Submitted to: Experiment Station Bulletins
Publication Type: Experiment Station
Publication Acceptance Date: June 15, 2006
Publication Date: July 13, 2006
Citation: Kepiro, J.L., Fjellstrom, R.G., McClung, A.M. 2006. Sheath blight resistance in Southern rice. Texas Rice. Highlighting Research in 2006. p. VIII.
Sheath blight is a serious fungal disease problem in southern US rice production, making it necessary for rice farmers to diligently use fungicides for its control. There are no long grain rice varieties adapted to commercial production in the southern US that have adequate resistance to sheath blight disease. DNA markers that indicate the presence of sheath blight resistance genes would be quite valuable for plant breeders in developing improved rice varieties for production throughout the South. Though molecular location of some foreign resistance genes have been reported, no studies had yet focused on identifying the genes already contained in the US adapted rice. Superior sheath blight resistance was identified in the medium grain variety Pecos, and our lab has been working hard at finding DNA markers associated with Pecos’ disease resistance genes. In our studies, we determined that the tall height of Pecos has a lot to do with its sheath blight resistance. Since most long grain rice varieties have semi-dwarf height (which keeps them from falling down easily from medium or high winds), we wanted to identify Pecos genes for sheath blight resistance unrelated to plant height. Fortunately, we were successful in finding two gene regions and DNA markers associated with them that explain a significant portion of the sheath blight resistance found in Pecos. The fact that these same genetic regions were previously found associated with sheath blight resistance in foreign rices adds to the confidence and excitement in our results. Because these resistance genes are already contained in rice adapted to the Southern US they will be more readily available and easier for US rice breeders to work with than the previously reported foreign genes. Now that genetic regions containing sheath blight resistance genes within US rice have been found, we are now in the process of ‘fine mapping’ these regions. Through detailed mapping efforts we will be able to find markers very closely linked to the desired genes in order to provide rice breeders with accurate and reliable DNA markers for selecting sheath blight resistant rice varieties.