Collaborative Research: RESEARCH-PGR: Genome-wide quest for non-host resistance mechanisms in plants

在全球范围内，约15%的作物损失是由各种侵袭性病原体特别是真菌造成的，这突显了作物保护免受病原体侵袭的重要性。在自然界中，大多数植物对大多数潜在的病原菌都具有抗性，这是因为一种现象，即非寄主抗性(NHR)。NHR的一个主要例子是水稻对锈病和白粉病的免疫力，这些疾病对包括小麦和大麦在内的许多其他谷类作物造成严重损害。因此，NHR为所有工厂提供了一个主要的安全屏障。不幸的是，由于其遗传的复杂性，NHR的分子基础在大多数情况下仍然难以捉摸，这严重限制了NHR潜在的免疫机制的开发，以提高作物对侵袭性病原菌的抗性。这一多机构合作研究项目旨在利用创新的组合正向和反向遗传学方法，在两种模式植物上剖析NHR抗潜在真菌病原体的遗传和分子机制。NHR所需的植物免疫基因的鉴定和功能鉴定不仅将揭示NHR的分子基础(NHR是植物-微生物相互作用的十大悬而未决的问题之一)，而且还将启发新的策略来设计更广泛和更强大的作物对各种病原菌的抗性。该项目还将为科学界研究植物免疫机制提供有价值的研究材料和工具。最后，该项目将把研究与教育和外联活动结合起来。例如，该项目团队每年都会举办一个“CRISPR技术与应用”暑期工作坊，以加强未被充分代表的少数族裔本科生对植物科学的参与。非寄主抗性(NHR)指的是一种植物物种的大多数测试基因类型对可能导致其他植物物种病害的最多测试变种的免疫力。与寄主抗性不同的是，NHR的遗传基础在很大程度上仍不清楚。该项目的长期目标是阐明NHR提高作物对侵袭性病原体抗性的分子机制。假设NHR在大多数情况下是多层的，通过常规方法是遗传上难以处理的，但可以通过逐步正向遗传学和/或CRISPR使能的反向遗传学方法来剖析。这个协作项目有四个具体目标。目的1是利用逐步正向遗传筛选方法，在拟南芥(作为模式双子叶植物)中寻找与非适应性白粉病和锈菌相关的NHR新基因。目的2是通过对多达50个不同的水稻免疫基因进行多重CRISPR突变，然后进行齿轮感染筛选，在水稻(作为模式单子叶植物)中鉴定NHR抗白粉病和锈菌以及其他病原菌所必需的基因。目的3通过比较转录组学、蛋白质组学和代谢组学等多种分子方法阐明调控NHR的新的免疫机制。目标4是促进社区研究和促进下一代植物科学家的教育，重点是培训代表不足的少数族裔学生。来自拟议研究的新知识可能有助于为NHR建立与公认的PAMP(病原体相关分子模式)触发的免疫和/或效应器触发的免疫相关的机制框架。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Globally, ~15% of crop losses are caused by various aggressive pathogens especially fungi, highlighting the importance of crop protection against pathogens. In nature, most plants are resistant to most potential pathogens because of a phenomenon, namely nonhost resistance (NHR). A prime example of NHR is rice’s immunity to rust and powdery mildew diseases that cause serious damages to many other cereal crops including wheat and barley. Hence, NHR provides a major safety barrier for all plants. Unfortunately, due to its genetic complexity, the molecular basis of NHR in most cases remains elusive, which severely limits the exploitation of the immunity mechanisms underlying NHR for improving crop resistance against aggressive pathogens. This multi-institutional collaborative research project aims to dissect genetic and molecular mechanisms of NHR against potential fungal pathogens in two model plants using innovative and combinatorial forward and reverse genetics approaches. Identification and functional characterization of plant immunity genes required for NHR will not only reveal the molecular basis of NHR (which is among the top 10 unanswered questions concerning plant-microbe interactions) but also inspire novel strategies to engineer broader and more robust resistance in crop plants against various pathogens. This project will also generate valuable research materials and tools for the scientific community to study plant immunity mechanisms. Finally, this project will integrate research with education and outreach activities. For example, a “CRISPR Technology and Application” summer workshop in each year will be run by the project team to enhance participation of under-represented minority undergraduate students in plant science.Nonhost resistance (NHR) refers to immunity of most tested genotypes of a plant species to most tested variants of a pathogen species that can cause diseases on other plant species. Unlike host resistance, which is mounted against adapted pathogens and has been well characterized at the molecular level, the genetic basis of NHR remains largely unknown. The long-term goal of this project is to elucidate the molecular mechanisms of NHR for improving crop resistance against aggressive pathogens. It is hypothesized that NHR in most cases is multi-layered and genetically intractable by conventional means but dissectible by stepwise forward genetics and/or CRISPR-enabled reverse genetics approaches. There are four specific objectives for this collaborative project. Aim 1 is to identify novel genes contributing to NHR in Arabidopsis (as a model dicot) against non-adapted powdery mildew and rust fungi using stepwise forward genetic screens. Aim 2 is to identify genes essential for NHR against powdery mildew and rust fungi, and other pathogens in rice (as a model monocot) using multiplexed CRISPR mutagenesis of up to 50 various rice immunity genes followed by geared infection screens. Aim 3 is to elucidate novel immune mechanisms controlling NHR via various molecular methods including comparative transcriptomics, proteomics and metabolomics. Aim 4 is to facilitate community research and promote education of next-generation plant scientists with a focus on training underrepresented minority students. New knowledge from the proposed research may help establish mechanistic frameworks for NHR in connection with the well-established PAMP (pathogen-associated molecular pattern)-triggered immunity and/or effector-triggered immunity.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.