Submitted to: Plant Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/23/2012
Publication Date: 1/3/2013
Publication URL: http://handle.nal.usda.gov/10113/58007
Citation: Liu, G., Jia, Y., McClung, A.M., Oard, J., Lee, F., Correll, J. 2013. Confirming QTLs and finding additional loci responsible for resistance to rice sheath blight disease. Plant Disease. 97:113-117. Interpretive Summary: Sheath blight disease of rice is one of the major constraints for securing stable rice production in the southern US and worldwide. Rice growers rely heavily on the use of fungicides in integrated cultural practices to manage this disease. In a previous study, controlled inoculation methods were developed to identify quantitative genetic resistant genes using a mapping population derived from two US adapted rice cultivars, Lemont and Jasmine 85. In the present study, the locations and DNA markers of these quantitative resistance genes were verified using phenotypic disease severity ratings from the same mapping population collected from replicated field experiments in three locations in Arkansas, Texas and Louisiana over a two year period. The data indicate that the previously identified quantitative resistance genes and DNA markers linked to these resistant genes can be used for marker assisted selection.
Technical Abstract: Rice sheath blight disease (Rhizoctonia solani AG1-1AKühn) is one of the most destructive rice diseases worldwide. Utilization of host resistance is the most economical and environmentally sound strategy in managing sheath blight (ShB). Ten ShB-QTLs were previously mapped in a LJRIL population using greenhouse inoculation methods at an early vegetative stage. However, confirmation of ShB resistant QTLs under field conditions is critical for their utilization in marker assisted selection (MAS) for improving ShB resistance in new cultivars. In the present study, we evaluated ShB resistance using 216 LJRILs under field conditions in Arkansas, Texas and Louisiana during 2008 and 2009. We confirmed the presence of the major ShB-QTL qShB9-2 based on the field data and also identified one new ShB-QTL between markers RM221 and RM112 on chromosome 2 across all three locations. Based on the field verification of sheath blight evaluations, the micro-chamber and mist chamber greenhouse assays were simple, effective and reliable methods to identify major ShB-QTLs like qShB9-2 at early vegetative stages. The markers RM215 and RM245 were found to be closely linked to qShB9-2 in greenhouse and field assays indicating that they will be useful for improving ShB resistance in rice breeding programs using MAS.