植物对病原菌的抗病反应主要包括识别'病原菌相关分子特征'而引发的抗病反应（PTI，也称为本底抗性）和识别病原菌效应蛋白而引发的抗病反应（ETI，也称为小种专化抗性）。miRNAs是真核生物中一类内源非编码小分子RNA，通过降解基因转录产物或抑制蛋白翻译进而调控真核生物众多基因的表达和功能。研究表明，miRNAs在植物先天免疫反应中发挥重要的调控作用。我们将构建大麦和大麦白粉病菌的亲和与不亲和反应的互作体系，研究miRNAs在大麦白粉菌抗病反应中的功能，尤其是参与调控大麦ETI抗病反应的分子机制，主要包括：筛选白粉菌诱导表达水平发生变化的大麦miRNA并鉴定它们的候选靶标基因；鉴定潜在的直接调控大麦抗白粉病Mla基因家族的miRNAs；研究相关miRNAs及其靶标基因在大麦对白粉菌抗病途径中的功能，重点是阐明miRNA在大麦小种专化抗性中的功能和作用机理。

Plants utilize at least two branches of immune system to combat pathogens. One branch is the PAMP-triggered immunity (PTI) and the other is the effector-triggered immunity (ETI). Plant microRNAs (miRNAs) are short endogenous nontranslated RNAs that are incorporated into silencing complexes, wherein they guide repression of target genes by mRNA cleavage or translational repression. Increasing evidence suggests that miRNAs play an essential role in regulating plant immune responses against diverse pathogens. In this study, we will take the advantage of the barley-powdery mildew interactions to study the functions of miRNAs in the regulation of barley immune responses to barley powdery mildew fungus, especially in regulating ETI. We will focus our work on (1) Identification of miRNAs that are differentially expressed in small RNAs samples extracted from barley leaves infected with compatible or incompatible Blumeria graminis fungus using Solexa deep sequencing technology; (2) identification of the target genes of candidate miRNAs; (3) verification of the function of miRNAs and their targeting genes in barley disease resistance against Blumeria graminis fungus; (4) predicting potential barley miRNAs that targets barley resistance gene MLA transcripts and verifying the biological function of these miRNAs; (5) generating barley and wheat transgenic lines expressing functional miRNAs and their target genes for further functional analysis.