花铃期干旱影响棉花花粉育性的生理生化机制与调控

The national policy points out that cotton production will focus on dry and saline-alkali areas. However, drought events occur frequently in these areas. It was observed that drought stress during flowering and boll setting stage could result in the increase of seed abortion rate in cotton production, which is closely related to the altered pollen fertility. In this study, drought experiments will be conducted with a drought-sensitive cotton cultivar and a drought-tolerance cotton cultivar. The research content will focus on the sensitivity of pollen at different developmental stages to drought stress, and the changes of pollen fertility, morphological structure, and physiological and biochemical activities under drought stress occurring at the most sensitive stage to elucidate the mechanism of drought affecting cotton pollen fertility. On this basis, appropriate concentrations of exogenous hormones will be screened and then are applied to the drought-stressed pollen to study their effects in regulating pollen fertility under drought stress. Through this study, it will be understood about the mechanism of drought affecting cotton pollen fertility and the regulation of exogenous hormones on drought-stressed pollen, which finally can provide the theoretical basis for the exploration of appropriate and timely drought-resistant cultivation measures in production.

国家宏观调控正引导棉花种植向干旱、盐碱地区转移，这些地区的气候特点决定了棉花生产遭遇干旱事件的概率增加。且目前生产中经常发生的棉花蕾铃发育期干旱胁迫，显著增加了不孕籽率。而不孕籽产生与棉花花粉育性变化密切相关。因此，本项目选择干旱敏感、弱敏感棉花品种在花粉发育阶段设置干旱试验，研究棉花花粉发育不同阶段的干旱敏感性；并在干旱敏感阶段，对不同处理下的棉花花粉“育性变化-形态结构改变-物质和酶学基础差异-同工酶谱和关键基因表达差异”进行剖析研究，逐步深入阐述干旱影响棉花花粉育性的机制；在此基础上，筛选并施用适宜浓度的外源植物激素，研究其调控干旱胁迫下花粉育性变化的效应。研究结果可为生产上适时、适度采取抗旱栽培调控措施提供理论依据。

棉花种植正向干旱盐碱地区转移，导致棉花生产易遭遇干旱事件，影响棉花花粉育性及产量。因此，本项目选择干旱敏感(豫早棉9110)、弱敏感棉花品种(德夏棉1号)设置干旱试验，研究了棉花花粉育性及生理生化机制的变化，并进行了外源褪黑素施用效果探索，取得如下进展：(1)花粉发育不同阶段干旱胁迫均对小孢子细胞学结构产生了不同的消极影响，均会降低花粉育性，其中减数分裂期干旱对花粉育性的不利影响最显著。(2)减数分裂期干旱胁迫抑制了两品种花粉成熟期花药蔗糖合成酶、酸性转化酶活性，导致成熟期花药葡萄糖含量减少；而蔗糖转运基因GhSUT3A/D、GhSWEET55表达下调导致最终蔗糖含量减少；尽管减数分裂期干旱导致花粉成熟期存在较高的颗粒结合型淀粉合成酶活性，但腺苷二磷酸葡萄糖焦磷酸化酶(AGPase)活性降低，最终导致淀粉含量下降。与德夏棉1号相比，豫早棉9110 受旱后，成熟期花药GhSUT9、GhSUT3A/D、GhSWEET55基因表达下调幅度更大，对蔗糖转运抑制效应更强，导致蔗糖含量更低；AGPase活性下降幅度更大，导致淀粉含量积累更少，这是其受旱后花粉育性较德夏棉1号下降更显著的一个重要原因。(3)减数分裂期干旱胁迫破坏了花药活性氧代谢系统，至花粉成熟期，尽管两品种花药过氧化物酶(POD)、过氧化氢酶(CAT)活性增强且抗坏血酸(AsA)及谷胱甘肽(GSH)含量上升，但仍存在大量O2.-及H2O2含量，引起丙二醛含量增加。与德夏棉1号相比，豫早棉9110受旱后花粉成熟期POD、CAT 活性及AsA、GSH含量增幅较小，导致O2.-、H2O2含量积累较多，这是其受旱后花粉育性较德夏棉1号下降更显著的另一个重要原因。(4)外源褪黑素可以缓解受旱棉花花药水分状况，增加花粉育性，其中200 μM的效果较好。本研究结果可为棉花生产上适时、适度采取抗旱栽培调控措施提供理论依据。