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，从而威胁全球粮食安全。 了解植物免疫的分子机制将最终有助于开发更好的疾病控制策略。 植物免疫的一个组成部分是在病原体感染时激活大量防御相关基因。 该项目的重点是一个潜在的主调节植物防御基因的表达与植物免疫的关键作用。 该项目的主要目标是：i）确定由调节剂直接调节的基因谱，ii）建立调节剂激活植物防御相关基因的机制，iii）确定调节剂在植物免疫应答激活过程中的调节。 该项目的结果将增强我们对差异基因表达过程的理解，这不仅对植物免疫系统至关重要，而且对活生物体中的所有复杂过程也至关重要。 该项目将把研究与培训、学习、多样性和外联活动结合起来。从事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。 该项目将纳入学生的课堂学习，包括代表性不足群体的学生和高中生，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通过特定转录因子（TF）的协同作用通过RNA聚合酶II（RNAP II）的募集或释放来实现。 RNAP II全酶含有一组一般转录因子（GTF），据信它们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）。 本项目的重点是拟南芥pBrp 1。 pbrp 1突变体在抗病性和防御基因表达方面都受到损害。在未感染的植物中，pBrp 1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pBrp 1。 病原体感染诱导pBrp 1积累。 这些结果表明，pBrp 1是一个特殊的RNAP II全酶，指导防御基因转录程序的调节GTF。 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pBrp 1的直接靶基因。 将使用免疫共沉淀法确定pBrp 1与RNAP II的直接缔合，以确认pBrp 1是RNAP II的GTF，并鉴定复合物中在pBrp 1的作用和调节中起作用的其他组分。 将操纵pBrp 1的蛋白质水平和核转位以确定pBrp 1的紧密调节对于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、准确和有效激活植物防御的复杂机制。该奖项反映了NSF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.