,2,*Expression and promoter activity of GhTFL1a and GhTFL1c in Upland cotton
ZHANG Xiao-Hong1, HU Gen-Hai1, WANG Han-Tao2, WANG Cong-Cong2, WEI Heng-Ling2, FU Yuan-Zhi1, YU Shu-Xun,2,*通讯作者:
第一联系人:
收稿日期:2018-06-20接受日期:2018-12-24网络出版日期:2019-01-04
| 基金资助: |
Received:2018-06-20Accepted:2018-12-24Online:2019-01-04
| Fund supported: |
摘要
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张晓红, 胡根海, 王寒涛, 王聪聪, 魏恒玲, 付远志, 喻树迅. 棉花中GhTFL1a和GhTFL1c基因的表达及启动子分析[J]. 作物学报, 2019, 45(3): 469-476. doi:10.3724/SP.J.1006.2019.84082
ZHANG Xiao-Hong, HU Gen-Hai, WANG Han-Tao, WANG Cong-Cong, WEI Heng-Ling, FU Yuan-Zhi, YU Shu-Xun.
棉花是我国最重要的经济作物之一, 在我国国民经济中占有举足轻重的地位。目前在棉花种植结构调整, 推进植棉全程机械化进程的大形势下, 早熟作为棉花育种的重要目标性状显得尤为重要[1]。开花是棉花由营养生长向生殖生长过渡的标志, 也是培育早熟棉的一个重要指标, 同时也是决定棉花能否获得丰产的重要农艺性状[2]。通过对花发育相关基因的功能分析, 进行棉花品种熟性分子改良, 对实现棉花机械化直播和采收具有重要意义。
磷脂酰乙醇胺结合蛋白(phosphatidylethanolamine binding protein, PEBP)在原核生物和真核生物中均被发现[3,4,5], 其氨基酸结构均有保守的磷脂酰乙醇胺结合蛋白结构域, 但是在原核生物和真核生物中仍然存在很大差异。TFL1 (TERMINAL FLOWER1)是磷脂酰乙醇胺结合蛋白中的一个亚组, 该亚组基因的功能大部分都集中在开花调控通路。在拟南芥中, BFT (BROTHER OF FT AND TFL1)是TFL1亚组中的一个基因, 其功能主要表现在盐胁迫信号途径[6]。TFL1和ATC (ARABIDOPSIS THALIANA CENTRORADIALIS)也是该亚组中的2个基因, 这2个基因在营养生长阶段顶芽中积累较少, 但是在开花之后其表达量急剧升高。拟南芥中TFL1通过维持茎顶端分生组织和花序分生组织的无限性, 延长植株的营养生长过程, 从而延迟植株的生殖生长进程[7]。Conti等[8]研究表明TFL1蛋白通过运输到达顶芽, 并且调控拟南芥的植株结构。同时, TFL1蛋白能抑制AP1和LFY基因的表达并且保持花序的无限生长[9]。对TFL1基因进行启动子结构的研究发现, 该基因是在营养器官的分生组织中表达来控制开花时间[10]。Liu等[11]在山茱萸中发现ClTFL1过表达转化拟南芥后, 拟南芥开花时间推迟, 植株高度增加, 顶端花芽和次生花序分枝增多。Rantanen等[12]发现在温度和光周期的互作下, 林地草莓中TFL1基因能适时调控开花时间。Si等[13]研究发现陆地棉GhTFL1基因与果枝形成发育相关, 但是棉花中该基因的启动子分析还无报道。
本研究依据棉花基因组测序结果[14,15], 克隆到GhTFL1a和GhTFL1c基因及其启动子, 同时进行光周期、激素和胁迫处理分析其表达模式, 并分析其启动子活性, 旨在摸清GhTFL1a和GhTFL1c表达调控的分子机制, 从而为棉花分子改良提供理论依据。
1 材料与方法
1.1 试验材料
选用陆地棉栽培种“中棉所36”和半野生种“尖斑棉”。试验所用到的DNA聚合酶、反转录酶、pMD18-T载体、质粒提取试剂盒、胶回收试剂盒和荧光定量试剂盒均购自Takara公司, RNA提取试剂盒购自天根公司, 大肠杆菌感受态DH5α、pBI121载体及农杆菌LBA4404由本实验室制备并保存。1.2 材料处理及取样
用于光周期处理试验的材料种植于中国农业科学院棉花研究所早熟组人工气候培养室, 栽培种为“中棉所36”和半野生种为“尖斑棉”, 培养条件为长日照, 等到二叶展平时期, 短日照处理一周, 并将处理过后的棉花分两批继续培养, 一批为长日照(14 h/10 h 光照/黑暗, 光照时间为8:00-22:00), 另一批为短日照(10 h/14 h 光照/黑暗, 光照时间为8:00-18:00), 温度都为28℃, 取样时期分别于子叶展平期到五叶展平期, 取样后快速放入液氮中冷冻并存于-80℃冰箱中备用。激素处理所用材料为“中棉所36”水培材料, 室内种植条件为14 h光照/10 h黑暗, 温度为26℃。于三叶期水培液中增加激素和胁迫处理, 以清水为对照。所用SA浓度为200 μmol L-1, ABA和GA浓度为100 μmol L-1, 处理后的1、3、7、12和24 h时间段进行根部取样, 选取10株左右水培苗剪下幼嫩根部, 吸取根部水分后液氮冷冻并置-80℃冰箱备用, 试验重复3次, 利用GraphPad Prism 5软件作图及统计分析。1.3 GhTFL1a和GhTFL1c的生物信息学分析
研究中所用到的氨基酸序列下载自NCBI网站, 使用ClustalX2软件多重序列比对, 使用MEGA6.06最大似然法构建进化树。利用ExPASy网站上的Compute pI/Mw (http://web.expasy.org/compute_pi/)对其蛋白质的理化性质进行预测和分析, 并用NCBI的CDD (https://www.ncbi. nlm.nih.gov/Structure/cdd/cdd.shtml)数据库对其结构域进行预测。用PlantCARE (http://bioinformatics.psb.ugent.be/ webtools/plantcare/html/)预测启动子区域顺式作用元件。1.4 基因的定量表达分析
RNA用天根多糖多酚RNA提取试剂盒提取, RNA的质量必须保证OD260/280为1.8~2.1, OD260/230大于1.8。用Takara RR047A试剂盒反转录, 使用gDNA Eraser消化总RNA中残留的基因组DNA后进行15 min的反转录反应合成cDNA。使用Takara RR420A试剂盒及SYBR Green分析荧光定量, 所用仪器为Applied Biosystems Q6实时荧光定量PCR仪。陆地棉中以ACTIN为内参。所用引物见表1。Table 1
表1
表1本研究所用引物
Table 1
| 引物名称 Primer name | 引物序列 Primer sequence (5′-3′) | 用途 Purpose |
|---|---|---|
| GhTFL1a-up | TCCCTGAGCCACTTACCGTTG | 荧光定量PCR qRT-PCR |
