Meiotic drive-based strategy to minimize mycotoxins in corn

Authors: Brown, Daren; Proctor, Robert; HAMMOND, THOMAS - Illinois State University

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 6/6/2018
Publication Date: 6/6/2018
Citation: Brown, D.W., Proctor, R., Hammond, T.M. 2018. Meiotic drive-based strategy to minimize mycotoxins in corn [abstract].

Interpretive Summary:

Technical Abstract: Some fungi pose a dual threat to corn production by causing disease (seedling, root, stalk or ear rots) and by producing mycotoxins that pose health risks to humans and domestic animals. For example, the fungus Fusarium verticillioides can cause stalk and ear rot of corn and produce fumonisins, a family of carcinogenic mycotoxins. The economic impact of fumonisin contamination of corn alone is over 100 million US dollars per year. Therefore, we need new strategies to reduce fumonisin contamination. We propose that meiotic drive elements could form the basis of such a strategy. A fundamental tenant of Mendelian inheritance is that two alleles of the same gene have an equal chance of transmission to meiotic progeny. In contrast to this, meiotic drive elements transmit in a biased manner and, as such, have the potential to spread widely and become the dominant allele in a population or even a species. To reduce fumonisin contamination, we propose to physically link a meiotic drive element to a gene that suppresses fumonisin production, which could lead to the spread of the suppressor gene in field populations of F. verticillioides. To this end, we have subjected the F. verticillioides meiotic drive element known as Spore killer (Skk), as well as its alternative or sensitive allele SkS, to molecular genetic characterization. Experiments done decades ago demonstrated that when a SkK strain mates with a SkS strain, only progeny that inherit the SkK allele survive. Progeny with the SkS allele abort during ascospore development. Using a genetic and genome sequencing approach, we recently determined that the SkK allele is a 213-bp gene, called SKC1, whereas the SkS allele is the absence of the gene. Skc1 shares no homology to proteins of known function. Now that we have determined the molecular genetic basis of SkK, we can combine this natural phenomenon with genetic engineering to decrease the proportion of F. verticillioides strains in a field that can synthesize fumonisin which could lead to less fumonisin contamination overall. To do this, we will first create a strain whereby we replace key fumonisin biosynthetic genes with the SkK gene. This strain, containing no foreign DNA, is unable to synthesis fumonisins and able to survive ascospore development after meiosis. We will test our approach by co-inoculating a test field plot with our biocontrol strain and a natural SkS strain and then survey population changes over time. We are also developing a synthetic meiotic drive element based on CRISPR technology, which could similarly lead to a biocontrol agent.