水稻和高粱浆片淀粉粒时空动态变化与颖花开放时间的关系

Regulation of timing of floret opening in gramineous plants is not only the pressing need for solving the problem of asynchronous floret opening between female and male parents in hybrid seed production, but also shows great potential in avoiding high temperature stress at flowering stage. To understand why different gramineous plants have their own specific timing of floret opening, rice and sorghum，which has specific timing of floret opening in the morning and at midnight，respectively, are used to conduct the following experiments: (1) observation of the temporal and spatial variability of starch granules of lodicules by paraffin section technique, and analysis of its relations to the timing of floret opening; (2) explorations of the types, activities of starch catabolic enzymes in lodicules and their differences between day time and night time, and analyses of their relations to the timing of floret opening; (3) studies on the effects of the known floret opening influencing factors such as MeJA and the influencing factors of starch catabolic enzyme activities on the temporal and spatial variability of lodicule starch granules, starch catabolic enzyme activities in lodicules and the timing of floret opening; (4) observation of the morphologic characteristics of lodicule strch granules with electron microscope. The project is expected to gain results for elucidating whether the accumulation and degradation of lodicule starch granules is controlled by specific circadian rhythm, whether the specific circadian degradation of lodicule starch granules is the mechanism for the controlling of the timing of floret opening, and whether this mechanism is the downstream events of MeJA, which is also a controlling factor of timing of floret opening. Also, the results is expected to provide new methods for the regulation of the timing of floret opening.

禾本科植物颖花开放时间的调控不仅是解决杂交制种父母本花时不遇难题的迫切需要，而且可望发展为避开花期高温为害的新技术。为探究不同禾本科植物的颖花为什么在一天中的不同特定时间开放，以分别在白天和夜间开颖的水稻和高粱为实验材料，开展以下研究：（1）采用石蜡切片观察颖花浆片淀粉粒的时空动态变化，分析其与颖花开放时间的关系；（2）分析颖花浆片淀粉降解酶的种类、活性、昼夜活性差异，及其与颖花开放时间的关系；（3）分析MeJA等颖花开放时间的外在影响因子和淀粉降解酶活性的调控因子对颖花浆片淀粉粒时空动态变化、浆片淀粉降解酶活性及颖花开放时间的影响；（4）电镜观察浆片淀粉粒的形态结构。研究不仅将阐明浆片淀粉粒的积累和降解是否受特定昼夜节律控制、淀粉粒降解的特定昼夜节律是否为颖花在一天中的特定时间开放的内在调控机制，以及这一调控机制是否为内在调控因子茉莉酸的下游机制，而且将为颖花开放时间的调控提供新的方法。

禾本科植物颖花开放时间的调控不仅是解决杂交制种父母本花时不遇难题的迫切需要，而且可望发展为避开花期高温为害的新技术。为探究不同禾本科植物的颖花为什么在一天中的不同特定时间开放，以分别在白天和夜间开颖的水稻和高粱为试材料，采用石蜡切片观察颖花浆片淀粉粒的动态变化与颖花开放时间的关系；分析颖花浆片淀粉降解酶的活性与颖花开放时间的关系；研究自然条件和茉莉酸甲酯处理条件下可能参与浆片吸水膨胀过程的生物学途径中的相关基因在成熟颖花开放前不同时刻浆片中的表达变化，分析花前12h和花前1h 两个时间点浆片样本的转录组变化。研究结果表明：（1）水稻浆片α-淀粉酶的活性在颖花开放前显著上升；水稻和高粱颖花开放前浆片淀粉粒数量和大小均明显减少；相对于花前12h，水稻和高粱浆片中α-淀粉酶基因家族和β-淀粉酶基因家族中都有多个基因成员在颖花开放2h之前被强烈诱导表达；提示颖花浆片淀粉粒的形成和降解可能是颖花开放的重要调控机制。（2）水稻和高粱浆片蔗糖转运酶相关基因、钾转运相关基因、水通道蛋白相关基因和钙结合蛋白相关基因的表达在颖花开放前几个小时明显上调；提示导致颖花浆片吸水膨大的多种因素在颖花开放前协同发挥作用，导致颖花开放。（3）颖花开放前12h和1h高粱浆片转录组中筛选出了23个参与JA信号转导途径的差异表达基因，临近颖花开放时高粱浆片中有多个JAZ基因和MYC2基因表达显著上调，其中SbJAZ （Sb01g023431.1）为高粱浆片在开花前1h特异表达的基因；提示茉莉酸信号途径参与颖花开放调控。本研究从形态解剖、生化和分子水平提供了浆片淀粉粒调控颖花开放的证据；丰富了颖花开放的调控机制，并为生产上调控颖花开放提供了新思路。