规的乙二醛酶（Gly I和Gly II）在GSH的帮助下将MG转化为D-乳酸,而Gly III含有DJ-1/PfpI结构域,能够在一步不可逆反应中将MG转化为D-乳酸,而不需要GSH（图3）,在单子叶植物、双子叶植物、石松类植物、裸子植物和苔藓植物中均检测到Gly III的存在[26]。
除了乙二醛酶系统外,其他几种途径也有利于植物体内MG的分解。依赖于NADPH的丙酮醛还原酶可以直接将MG还原成乳醛。依赖于NADPH的醛酮还原酶（Aldo-keto reductases,AKRs）和甘油脱氢酶可将MG还原成相应的醇[27,28]。最后一条途径是丙酮醛脱氢酶催化MG形成丙酮酸。在正常生理条件下,Gly系统是植物中最有效的MG分解系统[26],并且该途径对于非生物胁迫下植物来说非常重要。
3 非生物胁迫下植物体内丙酮醛代谢
3.1 非生物胁迫下丙酮醛的含量变化
在正常生理条件下,植物中MG保持低水平（30—75 μmol·L-1）[18],如水稻中的浓度约为2 μmol·g-1鲜重[12]。然而当植物受到非生物胁迫时,MG含量可以瞬间升高（表1）,据不完全统计,与各自的对照组相比,盐胁迫可使绿豆幼苗叶片内的MG含量升高74%—109%[29,30],玉米幼苗叶片内的MG含量可以升高2.41—2.36倍[31];重金属胁迫导致绿豆叶片内MG含量升高了86%—132%[32,33],水稻幼苗叶片内的MG含量较对照升高了22%—84%[34,35,36,37],豌豆幼苗叶片内MG含量较对照增加了20%—32%[38];碱胁迫导致玉米幼苗叶片内MG含量增加了27%—56%[39];干旱胁迫导致绿豆幼苗叶片内的MG含量较对照增加了90%—107%[40];高温胁迫导致绿豆幼苗叶片内的MG含量较对照增加了66%—91%[41]。虽有部分参考文献中尚未检测出MG含量[42,43,44,45,46,47,48,49,50,51],但多数参考文献的研究结果表明,植物体内MG含量的增加是植物对各种非生物胁迫的常见反应,并且随着胁迫程度的增加以及胁迫时间的延长,植物叶片内的MG含量逐渐升高[29-41,52-54]。Table 1
表1
表1非生物胁迫对植物体内丙酮醛含量和乙二醛酶系统的影响
Table 1
| 植物 Plant species | 胁迫类型 Types of stress | 丙酮醛浓度 Concentration of MG | 乙二醛酶活性 Glyoxalase activity | 文献来源 Reference |
|---|---|---|---|---|
| 油菜籽 Rapeseed (Brassica napus L.) | 盐胁迫 NaCl stress | ND | Gly I ↓; Gly II ↓ | [45] |
| 镉胁迫 Cadmium stress | [15,46] | |||
| 干旱 Drought | Gly I ↑; Gly II ↓ | [24] | ||
| 小麦 Wheat (Triticum aestivum L.) | 高温 Heat | ND | Gly I ↑; Gly II ↑ | [47] |
| 盐胁迫 NaCl stress | Gly I ↓; Gly II ↓ | [44] | ||
| 砷胁迫 Arsenic stress | [48] | |||
| 绿豆 Mung bean (Vigna radiata L.) | 低温胁迫 Chilling stress | ↑ | Gly I ↑; Gly II ↓ | [49] |
| 铝胁迫 Aluminum stress | [33] | |||
| 干旱或/和高温 Drought or/and heat | [16] | |||
| Gly I ↓; Gly II ↑ (High temperature) | [41] | |||
| Gly I ↑; Gly II ↑ (Drought) | [40] | |||
| 盐胁迫 Salt stress | ND | Gly I ↑; Gly II ↑ | [50] | |
| ↑ | Gly I ↓; Gly II ↓ | [29,30] | ||
| 镉胁迫 Cadmium stress | ND | Gly I ↑; Gly II ↓ | [51] | |
| ↑ | [32] | |||
| 水稻 Rice (Oryza sativa L.) | 盐胁迫 Salt stress | ND | Gly I ↓; Gly II ↓ | [42] |
| Gly I ↓; Gly II ↑ | [43] | |||
↑ | Gly I ↑; Gly II ↑ | [52-53] | ||
| 镉胁迫 Cadmium stress | Gly I ↑; Gly II ↓ | [54] | ||
| Gly I ↑; Gly II ↓ | [34] | |||
| Gly I ↑; Gly II ↑ | [35] | |||
| 砷胁迫 Arsenic stress | Gly I ↓; Gly II ↑ | [36] | ||
| 铜胁迫 Copper stress | Gly I ↑; Gly II ↑ | [37] | ||
| 豌豆 Pea (Pisum sativum L.) | 镉胁迫 Cadmium stress | ↑ | Gly I ↑; Gly II ↓ | [38] |
| 玉米 Maize (Zea mays L.) | 碱胁迫 Alkaline stress | ↑ | Gly I ↓; Gly II ↓ | [39] |
| 盐胁迫 Salt stress | Gly I ↑; Gly II ↓ | [31] |
新窗口打开|下载CSV
3.2 非生物胁迫下丙酮醛对植株的危害
非生物胁迫导致植物体内活性氧类物质（ROS）含量迅速升高已是不争的事实[1,2,3]。那么非生物胁迫下,植物体内MG与ROS之间又有怎样的关系呢?KAUR等[55]报道,非生物胁迫导致植物细胞中MG含量升高时,会直接加快ROS的生成,或间接促进高级糖基化终产物（AGEs）的积累而使ROS含量增加。MAETA等[56]认为ROS产生的增加可能与MG积累有关,一方面非生物胁迫下MG积累会降低GSH含量,破坏氧化应激下植物体内的抗氧化酶功能而间接导致ROS产量增加;另一方面MG可以作为希尔氧化剂（Hill oxidant）起催化作用,使光系统I（PSI）中的O2成为超氧阴离子（$\text{O}_{2}^{{\bar{.}}}$）,而$\text{O}_{2}^{{\bar{.}}}$的产生是有害的,可能导致细胞成分的氧化损伤[57]。0.5—10 mmol·L-1的MG喷施于烟草植株会导致其体内抗氧化酶（谷胱甘肽-S-转移酶和抗坏血酸过氧化物酶）的活性降低,致使植株发生氧化应激反应[58,59]。此外,SAITO等[57]也证明了MG在光合作用中可以诱导叶绿体产生$\text{O}_{2}^{{\bar{.}}}$。当植物体内MG含量超过最适浓度时,MG对植物细胞产生高度毒性,抑制细胞增殖[12],在缺乏足够的保护机制情况下,MG易与DNA、RNA和蛋白质等大分子反应并修饰大分子,从而形成AGEs [12,55,60],例如MG的醛基可与植物体内蛋白质的氨基之间发生非酶性糖基化反应,形成一系列具有高度异质性和高度活性的终产物,从而导致蛋白质功能失活和/或降解以及无法修复的代谢功能障碍和细胞死亡[61]。MG与DNA的脱氧鸟苷残基以及精氨酸的胍基反应形成AGEs,这些AGEs会破坏植物体内的抗氧化防御系统[18],THORNALLEY等[23]认为MG衍生的修饰既可以与DNA和/或RNA进行直接的相互作用,也可以通过修饰参与多种生物途径的蛋白质活性实现间接作用。
此外,胁迫诱导的MG作为毒性分子起作用,抑制不同的发育过程,包括种子萌发[18,62]、根生长[63]和光合作用[57,64-65]等,如MANO等[64]发现,MG对菠菜叶绿体的光合作用具有毒性,缺少TPI质体同种型的pdtpi突变体中,MG的积累会延缓菠菜的生长发育,增加萎黄症的发生[65]。此外,SAITO等[57]还发现,向叶绿体中添加MG可刺激类囊体膜中的光合电子传递,诱导叶绿体中$\text{O}_{2}^{{\bar{.}}}$的产生,从而抑制植物的光合作用。盐胁迫导致烟草叶片内MG的积累会抑制其种子萌发和幼苗的生长[18];HOQUE等[62]发现低于0.1 mmol·L-1的MG溶液对拟南芥种子萌发没有影响,但却会降低根的伸长率,培养拟南芥的MS培养基补充1 mmol·L-1的MG会对根系生长产生不利的影响[63,66],并存在剂量依赖性,随MG浓度的增加其抑制效果明显增强,当培养基中的MG浓度超过1 mmol·L-1后,随培养时间的延长幼苗逐渐褪绿出现白化现象。
3.3 非生物胁迫下乙二醛酶系统的变化
乙二醛酶途径的存在可以限制非生物胁迫下细胞内MG的积累,来抵抗MG过度产生的不利影响。大量研究发现,低水平的MG作为重要的信号分子,通过传播和放大细胞信号进而促进植物对非生物胁迫生长的适应性,还参与调节多种事件,例如细胞增殖和存活、控制细胞的氧化还原状态以及一般代谢和细胞稳态等许多其他方面[12,18,55]。为了使MG真正起特定信号分子的作用,必须存在一种机制来检测其在细胞中的含量变化情况,这可以通过MG介导的蛋白质中半胱氨酸残基的可逆修饰来实现[60],这种氧化还原调节反过来还可以改变蛋白质构象,从而触发细胞反应[12]。MAPKs是植物体内响应各种环境胁迫的信号分子,KAUR等[12]认为MAPKs级联途径能够将多种胁迫信号逐级放大、传递给靶蛋白,这可能是植物对MG胁迫耐受性的原因。通过施用不同浓度MG处理水稻幼苗发现,随着MG浓度的增加,幼苗的根长和株高受到抑制,当浓度高于10 mmol·L-1时抑制效果显著。KAUR等[12]为了深入了解MG反应的分子基础,使用GeneChip微阵列研究发现,MG可以作为一个信号分子,诱导信号转导基因和转录因子的表达,后者参与调节各种细胞过程,如代谢、运输、防御反应和蛋白质降解等。利用计算机分析,KAUR等[12]在MG响应基因的上游区域中鉴定了保守基序作为MG响应元件（MGRE）并提供了推定的MGRE序列（CTXXCTC和GGCGGCGX）。此外,CHO等[67]还发现MG可以诱导参与代谢信号传导的基因表达,如SnRK1型激酶,该基因编码一种能量传感器蛋白,该蛋白可以在消耗植物体内的能量时调节基因的表达。MG影响应激反应信号网络的能力凸显了MG在植物胁迫反应中的重要性。因此,MG和乙二醛酶现在被认为是评估植物非生物胁迫耐受性的潜在生物化学标记,并且正受到科学界的关注。乙二醛酶系统涉及各种细胞功能,但是该系统参与植物非生物胁迫反应,提高植物对非生物胁迫耐受性被认为是其最重要的作用[12]。非生物胁迫下,乙二醛酶系统可以减少MG的积累以及促进GSH的再生,GSH含量的增加以及GSH/GSSG比值的升高可以保护植物免受氧化应激,因为GSH可以直接或间接地促进各种抗氧化酶的活性,如谷胱甘肽过氧化物酶（GPX）、谷胱甘肽S-转移酶（GST）、抗坏血酸过氧化酶（APX）等。许多研究表明,非生物胁迫下植物中抗氧化剂和乙二醛酶系统之间存在密切联系,这表明乙二醛酶系统对ROS解毒的间接影响[18,43,68]。
各物种转录组和蛋白质组学的研究分析提高了我们对非生物胁迫下乙二醛酶系统的认识和理解[69,70,71],已经从各种植物中克隆了乙二醛酶基因（Gly I和GlyII）并进行了详细的表征描述。非生物胁迫下,植物体内的Gly I和Gly II基因表达量明显上调,Gly I和Gly II基因的超表达促进了Gly I和Gly II酶活性的增强（表2）,进而提高了植物对非生物胁迫的耐受性[70]。乙二醛酶基因超表达的转基因植物在非生物胁迫下具有较低的MG和ROS水平,因为它们具有更好的GSH稳态,并保留了更强的抗氧化酶功能。
Table 2
表2
表2转基因植物中乙二醛酶基因的过表达提高了植物的非生物胁迫耐受性
Table 2
| 基因 Gene | 植物种类 Plant species | 胁迫表现 Response phenotype | 参考文献 Reference |
|---|---|---|---|
| Gly I | 烟草 Tobacco (Nicotiana tabacum) | 提高植物的耐盐性 Improved salt stress tolerance | [18,72-73] |
| 黑棘豆 Black gram (Vigna mungo) | [74] | ||
