DEVELOPMENT OF A MICROSATELLITE FRAMEWORK MAP PROVIDING GENOME-WIDE COVERAGE IN RICE (ORYZA-SATIVA L.)

Ninety-four newly developed microsatellite markers were integrated int o existing RFLP framework maps of four rice populations, including two doubled haploid, a recombinant inbred, and an interspecific backcross population. These simple sequence repeats (SSR) were predominantly po ly(GA) motifs, targetted because of their abundance in rice. They were isolated from a previously described sheared library and a newly cons tructed enzyme-digested library. Differences in the average length of poly(GA) tracts were observed for clones isolated from the two librari es. The length of GA motifs averaged 21 repeat units for clones isolat ed from the Tsp-509-digested library, while motifs averaged 17 units f or clones from the sheared library. There was no evidence of clusterin g of microsatellite markers near centromeres or telomeres. Mapping of the 94 newly developed markers as well as of 27 previously reported mi crosatellites provided genome-wide coverage of the 12 chromosomes, wit h an average distance of 1 SSLP (simple sequence repeat polymorphism) per 16-20 cM.