| GhTFL1a-down | AAGCGTCTCTCATGTCGTTG | 荧光定量PCR qRT-PCR |
| GhTFL1c-up | TCATCTGTTGCCACCAAACCT | 荧光定量PCR qRT-PCR |
| GhTFL1c-down | TTCCCTTCCAAACGTGGCATC | 荧光定量PCR qRT-PCR |
| GhACTIN-up | ATCCTCCGTCTTGACCTTG | 荧光定量PCR qRT-PCR |
| GhACTIN-down | TGTCCGTCAGGCAACTCAT | 荧光定量PCR qRT-PCR |
| GhTFL1a-up | ATGTCAAGGGTCCCTGAG | 基因克隆 Gene cloning |
| GhTFL1a-down | TTATCTTCTTCTTGCAGCAGTTTC | 基因克隆 Gene cloning |
| GhTFL1c-up | ATGGGAGAGCCTCTCATTGTT | 基因克隆 Gene cloning |
| GhTFL1c-down | TTAGCGTCTCCTTGCAGCAGT | 基因克隆 Gene cloning |
| pGhTFL1a-up | AAGGAATATAGAGCACAACA | 启动子克隆 Promoter cloning |
| pGhTFL1a-down | GATGAACAAGACGATGTGTAT | 启动子克隆 Promoter cloning |
| pGhTFL1c-up | AGTTTAGATTCTTGTGCGAT | 启动子克隆 Promoter cloning |
| pGhTFL1c-down | TCTTGATGACAGTGAATGAA | 启动子克隆 Promoter cloning |
新窗口打开|下载CSV
1.5 GhTFL1a和GhTFL1c启动子克隆和瞬时表达
利用Perl语言编写的脚本, 从陆地棉基因组中获取GhTFL1a和GhTFL1c基因上游约2000 bp的序列, 根据启动子顺式作用元件预测结果设计引物(表1), 从翻译起始位点(ATG)上游开始, 以中棉所36基因组为模板, 克隆启动子片段。使用 Infusion 连接酶(宝生物, 大连)与载体pBI121连接启动子片段, 双酶切位点是Hind III和Xba I, 将pGhTFL1a和pGhTFL1c构建到启动子检测载体pBI121-GUS上形成融合表达载体, 将连接后新鲜菌液送金唯智生物科技有限公司测序, 并保存测序正确的单克隆菌液以供后续试验使用。本氏烟草(Nicotina benthamiana)按照Sparkes等[16]的方法种植和瞬时表达。1.6 GUS染色
取瞬转后的烟草叶片组织, 加入GUS染色液, 37℃培养箱中温育过夜24 h。接着, 依次用体积分数为70%、80%、90%和无水乙醇脱色。最后, 在体式显微镜(SOPTOP, SZN)下观察组织的染色情况并照相。2 结果与分析
2.1 陆地棉GhTFL1a和GhTFL1c的序列分析
GhTFL1a基因位于陆地棉A亚组第11染色体上, 编码框长522 bp, 编码氨基酸长度为173 aa。经ExPASy网站预测知, 其编码蛋白质约为19.3 kDa, 等电点为9.68。GhTFL1c基因位于D亚组第4染色体上, 编码框长519 bp, 编码氨基酸长度为172 aa, 编码蛋白质约为19.1 kDa, 等电点为8.09。进化树分析结果表明, GhTFL1a和GhTFL1c分别与拟南芥中的AtBFT和AtTFL1亲缘关系相近(图1-A), 根据TAIR网站提供的拟南芥TFL1氨基酸序列进行序列比对, 氨基酸序列具有比较保守的磷脂酰乙醇胺结合蛋白结构域(图1-B)。图1
新窗口打开|下载原图ZIP|生成PPT图1 GhTFL1a和GhTFL1c的进化树及氨基酸多重序列比对
A: 进化树分析; B: 氨基酸多重序列比对。*代表氨基酸完全一致, AtBFT、AtTFL1和AtATC序列号分别为NM_125597、U77674和NM_128315, GhTFL1a和GhTFL1c在陆地棉中序列号分别为Gh_A11G0088和Gh_D04G0971。
Fig. 1Phylogenetic and conserved domain analysis of GhTFL1a and GhTFL1c
A: phylogentic analysis of GhTFL1a/c and their homologous genes in Arabidopsis; B: alignment of amino acid sequences of GhTFL1a/c and their homologous genes in Arabidopsis. * indicates the same amino acid, the ID of AtBFT, AtTFL1, and AtATC is NM_125597, U77674, and NM_128315, respectively, the ID of GhTFL1a and GhTFL1c is Gh_A11G0088 and Gh_D04G0971, respectively.
2.2 苗期叶片中GhTFL1a和GhTFL1c基因的表达模式分析
为研究GhTFL1a和GhTFL1c是否受光周期影响, 利用光周期试验处理半野生种和栽培种材料, 对不同时期幼苗叶片取样分析表明, GhTFL1a和GhTFL1c在半野生种及栽培种陆地棉中表达趋势一致, GhTFL1a表达在长日照下明显高于短日照下(图2-A和图2-C), 而GhTFL1c三叶期的表达量在短日照下高于长日照下, 随后表达量逐渐降低并低于长日照下(图2-B和2-D)。同时, 对这2个基因在栽培种棉和半野生棉中的表达模式进行分析发现, GhTFL1a在半野生棉中表达量高于栽培棉(图3-A), 而GhTFL1c在栽培棉中表达量高于半野生棉(图3-B)。说明从半野生种棉到栽培种棉的进化过程中, 光照条件从短日照促进开花基因的表达向光照不敏感转化, 同时在光周期的影响下, GhTFL1a和GhTFL1c可能具有相反的生物学功能, 仍需对多个栽培种和半野生种材料进行后续验证。图2
新窗口打开|下载原图ZIP|生成PPT图2GhTFL1a和GhTFL1c在光周期处理试验中的表达模式分析
A和B为GhTFL1a和GhTFL1c基因在栽培种“中棉所36” 中的表达; C和D为GhTFL1a和GhTFL1c基因在半野生种“尖斑棉”中的表达。误差棒为3次重复的标准差。
Fig. 2Expression patterns of GhTFL1a and GhTFL1c genes during photoperiod treatment
A and B indicate the expression of GhTFL1a and GhTFL1c in cotton cultivar “CCRI 36”; C and D indicate the expression of GhTFL1a and GhTFL1c in semi-wild cotton. Error bars indicate the standard deviation (±SD).
