高温胁迫下棉花蕾铃脱落的“糖-激素”协同调控机制研究

As global warming intensifies, the cotton bud or boll abscission caused by high temperature stress will become a more important factor that restricting cotton yield in China, therefore, the abscission mechanism induced by high temperature stress needs to be further studied. This research proposal focus on study the mechanism by comparing study several important physiological indexes in the cotton variety which is easy to exfoliate and the variety which is not easy to exfoliate under high temperature stress. In the study, phloem chemical blocking technique will be applied; several major saccharides and plant hormones that may involve in abscission regulation and their balance changes in high temperature stress will be studied; and the differentiation between balance change and abscission in the two cultivars will be analyzed. Hopefully, the co-regulation mechanism of saccharides and plant hormones and the key factors that regulate bud and boll abscission will be explored. We believe that the findings of this research proposal will be very useful in understanding the cotton bud and boll abscission and in developing chemical control techniques in cotton cultivation practice.

随着全球温室化效应的加剧，高温导致的蕾铃脱落势将成为制约我国棉花高产高效的重要因素，高温防脱落机制亟待研究。本研究拟选择高温下极易脱落和高温下不易脱落两基因型棉花品种为材料，结合果枝韧皮部化学阻断技术，比较研究高温胁迫条件下1.两基因型品种“叶源-铃（蕾）库”间糖类物质与植物激素平衡变化的差异及其与脱落率差异形成的关系；2.高温与主要生长调节物质调控脱落生理基础的异同，解析高温调控棉花蕾铃脱落中的“糖物质-激素信号”协同作用机理，探明高温下防脱落的主控因子及其作用机制，为棉花高产防脱落栽培提供理论支撑。

全球温室化效应的加剧必将导致因高温导致的蕾铃脱落率大幅增加，将成为保障我国原棉有效供给的重要负面影响因素，因此高温防脱落机制亟待深入研究。本项目选用高温敏感性差异棉 花品种为材料，结合韧皮部阻断技术，研究了常温或高温胁迫条件下叶源-铃（蕾）库”间糖类物质与植物激素平衡变化及其与脱落率差异形成的关系，探讨了不同基因型品种主要生长调节物质调控脱落生理基础的异同，解析了高温调控棉花蕾铃脱落中的“糖类物质与激素信号”协同作用机理，初步探明了：.短期高温下棉铃脱落及铃重形成的信号主要来自于“叶源-铃库”系统的“库”端，环境高温诱导幼铃脱落可能的调控路径如下：棉铃中蔗糖卸载量下降，幼铃合成代谢大幅减弱，对位叶光合产物运输受阻，棉铃离区细胞受蔗糖或C/N信号激活，使得SnRK1表达增加，并正向调控ABA合成及其信号转导，同时生长素含量的减少以及ABA含量的增加又促进了ACC及乙烯的合成，乙烯及脱落酸等激素信号刺激了细胞壁水解酶的表达，进而促进了脱落。. 蕾铃脱落后，果枝叶中糖分积累和分配形式及内源激素信号发生显著改变并对其叶源能力产生显著影响。短期内（1-3天），果枝叶中糖类物质整体含量增加，尤其是非还原性糖累积幅度较大，源能力快速增强；但随着时间推移，源能力增强幅度下降，同时叶片有早衰趋势，叶绿素降解加速。即蕾铃脱落后，脱落蕾铃的果枝叶对其邻位铃的“辅助源”功能短期内（3天左右）快速上升，之后快速下降，后期其对邻位铃发育的贡献很小。. 该研究结论不仅丰富了棉花蕾铃脱落基础理论，还将为棉花高产防脱落栽培调节剂及其使用技术的研发提供理论支撑。