水稻隐性抗白叶枯病基因xa5介导的抗病途径中miRNA的功能研究

Epigenetics is one of the popular research fields in recent years. More and more studies show that miRNA plays a very important role in plant response to abiotic and biotic stresses. However, the function of miRNA in rice resistance, especially in the bacterial blight resistance, has been poorly studied. Previously, we carried out the analysis of global gene and miRNA expression profile between the near isogenic lines IRBB5 (containing the homozygous recessive resistance gene xa5 ) and IR24 (containing the homozygous gene Xa5), and obtained 15 miRNAs with obvious expresssion differences，including several novel miRNAs. This project aims to know about the functions of these miRNAs in resistance pathways mediated by the recessive bacterial blight resistance gene xa5 through bioinformatics and reverse genetics analysis. Expression analysis in the resistance reactions, Over-expresssion and suppressing tests will be carried out for the desired miRNAs and their targets. The purpose of this project is to obtain and illuminate the miRNAs with key functions in the resistance pathways mediated by the recessive bacterial blight resistance gene xa5 in rice and to produce new ideas for rice resistance breeding.

表观遗传学是近年来热门的研究领域之一。越来越多的研究表明miRNA在植物非生物胁迫和生物胁迫方面都起着重要作用，但在水稻抗病特别是抗白叶枯病方面的研究很少。我们详细分析了接种白叶枯病后的IRBB5（含纯合的xa5隐性抗性基因）和IR24（含纯合的显性基因Xa5）抗感近等基因系的数字基因表达谱和miRNA表达谱，获得了15个抗感表达有显著差异的miRNA，其中包括一些新预测的miRNA。本课题拟以这15个miRNA为起点，利用生物信息学和反向遗传学方法进行xa5基因介导的抗病途径中miRNA的功能研究。主要研究内容包括目标miRNA及其对应靶基因在抗病反应过程中的表达分析，以及miRNA-靶基因调控模块过表达试验和抑制试验。本研究的目标是获得并解析水稻xa5介导的抗病途径中起关键作用的miRNA调控因子，为水稻抗病育种提供新思路。

MicroRNA(miRNA)是植物中广泛存在的、长度约21-24nt的非编码小分子RNA，在植物非生物胁迫和生物胁迫方面都起着重要作用，但在水稻抗病特别是抗白叶枯病方面的研究很少。本研究详细分析了水稻白叶枯病感病材料IR24及其抗病近等基因系IRBB5(含纯合xa5基因)接种白叶枯菌小种PX086前后(0h,8h,24h)的小RNA及降解组测序数据，发现在水稻-Xoo相互作用中可能存在大量的miRNAs/靶基因调控单元。并通过对转基因植株的病斑表型鉴定，证实miR159b、miR164a、miR167d和miR1432等miRNAs引起的多样化防御反应，初步建立了miRNA参与调控水稻白叶枯病抗性反应的调控网络。研究还发现miR1432正向参与对水稻白叶枯病抗性的调控，过表达miR1432增强水稻对白叶枯病的抗性，并通过多种方法证明miR1432抑制其靶基因OsCML2在植物体内的表达。本研究鉴定并证明水稻抗病途径中起调控作用miRNAs的功能，为水稻抗病育种提供了新思路。