图3
新窗口打开|下载原图ZIP|生成PPT图3GhTFL1a和GhTFL1c在栽培种和半野生种中表达模式分析
横坐标代表取样时期, 分别为长日照子叶、一叶、二叶、三叶、四叶、五叶以及短日照三叶、四叶和五叶。
Fig. 3Expression patterns of GhTFL1a and GhTFL1c genes in cultivated cotton and semi-wild race cotton
The abscissa shows period, which from left to right is expanded cotyledon, first, second, third, forth, and fifth leaves in long day, and third, forth and fifth leaves in short day.
2.3 GhTFL1a和GhTFL1c的启动子分析及其对外源激素的应答
该基因拥有磷脂酰乙醇胺结合蛋白的保守结构域, 因此分析启动子的顺式作用元件对于揭示GhTFL1a和GhTFL1c的功能是非常必要的。从中棉所陆地棉基因组数据库中获取GhTFL1a和GhTFL1c基因起始密码子上游2000 bp的序列, 并利用PlantCARE数据库对其顺式作用元件进行了预测。结果如表2所示。这2个基因的启动子上主要存在两大类顺式作用元件, 一类是光响应元件和生物钟节律响应元件, 一类是胁迫响应元件, 如与胁迫相关的水杨酸、脱落酸和干旱胁迫等元件。已知GA是一种能促进种子发芽、植物生长和提早开花的生长调节剂, 而ABA、SA和盐胁迫都是与植物逆境和胁迫响应相关的因素。Table 2
表2
表2陆地棉基因GhTFL1a和GhTFL1c启动子顺式作用元件预测
Table 2
| 基因 Gene | 元件 Element | 序列 Sequence (5′-3′) | 功能 Function |
|---|---|---|---|
| GhTFL1a | CE3 | GACGCGTGTC | ABA和VP1响应元件 ABA and VP1 responsiveness element |
| MBS | TAACTG | 干旱诱导的MYB结合位点 MYB binding site involved in drought inducibility | |
| Nodule-site2 | CTTAAATTATTTATTT | 节结特异因子结合位点 Nodolue specific factor binding site | |
| as-2-box | GATAatGATG | 顶芽特异表达响应元件 Shoot specific expression element | |
| as-2-box | GATAatGATG | 顶芽特异表达响应元件 Shoot specific expression element | |
| Circadian | CAANNNNATC | 昼夜节律控制元件 Circadian rhythms element | |
| GhTFL1c | ERE | ATTTCAAA | 乙烯响应元件 Ethylene responsiveness element |
| ERE | ATTTCAAA | 乙烯响应元件 Ethylene responsiveness element | |
| MBS | CAACTG | 干旱诱导的MYB结合位点 MYB binding site involved in drought inducibility | |
| circadian | CAANNNNATC | 昼夜节律控制元件 Circadian rhythms element | |
| TCA-element | TCAGAAGAGG | 水杨酸响应元件 Salicylic acid responsiveness element | |
| TCA-element | CAGAAAAGGA | 水杨酸响应元件 Salicylic acid responsiveness element |
新窗口打开|下载CSV
利用棉花水培方法来研究GhTFL1a和GhTFL1c在激素和胁迫处理下的应答模式。经SA处理3 h后GhTFL1a的表达量开始升高, 12 h到达峰值, 表达量约是对照组的32倍(图4-A)。经ABA处理3 h后处理组中的GhTFL1a表达量开始升高, 7 h达到最大值, 随后下降(图4-B)。经GA处理后, GhTFL1a的表达量与对照相比没有显著的倍数差异(图4-C)。NaCl处理后, GhTFL1a的表达量在3 h和12 h出现峰值(图4-D)。以上结果表明, SA、ABA和盐胁迫都可以显著促进陆地棉中GhTFL1a的表达, 而GA对GhTFL1a的转录无明显作用, GhTFL1a可以响应SA、ABA和盐胁迫。经SA处理后, GhTFL1c的表达量一直在降低, 到12 h表达量降到最低点, 对照组中表达量约是该基因表达量的26倍(图5-A)。经ABA处理3 h后处理组中的GhTFL1c表达量开始下降, 7 h达到最小值, 随后上升(图5-B)。经GA处理后, GhTFL1c的表达量开始上升, 3 h后表达开始下降(图5-C)。NaCl处理后, GhTFL1c的表达量与对照相比没有明显的倍数差异(图5-D)。SA、ABA和GA处理后, GhTFL1c的表达量都比对照低。以上结果表明, SA、ABA和GA都可以抑制陆地棉中GhTFL1c的表达, 而盐胁迫对GhTFL1c的转录无明显作用, GhTFL1c可以响应SA、ABA和GA胁迫。
图4
新窗口打开|下载原图ZIP|生成PPT图4棉花水培苗经过处理后24 h内GhTFL1a基因表达量变化
A: 水杨酸; B: 脱落酸; C: 赤霉素; D: NaCl。误差棒为3次重复的标准差。
Fig. 4GhTFL1a expression profiles in the first 24 hours after the roots were treated
A: salicylic acid; B: gibberellins; C: abscisic acid; D: NaCl. Error bars on the columns indicate the standard deviation (±SD).
图5
新窗口打开|下载原图ZIP|生成PPT图5棉花水培苗经过处理后24小时内GhTFL1c基因表达量变化
A: 水杨酸; B: 赤霉素; C: 脱落酸; D: NaCl。误差棒为3次重复的标准差。
Fig. 5GhTFL1c expression profiles in the first 24 hours after the roots were treated
A: salicylic acid; B: gibberellins; C: abscisic acid; D: NaCl; Error bars indicate the standard deviation (±SD).
