Functions and mechanisms of A-to-I RNA editing in Fusarium graminearum

小麦赤霉病是美国小麦和大麦最具破坏性的病害之一。小麦赤霉病病原菌除了造成重大的产量损失外，还会产生对人类健康有害的有毒化合物。本项目旨在了解这种真菌病原体的RNA编辑现象在有性孢子产生和传播过程中的作用和机制。有性孢子是植物感染的主要接种物。RNA编辑允许一个基因产生不同形式的蛋白质，这些蛋白质的功能可能会有所不同。虽然这种病原体缺乏已知的在动物中编辑RNA的典型酶，但它有超过26,000个编辑位点，可能在感染相关蛋白的序列变化中发挥重要作用。这一研究结果将有助于理解RNA编辑在该重要病原菌以及可能在其他病原真菌中的功能和机制。抑制有性孢子的形成和释放可以用来开发针对头枯病和其他植物疾病的新的疾病控制策略。该项目将为参与的研究生提供分子遗传学和基因组学研究方面的扎实培训。在一所以本科为主的大学里，拟议的活动将使参与的学生熟悉基本的研究过程，并包括开发一个为期一周的暑期研讨会，旨在向高中教师提供信息。禾谷镰刀菌是一种重要的小麦病原菌和真菌毒素产生菌，虽然它缺乏ADAR(作用于RNA的腺苷脱氨酶)基因，但在有性繁殖过程中具有全基因组的A-to-I编辑。然而，目前尚不清楚编辑是否发生在其他发育或感染结构中，阶段特异性RNA编辑的分子机制也不清楚。本项目旨在表征A-to-I编辑在性发育和植物侵染过程中的功能，并表征真菌腺苷脱氨酶及其阶段特异性辅助因子。一个目标是确定在两个平行基因中编辑的生物学功能，并确定植物感染过程中的A-to-I编辑。RNA编辑可能在有性繁殖过程中平行基因的功能差异和植物侵染过程中感染相关基因的序列变化中发挥重要作用。另一个目的是确定Tad2和Tad3蛋白的编辑活性，并产生和鉴定Tad2和Tad3突变等位基因。在目标3中，将通过EMS诱变产生RNA编辑缺陷的突变株并对其进行鉴定。将为Tad2或Tad3相互作用的基因产生缺失突变，作为假定的阶段特定辅助因子用于RNA编辑。总体而言，该项目的结果将有助于更好地理解子囊孢子形成和释放的分子机制。RNA编辑可能会导致致病相关基因的序列变化，并有利于病原体的适应。这一奖项反映了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。

Head blight is one of the most destructive diseases of wheat and barley in the US. Besides causing significant yield losses, the Wheat Head Blight fungal pathogen also produces toxic compounds that are harmful to human health. This project aims to understand the role and mechanism of a phenomenon known as RNA editing for this fungal pathogen during the production and dispersal of sexual spores, the primary inoculum for infection of plants. RNA editing allows one gene to produce different forms of proteins that may vary in functions. Although this pathogen lacks the typical enzymes known to edit RNA in animals, it has over 26,000 editing sites that may play important roles in sequence variations of infection-related proteins. Results from this study will be helpful to understand functions and mechanisms of RNA editing in this important pathogen and possibly other pathogenic fungi. Inhibition of sexual spore formation and discharge can be used to develop novel disease control strategies for the head blight and perhaps other plant diseases. This project will provide participating graduate students solid training in molecular genetics and genomics studies. Proposed activities at a primarily undergraduate college will familiarize participating students with basic research processes and include development of a week-long summer workshop designed to inform high school teachers. Although it lacks ADAR (adenosine deaminase acting on RNA) genes, Fusarium graminearum, an important wheat pathogen and mycotoxin producer, has genome-wide A-to-I editing during sexual reproduction. However, it is not clear whether editing occurs in other developmental or infection structures and the molecular mechanisms of stage-specific RNA editing is not known. This project aims to characterize functions of A-to-I editing in sexual development and during plant infection, and to characterize fungal adenosine deaminases and their stage-specific co-factors. One objective is to determine biological functions of editing in two paralogous genes and identify A-to-I editing during plant infection. RNA editing may play important roles in functional divergence of paralogous genes during sexual reproduction and sequence variations of infection-related genes during plant infection. Another objective is to determine the editing activities of Tad2 and Tad3 proteins and to generate and characterize TAD2 and TAD3 mutant alleles. In Objective 3, mutants defective in RNA editing will be generated by EMS mutagenesis and characterized. Deletion mutants will be generated for Tad2 or Tad3-interacting genes as putative stage-specific cofactors for RNA editing. Overall, results from the project will be helpful for understanding better the molecular mechanisms involved in ascospore formation and discharge. RNA editing may result in sequence variations of pathogenesis-related genes and be beneficial to pathogen adaptation.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.