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Poster: Biology & Disease Mgmt: Genetics of Resistance


Response of sweet sorghum lines to stalk pathogens Fusarium thapsinum and Macrophomina phaseolina
D. FUNNELL-HARRIS (1), P. O'Neill (1), S. Sattler (1) (1) USDA-ARS; Grain, Forage and Bioenergy Research Unit, U.S.A.

Sweet sorghum [Sorghum bicolor (L.) Moench] has potential for bioenergy. It is adapted to a variety of U.S. locations and the extracted juice can be directly fermented into ethanol. However, little research on fungal stalk rots has been reported, even though these diseases pose serious constraints for yield, juice quality and biomass usability. A greenhouse bioassay was designed to assess charcoal rot (Macrophomina phaseolina) and Fusarium stalk rot (Fusarium thapsinum) susceptiliby at maturity, when these diseases are manifested in the field. Multiple plantings of a susceptible grain line, RTx430, were used as a control for variation in flowering times amongst sweet sorghum lines. Lesion length measurements in inoculated peduncles were used to quantify disease severity. Sweet sorghum lines ‘Rio’ and M81E exhibited resistance to F. thapsinum and M. phaseolina, respectively, and in contrast, line ‘Colman’ exhibited susceptibility to both pathogens. Lesion development over time was monitored in Colman. These results will enhance molecular and biochemical analyses of sweet sorghum responses to pathogens, and breeding stalk rot resistant sweet sorghum.