| 拟南芥 (Arabidopsis thaliana) | [75] | ||
| 水稻 Rice (Oryza sativa) | [76] | ||
| 小麦 Wheat (Triticum aestivum L.) | 提高植物的耐锌性 Improved zinc tolerance | [77] | |
| Gly II | 水稻 Rice (Oryza sativa) | 提高植物的耐盐性 Improved salt stress tolerance | [78-79] |
| 芥菜 Mustard (Beassica juncea) | [80] | ||
| 烟草 Tobacco (Nicotiana tabacum) | [81] | ||
| 拟南芥 (Arabidopsis thaliana) | 提高植物的耐盐和淹水性 Improved salt and anoxic stress tolerance | [82] | |
| Gly I + Gly II | 烟草 Tobacco (Nicotiana tabacum) | 提高植物的耐盐性 Improved salt stress tolerance | [83-84] |
| 西红柿 Tomato (Solanum lycopersicum Mill.) | [85] |
新窗口打开|下载CSV
4 展望
非生物胁迫会伴随着植物的整个生长发育过程,严重威胁到了植物的分布、生长、品质和产量,甚至生存。最近对丙酮醛（MG）代谢的研究已经揭示了MG与植物非生物胁迫反应和耐受性有关的许多重要功能。非生物胁迫下,植物体内MG的过度积累是不可避免,但MG可以刺激不同胁迫保护途径的组分,被认为是植物对非生物胁迫的适应过程。乙二醛酶途径通过清除MG赋予了植物对多种非生物胁迫的耐受性,因此,MG水平和乙二醛酶途径与植物的非生物胁迫耐受性密切相关,在今后研究植物非生物胁迫耐受性方面,应该更加注重MG的代谢情况。参考文献 原文顺序
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被引期刊影响因子
DOI:10.1016/j.plaphy.2010.08.016URL [本文引用: 3]
Abstract
Various abiotic stresses lead to the overproduction of reactive oxygen species (ROS) in plants which are highly reactive and toxic and cause damage to proteins, lipids, carbohydrates and DNA which ultimately results in oxidative stress. The ROS comprises both free radical (O2
−, superoxide radicals; OH, hydroxyl radical; HO2, perhydroxy radical and RO, alkoxy radicals) and non-radical (molecular) forms (H2O2, hydrogen peroxide and 1O2, singlet oxygen). In chloroplasts, photosystem I and II (PSI and PSII) are the major sites for the production of 1O2 and O2−. In mitochondria, complex I, ubiquinone and complex III of electron transport chain (ETC) are the major sites for the generation of O2−. The antioxidant defense machinery protects plants against oxidative stress damages. Plants possess very efficient enzymatic (superoxide dismutase, SOD; catalase, CAT; ascorbate peroxidase, APX; glutathione reductase, GR; monodehydroascorbate reductase, MDHAR; dehydroascorbate reductase, DHAR; glutathione peroxidase, GPX; guaicol peroxidase, GOPX and glutathione-S- transferase, GST) and non-enzymatic (ascorbic acid, ASH; glutathione, GSH; phenolic compounds, alkaloids, non-protein amino acids and α-tocopherols) antioxidant defense systems which work in concert to control the cascades of uncontrolled oxidation and protect plant cells from oxidative damage by scavenging of ROS. ROS also influence the expression of a number of genes and therefore control the many processes like growth, cell cycle, programmed cell death (PCD), abiotic stress responses, pathogen defense, systemic signaling and development. In this review, we describe the biochemistry of ROS and their production sites, and ROS scavenging antioxidant defense machinery.Research highlights
? Various abiotic stresses lead to the overproduction of reactive oxygen species (ROS) in plants which are highly reactive and toxic and cause damage to proteins, lipids, carbohydrates, DNA which ultimately results in oxidative stress. ? The antioxidant defense machinery protects plants against oxidative stress damages. ? Plants possess very efficient enzymatic (superoxide dismutase, SOD; catalase, CAT; ascorbate peroxidase, APX; glutathione reductase, GR; monodehydroascorbate reductase, MDHAR; dehydroascorbate reductase, DHAR; glutathione peroxidase, GPX; guaicol peroxidase, GOPX and glutathione-S- transferase, GST) and non-enzymatic (ascorbic acid, ASH; glutathione, GSH; phenolic compounds, alkaloids, non-protein amino acids and α-tocopherols) antioxidant defense systems which work in concert to control the cascades of uncontrolled oxidation and protect plant cells from oxidative damage by scavenging of ROS. ? ROS also influence the expression of a number of genes and therefore control the many processes like growth, cell cycle, programmed cell death (PCD), abiotic stress responses, pathogen defense, systemic signaling and development. In this review, we describe the biochemistry of ROS and their production sites, and ROS scavenging antioxidant defense machinery.[本文引用: 2]
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DOI:10.3724/SP.J.1123.2013.10011URL [本文引用: 1]
An HPLC method was developed for the determination of methylglyoxal in Manuka honey of New Zealand. The honey sample was dissolved in water and mixed with o-phenylenediamine solution for derivatization. After the reaction for at least 8 h in the dark at room temperature, the solution was filtered with 0.22 μm membrane and injected into an HPLC system for analysis. The separation was carried out on a Kromasil reversed phase column with gradient elution. The mobile phases were methanol and 0.1% (v/v) acetic acid aqueous solution. The detection wavelength was 318 nm. The external standard method was used for quantitation. The linear range of methylglyoxal was 1-50 mg/L with a correlation coefficient of 0.9999. The LOD (S/N=3) and LOQ (S/N=10) were 0.02 mg/L and 0.06 mg/L, respectively. The recoveries at the spiked levels of 50, 100, 200 mg/kg were 98.3%-101.5% and the RSDs (n=5) were less than 5%. The derivative of methylglyoxal was stable within 24 h. The results showed that the pretreatment of this method is simple and the sensitivity, the recovery and repeatability are good. This method can be used for the quality control of Manuka honey of New Zealand, and also for the detection of methylglyoxal in Chinese honey.
