水稻PIFs转录因子的节水抗旱功能及调控机理研究

The shortage of water resources is the main fact that restricts the agricultural production. Biological water saving plays an important role in agricultural water saving and drought resistance. Phytochrome-interacting factors (PIFs), as cellular signaling hubs, play a pivotal role in plant growth and development. We found from the previous study that maize PIFs transcription factors could significantly improve water-saving and drought-resistant ability of transgenic rice. Moreover, maize PIFs transcription factors were able to increase grain yield in transgenic rice. However, the function of PIFs involved in water-saving and drought-resistant has not been reported. On the basis of selected gene OsPIL15 from rice, which shares the highest homology with PIFs gene in maize, we construct the over-expression and knockout transgenic materials. This project aims to carry out researches as follows: ①The over-expression and knockout transgenic materials analyzing the function of water-saving and drought-resistant of OsPIL15 based on the phenotypic and physiological changes of transgenic plants. ②Screening the interacting protein and the downstream regulatory gene of OsPIL15 by the yeast two hybrid, ChIP-seq and RNA-seq analysis. Combined with the experimental data of PIFs gene obtained from maize and Arabidopsis thaliana, this project aims to explore the novel water-saving and drought-resistant regulatory mechanisms of the transcription factor PIFs, thereby providing new gene and idea for the genetic improvement of drought-resistant crops.

水资源短缺是制约农业生产的主要问题，生物节水在农业节水抗旱中具有重要作用。转录因子PIFs（光敏色素作用因子）在植物生长发育和信号调控中发挥枢纽作用。申请人前期研究发现玉米PIFs基因能够显著提高转基因水稻的节水抗旱性，且转基因水稻具有较好的农艺性状。但目前为止，还没有PIFs基因参与节水抗旱的报道。在此基础上，申请人筛选获得水稻PIFs家族基因OsPIL15（与玉米PIFs同源性最高），利用其过表达和敲除植株，拟开展以下工作：①过表达和敲除植株抗旱表型、生理和农艺性状分析，推断PIFs的节水抗旱功能；②酵母双杂交文库筛选、染色质免疫共沉淀-测序（ChIP-seq）和转录组测序（RNA-seq），获得PIFs节水抗旱蛋白复合体组成蛋白和下游调控基因。结合申请人已获取的玉米和拟南芥PIFs实验数据，解析水稻PIFs转录因子的节水抗旱调控机理，为作物抗旱分子遗传改良提供新的基因元件和策略。

缺水和干旱是目前制约农业生产的主要问题。水稻是农业用水的第一大户，约占中国农业用水总量的70%左右，因此水稻的节水抗旱研究在农业节水抗旱中具有突出意义。节水抗旱是生物节水和抗旱研究的交叉结合，指植物通过减少水分散失，降低耗水，保存水分，避免或延迟植株遭受干旱。减少水分散失是植物节水抗旱中的重要环节，植物蒸腾是植物耗水的重要途径，气孔蒸腾占总蒸腾量的80%-90%是影响植株蒸腾的主要因素。气孔运动指气孔的打开或关闭，直接影响植物气孔蒸腾，是蒸腾失水的关键生理过程。.植物光敏色素互作因子 (PIFs) 属于碱性螺旋-环-螺旋 (bHLH) 转录因子家族。本项目通过一系列表型、生理、分子和生化实验，在水稻中探索PIFs转录因子的节水抗旱功能及调控机理。主要有以下方面结果：①利用过表达、敲除、回补等转基因水稻材料，发现了水稻PIFs家族基因OsPIL15能够调控水稻气孔运动，影响蒸腾，具有节水抗旱功能。②通过与脱落酸（ABA）的相关性分析，发现OsPIL15通过ABA信号通路调控气孔运动，影响水稻蒸腾。③进一步探究其分子机制，发现OsPIL15通过激活ABA信号传导的关键正调节因子OsABI5来调节气孔运动。④OsPIL15与NIGT1/HRS1/HHO家族转录因子OsHHO3相互作用，形成转录因子复合体，共同调控OsABI5的表达，增强气孔运动，调控水稻蒸腾。通过本项目的研究揭示了水稻PIFs转录因子OsPIL15的节水抗旱功能，阐明了OsPIL15节水抗旱的分子机制，为水稻的节水抗旱分子遗传改良，发展节水抗旱水稻新品种提供基因资源和研究策略。