2.5 GhTFL1a和GhTFL1c的启动子活性分析
对GhTFL1a和GhTFL1c的启动子进行克隆, 得到GhTFL1a基因启动子全长1558 bp, GhTFL1c基因启动子全长1631 bp。以烟草瞬时表达分析启动子活性表明, GhTFL1a和GhTFL1c基因的启动子都具有启动活性, 与阳性对照pBI121相比, 活性较弱(图6)。图6
新窗口打开|下载原图ZIP|生成PPT图6烟草瞬时表达GhTFL1a和GhTFL1c的启动子
A: 阳性对照pBI121; B: pGhTFL1a∷GUS; C: pGhTFL1c∷GUS; D: 阴性对照。
Fig. 6Transient expression of GhTFL1a and GhTFL1c promoter in tobacco
A: positive control pBI121; B: pGhTFL1a∷GUS; C: pGhTFL1c∷GUS; D: negative control.
3 讨论
开花是陆地棉的重要农艺性状之一。花期的早晚影响产量, 也影响品种的区域适应性。虽然开花是一个由多基因控制的数量性状, 经典遗传学研究也表明许多开花相关的基因符合孟德尔遗传定律[17]。陆地棉全基因组测序的完成对深入研究目标性状的遗传控制具有重要的意义和推动作用[14,15]。近年来, 对棉花开花相关基因的克隆及功能研究较多[18,19,20], 而针对开花基因的启动子的结构分析和蛋白表达调控等研究较少。本研究从陆地棉基因组数据库中共检索到4条TFL1亚组基因, 并对其中的GhTFL1a和GhTFL1c进行表达调控、启动子结构和活性分析。启动子顺式作用元件预测出GhTFL1a和GhTFL1c启动子区域不仅包括基本的调控元件, 还包含许多与光、生物钟、植物激素和逆境响应相关的调控元件。在植物的生长发育过程中, 光周期是一种重要的信号途径来调控开花相关基因的表达[21,22]。本研究利用光周期对不同材料的陆地棉(栽培种和半野生种)处理发现GhTFL1a和GhTFL1c在半野生种及栽培种陆地棉中表达趋势一致, 这也说明从半野生种棉到栽培种棉的进化过程中, 光照条件从短日照促进开花基因的表达向光照不敏感转化。Zhang等[23]研究表明GhTFL1a和GhTFL1c在根中优势表达, 我们根据启动子区域的调控元件选择了几种激素和胁迫对棉花的水培苗进行处理, 并对这2个基因表达模式分析表明SA、ABA和盐胁迫都可以促进陆地棉中GhTFL1a的表达, GhTFL1a与拟南芥中的BFT亲缘关系相近, 在高盐胁迫下, BFT基因通过介导FT-FD模型来提供合适的保护机制适应光周期途径并促使开花[24]。由此推测GhTFL1a可能参与盐胁迫响应的调控通路。而陆地棉中GhTFL1c与拟南芥中TFL1亲缘关系相近, 该基因的表达在SA和GA处理下受到抑制。同时, GhTFL1a和GhTFL1c基因启动子在烟草瞬时表达中具有活性。上述试验处理都呈现出GhTFL1a和GhTFL1c在表达分析上是一种相反的表达模式, 这种结果是否可以推测2个基因具有相反的生物学功能, 还需要进一步通过转基因对其进行验证, 并通过对转基因后代植株的胁迫处理来分析; 同时启动子分析试验表明这2个基因的启动子都具有活性, 后期还需在拟南芥中进行表达部位的验证来确定其是专化性抑或是组成性启动子, 这样才能进一步深入掌握GhTFL1a和GhTFL1c基因及其启动子的功能。
参考文献 原文顺序
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文中引用次数倒序
被引期刊影响因子
DOI:10.7606/j.issn.1004-1389.2014.12.015URL [本文引用: 1]
In this paper, major polygene jointing generations analyses were used to investigate the earliness and its related traits of upland cotton(Gossypium hirsutum L.) in Xinjiang, by making crosses between main cultivars in early maturing cotton area and genetic standard line.The results showed that the major genes controlling five early maturing traits were always detected in two crosses except for the seedling period in crossⅠ.In two crosses, optimum genetic models of growth period were identical, and the tendencies of their major gene heritability proportion were also consistent as well as that of polygene.By the comparison of total heritability of earliness associated traits in two crosses, growth period was the highest.According to analysis of the gene heritability proportion, growth period and bud period were all mainly controlled by polygene; seedling period, flower and boll period and fruit branch beginning site were mainly controlled by polygene in cross Ⅰ.On the contrary, these traits were mainly controlled by major gene in cross Ⅱ.To improve breeding efficiency, single cross recombination or simple backcross should be adopted for the traits mainly controlled by major gene, while polymerization backcross or recurrent selection to cumulate positive alleles should be adopted for the traits mainly controlled by polygene.The conclusion provides theoretical guidance for cotton genetic improvement in Xinjiang.
DOI:10.7606/j.issn.1004-1389.2014.12.015URL [本文引用: 1]
In this paper, major polygene jointing generations analyses were used to investigate the earliness and its related traits of upland cotton(Gossypium hirsutum L.) in Xinjiang, by making crosses between main cultivars in early maturing cotton area and genetic standard line.The results showed that the major genes controlling five early maturing traits were always detected in two crosses except for the seedling period in crossⅠ.In two crosses, optimum genetic models of growth period were identical, and the tendencies of their major gene heritability proportion were also consistent as well as that of polygene.By the comparison of total heritability of earliness associated traits in two crosses, growth period was the highest.According to analysis of the gene heritability proportion, growth period and bud period were all mainly controlled by polygene; seedling period, flower and boll period and fruit branch beginning site were mainly controlled by polygene in cross Ⅰ.On the contrary, these traits were mainly controlled by major gene in cross Ⅱ.To improve breeding efficiency, single cross recombination or simple backcross should be adopted for the traits mainly controlled by major gene, while polymerization backcross or recurrent selection to cumulate positive alleles should be adopted for the traits mainly controlled by polygene.The conclusion provides theoretical guidance for cotton genetic improvement in Xinjiang.