DOI:10.3724/SP.J.1123.2013.10011URL [本文引用: 1]
An HPLC method was developed for the determination of methylglyoxal in Manuka honey of New Zealand. The honey sample was dissolved in water and mixed with o-phenylenediamine solution for derivatization. After the reaction for at least 8 h in the dark at room temperature, the solution was filtered with 0.22 μm membrane and injected into an HPLC system for analysis. The separation was carried out on a Kromasil reversed phase column with gradient elution. The mobile phases were methanol and 0.1% (v/v) acetic acid aqueous solution. The detection wavelength was 318 nm. The external standard method was used for quantitation. The linear range of methylglyoxal was 1-50 mg/L with a correlation coefficient of 0.9999. The LOD (S/N=3) and LOQ (S/N=10) were 0.02 mg/L and 0.06 mg/L, respectively. The recoveries at the spiked levels of 50, 100, 200 mg/kg were 98.3%-101.5% and the RSDs (n=5) were less than 5%. The derivative of methylglyoxal was stable within 24 h. The results showed that the pretreatment of this method is simple and the sensitivity, the recovery and repeatability are good. This method can be used for the quality control of Manuka honey of New Zealand, and also for the detection of methylglyoxal in Chinese honey.
DOI:10.1002/mnfr.200700282URLPMID:18210383 [本文引用: 1]
The 1,2-dicarbonyl compounds 3-deoxyglucosulose (3-DG), glyoxal (GO), and methylglyoxal (MGO) were measured as the corresponding quinoxalines after derivatization with orthophenylendiamine using RP-HPLC and UV-detection in commercially available honey samples. Whereas for most of the samples values for 3-DG, MGO, and GO were comparable to previously published data, for six samples of New Zealand Manuka (Leptospermum scoparium) honey very high amounts of MGO were found, ranging from 38 to 761 mg/kg, which is up to 100-fold higher compared to conventional honeys. MGO was unambigously identified as the corresponding quinoxaline via photodiodearry detection as well as by means of mass spectroscopy. Antibacterial activity of honey and solutions of 1,2-dicarbonyl towards Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) were analyzed using an agar well diffusion assay. Minimum concentrations needed for inhibition of bacterial growth (minimum inhibitory concentration, MIC) of MGO were 1.1 mM for both types of bacteria. MIC for GO was 6.9 mM (E. coli) or 4.3 mM (S. aureus), respectively. 3-DG showed no inhibition in concentrations up to 60 mM. Whereas most of the honey samples investigated showed no inhibition in dilutions of 80% (v/v with water) or below, the samples of Manuka honey exhibited antibacterial activity when diluted to 15-30%, which corresponded to MGO concentrations of 1.1-1.8 mM. This clearly demonstrates that the pronounced antibacterial activity of New Zealand Manuka honey directly originates from MGO.
URL [本文引用: 1]
A method for detecting 14 mono- and 2 dicarbonyl compounds in one run was established. The carbonyls were collected on solid sorbent (Tenax-TA) coated with derivating agent O-(2,3,4,5,6-Pentafluorobenzyl) hydroxylamine hydrochloride (PFBHA), followed by solvent desorption, concentration and gas chromatography/mass spectrometry analysis. The coating amount and the sampling flow rate were optimized. The results showed that the best collection efficiency was achieved when the coating amount was 260 nmol and the sampling flow rate was 50 mL·min-1 for a loading of 50 mg Tenax-TA. The limits of detection were in the range of 0.54~3.83 ng·m-3. The relative standard deviations of parallel samples were 1.0%~14.2% and the recoveries of the spiked standards were 89.2%~113.8%. The time resolution could be 30 min to 8 h for ambient air sampling. The method was successfully applied to measure 16 mono- and dicarbonyls in the ambient air of Baoshan District of Shanghai and the detected carbonyls have significant diurnal variation.
URL [本文引用: 1]
A method for detecting 14 mono- and 2 dicarbonyl compounds in one run was established. The carbonyls were collected on solid sorbent (Tenax-TA) coated with derivating agent O-(2,3,4,5,6-Pentafluorobenzyl) hydroxylamine hydrochloride (PFBHA), followed by solvent desorption, concentration and gas chromatography/mass spectrometry analysis. The coating amount and the sampling flow rate were optimized. The results showed that the best collection efficiency was achieved when the coating amount was 260 nmol and the sampling flow rate was 50 mL·min-1 for a loading of 50 mg Tenax-TA. The limits of detection were in the range of 0.54~3.83 ng·m-3. The relative standard deviations of parallel samples were 1.0%~14.2% and the recoveries of the spiked standards were 89.2%~113.8%. The time resolution could be 30 min to 8 h for ambient air sampling. The method was successfully applied to measure 16 mono- and dicarbonyls in the ambient air of Baoshan District of Shanghai and the detected carbonyls have significant diurnal variation.
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DOI:10.1042/bst0210549URLPMID:8359530 [本文引用: 1]
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DOI:10.1007/s00709-016-0965-zURLPMID:27032937 [本文引用: 2]
High temperature and drought stress often occur simultaneously, and due to global climate change, this kind of phenomenon occurs more frequently and severely, which exerts devastating effects on plants. Polyamines (PAs) play crucial roles in conferring abiotic stress tolerance in plants. Present study investigated how exogenous pretreatment of spermine (Spm, 0.2 mM) enhances mung bean (Vigna radiata L. cv. BARI Mung-2) seedlings tolerance to high temperature (HT, 40 degrees C) and drought [induced by 5 % polyethyleneglycol (PEG)] stress individually and in combination. Spm pretreatment reduced reactive oxygen species (ROS) production including H2O2 and O2(*-), lipoxygenase (LOX) activity, and membrane lipid peroxidation (indicated by malondialdehyde, MDA) under HT and/or drought stress. Histochemical staining of leaves with diaminobenzidine and nitro blue tetrazolium chloride also confirmed that Spm-pretreated seedlings accumulated less H2O2 and O2(*-) under HT and/or drought stress. Spermine pretreatment maintained the ascorbate (AsA) and glutathione (GSH) levels high, and upregulated the activities of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPX), dehydroascorbate reductase (DHAR), and glutathione reductase (GR) which were vital for imparting ROS-induced oxidative stress tolerance under HT and/or drought stress. The cytotoxic compound methylglyoxal (MG) was overproduced due to HT and/or drought, but exogenous Spm pretreatment reduced MG toxicity enhancing the glyoxalase system. Spermine pretreatment modulated endogenous PA levels. Osmoregulation and restoration of plant water status were other major contributions of Spm under HT and/or drought stress. Preventing photosynthetic pigments and improving seedling growth parameters, Spm further confirmed its influential roles in HT and/or drought tolerance.
DOI:10.1007/BF00020464URLPMID:8616220 [本文引用: 1]
A cDNA, GLX1, encoding glyoxalase-I was isolated by differential screening of salt-induced genes in tomato. Glyoxalases-I and -II are ubiquitous enzymes whose functions are not clearly understood. They may serve to detoxify methylglyoxal produced from triosephosphates in all cells. The protein encoded by GLX1 shared 49.4% and 58.5% identity with glyoxalase-I isolated from bacteria and human, respectively. Furthermore, yeast cells expressing GLX1 showed a glyoxalase-I specific activity 20-fold higher than non-transformed cells. Both GLX1 mRNA and glyoxalase-I polypeptide levels increased 2- to 3-fold in roots, stems and leaves of plants treated with either NaCl, mannitol, or abscisic acid. Immunohistochemical localization indicated that glyoxalase-I was expressed in all cell types, with preferential accumulation in phloem sieve elements. This expression pattern was not appreciably altered by salt-stress. We suggest that the increased expression of glyoxalase-I may be linked to a higher demand for ATP generation and to enhanced glycolysis in salt-stressed plants.
