Poster Session: Mycology

33-P

Characterization of Stenocarpella maydis mutants.
M. P. ROMERO (1), C. Liu (2), C. Woloshuk (1)
(1) Purdue University, West Lafayette, IN, U.S.A.; (2) South China Agricultural University, Guangzhou, China

Stenocarpella maydis is a major fungal pathogen of Midwest corn, causing both ear and stalk rot diseases. To better understand the molecular mechanisms that regulate development and metabolism in this fungus, we screened 1,000 insertion mutants generated by Agrobacterium tumefaciens-mediated transformation (ATMT). The screen examined pycnidia production, growth, and secondary metabolism, especially the production of diplodiatoxin. Here we describe the characterization of a mutant (strain 174) that secretes an unidentified green metabolite into droplets on aerial mycelia. Production of the metabolite is under circadian rhythm control, requiring a light-dark cycle. Strain 174 produces normal pycnidia, is pathogenic to developing corn ears, and produces diplodiatoxin. Southern analysis indicated that strain 174 contains a single copy of insertion T-DNA. DNA sequence at the border of the insertion site was obtained by thermal asymmetric interlaced PCR (TAIL-PCR). DNA sequence alignment of the TAIL-PCR product to a whole genome assembly database of S. maydis identified Contig 3148, which is 12 kb. Subsequent PCR analysis verified the site of the T-DNA insertion at the locus corresponding to this contig. Furthermore, the T-DNA landed 5’ to a putative gene encoding a histidine kinase. Our current goal is to determine if this histidine kinase regulates the production of the green metabolite.