2001 AACC Annual Meeting Charlotte, North Carolina October 14-18, 2001 Charlotte Convention Center

Sorghum lines and hybrids have been identified or developed that have improved tolerance to grain molding and weathering; but no commercial hybrid is resistant in hot, humid environments. Improved grain mold resistance correlates to more antifungal proteins (AFP) at combine harvest maturity (50 days after anthesis, DAA) and/or with more retention of AFP after physiological maturity (30 DAA). Commercial hybrids (20) and public breeders elite lines (50) and hybrids (28) were grown in College Station during spring and summer of 2000. Samples of grain were collected at 30 and 50 DAA. Proteins were extracted, separated using electrophoresis, western blotted, visualized using immuno-assays, and quantified for two AFP (chitinase and sormatin). The environment at College Station in 2000 was not conducive for fungal deterioration of grain and low levels of grain molding were observed. About 35 genotypes had high levels of chitinase or sormatin, while 17 genotypes had high levels of chitinase and sormatin at 50 DAA. Only two of these 17 genotypes had substantially higher levels of both chitinase and sormatin at 50 DAA compared to 30 DAA. Hence, sorghum genotypes varied in their amounts of AFP and their ability to increase retention of AFP after physiological maturity. The increased retention and higher levels of AFP should correspond to less grain molding of sorghum in mold-conducive environments.