DOI:10.1016/j.bbrc.2005.08.263URLPMID:16176800 [本文引用: 8]
Methylglyoxal (MG), a cytotoxic by-product produced mainly from triose phosphates, is used as a substrate by glyoxalase I. In this paper, we report on the estimation of MG level in plants which has not been reported earlier. We show that MG concentration varies in the range of 30-75 microM in various plant species and it increases 2- to 6-fold in response to salinity, drought, and cold stress conditions. Transgenic tobacco underexpressing glyoxalase I showed enhanced accumulation of MG which resulted in the inhibition of seed germination. In the glyoxalase I overexpressing transgenic tobacco, MG levels did not increase in response to stress compared to the untransformed plants, however, with the addition of exogenous GSH there was a decrease in MG levels in both untransformed and transgenic plants. The exogenous application of GSH reduced MG levels in WT to 50% whereas in the transgenic plants a 5-fold decrease was observed. These studies demonstrate an important role of glyoxalase I along with GSH concentration in maintaining MG levels in plants under normal and abiotic stress conditions.
DOI:10.1111/j.1432-1033.1993.tb17638.xURLPMID:8444148 [本文引用: 1]
In Krebs-Ringer phosphate buffer, the rate of formation of methylglyoxal from glycerone phosphate and glyceraldehyde 3-phosphate was first order with respect to the triose phosphate with rates constant values of 1.94 +/- 0.02 x 10(-5) s-1 (n = 18) and 1.54 +/- 0.02 x 10(-4) s-1 (n = 18) at 37 degrees C, respectively. The rate of formation of methylglyoxal from glycerone phosphate and glyceraldehyde 3-phosphate in the presence of red blood cell lysate was not significantly different from the non-enzymatic value (P > 0.05). Methylglyoxal formation from glycerone phosphate was increased in the presence of triose phosphate isomerase but this may be due to the faster non-enzymatic formation from the glyceraldehyde 3-phosphate isomerisation product. For red blood cells in vitro, the predicted non-enzymatic rate of formation of methylglyoxal from glycerone phosphate and glyceraldehyde 3-phosphate may account for the metabolic flux through the glyoxalase system. The reactivity of glycerone phosphate and glyceraldehyde 3-phosphate towards the non-enzymatic formation of methylglyoxal under physiological conditions suggests that methylglyoxal formation is unavoidable from the Embden-Meyerhof pathway.
DOI:10.1021/bi00465a005URLPMID:2185832 [本文引用: 1]
The function of the mobile loop of triosephosphate isomerase has been investigated by deleting four contiguous residues from the part of this loop that interacts directly with the bound substrate. From the crystal structure of the wild-type enzyme, it appears that this excision will not significantly alter the conformation of the rest of the main chain of the protein. The specific catalytic activity of the purified mutant enzyme is nearly 10(5)-fold lower than that of the wild type. Kinetic measurements and isotopic partitioning studies show that the decrease in activity is due to much higher activation barriers for the enolization of enzyme-bound substrate. Although the substrates bind somewhat more weakly to the mutant enzyme than to the wild type, the intermediate analogue phosphoglycolohydroxamate binds much less well (by 200-fold) to the mutant. It seems that the deleted residues of the loop contribute critically to the stabilization of the enediol phosphate intermediate. Consistent with this view, the mutant enzyme can no longer prevent the loss of the enediol phosphate from the active site and its rapid decomposition to methylglyoxal and inorganic phosphate. Indeed, when glyceraldehyde 3-phosphate is the substrate, the enediol phosphate intermediate is lost (and decomposes) 5.5 times faster than it reprotonates to form the product dihydroxyacetone phosphate.(ABSTRACT TRUNCATED AT 250 WORDS)
DOI:10.3109/10715762.2013.815348URL [本文引用: 1]
DOI:10.1016/s0378-4274(99)00160-5URLPMID:10597025 [本文引用: 2]
Despite the growing interest towards methylglyoxal and glyoxalases their real role in metabolic network is still obscure. In the light of developments several reviews have been published in this field mainly dealing with only a narrow segment of this research area. In this article a trial is made to present a comprehensive overview of methylglyoxal research, extending discussion from chemistry to biological implications by reviewing some important characteristics of methylglyoxal metabolism and toxicity in a wide variety of species, and emphasizing the action of methylglyoxal on energy production, free radical generation and cell killing. Special attention is paid to the discussion of alpha-oxoaldehyde production in the environment as a potential risk factor and to the possible role of this a-dicarbonyl in diseases. Concerning the interaction of methylglyoxal with biological macromolecules (DNA, RNA, proteins) an earlier review (Kalapos, Toxicology Letters, 73, 1994, 3-24) means a supplementation to this paper, thus hoping the avoidance of unnecessary bombast. The paper arrives at the conclusion that since the early stage of evolution the function of methylglyoxalase pathway has been related to carbohydrate metabolism, but its significance has been changed over the thousands of years. Namely, at the beginning of evolution methylglyoxalase path was essential for the reductive citric acid cycle as an anaplerotic route, while in the extant metabolism it concerns with the detoxification of methylglyoxal and plays some regulatory role in triose-phosphate household. As there is a tight junction between methylglyoxal and carbohydrate metabolism its pathological role in the events of the development of diabetic complications emerges in a natural manner and further progress is hoped in this field. In contrast, significant advancement cannot be expected in relation to cancer research.
DOI:10.1016/0306-3623(95)02054-3URLPMID:8853285 [本文引用: 3]
1. Methylglyoxal is a reactive alpha-oxoaldehyde and physiological metabolite formed by the fragmentation of triose-phosphates, and by the metabolism of acetone and aminoacetone. 2. Methylglyoxal modifies guanylate residues to form 6,7-dihydro-6,7-dihydroxy-6-methyl-imidazo[2,3-b]purine-9(8)one and N2-(1-carboxyethyl)guanylate residues and induces apoptosis. 3. Methylglyoxal modifies arginine residues in proteins to form N(delta)-(4,5-dihydroxy-4-methylimidazolidin-2-yl) ornithine, N(delta)-(5-hydro-5-methylimidazol-4-on-2-yl)ornithine and N(delta)-(5)methylimidazol-4-on-2-yl)ornithine residues. 4. Methylglyoxal-modified proteins undergo receptor-mediated endocytosis and lysosomal degradation in monocytes and macrophages, and induce cytokine synthesis and secretion. 5. Methylglyoxal is detoxified by the glyoxalase system. Decreased detoxification of methylglyoxal may be induced pharmacologically by glyoxalase I inhibitors which have anti-tumor and anti-malarial activities. 6. The modification of nucleic acids and protein by methylglyoxal is a signal for their degradation and may have a role in the development of diabetic complications, atherosclerosis, the immune response in starvation, aging and oxidative stress.
DOI:10.1007/s12011-011-8998-9URL [本文引用: 2]
In order to observe the possible regulatory role of selenium (Se) in relation to the changes in ascorbate (AsA) glutathione (GSH) levels and to the activities of antioxidant and glyoxalase pathway enzymes, rapeseed (Brassica napus) seedlings were grown in Petri dishes. A set of 10-day-old seedlings was pretreated with 25 mu M Se (Sodium selenate) for 48 h. Two levels of drought stress (10% and 20% PEG) were imposed separately as well as on Se-pretreated seedlings, which were grown for another 48 h. Drought stress, at any level, caused a significant increase in GSH and glutathione disulfide (GSSG) content; however, the AsA content increased only under mild stress. The activity of ascorbate peroxidase (APX) was not affected by drought stress. The monodehydroascorbate reductase (MDHAR) and glutathione reductase (GR) activity increased only under mild stress (10% PEG). The activity of dehydroascorbate reductase (DHAR), glutathione S-transferase (GST), glutathione peroxidase (GPX), and glyoxalase I (Gly I) activity significantly increased under any level of drought stress, while catalase (CAT) and glyoxalase II (Gly II) activity decreased. A sharp increase in hydrogen peroxide (H(2)O(2)) and lipid peroxidation (MDA content) was induced by drought stress. On the other hand, Se-pretreated seedlings exposed to drought stress showed a rise in AsA and GSH content, maintained a high GSH/GSSG ratio, and evidenced increased activities of APX, DHAR, MDHAR, GR, GST, GPX, CAT, Gly I, and Gly II as compared with the drought-stressed plants without Se. These seedlings showed a concomitant decrease in GSSG content, H(2)O(2), and the level of lipid peroxidation. The results indicate that the exogenous application of Se increased the tolerance of the plants to drought-induced oxidative damage by enhancing their antioxidant defense and methylglyoxal detoxification systems.