DOI:10.11963/1002-7807.ysxysx.20170825URL [本文引用: 1]
早熟棉适于麦(油)后直播,实现粮棉一年两熟,对棉花产业稳定发展具有重要意义。本文对早熟性的遗传特性、早熟相关QTL定位、早熟相关基因挖掘的进展进行了阐述;总结了早熟棉的发展与育种现状以及早熟棉种质资源的创新利用;介绍了早熟棉在我国黄河流域、长江流域、西北内陆棉区的生产示范应用情况;提出了我国早熟棉育种的研究展望,为我国早熟棉育种提供参考。
DOI:10.11963/1002-7807.ysxysx.20170825URL [本文引用: 1]
早熟棉适于麦(油)后直播,实现粮棉一年两熟,对棉花产业稳定发展具有重要意义。本文对早熟性的遗传特性、早熟相关QTL定位、早熟相关基因挖掘的进展进行了阐述;总结了早熟棉的发展与育种现状以及早熟棉种质资源的创新利用;介绍了早熟棉在我国黄河流域、长江流域、西北内陆棉区的生产示范应用情况;提出了我国早熟棉育种的研究展望,为我国早熟棉育种提供参考。
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DOI:10.1128/EC.3.2.459-470.2004URLPMID:15075275 [本文引用: 1]
Ras proteins are guanine nucleotide-binding proteins that are highly conserved among eukaryotes. They are involved in signal transduction pathways and are tightly regulated by two sets of antagonistic proteins: GTPase-activating proteins (GAPs) inhibit Ras proteins, whereas guanine exchange factors activate them. In this work, we describe Tfs1p, the first physiological inhibitor of a Ras GAP, Ira2p, in Saccharomyces cerevisiae. TFS1 is a multicopy suppressor of the cdc25-1 mutation in yeast and corresponds to the so-called Ic CPY cytoplasmic inhibitor. Moreover, Tfs1p belongs to the phosphatidylethanolamine-binding protein (PEBP) family, one member of which is RKIP, a kinase and serine protease inhibitor and a metastasis inhibitor in prostate cancer. In this work, the results of (i) a two-hybrid screen of a yeast genomic library, (ii) glutathione S-transferase pulldown experiments, (iii) multicopy suppressor tests of cdc25-1 mutants, and (iv) stress resistance tests to evaluate the activation level of Ras demonstrate that Tfs1p interacts with and inhibits Ira2p. We further show that the conserved ligand-binding pocket of Tfs1-the hallmark of the PEBP family-is important for its inhibitory activity.
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DOI:10.1074/jbc.M002524200URLPMID:11034991 [本文引用: 1]
Serine proteases are involved in many processes in the nervous system and specific inhibitors tightly control their proteolytic activity. Thrombin is thought to play a role in tissue development and homeostasis. To date, protease nexin-1 is the only known endogenous protease inhibitor that specifically interferes with thrombotic activity and is expressed in the brain. In this study, we report the detection of a novel thrombin inhibitory activity in the brain of protease nexin-1mice. Purification and subsequent analysis by tandem mass spectrometry identified this protein as the phosphatidylethanolamine-binding protein (PEBP). We demonstrate that PEBP exerts inhibitory activity against several serine proteases including thrombin, neuropsin, and chymotrypsin, whereas trypsin, tissue type plasminogen activator, and elastase are not affected. Since PEBP does not share significant homology with other serine protease inhibitors, our results define it as the prototype of a novel class of serine protease inhibitors. PEBP immunoreactivity is found on the surface of Rat-1 fibroblast cells and although its sequence contains no secretion signal, PEBP-Hcan be purified from the conditioned medium upon recombinant expression.
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DOI:10.1016/S0969-2126(98)00125-7URLPMID:9782050 [本文引用: 1]
Abstract BACKGROUND: Proteins belonging to the phosphatidylethanolamine-binding protein (PEBP) family are highly conserved throughout nature and have no significant sequence homology with other proteins of known structure or function. A variety of biological roles have previously been described for members of this family, including lipid binding, roles as odorant effector molecules or opioids, interaction with the cell-signalling machinery, regulation of flowering plant stem architecture, and a function as a precursor protein of a bioactive brain neuropeptide. To date, no experimentally derived structural information has been available for this protein family. In this study we have used X-ray crystallography to determine the three-dimensional structure of human PEBP (hPEBP), in an attempt to clarify the biological role of this unique protein family. RESULTS: The crystal structures of two forms of hPEBP have been determined: one in the native state (at 2.05 A resolution) and one in complex with cacodylate (at 1.75 A resolution). The crystal structures reveal that hPEBP adopts a novel protein topology, dominated by the presence of a large central beta sheet, and is expected to represent the archaetypal fold for this family of proteins. Two potential functional sites have been identified from the structure: a putative ligand-binding site and a coupled cleavage site. hPEBP forms a dimer in the crystal with a distinctive dipole moment that may orient the oligomer for membrane binding. CONCLUSIONS: The crystal structure of hPEBP suggests that the ligand-binding site could accommodate the phosphate head groups of membrane lipids, therefore allowing the protein to adhere to the inner leaf of bilipid membranes where it would be ideally positioned to relay signals from the membrane to the cytoplasm. The structure also suggests that ligand binding may lead to coordinated release of the N-terminal region of the protein to form the hippocampal neurostimulatory peptide, which is known to be active in the development of the hippocampus. These studies are consistent with a primary biological role for hPEBP as a transducer of signals from the interior membrane surface.
DOI:10.1007/s10059-011-0112-9URLPMID:3887636 [本文引用: 1]
Floral transition is coordinately regulated by both endogenous and exogenous cues to ensure reproductive success under fluctuating environmental conditions. Abiotic stress conditions, including drought and high salinity, also have considerable influence on this developmental process. However, the signaling components and molecular mechanisms underlying the regulation of floral transition by environmental factors have not yet been defined. In this work, we show that the Arabidopsis BROTHER OF FT AND TFL1 (BFT) gene, which encodes a member of the FLOWERING LOCUS T (FT)/TERMINAL FLOWER 1 (TFL1) family, regulates floral transition under conditions of high salinity. The BFT gene was transcriptionally induced by high salinity in an abscisic acid (ABA)-dependent manner. Transgenic plants overexpressing the BFT gene (35S:BFT) and BFT-deficient mutant (bft-2) plants were phenotypically indistinguishable from Col-0 plants in seed germination and seedling growth under high salinity. In contrast, although the floral transition was delayed significantly in Col-0 plants under high salinity, that of the bft-2 mutant was not affected by high salinity. We also observed that expression of the APETALA1 (AP1) gene was suppressed to a lesser degree in the bft-2 mutant than in Col-0 plants. Taken together, our observations suggest that BFT mediates salt stress-responsive flowering, providing an adaptive strategy that ensures reproductive success under unfavorable stress conditions.
