Location: Crop Germplasm ResearchTitle: Evaluation of Gambian and Malian sorghum germplasm against downy mildew pathogen, Peronosclerospora sorghi, in Mexico and the USA Author
Submitted to: Journal of General Plant Pathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/7/2014
Publication Date: 1/1/2015
Citation: Prom, L.K., Perumal, R., Montes-Garcia, N., Isakeit, T., Odvody, G.N., Rooney, W.L., Little, C.R., Magill, C. 2015. Evaluation of Gambian and Malian sorghum germplasm against downy mildew pathogen, Peronosclerospora sorghi, in Mexico and the USA. Journal of General Plant Pathology. 81:24-31. Interpretive Summary: Sorghum downy mildew is a serious fungal disease which can reduce the crop yield and quality, especially if susceptible sorghum lines are planted in areas where the disease occurs. In recent years, a new race of the sorghum downy mildew fungus was identified in Wharton County and other areas in southeast Texas. Due to the appearance of this new race, sorghum lines from Gambia and Mali, West Africa, and the sorghum differentials were screened in Texas and Mexico to identify new sources of downy mildew resistance and new races of the fungus. Two accessions PI609151 and PI609442 from Mali had high levels of resistance to the disease at all locations. Two other Malian accessions, PI585852 and PI612815 had high levels of resistance to the disease in two out of the three locations. The reaction of the sorghum differentials suggested the presence of a race of the fungus at the location in Mexico that differed from those at the USA locations.
Technical Abstract: The recent outbreak of sorghum downy mildew (SDM) in Texas, USA, caused by a Peronosclerospora sorghi pathotype P3 resistant to the standard fungicide seed treatment, as well as the subsequent development of a new pathotype P6 that overcame resistance in some hybrids, has emphasized the importance in continuing to develop new sources with genetic resistance to this disease. Field experiments were conducted with eighty-two exotic Gambian and Malian germplasm in a randomized complete block design replicated three times at one Mexico location (Ocotlán, Jalisco) in 2004 and 2005, and two USA locations (Louise and New Taiton, Texas) for one year in 2005 to identify new sources of SDM resistance. Additionally, ten sorghum lines commonly used as SDM pathotype differentials were evaluated at these sites. Accessions PI609151 and PI609442 from Mali had high levels of SDM resistance at all locations. Two other Malian accessions, PI585852 and PI612815 exhibited a high degree of SDM resistance in two out of the three locations. The reaction of the ten lines used as differentials suggested the presence of a SDM pathotype at the Mexico location that differed from those at the USA locations.