DOI:10.1007/s00726-010-0783-0URL [本文引用: 1]
Methylglyoxal (MG) is a potent protein glycating agent. Glycation is directed to guanidino groups of arginine residues forming mainly hydroimidazolone N (delta)-(5-hydro-5-methyl-4-imidazolon-2-yl)-ornithine (MG-H1) residues. MG-H1 formation is damaging to the proteome as modification is often directed to functionally important arginine residues. MG-H1 content of proteins is quantified by stable isotopic dilution analysis tandem mass spectrometry and also by immunoblotting with specific monoclonal antibodies. MG-glycated proteins undergo cellular proteolysis and release MG-H1 free adduct for excretion. MG-H1 residues have been found in proteins of animals, plants, bacteria, fungi and protoctista. MG-H1 is often the major advanced glycation endproduct in proteins of tissues and body fluids, increasing in diabetes and associated vascular complications, renal failure, cirrhosis, Alzheimer's disease, arthritis, Parkinson's disease and ageing. Glyoxalase 1 and aldo-keto reductase 1B1 metabolise > 99% MG to innocuous products and thereby protect the proteome, providing an enzymatic defence against MG-mediated glycation. Proteins susceptible to MG modification with related functional impairment are called the "dicarbonyl proteome" (DCP). DCP includes albumin, haemoglobin, transcription factors, mitochondrial proteins, extracellular matrix proteins, lens crystallins and other proteins. DCP component proteins are linked to mitochondrial dysfunction in diabetes and ageing, oxidative stress, dyslipidemia, cell detachment and anoikis and apoptosis. Biochemical and physiological susceptibility of a protein to modification by MG and sensitivity of biochemical pathways and physiological systems to related functional impairment under challenge of physiologically relevant increases in MG exposure are key concepts. Improved understanding of the DCP will likely have profound importance for human health, longevity and treatment of disease.
DOI:10.1038/srep18358URL [本文引用: 3]
DOI:10.1074/jbc.M110.202226URL [本文引用: 1]
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DOI:10.1007/s10535-015-0542-xURL [本文引用: 1]
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DOI:10.1016/j.ecoenv.2015.12.026URL [本文引用: 1]
DOI:10.1007/s10646-016-1742-7URLPMID:27819118 [本文引用: 1]
The western honey bee Apis mellifera is the most important managed pollinator species in the world. Multiple factors have been implicated as potential causes or factors contributing to colony collapse disorder, including honey bee pathogens and nutritional deficiencies as well as exposure to pesticides. Honey bees' genome is characterized by a paucity of genes associated with detoxification, which makes them vulnerable to specific pesticides, especially to combinations of pesticides in real field environments. Many studies have investigated the mechanisms involved in detoxification of xenobiotics/pesticides in honey bees, from primal enzyme assays or toxicity bioassays to characterization of transcript gene expression and protein expression in response to xenobiotics/insecticides by using a global transcriptomic or proteomic approach, and even to functional characterizations. The global transcriptomic and proteomic approach allowed us to learn that detoxification mechanisms in honey bees involve multiple genes and pathways along with changes in energy metabolism and cellular stress response. P450 genes, is highly implicated in the direct detoxification of xenobiotics/insecticides in honey bees and their expression can be regulated by honey/pollen constitutes, resulting in the tolerance of honey bees to other xenobiotics or insecticides. P450s is also a key detoxification enzyme that mediate synergism interaction between acaricides/insecticides and fungicides through inhibition P450 activity by fungicides or competition for detoxification enzymes between acaricides. With the wide use of insecticides in agriculture, understanding the detoxification mechanism of insecticides in honey bees and how honeybees fight with the xenobiotis or insecticides to survive in the changing environment will finally benefit honeybees' management.
DOI:10.1007/s40415-015-0240-0URL [本文引用: 1]
DOI:10.1038/srep14078URLPMID:26361343 [本文引用: 1]
We investigated the physiological and biochemical mechanisms by which H2S mitigates the cadmium stress in rice. Results revealed that cadmium exposure resulted in growth inhibition and biomass reduction, which is correlated with the increased uptake of cadmium and depletion of the photosynthetic pigments, leaf water contents, essential minerals, water-soluble proteins, and enzymatic and non-enzymatic antioxidants. Excessive cadmium also potentiated its toxicity by inducing oxidative stress, as evidenced by increased levels of superoxide, hydrogen peroxide, methylglyoxal and malondialdehyde. However, elevating endogenous H2S level improved physiological and biochemical attributes, which was clearly observed in the growth and phenotypes of H2S-treated rice plants under cadmium stress. H2S reduced cadmium-induced oxidative stress, particularly by enhancing redox status and the activities of reactive oxygen species and methylglyoxal detoxifying enzymes. Notably, H2S maintained cadmium and mineral homeostases in roots and leaves of cadmium-stressed plants. By contrast, adding H2S-scavenger hypotaurine abolished the beneficial effect of H2S, further strengthening the clear role of H2S in alleviating cadmium toxicity in rice. Collectively, our findings provide an insight into H2S-induced protective mechanisms of rice exposed to cadmium stress, thus proposing H2S as a potential candidate for managing toxicity of cadmium, and perhaps other heavy metals, in rice and other crops.
DOI:10.1155/2015/340812URLPMID:26798635 [本文引用: 1]
The effect of exogenous calcium (Ca) on hydroponically grown rice seedlings was studied under arsenic (As) stress by investigating the antioxidant and glyoxalase systems. Fourteen-day-old rice (Oryza sativa L. cv. BRRI dhan29) seedlings were exposed to 0.5 and 1 mM Na2HAsO4 alone and in combination with 10 mM CaCl2 (Ca) for 5 days. Both levels of As caused growth inhibition, chlorosis, reduced leaf RWC, and increased As accumulation in the rice seedlings. Both doses of As in growth medium induced oxidative stress through overproduction of reactive oxygen species (ROS) by disrupting the antioxidant defense and glyoxalase systems. Exogenous application of Ca along with both levels of As significantly decreased As accumulation and restored plant growth and water loss. Calcium supplementation in the As-exposed rice seedlings reduced ROS production, increased ascorbate (AsA) content, and increased the activities of monodehydroascorbate reductase (MDHAR), dehydroascorbate reductase (DHAR), catalase (CAT), glutathione peroxidase (GPX), superoxide dismutase (SOD), and the glyoxalase I (Gly I) and glyoxalase II (Gly II) enzymes compared with seedlings exposed to As only. These results suggest that Ca supplementation improves rice seedlings tolerance to As-induced oxidative stress by reducing As uptake, enhancing their antioxidant defense and glyoxalase systems, and also improving growth and physiological condition.
DOI:10.1038/srep11433URLPMID:26073760 [本文引用: 1]
In this study, we examined the possible mechanisms of trehalose (Tre) in improving copper-stress (Cu-stress) tolerance in rice seedlings. Our findings indicated that pretreatment of rice seedlings with Tre enhanced the endogenous Tre level and significantly mitigated the toxic effects of excessive Cu on photosynthesis- and plant growth-related parameters. The improved tolerance induced by Tre could be attributed to its ability to reduce Cu uptake and decrease Cu-induced oxidative damage by lowering the accumulation of reactive oxygen species (ROS) and malondialdehyde in Cu-stressed plants. Tre counteracted the Cu-induced increase in proline and glutathione content, but significantly improved ascorbic acid content and redox status. The activities of major antioxidant enzymes were largely stimulated by Tre pretreatment in rice plants exposed to excessive Cu. Additionally, increased activities of glyoxalases I and II correlated with reduced levels of methylglyoxal in Tre-pretreated Cu-stressed rice plants. These results indicate that modifying the endogenous Tre content by Tre pretreatment improved Cu tolerance in rice plants by inhibiting Cu uptake and regulating the antioxidant and glyoxalase systems, and thereby demonstrated the important role of Tre in mitigating heavy metal toxicity. Our findings provide a solid foundation for developing metal toxicity-tolerant crops by genetic engineering of Tre biosynthesis.
