Elucidation of translational regulatory mechanisms of plant immune responses

在过去的二十年中，在理解植物如何控制编码防御蛋白的信使RNA的产生方面取得了重大进展，但对这些信使RNA的翻译是否以及如何被调节以产生蛋白质知之甚少。随着基于测序的技术的发展，用于测量信使RNA翻译的速率，很明显，防御蛋白的合成在植物中受到严格的调控。该项目旨在了解这种调节是如何进行的，并确定信使RNA的特征和参与这种调节的重要分子。该项目的成功不仅将填补植物免疫机制知识的空白，而且将通过更精确地控制防御蛋白的产生来彻底改变工程抗病作物的策略。这一新战略将使工程广谱抗病性，而不损害植物的健康，从而减少农药的使用和减轻抗性病原体的选择压力。该项目还将培训从事前沿研究的科学家，从高中生到博士后研究人员。本项目的长期目标是阐明植物免疫反应的翻译调控机制。植物免疫转录因子TBF 1的研究表明，其翻译受上游两个开放阅读框（uORF）控制。这些uORF通常阻止核糖体到达主要ORF。在免疫诱导后，这种抑制作用迅速减轻，导致TBF 1翻译。这表明，去抑制预先存在的免疫TF mRNA的翻译可能是一种快速响应病原体挑战的策略。使用核糖体足迹的全局翻译组分析表明，在模式触发免疫（PTI）期间，翻译的变化与转录没有很好的相关性。在PTI期间具有改变的翻译效率（TE）的基因属于不同的功能组，并且包含这种免疫应答的新调节剂。此外，mRNA的共识（uR-基序）被发现显着富集在5'前导区的转录本增加TE在PTI。该项目旨在生成更多的translatome图谱和第一个植物tRNAome数据集，这对于研究植物防御反应期间的全球翻译变化至关重要，并阐明tRNA水平如何变化，mRNA序列特征（例如，uORF和R-motif），反式作用因子调节翻译。该项目将深入了解植物如何选择性地翻译防御相关蛋白，并确定不同免疫反应的新调节因子。该项目还将涉及培训两名博士后研究人员，并继续开展外联活动，包括为当地高中和社区大学学生举办实验室图尔斯参观活动，并为少数民族大学生暑期研究的SROP方案提供指导。

In the past two decades, significant progress has been made in understanding how plants control the production of messenger RNAs encoding defense proteins when challenged by pathogens, but very little is known about whether and how translation of these messenger RNAs is regulated to produce proteins. With the development of a sequencing-based technology for measuring the rate of messenger RNA translation, it becomes clear that defense protein synthesis is tightly regulated in plants. This project aims to understand how this regulation is carried out and to identify messenger RNA features and important molecules involved in this regulation. The success of this project will not only fill a gap in the knowledge of the plant immune mechanisms, but also revolutionize strategies of engineering disease resistant crops by more precisely control defense proteins production. This new strategy will enable engineering broad-spectrum disease resistance without compromising plant fitness, leading to reduced use of pesticides and lightening of selective pressure for resistant pathogens. This project will also result in training of scientists from high school students to postdoctoral researchers in performing frontier research. The long-term goal of this project is to elucidate the translational regulatory mechanisms of plant immune responses. Studies of TBF1, a key plant immune transcription factor (TF), showed that its translation is controlled by two upstream open reading frames (uORFs). These uORFs normally block ribosomes from reaching the major ORF. Upon immune induction, this inhibitory effect is rapidly alleviated, leading to TBF1 translation. This suggests that de-repressing translation of pre-existing immune TF mRNA may be a strategy for rapid response to pathogen challenge. Global translatome profiling using ribosome footprinting showed that during pattern-triggered immunity (PTI), changes in translation did not correlate well with transcription. Genes with altered translational efficiency (TE) during PTI belong to diverse functional groups and contain novel regulators of this immune response. Moreover, an mRNA consensus (uR-motif) was found to be significantly enriched in the 5' leader regions of transcripts with increased TE during PTI. This project aims to generate more translatome profiles and the first plant tRNAome datasets, essential for studying global translational changes during plant defense responses, and elucidate how tRNA level changes, mRNA sequence features (e.g., uORFs and R-motif), and trans-acting factors regulate translation. The project will lead to insight into how plants selectively translate defense-related proteins and identify new regulators of different immune responses. The project will also involve training of two postdoctoral researchers and enable continuation in outreach activities, including hosting lab tours for local high school and community college students, and mentoring for the SROP Program for minority undergraduate summer research.