A pathogen-activated transcription program directed by TFIIB-related pBrp1 in plant immunity

植物病原体可导致严重的作物产量损失，从而威胁到全球粮食安全。了解植物免疫的分子机制将最终有助于制定更好的疾病控制策略。植物免疫的一个重要组成部分是在病原体感染时大量防御相关基因的激活。本项目的重点是寻找在植物免疫中起关键作用的植物防御基因表达的潜在主调控因子。该项目的主要目标是：(1)确定由调节剂直接调控的基因谱；(2)建立调节剂激活植物防御相关基因的机制；(3)确定调节剂在激活植物免疫应答过程中的调控作用。这个项目的结果将增强我们对差异基因表达过程的理解，这不仅是植物免疫系统的基础，也是生物体内所有复杂过程的基础。该项目将把研究与培训、学习、多样性和外展活动结合起来。参与该项目的博士后研究员和学生将接受广泛的分子方法的跨学科培训。该项目将整合到学生的课堂学习中，包括那些来自弱势群体和高中生的学生，以提高公众对科学和技术的认识。植物免疫中的转录重编程是通过特异性转录因子（tf）的协同作用，通过募集或释放RNA聚合酶II （RNAP II）来实现的。RNAP II全酶含有一组通用tf (gtf)，被认为是所有基因转录所必需的。转录因子IIB （TFIIB）是RNAP II的GTF。有趣的是，拟南芥有14个基因编码tfiib相关蛋白，包括6个植物特异性tfiib相关蛋白（pBrps）。本项目以拟南芥pBrp1为研究对象。pbrp1突变体在抗病和防御基因表达方面都受到损害。在未感染的植物中，pBrp1蛋白保留在质体包膜上，只有当蛋白酶体途径被抑制时，才能检测到核pBrp1。病原体感染诱导pBrp1积累。这些结果表明，pBrp1是一种特殊RNAP II全酶的受调控的GTF，该全酶指导防御基因转录程序。为了验证这一假设，该项目将使用全基因组转录组分析和ChIP-seq识别pBrp1的直接靶基因。pBrp1与RNAP II的直接关联将通过共免疫沉淀来确定，以确认pBrp1是RNAP II的GTF，并确定复合物中参与pBrp1作用和调控的其他成分。pBrp1的蛋白水平和核易位将被操纵，以确定pBrp1的严格调控对平衡植物防御与适应性的重要性。这些研究将有助于阐明植物免疫的转录调控，以及及时、准确、有效地激活植物防御的复杂机制。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Plant pathogens can lead to severe crop yield loss, thereby threatening global food security. Understanding the molecular mechanisms of plant immunity will ultimately help develop better disease control strategies. An integral part of plant immunity is the activation of a large number of defense-related genes upon pathogen infection. This project is focused on a potential master regulator of plant defense gene expression with a critical role in plant immunity. The main goals of the project are to i) identify the spectrum of genes that are directly regulated by the regulator, ii) establish the mechanisms by which the regulator activates plant defense-related genes and iii) determine the regulation of the regulator during the activation of plant immune responses. Results from this project will enhance our understanding of the process of differential gene expression fundamental not only to plant immune systems but also to all complex processes in living organisms. This project will integrate research with training, learning, diversity and outreach activities. Postdoctoral fellows and students working on the project will receive interdisciplinary training in a wide range of molecular approaches. The project will be integrated into classroom learning for students, including those from underrepresented groups and high school students, to increase the general public's awareness of science and technology. Transcription reprogramming in plant immunity is achieved through concerted action of specific transcription factors (TFs) through recruitment or release of RNA polymerase II (RNAP II). The RNAP II holoenzyme contains a group of general TFs (GTFs), which are believed to be required for transcription of all genes. Transcription factor IIB (TFIIB) is a GTF for RNAP II. Interestingly, Arabidopsis have 14 genes encoding TFIIB-related proteins including six plant-specific TFIIB-related proteins (pBrps). This project is focused on Arabidopsis pBrp1. The pbrp1 mutants are compromised in both disease resistance and defense gene expression. In uninfected plants, the pBrp1 protein is retained on the plastid envelop and nuclear pBrp1 is detected only when proteasome pathways are inhibited. Pathogen infection induces pBrp1 accumulation. These results suggest that pBrp1 is a regulated GTF of a special RNAP II holoenzyme that directs a defense gene transcription program. To test this hypothesis, the project will identify the direct target genes of pBrp1 using genome-wide transcriptome profiling and ChIP-seq. The direct association of pBrp1 with RNAP II will be determined using co-immunoprecipitation to confirm pBrp1 is a GTF for RNAP II and to identify other components in the complexes with roles in the action and regulation of pBrp1. The protein levels and nuclear translocation of pBrp1 will be manipulated to determine the importance of the tight regulation of pBrp1 for balancing plant defense with fitness. These studies will help elucidate transcriptional regulation of plant immunity, as well as the intricate mechanisms for timely, accurate and effective activation of plant defense.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.