DOI:10.1186/s12870-018-1359-5URLPMID:30012086 [本文引用: 1]
BACKGROUND: This study assessed the effects of 24-epibrassinolide (EBL, 10(-7)M) and silicon (2 mM) on the alleviation of cadmium (Cd, 150 mg L(-1)) toxicity in Pisum sativum L. seedlings via the modulation of growth, antioxidant defense, glyoxalase system, and nutrient uptake. RESULTS: Shoot and root lengths declined by 46.43% and 52.78%, respectively, following Cd stress. Shoot and root dry weights also declined with Cd toxicity. Biochemical and physiological aspects exhibit significant decline including total chlorophyll (33.09%), carotenoid (51.51%), photosynthetic efficiency (32.60%), photochemical quenching (19.04%), leaf relative water content (40.18%), and gas exchange parameters (80.65%). However, EBL or Si supplementation alone or in combination modulates the previously mentioned parameters. Cadmium stress increased proline and glycine betaine (GB) contents by 4.37 and 2.41-fold, respectively. Exposure of plants to Cd stress increased the accumulation of H2O2, malondialdehyde content, electrolyte leakage, and methylglyoxal, which declined significantly with EBL and Si supplementation, both individually and in combination. Similarly, Cd stress adversely affected enzymatic and non-enzymatic antioxidants, but EBL and/or Si supplementation maintained antioxidant levels. Glyoxalase I (GlyI) accumulated after Cd stress and increased further with the application of EBL and Si. However, GlyII content declined after Cd stress but increased with supplementation of EBL and Si. Cadmium accumulation occurred in the following order: roots > shoots>leaves. Supplementation with EBL and Si, individually and in combination reduced Cd accumulation and enhanced the uptake of macronutrients and micronutrients in shoots and roots, which declined with Cd toxicity. CONCLUSION: The application of 24-EBL and Si, individually and in combination, alleviated the adverse effects of Cd by improving growth, biochemical parameters, nutrient uptake, osmolyte accumulation, and the anti-oxidative defense and glyoxalase systems in Pisum sativum seedlings.
DOI:10.1038/s41598-018-21097-3URLPMID:29434207 [本文引用: 1]
Environmental pollution by alkaline salts, such as Na2CO3, is a permanent problem in agriculture. Here, we examined the putative role of jasmonic acid (JA) in improving Na2CO3-stress tolerance in maize seedlings. Pretreatment of maize seedlings with JA was found to significantly mitigate the toxic effects of excessive Na2CO3 on photosynthesis- and plant growth-related parameters. The JA-induced improved tolerance could be attributed to decreased Na uptake and Na2CO3-induced oxidative damage by lowering the accumulation of reactive oxygen species and malondialdehyde. JA counteracted the salt-induced increase in proline and glutathione content, and significantly improved ascorbic acid content and redox status. The major antioxidant enzyme activities were largely stimulated by JA pretreatment in maize plants exposed to excessive alkaline salts. Additionally, increased activities of glyoxalases I and II were correlated with reduced levels of methylglyoxal in JA-pretreated alkaline-stressed maize plants. These results indicated that modifying the endogenous Na(+) and K(+) contents by JA pretreatment improved alkaline tolerance in maize plants by inhibiting Na uptake and regulating the antioxidant and glyoxalase systems, thereby demonstrating the important role of JA in mitigating heavy metal toxicity. Our findings may be useful in the development of alkali stress tolerant crops by genetic engineering of JA biosynthesis.
URLPMID:33442464 [本文引用: 1]
Habitat fragmentation strongly affects the genetic diversity of plant populations, and this has always attracted much research interest. Although numerous studies have investigated the effects of habitat fragmentation on the genetic diversity of plant populations, fewer studies have compared species with contrasting breeding systems while accounting for phylogenetic distance. Here, we compare the levels of genetic diversity and differentiation within and among subpopulations in metapopulations (at fine-scale level) of two closely related Zingiber species, selfing Zingiber corallinum and outcrossing Zingiber nudicarpum. Comparisons of the genetic structure of species from unrelated taxa may be confounded by the effects of correlated ecological traits or/and phylogeny. Thus, we possibly reveal the differences in genetic diversity and spatial distribution of genetic variation within metapopulations that relate to mating systems. Compared to outcrossing Z. nudicarpum, the subpopulation genetic diversity in selfing Z. corallinum was significantly lower, but the metapopulation genetic diversity was not different. Most genetic variation resided among subpopulations in selfing Z. corallinum metapopulations, while a significant portion of variation resided either within or among subpopulations in outcrossing Z. nudicarpum, depending on whether the degree of subpopulation isolation surpasses the dispersal ability of pollen and seed. A stronger spatial genetic structure appeared within subpopulations of selfing Z. corallinum potentially due to restricted pollen flow and seed dispersal. In contrast, a weaker genetic structure was apparent in subpopulations of outcrossing Z. nudicarpum most likely caused by extensive pollen movement. Our study shows that high genetic variation can be maintained within metapopulations of selfing Zingiber species, due to increased genetic differentiation intensified primarily by the stochastic force of genetic drift among subpopulations. Therefore, maintenance of natural variability among subpopulations in fragmented areas is key to conserve the full range of genetic diversity of selfing Zingiber species. For outcrossing Zingiber species, maintenance of large populations is an important factor to enhance genetic diversity. Compared to outcrossing Z. nudicarpum, the subpopulation genetic diversity in selfing Z. corallinum was significantly lower, but the metapopulation genetic diversity did not differ. Most genetic variation resided among subpopulations in selfing Z. corallinum metapopulations, while a significant portion of variation resided either within or among subpopulations in outcrossing Z. nudicarpum, depending on whether the degree of subpopulation isolation surpasses the dispersal ability of pollen and seed. Our study shows that selfing Z. corallinum could maintain high genetic diversity through differentiation intensified primarily by the stochastic force of genetic drift among subpopulations at fine-scale level, but not local adaptation.
DOI:10.1016/j.envexpbot.2014.12.001URL [本文引用: 2]
DOI:10.1007/s00709-010-0144-6URL [本文引用: 1]
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DOI:10.3390/ijms161226220URLPMID:26694373 [本文引用: 1]
The role of exogenous spermidine (Spd) in alleviating low temperature (LT) stress in mung bean (Vigna radiata L. cv. BARI Mung-3) seedlings has been investigated. Low temperature stress modulated the non-enzymatic and enzymatic components of ascorbate-glutathione (AsA-GSH) cycle, increased H(2)O(2) content and lipid peroxidation, which indicate oxidative damage of seedlings. Low temperature reduced the leaf relative water content (RWC) and destroyed leaf chlorophyll, which inhibited seedlings growth. Exogenous pretreatment of Spd in LT-affected seedlings significantly increased the contents of non-enzymatic antioxidants of AsA-GSH cycle, which include AsA and GSH. Exogenous Spd decreased dehydroascorbate (DHA), increased AsA/DHA ratio, decreased glutathione disulfide (GSSG) and increased GSH/GSSG ratio under LT stress. Activities of AsA-GSH cycle enzymes such as ascorbate peroxidase (APX), monodehydroascorbate reductase (MDHAR), dehydroascorbate reductase (DHAR) and glutathione reductase (GR) increased after Spd pretreatment in LT affected seedlings. Thus, the oxidative stress was reduced. Protective effects of Spd are also reflected from reduction of methylglyoxal (MG) toxicity by improving glyoxalase cycle components, and by maintaining osmoregulation, water status and improved seedlings growth. The present study reveals the vital roles of AsA-GSH and glyoxalase cycle in alleviating LT injury.
DOI:10.1007/s12298-010-0003-0URL [本文引用: 1]
In mung bean seedlings, salt stress (300 mM NaCl) caused a significant increase in reduced glutathione (GSH) content within 24 h of treatment as compared to control whereas a slight increase was observed after 48 h of treatment. Highest oxidized glutathione (GSSG) content was observed after 48 h to treatment with a concomitant decrease in glutathione redox state. Glutathione peroxidase, glutathione S-transferase, and glyoxalase II enzyme activities were significantly elevated up to 48 h, whereas glutathione reductase and glyoxalase I activities were increased only up to 24 h and then gradually decreased. Application of 15 mM proline or 15 mM glycinebetaine resulted in an increase in GSH content, maintenance of a high glutathione redox state and higher activities of glutathione peroxidase, glutathione S-transferase, glutathione reductase, glyoxalase I and glyoxalase II enzymes involved in the ROS and methylglyoxal (MG) detoxification system for up to 48 h, compared to those of the control and mostly also salt stressed plants, with a simultaneous decrease in GSSG content, H2O2 and lipid peroxidation level. The present study suggests that both proline and glycinebetaine provide a protective action against saltinduced oxidative damage by reducing H2O2 and lipid peroxidation level and by enhancing antioxidant defense and MG detoxification systems.
