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

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. <br/><br/>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.<br/><br/>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.