A meiotic drive element in the maize pathogen Fusarium verticillioides is located within a 102-kb region of chromosome V

Authors: PYLE, JAY - Illinois State University; MERRIL, BRIANNA - Illinois State University; PATEL, TEJAS - Illinois State University; MCCALL, MORGAN - Illinois State University; Proctor, Robert; Brown, Daren; HAMMOND, THOMAS - Illinois State University

Submitted to: Genes, Genomes, Genetics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/6/2016
Publication Date: 8/1/2016
Publication URL: https://handle.nal.usda.gov/10113/5695394
Citation: Pyle, J., Patel, T., Merrill, B., Nsokoshi, C., McCall, M., Proctor, R.H., Brown, D.W., Hammond, T.M. 2016. A meiotic drive element in the maize pathogen Fusarium verticillioides is located within a 102-kb region of chromosome V. Genes, Genomes, Genetics. 6(8):2543-2552.

Interpretive Summary: The fungus Fusarium verticillioides occurs commonly on corn, where it can cause both ear and stalk rot diseases. The fungus can also produce toxins known as fumonisins that can accumulate in corn to levels that pose health risks to humans and livestock animals. For example, fumonisins can cause brain lesions in horses, fluid buildup in lungs of pigs, and cancer in laboratory rodents. In addition, there is a positive correlation between consumption of fumonisin contaminated corn and cancer of the esophagus in certain human populations that eat a lot of corn. Some organisms have ‘selfish’ forms of genes that increase the frequency with which they are passed from parent to offspring by killing offspring that carry other forms of the same gene. In fungi, such as F. verticillioides, this phenomenon is evident when half of the spores produced during sexual reproduction die and degenerate. However, the mechanism by which this spore killing phenomenon occurs is poorly understood in most fungi. In this study, we determined the approximate location of a selfish gene within a region of F. verticillioides Chromosome 5. The region includes 50 genes. Thus, one of these genes is most likely the selfish gene that kills sexual spores of the fungus. This research provides a foundation for understanding how spore killing works in F. verticillioides and will be of use to plant pathologists, plant breeders, and other scientists involved in the development of new ways to limit diseases and toxin contamination in corn.

Technical Abstract: Fusarium verticillioides is an agriculturally important fungus because of its association with maize and its propensity to contaminate grain with toxic compounds. Some isolates of the fungus harbor a meiotic drive element known as Spore killer (SkK) that causes nearly all surviving meiotic progeny from an SkK × Spore killer-susceptible (SkS) cross to inherit the SkK allele. SkK has been mapped to chromosome V but the genetic element responsible for meiotic drive has yet to be identified. In this study, we used cleaved amplified polymorphic sequence markers to genotype individual progeny from an SkK × SkS mapping population. We also sequenced the genomes of three progeny from the mapping population to determine their single nucleotide polymorphisms. These techniques allowed us to refine the location of SkK to a contiguous 102 kb interval of chromosome V, herein referred to as the Sk region. Relative to SkS genotypes, SkK genotypes have one extra gene within this region for a total of 42 genes. The additional gene in SkK genotypes, herein named SKC1 for Spore Killer Candidate 1, is the most highly expressed gene from the Sk region during early stages of sexual development. The Sk region also has three hyper-variable regions, the longest of which includes SKC1. The possibility that SKC1, or another gene from the Sk region, is an essential component of meiotic drive and spore killing is discussed.