DOI:10.1007/s12298-010-0028-4URL [本文引用: 1]
The present study investigates the possible mediatory role of exogenously applied glycinebetaine (betaine) and proline on reactive oxygen species (ROS) and methylglyoxal (MG) detoxification systems in mung bean seedlings subjected to cadmium (Cd) stress (1mM CdCl2, 48h). Cadmium stress caused a significant increase in glutathione (GSH) and glutathione disulfide (GSSG) content, while the ascorbate (AsA) content decreased significantly with a sharp increase in hydrogen peroxide (H2O2) and lipid peroxidation level (MDA). Ascorbate peroxidase (APX), glutathione S-transferase (GST), glutathione peroxidase (GPX), and glyoxalase I (Gly I) activities were increased in response to Cd stress, while the activities of catalase (CAT), monodehydroascorbate reductase (MDHAR), dehydroascorbate reductase (DHAR), glutathione reductase (GR) and glyoxalase II (Gly II) were sharply decreased. Exogenous application of 5mM betaine or 5mM proline resulted in an increase in GSH and AsA content, maintenance of a high GSH/GSSG ratio and increased the activities of APX, DHAR, MDHAR, GR, GST, GPX, CAT, Gly I and Gly II involved in ROS and MG detoxification system as compared to the control and mostly also Cd-stressed plants, with a concomitant decrease in GSSG content, H2O2 and lipid peroxidation level. These findings together with our earlier findings suggest that both betaine and proline provide a protective action against Cd-induced oxidative stress by reducing H2O2 and lipid peroxidation levels and by increasing the antioxidant defense and MG detoxification systems.
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DOI:10.1007/s12298-016-0371-1URLPMID:27729716 [本文引用: 1]
Hydroponically grown 12-day-old rice (Oryza sativa L. cv. BRRI dhan47) seedlings were exposed to 150 mM NaCl alone and combined with 0.5 mM MnSO4. Salt stress resulted in disruption of ion homeostasis by Na(+) influx and K(+) efflux. Higher accumulation of Na(+) and water imbalance under salinity caused osmotic stress, chlorosis, and growth inhibition. Salt-induced ionic toxicity and osmotic stress consequently resulted in oxidative stress by disrupting the antioxidant defense and glyoxalase systems through overproduction of reactive oxygen species (ROS) and methylglyoxal (MG), respectively. The salt-induced damage increased with the increasing duration of stress. However, exogenous application of manganese (Mn) helped the plants to partially recover from the inhibited growth and chlorosis by improving ionic and osmotic homeostasis through decreasing Na(+) influx and increasing water status, respectively. Exogenous application of Mn increased ROS detoxification by increasing the content of the phenolic compounds, flavonoids, and ascorbate (AsA), and increasing the activities of monodehydroascorbate reductase (MDHAR), dehydroascorbate reductase (DHAR), superoxide dismutase (SOD), and catalase (CAT) in the salt-treated seedlings. Supplemental Mn also reinforced MG detoxification by increasing the activities of glyoxalase I (Gly I) and glyoxalase II (Gly II) in the salt-affected seedlings. Thus, exogenous application of Mn conferred salt-stress tolerance through the coordinated action of ion homeostasis and the antioxidant defense and glyoxalase systems in the salt-affected seedlings.
DOI:10.1016/j.crvi.2016.08.002URL [本文引用: 1]
DOI:10.1007/s11816-011-0189-9URL [本文引用: 1]
The present study investigates the possible regulatory role of exogenous nitric oxide (NO) in antioxidant defense and methylglyoxal (MG) detoxification systems of wheat seedlings exposed to salt stress (150 and 300 mM NaCl, 4 days). Seedlings were pre-treated for 24 h with 1 mM sodium nitroprusside, a NO donor, and then subjected to salt stress. The ascorbate (AsA) content decreased significantly with increased salt stress. The amount of reduced glutathione (GSH) and glutathione disulfide (GSSG) and the GSH/GSSG ratio increased with an increase in the level of salt stress. The glutathione S-transferase (GST) activity increased significantly with severe salt stress (300 mM). The ascorbate peroxidase (APX), monodehydroascorbate reductase (MDHAR), dehydroascorbate reductase (DHAR), catalase (CAT) and glutathione peroxidase (GPX) activities did not show significant changes in response to salt stress. The glutathione reductase (GR), glyoxalase I (Gly I), and glyoxalase II (Gly II) activities decreased upon the imposition of salt stress, especially at 300 mM NaCl, with a concomitant increase in the H(2)O(2) and lipid peroxidation levels. Exogenous NO pretreatment of the seedlings had little influence on the nonenzymatic and enzymatic components compared to the seedlings of the untreated control. Further investigation revealed that NO pre-treatment had a synergistic effect; that is, the pre-treatment increased the AsA and GSH content and the GSH/GSSG ratio, as well as the activities of MDHAR, DHAR, GR, GST, GPX, Gly I, and Gly II in most of the seedlings subjected to salt stress. These results suggest that the exogenous application of NO rendered the plants more tolerant to salinity-induced oxidative damage by enhancing their antioxidant defense and MG detoxification systems.
DOI:10.1007/s12011-011-8958-4URL [本文引用: 1]
The present study investigates the regulatory role of exogenous selenium (Se) in the antioxidant defense and methylglyoxal (MG) detoxification systems in rapeseed seedlings exposed to salt stress. Twelve-day-old seedlings, grown in Petri dishes, were supplemented with selenium (25 mu M Na(2)SeO(4)) and salt (100 and 200 mM NaCl) separately and in combination, and further grown for 48 h. The ascorbate (AsA) content of the seedlings decreased significantly with increased salt stress. The amount of reduced glutathione (GSH) and glutathione disulfide (GSSG) increased with an increase in the level of salt stress, while the GSH/GSSG ratio decreased. In addition, the ascorbate peroxidase (APX) and glutathione S-transferase (GST) activity increased significantly with increased salt concentration (both at 100 and 200 mM NaCl), while glutathione peroxidase (GPX) activity increased only at moderate salt stress (100 mM NaCl). Glutathione reductase (GR) activity remained unchanged at 100 mM NaCl, while it was decreased under severe (200 mM NaCl) salt stress. Monodehydroascorbate reductase (MDHAR), dehydroascorbate reductase (DHAR), catalase (CAT), glyoxalase I (Gly I), and glyoxalase II (Gly II) activities decreased upon the imposition of salt stress, whereas a sharp decrease of these activities was observed under severe salt stress (200 mM NaCl). Concomitant increases in the levels of H(2)O(2) and lipid peroxidation (MDA) were also measured. Exogenous Se treatment alone had little effect on the non-enzymatic and enzymatic components. However, further investigation revealed that Se treatment had a synergistic effect: in salt-stressed seedlings, it increased the AsA and GSH contents; GSH/GSSG ratio; and the activities of APX, MDHAR, DHAR, GR, GST, GPX, CAT, Gly I, and Gly II. As a result, addition of Se in salt-stressed seedlings led to a reduction in the levels of H(2)O(2) and MDA as compared to salt stress alone. These results suggest that the exogenous application of Se rendered the plants more tolerant to salt stress-induced oxidative damage by enhancing their antioxidant defense and MG detoxification systems.
DOI:10.1007/s12011-012-9419-4URL [本文引用: 1]
The protective effect of selenium (Se) on antioxidant defense and methylglyoxal (MG) detoxification systems was investigated in leaves of rapeseed (Brassica napus cv. BINA sharisha 3) seedlings under cadmium (Cd)-induced oxidative stress. Two sets of 11-day-old seedlings were pretreated with both 50 and 100 mu M Se (Na2SeO4, sodium selenate) for 24 h. Two concentrations of CdCl2 (0.5 and 1.0 mM) were imposed separately or on the Se-pretreated seedlings, which were grown for another 48 h. Cadmium stress at any levels resulted in the substantial increase in malondialdehyde and H2O2 levels. The ascorbate (AsA) content of the seedlings decreased significantly upon exposure to Cd stress. The amount of reduced glutathione (GSH) increased only at 0.5 mM CdCl2, while glutathione disulfide (GSSG) increased at any level of Cd, with concomitant decrease in GSH/GSSG ratio. The activities of ascorbate peroxidase (APX) and glutathione S-transferase (GST) increased significantly with increased concentration of Cd (both at 0.5 and 1.0 mM CdCl2), while the activities of glutathione reductase (GR) and glutathione peroxidase (GPX) increased only at moderate stress (0.5 mM CdCl2) and then decreased at 1.0 mM severe stress (1.0 mM CdCl2). Monodehydroascorbate reductase (MDHAR), dehydroascorbate reductase (DHAR), catalase (CAT), glyoxalase I (Gly I), and glyoxalase II (Gly II) activities decreased upon exposure to any levels of Cd. Selenium pretreatment had little effect on the nonenzymatic and enzymatic components of seedlings grown under normal conditions; i.e., they slightly increased the GSH content and the activities of APX, GR, GST, and GPX. On the other hand, Se pretreatment of seedlings under Cd-induced stress showed a synergistic effect; it increased the AsA and GSH contents, the GSH/GSSG ratio, and the activities of APX, MDHAR, DHAR, GR, GPX, CAT, Gly I, and Gly II which ultimately reduced the MDA and H2O2 levels. However, in most cases, pretreatment with 50 mu M Se showed better results compared to pretreatment with 100 mu M Se. The results indicate that the exogenous application of Se at low concentrations increases the tolerance of plants to Cd-induced oxidative damage by enhancing their antioxidant defense and MG detoxification systems.
