Molecular Plant-Microbe Interactions

植物利用组成型和诱导型防御来抵抗微生物的攻击，包括RNA沉默、基础和高度特异性抗性。基础耐药（PTI，PAMP触发免疫）通常通过检测病原体相关分子模式（PAMP）介导。然而，适应的微生物表达了一套效应蛋白，这些效应蛋白通常会抑制这些防御。植物已经进化出称为抗性蛋白（R蛋白）的其他受体，它们检测这些病原体效应物并激活称为效应物触发免疫（ETI）的强大防御。RNA沉默是一种核苷酸序列特异性的RNA更新机制，在真核生物中高度保守。不同生物体中RNA沉默的共同特征是双链（ds）RNA作为起始分子的参与和21- 25 nt的小（s）RNA的存在，所述小（s）RNA由称为Dicer的RNA酶III样酶从dsRNA加工而成。sRNA赋予RNA诱导的沉默复合物（RISC）序列特异性，其特征在于降解与激活dsRNA分子的任何RNA共享序列同源性的核酸酶。在上一个资助期间，我们发现植物病原体使用几种策略，包括抑制免疫力，操纵宿主基因，以使疾病发生。我们还发现，植物能够感知RNAi途径的抑制子，作为诱导ETI的反-反防御策略。在接下来的资助中，我将专注于水杨酸如何诱导某些病原体的毒力，植物病原体如何操纵宿主基因以抑制先天免疫以及植物如何感知RNAi途径的抑制因子从而激活ETI。所获得的知识将有助于制定新的战略，不仅在加拿大，而且在世界各地更好地管理疾病问题。

Plants fight microbial attacks using both constitutive and induced defenses which include RNA silencing, basal and highly specific resistance. Basal resistance (PTI, for PAMP Triggered Immunity) is very often mediated via the detection of pathogen-associated molecular patterns (PAMPs). However, adapted microbes express a suite of effector proteins that often act to suppress these defenses. Plants have evolved other receptors called resistance proteins (R proteins) that detect these pathogen effectors and activate strong defenses called Effector Triggered Immunity (ETI). RNA silencing is a nucleotide sequence-specific RNA turnover mechanism that is highly conserved among eukaryotes. Common features of the RNA silencing in different organisms are the involvement of double-stranded (ds)RNA as initiator molecule and the presence of small (s)RNAs of 21-25nt that are processed from dsRNA by an RNAse III-like enzyme named Dicer. The sRNAs confer sequence specificity to a RNA-induced silencing complex (RISC) featuring a nuclease that degrades any RNA-sharing sequence homology to the activating dsRNA molecules. During the last funding period we showed that plant pathogens use several strategies, including suppression of immunity, manipulation of host genes, to enable disease. We also showed that plant is able to sense a suppressor of RNAi pathway as a counter-counter defense strategy to induce ETI. In the next funding, I will focus on how salicylic acid induces virulence of some pathogens, how plant pathogens manipulate host genes to suppress innate immunity and how plant sense a suppressor of RNAi pathway leading to activation of ETI. The knowledge obtained will contribute to the development of new strategies to better manage the disease problems not only in Canada, but around the world.