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DOI:10.1073/pnas.0500932102URLPMID:15894619 [本文引用: 1]
Homologous proteins occurring through gene duplication may give rise to novel functions through mutations affecting protein sequence or expression. Comparison of such homologues allows insight into how morphological traits evolve. However, it is often unclear which changes are key to determining new functions. To address these ideas, we have studied a system where two homologues have evolved clear and opposite functions in controlling a major developmental switch. In plants, flowering is a major developmental transition that is critical to reproductive success. Arabidopsis phosphatidylethanolamine-binding protein homologues TERMINAL FLOWER 1 (TFL1) and FLOWERING LOCUS T (FT) are key controllers of flowering, determining when and where flowers are made, but as opposing functions: TFL1 is a repressor, FT is an activator. We have uncovered a striking molecular basis for how these homologous proteins have diverged. Although <60% identical, we have shown that swapping a single amino acid is sufficient to convert TFL1 to FT function and vice versa. Therefore, these key residues may have strongly contributed to the selection of these important functions over plant evolution. Further, our results suggest that TFL1 and FT are highly conserved in biochemical function and that they act as repressors or activators of flowering through discrimination of structurally related interactors by a single residue.
DOI:10.1105/tpc.106.049767URLPMID:17369370 [本文引用: 1]
Shoot meristems harbor stem cells that provide key growing points in plants, maintaining themselves and generating all above-ground tissues. Cell-to-cell signaling networks maintain this population, but how are meristem and organ identities controlled? TERMINAL FLOWER1 (TFL1) controls shoot meristem identity throughout the plant life cycle, affecting the number and identity of all above-ground organs generated; tfl1 mutant shoot meristems make fewer leaves, shoots, and flowers and change identity to flowers. We find that TFL1 mRNA is broadly distributed in young axillary shoot meristems but later becomes limited to central regions, yet affects cell fates at a distance. How is this achieved? We reveal that the TFL1 protein is a mobile signal that becomes evenly distributed across the meristem. TFL1 does not enter cells arising from the flanks of the meristem, thus allowing primordia to establish their identity. Surprisingly, TFL1 movement does not appear to occur in mature shoots of leafy (lfy) mutants, which eventually stop proliferating and convert to carpel/floral-like structures. We propose that signals from LFY in floral meristems may feed back to promote TFL1 protein movement in the shoot meristem. This novel feedback signaling mechanism would ensure that shoot meristem identity is maintained and the appropriate inflorescence architecture develops.
DOI:10.1105/tpc.111.088641URL [本文引用: 1]
TERMINAL FLOWER1 (TFL1) is a key regulator of flowering time and the development of the inflorescence meristem in Arabidopsis thaliana. TFL1 and FLOWERING LOCUS T (FT) have highly conserved amino acid sequences but opposite functions. For example, FT promotes flowering and TFL1 represses it; FT-overexpressing plants and TFL1 loss-of-function mutants have a similar phenotype production of terminal flowers in the shoot apex. FT is believed to function in a transcriptional activator complex by interacting with FD. Here, we demonstrate that TFL1 is involved in the transcriptional repression of genes that are activated by FT. We analyzed transgenic plants overexpressing TFL1 fused to a transcriptional repressor domain (TFL1-SRDX) or an activator domain (TFL1-VP16). Plants carrying 35S:TFL1-SRDX showed delayed flowering similar to 35S:TFL1 plants, and plants carrying 35S:TFL1-VP16 showed an early flowering phenotype and produced terminal flowers. Furthermore, the tfl1 and 35S:TFL1-VP16 plant phenotypes were strongly suppressed by the fd mutation, and TFL1 interacted with FD in the cell nucleus, as shown by bimolecular fluorescence complementation experiments. We conclude that TFL1 negatively modulates the FD-dependent transcription of target genes to fine-tune flowering time and the development of the inflorescence meristem.
[本文引用: 1]
DOI:10.1007/s00425-016-2466-xURLPMID:26825444 [本文引用: 1]
Abstract Main conclusion: Two TFL1 -like genes, CorfloTFL1 and CorcanTFL1 cloned from Cornus florida and C. canadensis, function in regulating the transition to reproductive development in Arabidopsis. TERMINAL FLOWER 1 (TFL1) is known to regulate inflorescence development in Arabidopsis thaliana and to inhibit the transition from a vegetative to reproductive phase within the shoot apical meristem. Despite the importance, TFL1 homologs have been functionally characterized in only a handful eudicots. Here we report the role of TFL1 homologs of Cornus L. in asterid clade of eudicots. Two TFL1-like genes, CorfloTFL1 and CorcanTFL1, were cloned from Cornus florida (a tree) and C. canadensis (a subshrub), respectively. Both are deduced to encode proteins of 175 amino acids. The amino acid sequences of these two Cornus TFL1 homologs share a high similarity to Arabidopsis TFL1 and phylogenetically more close to TFL1 paralogous copy ATC (Arabidopsis thaliana CENTRORADIALIS homologue). Two genes are overexpressed in wild-type and tfl1 mutant plants of A. thaliana. The over-expression of each gene in wild-type Arabidopsis plants results in delaying flowering time, increase of plant height and cauline and rosette leaf numbers, excessive shoot buds, and secondary inflorescence branches. The over-expression of each gene in the tfl1 mutant rescued developmental defects, such as the early determinate inflorescence development, early flowering time, and other vegetative growth defects, to normal phenotypes of wild-type plants. These transgenic phenotypes are inherited in progenies. All data indicate that CorfloTFL1 and CorcanTFL1 have conserved the ancestral function of TFL1 and CEN regulating flowering time and inflorescence determinacy.
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DOI:10.1111/tpj.12809URLPMID:25720985 [本文引用: 1]
Summary Photoperiod and temperature are major environmental signals affecting flowering in plants. Although molecular pathways mediating these signals have been well characterized in the annual model plant Arabidopsis , much less information is known in perennials. Many perennials including the woodland strawberry ( Fragaria vesca L.) are induced to flower in response to decreasing photoperiod and temperature in autumn and they flower following spring. We showed earlier that, in contrast with Arabidopsis , the photoperiodic induction of flowering in strawberry occurs in short days (SD) when the decrease in FvFT1 ( FLOWERING LOCUS T ) and FvSOC1 ( SUPPRESSOR OF THE OVEREXPRESSION OF CONSTANS1 ) expression leads to lower mRNA levels of the floral repressor, FvTFL1 (TERMINAL FLOWER1). By using transgenic lines and gene expression analyses, we show evidence that the temperature-mediated changes in the FvTFL1 mRNA expression set critical temperature limits for the photoperiodic flowering in strawberry. At temperatures below 13°C, low expression level of FvTFL1 in both SD and long days (LD) allows flower induction to occur independently of the photoperiod. Rising temperature gradually increases FvTFL1 mRNA levels under LD, and at temperatures above 13°C, SD is required for the flower induction that depends on the deactivation of FvSOC1 and FvTFL1 . However, an unknown transcriptional activator, which functions independently of FvSOC1, enhances the expression of FvTFL1 at 23°C preventing photoperiodic flowering. We suggest that the observed effect of the photoperiod02×02temperature interaction on FvTFL1 mRNA expression may allow strawberry to induce flowers in correct time in different climates.
