Title: Maize chiA as a Potential Genetic Marker for Stenocarpella maydis Ear Rot Resistance Author
Submitted to: American Phytopathological Society Annual Meeting
Publication Type: Abstract Only
Publication Acceptance Date: August 11, 2010
Publication Date: August 11, 2010
Citation: Naumann, T.A. 2010. Maize chiA as a Potential Genetic Marker for Stenocarpella maydis Ear Rot Resistance. American Phytopathological Society Annual Meeting. Technical Abstract: Stenocarpella maydis (Diplodia maydis) is the most prevalent ear rot pathogen in nearly all countries where maize is produced. The genetic basis of plant resistance to S. maydis appears to rely on multiple genetic factors, none of which are known. We previously reported that S. maydis secretes a protein, Stm-cmp, that modifies maize ChitA, a chitinase that is produced abundantly during seed development. We also demonstrated that ChitA protein from inbred B73 is highly susceptible to Stm-cmp modification while ChitA from inbred LH82 is resistant. These ChitA proteins are encoded by alleles of the chiA gene that encode proteins with six polymorphisms. Here I report cDNA cloning of both chiA genes, construction of yeast strains that produce the ChitAs, purification of yeast-produced ChitAs, and their in vitro modification by fungal St-cmp. In addition, I created yeast strains that produce mutant versions of ChitA. By comparing the susceptibility to Stm-cmp modification of the mutant ChitA proteins I determined that a single amino acid, encoded by a chiA single nucleotide polymorphism (SNP) results in resistance. This SNP may be a useful marker for breeding resistance to S. maydis ear rot.