黄酮醇作为信号分子增强小麦抗旱性的机理研究

Drought seriously affects the production of common wheat (Triticum aestivum L.), so it is urgent to recognize wheat drought resistant mechanism and cultivate drought-resistant wheat cultivars. We previously bred wheat introgression cultivar SR3 with superior salt and drought tolerance using the asymmetric somatic hybridization approach. In previous research, we found the transcriptional level of TaFLS1 significantly improved. In comparison with its parent wheat cultivar JN177, SR3 had lower water loss rate, higher percentage of closed stomata, and more flavonols in guard cell under drought, suggesting a close relationship between flavonols accumulation and SR3’s drought tolerance. We verified flavonols enhanced wheat’s tolerance to drought via the modulation of stomatal movement. However, whether flavonols can function as antioxidant or signal molecules in the process remains elusive. In this project, we propose to discover the flavonol binding proteins, and analyze the effects of flaovnols on the activities of the binding proteins, with aim to preliminary explicit the molecular mechanism of flavonols underlying the modulation on stomatal movement to improve drought resistance. Our research will provide molecular clue to further expound the mechanism of stomatal movement regulation and offer molecular element to cultivate new drought-resistant wheat cultivars.

干旱严重影响小麦产量，因此认识小麦抗旱机制、培育抗旱新品种具有重要意义。本实验前期利用不对称体细胞杂交技术，培育了耐盐抗旱小麦品种山融3号（SR3）。前期研究发现，旱胁迫下其叶片中黄酮醇合成酶基因TaFLS1明显提高。与亲本济南177（JN177）相比，SR3失水率变慢，干旱胁迫下关闭气孔比例及保卫细胞中黄酮醇含量更高，表明黄酮醇富集水平与SR3的抗旱性密切相关；利用构建的TaFLS1过表达和突变体株系，我们证实了黄酮醇通过调控气孔运动来提高小麦的抗旱性。但是黄酮醇是作为氧化剂还是信号分子在此过程中起作用尚不清楚。本项目拟寻找小麦体内黄酮醇直接作用的靶蛋白，分析黄酮醇对互作蛋白活性以及气孔运动信号通路的影响，初步明确黄酮醇通过调控气孔运动提高抗旱性的分子机理。本项目能为进一步阐明气孔运动调控机制提供分子线索，并为抗旱小麦（作物）新品种培育提供重要的分子元件。

干旱严重影响小麦产量，因此认识小麦抗旱机制、培育抗旱新品种具有重要意义。本实验前期利用非对称体细胞杂交技术，培育了耐盐抗旱小麦品种山融3号（SR3）。前期研究发现，与亲本济南177（JN177）相比，旱胁迫下SR3叶片中黄酮醇合成酶基因TaFLS1表达明显提高，失水率降低，干旱胁迫下关闭气孔比例及保卫细胞中黄酮醇含量升高，表明黄酮醇富集水平与SR3的抗旱性密切相关；利用构建的TaFLS1过表达和突变体株系，我们证实了黄酮醇可以通过调控气孔运动来提高小麦的抗旱性；并且发现，干旱胁迫下，黄酮醇作为信号分子通过与PP2C竞争结合SNRK，解除了PP2C对其的抑制作用，激活下游SLAC1离子通道活性，使得气孔关闭增强小麦的抗旱性，从而解析了黄酮醇作为信号分子提高小麦抗旱性的分子机制。三年以上的大田试验表明，FLS1过表达系及外源施加槲皮素可以提高干旱条件下小麦的光合作用和产量，揭示了黄酮醇增强小麦抗旱性的应用价值。本项目的完成为植物中次生代谢物作为信号分子调控气孔信号通路的研究提供了线索，并为小麦抗旱节水及干旱条件下稳产甚至增产提供了重要的思路。