DOI:10.1007/s10646-013-1050-4URL [本文引用: 1]
The present study investigates the possible regulatory role of exogenous nitric oxide (NO) in mitigating oxidative stress in wheat seedlings exposed to arsenic (As). Seedlings were treated with NO donor (0.25 mM sodium nitroprusside, SNP) and As (0.25 and 0.5 mM Na2HAsO4 center dot 7H(2)O) separately and/or in combination and grown for 72 h. Relative water content (RWC) and chlorophyll (chl) content were decreased by As treatment but proline (Pro) content was increased. The ascorbate (AsA) content was decreased significantly with increased As concentration. The imposition of As caused marked increase in the MDA and H2O2 content. The amount of reduced glutathione (GSH) and glutathione disulfide (GSSG) significantly increased with an increase in the level of As (both 0.25 and 0.5 mM), while the GSH/GSSG ratio decreased at higher concentration (0.5 mM). The ascorbate peroxidase and glutathione S-transferase activities consistently increased with an increase in the As concentration, while glutathione reductase (GR) activities increased only at 0.25 mM. The monodehydroascorbate reductase (MDHAR) and catalase (CAT) activities were not changed upon exposure to As. The activities of dehydroascorbate reductase (DHAR) and glyoxalase I (Gly I) decreased at any levels of As, while glutathione peroxidase (GPX) and glyoxalase II (Gly II) activities decreased only upon 0.5 mM As. Exogenous NO alone had little influence on the non-enzymatic and enzymatic components compared to the control seedlings. These inhibitory effects of As were markedly recovered by supplementation with SNP; that is, the treatment with SNP increased the RWC, chl and Pro contents; AsA and GSH contents and the GSH/GSSG ratio as well as the activities of MDHAR, DHAR, GR, GPX, CAT, Gly I and Gly II in the seedlings subjected to As stress. These results suggest that the exogenous application of NO rendered the plants more tolerant to As-induced oxidative damage by enhancing their antioxidant defense and glyoxalase system.
DOI:10.1042/BST20130242URLPMID:24646265 [本文引用: 3]
The glyoxalase pathway is required for detoxification of cytotoxic metabolite MG (methylglyoxal) that would otherwise increase to lethal concentrations under adverse environmental conditions. Since its discovery 100 years ago, several roles have been assigned to glyoxalases, but, in plants, their involvement in stress response and tolerance is the most widely accepted role. The plant glyoxalases have emerged as multigene family and this expansion is considered to be important from the perspective of maintaining a robust defence machinery in these sessile species. Glyoxalases are known to be differentially regulated under stress conditions and their overexpression in plants confers tolerance to multiple abiotic stresses. In the present article, we review the importance of glyoxalases in plants, discussing possible roles with emphasis on involvement of the glyoxalase pathway in plant stress tolerance.
DOI:10.1074/jbc.M408061200URL [本文引用: 1]
DOI:10.1111/pce.2011.34.issue-9URL [本文引用: 4]
DOI:10.1271/bbb.100393URL [本文引用: 1]
DOI:10.1002/jbt.21423URL [本文引用: 1]
Methylglyoxal (MG) is one of the aldehydes accumulated in plants under environmental stress. Cytosolic ascorbate peroxidase (cAPX) plays a key role in the protection of cells from oxidative damage by scavenging reactive oxygen species in higher plants. A cDNA encoding cAPX, named NtcAPX, was isolated from Nicotiana tabacum. We characterized recombinant NtcAPX (rNtcAPX) as a fusion protein with glutathione S-transferase to investigate the effects of MG on APX. NtcAPX consists of 250 amino acids and has a deduced molecular mass of 27.5 kDa. The rNtcAPX showed a higher APX activity. MG treatments resulted in a reduction of APX activity and modifications of amino groups in rNtcAPX with increasing Km for ascorbate. On the contrary, neither NaCl nor cadmium reduced the activity of APX. The present study suggests that inhibition of APX is in part due to the modification of amino acids by MG. (c) 2012 Wiley Periodicals, Inc. J Biochem Mol Toxicol 26:315321, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/jbt.21423
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DOI:10.1007/s002030050635URLPMID:9732434 [本文引用: 1]
Methylglyoxal is a toxic electrophile. In Escherichia coli cells, the principal route of methylglyoxal production is from dihydroxyacetone phosphate by the action of methylglyoxal synthase. The toxicity of methylglyoxal is believed to be due to its ability to interact with the nucleophilic centres of macromolecules such as DNA. Bacteria possess an array of detoxification pathways for methylglyoxal. In E. coli, glutathione-based detoxification is central to survival of exposure to methylglyoxal. The glutathione-dependent glyoxalase I-II pathway is the primary route of methylglyoxal detoxification, and the glutathione conjugates formed can activate the KefB and KefC potassium channels. The activation of these channels leads to a lowering of the intracellular pH of the bacterial cell, which protects against the toxic effects of electrophiles. In addition to the KefB and KefC systems, E. coli cells are equipped with a number of independent protective mechanisms whose purpose appears to be directed at ensuring the integrity of the DNA. A model of how these protective mechanisms function will be presented. The production of methylglyoxal by cells is a paradox that can be resolved by assigning an important role in adaptation to conditions of nutrient imbalance. Analysis of a methylglyoxal synthase-deficient mutant provides evidence that methylglyoxal production is required to allow growth under certain environmental conditions. The production of methylglyoxal may represent a high-risk strategy that facilitates adaptation, but which on failure leads to cell death. New strategies for antibacterial therapy may be based on undermining the detoxification and defence mechanisms coupled with deregulation of methylglyoxal synthesis.
DOI:10.1271/bbb.110885URL [本文引用: 2]
Methylglyoxal (MG) is a reactive aldehyde derived by glycolysis. In Arabidopsis, MG inhibited light-induced stomatal opening in a dose-dependent manner. It significantly inhibited both inward-rectifying potassium (K-in) channels in guard-cell protoplasts and an Arabidopsis K-in channel, KAT1, heterologously expressed in Xenopus oocytes. Thus it appears that MG inhibition of stomatal opening involves MG inhibition of K+ influx into guard cells.
DOI:10.1074/jbc.M109.021253URL [本文引用: 2]
DOI:10.1007/s00425-009-0964-9URL [本文引用: 2]
Aldehydes produced under various environmental stresses can cause cellular injury in plants, but their toxicology in photosynthesis has been scarcely investigated. We here evaluated their effects on photosynthetic reactions in chloroplasts isolated from Spinacia oleracea L. leaves. Aldehydes that are known to stem from lipid peroxides inactivated the CO2 photoreduction to various extents, while their corresponding alcohols and carboxylic acids did not affect photosynthesis. α,β-Unsaturated aldehydes (2-alkenals) showed greater inactivation than the saturated aliphatic aldehydes. The oxygenated short aldehydes malondialdehyde, methylglyoxal, glycolaldehyde and glyceraldehyde showed only weak toxicity to photosynthesis. Among tested 2-alkenals, 2-propenal (acrolein) was the most toxic, and then followed 4-hydroxy-(E)-2-nonenal and (E)-2-hexenal. While the CO2-photoreduction was inactivated, envelope intactness and photosynthetic electron transport activity (H2O→ferredoxin) were only slightly affected. In the acrolein-treated chloroplasts, the Calvin cycle enzymes phosphoribulokinase, glyceraldehyde-3-phosphate dehydrogenase, fructose-1,6-bisphophatase, sedoheptulose-1,7-bisphosphatase, aldolase, and Rubisco were irreversibly inactivated. Acrolein treatment caused a rapid drop of the glutathione pool, prior to the inactivation of photosynthesis. GSH exogenously added to chloroplasts suppressed the acrolein-induced inactivation of photosynthesis, but ascorbic acid did not show such a protective effect. Thus, lipid peroxide-derived 2-alkenals can inhibit photosynthesis by depleting GSH in chloroplasts and then inactivating multiple enzymes in the Calvin cycle.
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