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DOI:10.1093/jxb/ery093URLPMID:29547987 [本文引用: 1]
We characterizeGoSPgenes underlying the development of cotton plants with short branches and clustered bolls, a phenotype that allows higher planting density and promotes increased fiber yield per acre. In cotton, the formation of fruiting branches affects both plant architecture and fiber yield. Here, we report map-based cloning of the axillary flowering mutation gene (GbAF) that causes bolls to be borne directly on the main plant stem inGossypium barbadense,and of the clustered boll mutation gene (cl1) inG. hirsutum. Both mutant alleles were found to represent point mutations at theCl1locus. Therefore, we propose that theGbAFmutation be referred to ascl1b. TheseCl1loci correspond to homologs of tomatoSELF-PRUNING(SP), i.e.Gossypiumspp. SP(GoSP) genes. In tetraploid cottons, single monogenic mutation of either duplicateGoSPgene (one in the A and one in the D subgenome) is associated with the axillary cluster flowering phenotype, although the shoot-indeterminate state of the inflorescence is maintained. By contrast, silencing of bothGoSPsleads to the termination of flowering or determinate plants. The architecture of axillary flowering cotton allows higher planting density, contributing to increased fiber yield. Taken together the results provide new insights into the underlying mechanism of branching in cotton species, and characterization ofGoSPgenes may promote the development of compact cultivars to increase global cotton production.
DOI:10.1038/nbt.3208URLPMID:25893780 [本文引用: 2]
Abstract Gossypium hirsutum has proven difficult to sequence owing to its complex allotetraploid (AtDt) genome. Here we produce a draft genome using 181-fold paired-end sequences assisted by fivefold BAC-to-BAC sequences and a high-resolution genetic map. In our assembly 88.5% of the 2,173-Mb scaffolds, which cover 89.6% 96.7% of the AtDt genome, are anchored and oriented to 26 pseudochromosomes. Comparison of this G. hirsutum AtDt genome with the already sequenced diploid Gossypium arboreum (AA) and Gossypium raimondii (DD) genomes revealed conserved gene order. Repeated sequences account for 67.2% of the AtDt genome, and transposable elements (TEs) originating from Dt seem more active than from At. Reduction in the AtDt genome size occurred after allopolyploidization. The A or At genome may have undergone positive selection for fiber traits. Concerted evolution of different regulatory mechanisms for Cellulose synthase (CesA) and 1-Aminocyclopropane-1-carboxylic acid oxidase1 and 3 (ACO1,3) may be important for enhanced fiber production in G. hirsutum.
DOI:10.1038/nbt.3207URLPMID:25893781 [本文引用: 2]
http://www.nature.com/doifinder/10.1038/nbt.3207
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DOI:10.1038/nprot.2006.286URLPMID:17487191 [本文引用: 1]
Expression and tracking of fluorescent fusion proteins has revolutionized our understanding of basic concepts in cell biology. The protocol presented here has underpinned much of the in vivo results highlighting the dynamic nature of the plant secretory pathway. Transient transformation of tobacco leaf epidermal cells is a relatively fast technique to assess expression of genes of interest. These cells can be used to generate stable plant lines using a more time-consuming, cell culture technique. Transient expression takes from 2 to 4 days whereas stable lines are generated after approximately 2 to 4 months.
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DOI:10.1007/s00122-016-2773-4URL [本文引用: 1]
Key message Integration of previous Mendelian genetic analyses and recent molecular genomics approaches, such as linkage mapping and QTL cloning, dramatically strengthened our current understanding...
DOI:10.3969/j.issn.1002-7807.2011.06.005URL [本文引用: 1]
通过RT-PCR结合RACE技术,从新疆陆地棉品种新陆早33 中克隆到一个FT类似基因,命名为GhFTLl基因(登录号:HM631972).该基因ORF(Open Reading Frame)全长为525 bp,可编码174个氨基酸,与其它植物中克隆的FT同源蛋白高度相似,含有FT蛋白亚家族两个关键的氨基酸残基及保守氨基酸基序.该基因在根、茎、花、 叶片、纤维和胚珠中均有表达,且在叶片和胚珠中的表达要稍高于其它组织.系统进化分析表明GhFTLl属于FT亚家族成员.在18个已经证明可以促进植物 开花的FT同源基因中,GhFTL1同苹果的MdFT1的遗传距离最接近.在拟南芥中过量表达GhFTL1,T1转基因植株要比野生型明显提早开花.表明 GhFTLl可能属于开花途径中的重要作用因子之一.
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DOI:10.3969/j.issn.1002-7807.2011.06.005URL [本文引用: 1]
通过RT-PCR结合RACE技术,从新疆陆地棉品种新陆早33 中克隆到一个FT类似基因,命名为GhFTLl基因(登录号:HM631972).该基因ORF(Open Reading Frame)全长为525 bp,可编码174个氨基酸,与其它植物中克隆的FT同源蛋白高度相似,含有FT蛋白亚家族两个关键的氨基酸残基及保守氨基酸基序.该基因在根、茎、花、 叶片、纤维和胚珠中均有表达,且在叶片和胚珠中的表达要稍高于其它组织.系统进化分析表明GhFTLl属于FT亚家族成员.在18个已经证明可以促进植物 开花的FT同源基因中,GhFTL1同苹果的MdFT1的遗传距离最接近.在拟南芥中过量表达GhFTL1,T1转基因植株要比野生型明显提早开花.表明 GhFTLl可能属于开花途径中的重要作用因子之一.
