Redox Regulation of mRNA Destablization and Gene Transcription During the Defense Response in Plants

9729537 Mehdy 植物抗病机制包括响应病原体攻击而快速产生活性氧。 过氧化氢等活性氧物质作为第二信使来动员一些防御相关基因表达的变化。 Mehdy 博士和她的同事之前对用真菌引发剂处理的培养矮法国豆细胞进行的研究提供了证据，证明氧化爆发产生的过氧化氢会导致通常稳定的细胞壁富含脯氨酸的蛋白质 mRNA PvPRP1 快速降解。 随后 PvPRP1 蛋白合成的减少可能有助于细胞壁的重塑，使其更能抵抗病原体的攻击。 为了了解 PvPRP1 mRNA 下调的机制，Mehdy 博士和她的同事将重点研究与 PvPRP1 mRNA 特异性结合的 50-kD RNA 结合蛋白的生化表征和克隆。 由于纯化的蛋白质需要还原的巯基来实现 RNA 结合活性，因此将在体外测定中研究可能发挥调节作用的特定细胞还原剂。 第三，Mehdy 博士和她的同事将开始使用基因上适合的豆科植物——蒺藜苜蓿（Medicago truncatula）来筛选位于病原体诱导的过氧化氢和 PvPRP1 mRNA 表达调节之间的成分突变。 这项研究将有助于了解涉及活性氧的信号通路，并提出提高作物抗病性的策略。

9729537 Mehdy Plant disease resistance mechanisms include the rapid production of active oxygen species in response to pathogen attack. Active oxygen species such as hydrogen peroxide serve as secondary messengers to mobilize changes in the expression of some defense-related genes. Dr. Mehdy and her associate's prior studies of cultured dwarf French bean cells treated with fungal elicitor provided evidence that hydrogen peroxide from the oxidative burst results in the rapid degradation of a normally stable cell wall proline-rich protein mRNA, PvPRP1. The ensuing reduced synthesis of the PvPRP1 protein is likely to contribute to remodeling of the cell wall to make it more resistant to pathogen attack. To understand the mechanism of PvPRP1 mRNA downregulation, Dr. Mehdy and her associates will focus on the biochemical characterization and cloning of a 50-kD RNA binding protein that specifically binds to the PvPRP1 MRNA. Since the purified protein requires reduced sulfhydryl group(s) for RNA binding activity, specific cellular reductants that may play a regulatory role will be investigated in in vitro assays. Thirdly, Dr. Mehdy and her associates will begin to use the genetically amenable legume species, Medicago truncatula, to screen for mutations in components that lie between pathogen-induced hydrogen peroxide and regulation of PvPRP1 mRNA expression. This study will contribute to understanding signalling pathways involving active oxygen species and suggest strategies for improving disease resistance in crops.