The Role of the FLOWERING LOCUS K (FLK) gene in Regulating Defense and Development

植物不断受到病原体和害虫的挑战。虽然植物是无根的，但它们已经进化出了复杂的机制来识别入侵者并激活防御反应。然而，防御是一个耗费能量的过程；防御激活可能以牺牲植物发育为代价。开花是植物生命周期中最重要的发育标志之一。已有研究表明，植物防御与花期调控之间存在一定的联系。然而，这种联系背后的分子基础尚未被很好地理解。为了发现新的防御基因，我们在模式植物拟南芥中进行了大规模的突变筛选，发现了开花时间调节基因FLK（开花位点K）的一个新的突变体，我们的额外数据支持FLK的防御作用。本项目将研究FLK在防御和控制开花中的双重作用。从这项研究中获得的知识将阐明植物如何协调生长、发育和对病原体的反应。没有这些知识，我们在改善作物健康和产量方面的策略设计将受到限制。此外，该项目将为PI提供一个平台，让不同背景的学生参与研究培训，包括博士后、研究生、本科生、K-12教师和来自未被充分代表的少数民族的高中生。植物防御是一个复杂的过程，应该与发育保持复杂的平衡。越来越多的证据表明RNA结合蛋白对植物防御和发育的转录后调控的重要性。K同源（KH）重复序列是一种古老的RNA结合基序，存在于多种生物的蛋白质中。KH结构域蛋白在病原菌抗性中的作用尚不清楚。通过对拟南芥新防御基因的遗传筛选，发现了典型开花基因开花位点K （FLK）的一个新等位基因，该等位基因与病原体防御和晚开花有关。FLK编码一个三重kh重复蛋白。来自PI实验室的数据首次表明FLK是一个调节转录水平和/或靶基因的选择性剪接的多功能基因。但是，卢旺达爱国阵线的具体作用机制，特别是在国防控制方面的作用机制仍有待阐明。本研究的总体目标是揭示FLK及其通路基因调控植物防御和发育的分子基础。该项目将研究FLK蛋白的结构-功能，鉴定和表征FLK靶基因，并表征FLK在防御和发展中的相互作用蛋白。一些FLK靶基因可以在分子水平上解偶联FLK的多功能性。FLK和FLK通路基因，特别是那些解开FLK多功能性的基因，是开发新的生物技术策略来精确控制作物性状的潜在强大的分子工具。基因组编辑可以用来修饰这些基因，以提高作物对天然病原体的抗病性，同时最大限度地减少对植物发育的负面影响。有关FLK功能、其相互作用物和靶基因的信息也将为其他生物中KH结构域蛋白的研究提供见解。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。

Plants are constantly challenged by pathogens and pests. Although being sessile, plants have evolved sophisticated mechanisms to recognize the invaders and activate defense responses. However, defense is an energetically costly process; defense activation can come at the expense of plant development. Flowering is one of the most critical developmental landmarks in the lifecycle of plants. Prior studies showed that plant defense and flowering time control are connected. However, the molecular basis underlying this connection has not been well understood. From a large-scale mutant screen in the model plant Arabidopsis that aimed to uncover novel defense genes, we identified a new mutant of a flowering time regulatory gene called FLOWERING LOCUS K (FLK) and our additional data support a defense role of FLK. This project will investigate the dual role of FLK in defense and flowering control. Knowledge obtained from this study shall shed light on how plants coordinate growth, development, and responses to pathogens. Without such knowledge, our design of strategies in improving the health and yield of crop plants will be limited. Furthermore, this project will provide a platform for the PI to engage students of diverse backgrounds in research training, including a postdoc, a graduate student, and undergraduates, K-12 teachers and high school students from underrepresented minority groups. Plant defense is a complex process that should be maintained in an intricate balance with development. Increasing evidence indicates the importance of post-transcriptional regulation of plant defense and development by RNA binding proteins. The K homology (KH) repeat is an ancient RNA binding motif found in proteins from diverse organisms. The role of KH domain proteins in pathogen resistance has not been well known. From a genetic screen for novel defense genes in Arabidopsis, a new allele of the canonical flowering gene FLOWERING LOCUS K (FLK) was identified and was associated with pathogen defense and late flowering. FLK encodes a triple KH-repeat protein. Data from the PI’s laboratory suggest for the first time that FLK is a multifunctional gene regulating transcript levels and/or alternative splicing of target genes. However, the detailed mechanisms of action of FLK, in particular in defense control, remain to be elucidated. The overall goal of this research is to uncover the molecular basis underlying how FLK and its pathway genes regulate plant defense and development. The PI will investigate structure-function of the FLK protein, identify and characterize FLK target genes, and characterize FLK interacting proteins in defense and development. Some FLK target genes could uncouple FLK multifunctionality at the molecular level. FLK and FLK pathway genes, especially those that uncouple multifunctionality of FLK, are potentially powerful molecular tools for developing novel biotechnological strategies to precisely control crop traits. Genome editing could be utilized to modify these genes to improve crop plants with better disease resistance against their natural pathogens while minimizing negative impacts on plant development. Information regarding FLK function, its interactors, and target genes will also provide insights to the study of KH domain proteins in other organisms.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.