DOI:10.3969/j.issn.1002-7807.2010.05.001URL [本文引用: 1]
以中棉所36均一化全长cDNA文库为基础,利用RT-PCR技术从棉花中克隆了一个新的CO蛋白基因,命名为GhCO(GenBank:HM006910)。GhCO cDNA的ORF全长为1017 bp,编码338个氨基酸,含有一个CCT域和两个BBOX域。序列比较分析结果表明,GhCO蛋白与蓖麻RcCO、芒果MiCO具有较高的同源性,是棉花CO蛋白家族中的新成员。QRT-PCR结果表明,GhCO在棉花的花、蕾、胚珠等均有表达,而且在蕾和花中优势表达。GhCO在花芽分化形态出现以前就已经高调表达,推测可能与棉花的花芽分化有关。AtCO已经证明在花发育过程中对开花时间起正向调节因子的作用,推测GhCO蛋白在花发育过程中可能起重要作用。因此,构建了pBIGhCO过量表达载体,为进一步研究GhCO的功能奠定了重要的基础。
DOI:10.3969/j.issn.1002-7807.2010.05.001URL [本文引用: 1]
以中棉所36均一化全长cDNA文库为基础,利用RT-PCR技术从棉花中克隆了一个新的CO蛋白基因,命名为GhCO(GenBank:HM006910)。GhCO cDNA的ORF全长为1017 bp,编码338个氨基酸,含有一个CCT域和两个BBOX域。序列比较分析结果表明,GhCO蛋白与蓖麻RcCO、芒果MiCO具有较高的同源性,是棉花CO蛋白家族中的新成员。QRT-PCR结果表明,GhCO在棉花的花、蕾、胚珠等均有表达,而且在蕾和花中优势表达。GhCO在花芽分化形态出现以前就已经高调表达,推测可能与棉花的花芽分化有关。AtCO已经证明在花发育过程中对开花时间起正向调节因子的作用,推测GhCO蛋白在花发育过程中可能起重要作用。因此,构建了pBIGhCO过量表达载体,为进一步研究GhCO的功能奠定了重要的基础。
[本文引用: 1]
[本文引用: 1]
DOI:10.1534/genetics.104.033357URL [本文引用: 1]
Photoperiod has been known to regulate flowering time in many plant species. In Arabidopsis, genes in the long day (LD) pathway detect photoperiod and promote flowering under LD. It was previously reported that clavata2 (clv2) mutants grown under short day (SD) conditions showed suppression of the flower meristem defects, namely the accumulation of stem cells and the resulting production of extra floral organs. Detailed analysis of this phenomenon presented here demonstrates that the suppression is a true photoperiodic response mediated by the inactivation of the LD pathway under SD. Inactivation of the LD pathway was sufficient to suppress the clv2 defects under LD, and activation of the LD pathway under SD conditions restored clv2 phenotypes. These results reveal a novel role of photoperiod in flower meristem development in Arabidopsis. Flower meristem defects of clv1 and clv3 mutants are also suppressed under SD, and 35S:CO enhanced the defects of clv3, indicating that the LD pathway works independently from the CLV genes. A model is proposed to explain the interactions between photoperiod and the CLV genes.
DOI:10.1111/pce.13000URLPMID:28628949 [本文引用: 1]
Photoperiod duration can be predicted from previous days but irradiance fluctuates in an unpredictable manner. To investigate how allocation to starch responds to changes in these two environmental variables, Arabidopsis Col‐0 was grown in a 6‐h and a 12‐h photoperiod at three different irradiances. The absolute rate of starch accumulation increased when photoperiod duration was shortened and when irradiance was increased. The proportion of photosynthate allocated to starch increased strongly when photoperiod duration was decreased but only slightly when irradiance was decreased. There was a small increase in the daytime level of sucrose and two‐fold increases in glucose, fructose and glucose 6‐phosphate at a given irradiance in short photoperiods compared to long photoperiods. The rate of starch accumulation correlated strongly with sucrose and glucose levels in the light, irrespective of whether these sugars were responding to a change in photoperiod or irradiance. Whole plant carbon budget modelling revealed a selective restriction of growth in the light period in short photoperiods. It is proposed that photoperiod‐sensing, possibly related to the duration of the night, restricts growth in the light period in short photoperiods, increasing allocation to starch and providing more carbon reserves to support metabolism and growth in the long night.
DOI:10.1371/journal.pone.0161080URLPMID:725 [本文引用: 1]
Upland cotton (Gossypium hirsutumL.) is a naturally occurring photoperiod-sensitive perennial plant species. However, sensitivity to the day length was lost during domestication. The phosphatidylethanolamine-binding protein (PEBP) gene family, of which three subclades have been identified in angiosperms, functions to promote and suppress flowering in photoperiod pathway. Recent evidence indicates that PEBP family genes play an important role in generating mobile flowering signals. We isolated homologues of thePEBPgene family in upland cotton and examined their regulation and function. NinePEBP-like genes were cloned and phylogenetic analysis indicated the genes belonged to four subclades (FT,MFT,TFL1andPEBP). CottonPEBP-like genes showed distinct expression patterns in relation to different cotton genotypes, photoperiod responsive and cultivar maturity. TheGhFTgene expression of a semi-wild race of upland cotton were strongly induced under short day condition, whereas theGhPEBP2gene expression was induced under long days. We also elucidated that GhFT but not GhPEBP2 interacted with FD-like bZIP transcription factor GhFD and promote flowering under both long- and short-day conditions. The present result indicated thatGhPEBP-like genes may perform different functions. This work corroborates the involvement ofPEBP-like genes in photoperiod response and regulation of flowering time in different cotton genotypes, and contributes to an improved understanding of the function ofPEBP-like genes in cotton.
DOI:10.1093/mp/sst114URLPMID:23935007 [本文引用: 1]
Soil salinity is one of the most serious agricultural problems that significantly reduce crop yields in the arid and semi-arid regions. It influences various phases of plant growth and developmental processes, such as seed germination, leaf and stem growth, and reproductive propagation. Salt stress delays the onset of flowering in many plant species. We have previously reported that the Arabidopsis BROTHER OF FT AND TFL1 (BFT) acts as a floral repressor under salt stress. However, the molecular mechanisms underlying the BFT function in the salt regulation of flowering induction is unknown. In this work, we found that BFT delays flowering under high salinity by competing with FLOWERING LOCUS T (FT) for binding to the FD transcription factor. The flowering time of FD-deficient fd-2 mutant was insensitive to high salinity. BFT interacts with FD in the nucleus via the C-terminal domain of FD, which is also required for the interaction of FD with FT, and interferes with the FT–FD interaction. These observations indicate that BFT constitutes a distinct salt stress signaling pathway that modulates the function of the FT–FD module and possibly provides an adaptation strategy that fine-tunes photoperiodic flowering under high salinity. Under high salinity, the floral repressor BFT competes with FT for FD binding and thus interferes with the FT–FD function, resulting in delayed flowering. The BFT-mediated salt stress signaling scheme provides an adaptation strategy by fine-tuning photoperiodic flowering under high salinity.
