Location: Wheat, Sorghum and Forage ResearchTitle: Response of sweet sorghum lines to stalk pathogens Fusarium thapsinum and Macrophomina phaseolina
Submitted to: Plant Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/4/2016
Publication Date: 5/1/2016
Publication URL: http://handle.nal.usda.gov/10113/62613
Citation: Funnell-Harris, D.L., Oneill, P.M., Sattler, S.E., Yerka, M.K. 2016. Response of sweet sorghum lines to stalk pathogens Fusarium thapsinum and Macrophomina phaseolina. Plant Disease. 100:896-903.
Interpretive Summary: Sweet sorghum [Sorghum bicolor (L.) Moench] has potential for bioenergy. This crop can be grown in several regions in the U. S. and the juice extracted from the stalks can be used directly in ethanol production. However, research is needed to determine whether stalk rot diseases pose serious problems on yield and quality of juice and biomass of sweet sorghum. We designed a greenhouse test to determine how sweet sorghum varieties respond to two major stalk diseases: charcoal rot and Fusarium stalk rot. The key to this experiment was to stagger plantings of a sorghum variety susceptible to both diseases. We determined that sweet sorghum varieties ‘Rio’ and M81E were resistant to Fusarium stalk rot and charcoal rot, respectively, while line ‘Colman’ was susceptible to both diseases. In addition to determining susceptibility of the sweet sorghum varieties, we documented how the two stalk rot diseases progressed over time in Colman. These results can be used to breed stalk rot resistant sweet sorghum varieties.
Technical Abstract: 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, diseases that pose serious constraints for yield and quality of juice and biomass, has been reported. A greenhouse bioassay was designed to assess charcoal rot (Macrophomina phaseolina) and Fusarium stalk rot (Fusarium thapsinum) in plants at maturity, the developmental stage at which these diseases are manifested. Multiple plantings of a susceptible grain line, RTx430, were used as a control for variation in flowering times among 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, ‘Colman’ sorghum exhibited susceptibility to both pathogens. Lesion development over time in Colman was monitored. These results will enhance molecular and biochemical analyses of responses to pathogens, and breeding stalk-rot-resistant sweet sorghum lines.