Wednesday, November 7, 2007
259-4
Development and Characterization of RiceCAP QTL Mapping Population for Sheath Blight Resistance.
Anna McClung1, Donald Groth2, James H. Oard3, Herry Utomo4, Karen Ann Kuenzel Moldenhauer5, Edward Boza6, Brian Scheffler7, Yulin Jia1, Guangi Liu8, Fernando Correa9, and Robert Fjellstrom10. (1) USDA-ARS, 2890 Hwy 130 East, Stuttgart, AR 72160, (2) Rice Research Station, LSU Agricultural Center, Crowley, LA 70578, (3) School of Plant, Environmental, and Soil Sciences, LSU Agricultural Center, BATON ROUGE, LA 70803, (4) Louisiana State University - Agronomy & Environmental Management, Rice Research Station LSU Agric. Center, 1373 Caffey Rd., Rayne, LA 70578, (5) 2900 Highway 130E, University of Arkansas, University of Arkansas, Rice Research Institute & Extension, Stuttgart, AR 72160, (6) Rice Research and Extension Center, University of Arkansas, Stuttgart, AR 72160, (7) MSA Genomics Laboratory, USDA-ARS, 141 Experiment Station Road, JWDSRC, Stoneville, MS 38776, (8) University of Arkansas, 2890 Hwy 130 East, Stuttgart, AR 72160, (9) CIAT, A.A. 6713, Cali, Colombia, (10) USDA ARS, Rice Research Unit, 1509 Aggie Dr., Beaumont, TX 77713
RiceCAP is a USDA CSREES funded project that has as one of its main objectives developing genetic markers associated with sheath blight resistance. Sheath blight, caused by Rhizoctonia solani, is an important disease of rice in the southern US. Tolerance to the disease is quantitatively inherited and easily confounded by plant height and maturity. Developing selectable markers associated with resistance to this disease will help breeders to develop improved varieties more efficiently and effectively. A mapping population consisting of 325 double haploid (DH) lines developed from a cross of Cocodrie (susceptible) and MCR01–0277 (partial resistance) (Chu et al 2006) was used to identify QTL regions associated with resistance. Some 225 polymorphic SSR markers were evaluated to identify over 100 markers that could be readily scored in the population. The families were evaluated in replicated field trials conducted in Crowley, LA and Stuttgart, AR during 2006 and 2007 that were inoculated prior to heading. In addition, the population was evaluated using inoculated seedlings evaluated in a micro-chamber (Stuttgart ) and a mist-chamber (Cali, Colombia ). The micro-chamber method was strongly correlated with the 2006 field results (AR r=0.69 and LA r=0.59) indicating that it identifies at least some of the same resistance components that are important under field conditions. The mist-chamber technique had good repeatability compared with the micro-chamber method but took longer to evaluate. Although the population mean was more susceptible than the Cocodrie parent, some 2% of the population was more tolerant than the resistant parent, MCR10277. These results verify that this is an excellent mapping population that appears to be segregating widely for sheath blight resistance that can be detected using a number of disease screening methods. Results from additional field tests and marker analyses will be presented.