水稻RNA结合蛋白DSG调控株高的分子机制研究

Plant height is an important agronomic trait related to crop yield and plant lodging in rice. It is the main challenge to identify novel plant height genes and elucidate the molecular mechanisms of plant-height morphogenesis. Up to date,dwarf genes which have been cloned and characterized are mainly relevant to hormones including gibberellins (GA), brassinosteroids (BR) and strigolactone(SL). The regulation process involved hormone synthesis and signaling pathways and interactions between them. However, RNA-binding proteins implicated in the abscisic acid (ABA) signaling pathway that regulates plant height have not been reported. In our previous study, a dwarf and small grain (dsg) mutant with high content of ABA was isolated and a candidate gene， DSG which encodes a RNA binding protein was cloned. This project will further elucidate the regulation mechanisms of RNA bing protein involved in ABA signaling pathway, and characterize the gene function on controlling of plant height. The results will provide theoretical directions for plant architecture improvement and a novel gene germplasm resource in rice breeding.

水稻株高是与产量、抗倒性密切相关的重要农艺性状。利用株高突变体克隆株高调控基因，解析株高形成的分子机制，是水稻分子生物学研究的重要内容。到目前为止，已经克隆的水稻株高基因多数都与赤霉素、油菜素内酯和独角金内酯等激素的代谢或信号转导有关，而对通过ABA信号调控株高的编码RNA结合蛋白基因的研究尚未见报道。申请者在前期研究中筛选到一个水稻ABA含量增加的矮秆突变体dsg（dwarf and small grain），通过图位克隆和转基因互补验证，确认了一个编码RNA结合蛋白的基因为目标基因DSG，并发现该基因有可能参与ABA信号转导途径。在此基础上，本项目拟深入研究DSG蛋白参与ABA信号调节调控的作用机制，挖掘基因转录后调控途径中DSG的互作蛋白、下游调控基因，进而阐明DSG蛋白调控株高等重要农艺性状的分子机制，为水稻株型调控及理想株型育种提供新思路和有重要价值的新基因资源。

水稻株高是与产量、抗倒性密切相关的重要农艺性状。利用株高突变体克隆株高调控基因，解析株高形成的分子机制，是水稻分子生物学研究的重要内容。到目前为止，已经克隆的水稻株高基因多数都与赤霉素、油菜素内酯和独角金内酯等激素的代谢或信号转导有关，而对通过独角金内酯信号调控株高的编码RNA结合蛋白基因的研究尚未见报道。本研究报道了一个水稻矮秆多分蘖突变体（dwarf and high tillering1 (dht1/原命名dsg)，通过图位克隆和转基因互补验证，确认了一个编码RNA结合蛋白的基因为目标基因DHT1。进一步研究发现，DHT1编码一个新的单子叶植物特有的hnRNP类蛋白，它可以作为剪切体组分调控包括独角金内酯（SLs）信号途径的D14等许多基因前体mRNA的内含子剪接。研究结果表明，DHT1I232F突变体蛋白稳定性和结合RNA能力受损，进而导致突变体中D14前体mRNA剪接、稳定及表达均受到影响，使得dht1突变体产生类似独脚金内酯缺陷表型。本研究结果深入阐明了hnRNP类蛋白可以作为剪切体组分调控前体mRNA剪接的新功能，并在D14前体mRNA的转录后剪接和SL信号转导与株型调控发育之间建立了新的功能联系，为水稻株型调控及理想株型育种提供新思路和有重要价值的新基因资源。