Elucidating the mechanism of meiotic drive by mRNA editing-mediated spore killing in Neurospora fungi.

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This project will investigate genes that are transmitted from parents to offspring in a biased manner. Research on genes with this ability, referred to as cheating genes or cheaters, can aid efforts to engineer synthetic cheating genes. Synthetic cheaters can be used to propagate desirable traits through populations of economically important organisms. Although cheaters have been identified in a broad range of organisms, they are perhaps most easily studied in microorganisms. Therefore, this project will focus on cheating genes in the filamentous fungus Neurospora crassa. The primary aim of this project is to elucidate the molecular mechanism of spore killing, a process commonly used by fungal cheaters to achieve biased transmission rates. The primary aim will be pursued while providing research training to graduate students, undergraduate students, and a GK-12 STEM teacher.The primary subjects of this project will be two sets of cheating genes: Sk-2 and Sk-3. When an Sk-2 or an Sk-3-carrying strain mates with a non-spore killing strain, only spores (offspring) that inherit an Sk gene set survive. The selective killing of non-Sk genotypes appears to require at least two genes: one that produces a poison and one that produces an antidote. With respect to Sk-2, the poison and antidote genes have been identified. Furthermore, transcripts from the poison-producing gene undergo mRNA editing, a recently discovered and poorly understood phenomenon in fungi. With respect to Sk-3, only the antidote gene has been identified and the role of mRNA editing is unclear. The goals of this project are thus to identify the Sk-3 poison gene, to reveal the cellular target(s) of the Spore killer poisons, to discover the molecular process by which Spore killer poisons are neutralized by Spore killer antidotes, and to understand the role of RNA secondary structure in the editing of Spore killer mRNAs.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.