Submitted to: Experiment Station Bulletins
Publication Type: Experiment Station
Publication Acceptance Date: June 20, 2005
Publication Date: July 5, 2005
Citation: Fjellstrom, R.G. 2005. Molecular markers in rice breeding. Texas Rice, Highlighting Research in 2005. p. X
Researchers in the USDA/TAES/TAMU Molecular Genetics Laboratory are continuing to develop and analyze markers for several economically important traits in rice. We are presently active in a multi-institute Coordinated Agricultural Project (RiceCAP) funded by the USDA National Research Initiative to develop DNA markers associated with milling yield and sheath blight disease (Rhizoctonia solani) resistance (see www.uark.edu/ua/ricecap for more details). Genetic markers well-distributed throughout the rice genome will be analyzed for their association with increased milling yield or sheath blight resistance. To find these markers, rice mapping populations are being tested across several southern USA environments in multiple years. A total of 450 simple sequence repeat (SSR) DNA markers have been screened for genetic differences (polymorphisms) in the eleven parental lines used in the RiceCAP mapping populations. The research shows that 77% or more of the markers screened in MY1 and SB4 populations are polymorphic (different between the two parents). These genetically diverse populations are derived from relatively wide crosses between the US cultivars Cypress and Lemont and indica germplasm (RT0034 and TeQing). The other more-narrow cross populations show less polymorphism and will require screening more markers to identify 150 well-dispersed polymorphic markers within each population. Even though 150 polymorphic SSRs have been identified between the MY2 parents, large gaps are present between markers that will need to be filled in with additional markers. Saturating the genetic map with well dispersed markers is necessary to find genes anywhere on the 12 chromosomes that are associated with the two traits. This research has been supported in part by USDA-CSREES-NRI and the Rice Foundation. Project participants include Eric Christensen, Fran Pontasch, Shannon Pinson, Anna McClung, and Bob Fjellstrom; Molecular Genetics, Variety Improvement, and Genetics Programs; USDA-ARS, Beaumont, TX.