|Munkvold, Gary - IOWA STATE UNIV, AMES, IA|
Submitted to: Fungal Genetics Conference Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: March 18, 2001
Publication Date: N/A
Technical Abstract: A polyketide synthase gene, FUM5, required for fumonisin biosynthesis was cloned from F. verticillioides. Two fumonisin-nonproducing (FUM5-) strains generated by FUM5 disruption and the two fumonisin-producing (FUM5+) strains from which they were derived were tested in the field for ability to infect maize ears and to cause ear rot. Fungal spores were applied to ears by silk-channel injection and by silk-spray, to stalks by injection, and to seeds by planting next to a fungal-infested toothpick. Disease severity, fumonisin levels, and presence of applied strains in kernels were determined. Following silk-channel application, FUM5- strains infected kernels, caused ear rot, and inhibited accumulation of fumonisins in kernels. Application of FUM5- strains by silk-spray, stalk injection, or seed treatment increased frequency of these strains in kernels but did not increase levels of ear rot or affect the concentrations of fumonisins in kernels. These results show that production of fumonisins is not required for F. verticillioides to cause ear rot following silk-channel injection, or to infect maize ears following silk-spray inoculation, stalk injection, or seed treatment. Thus, the importance of fumonisins in the ecology of F. verticillioides remains unclear.