Abstract: To identify genetic loci controlling grain weight, F2, F3 and BC2F2 derived from a cross between indica rice variety Baodali with large grains and japonica rice variety Zhonghua11 with normal grains were used as mapping populations. Linkage analyses demonstrated that two genes controlling grain weight, designated as GW3 and GW6, were mapped to chromosome 3 and chromosome 6, respectively. Fine mapping delimited GW3 to a 122kb physical distance between two STS markers (WGW16 and WGW19) containing 16 ORFs annotated by TIGR (http://www.tigr.org). GW6 was further mapped between two SSR markers (RM7179 and RM3187). These results are useful for both marker assisted selection (MAS) of grain weight, and for further cloning of GW genes, which will contribute to the dissection of the molecular mechanism underlying grain weight in rice.

Key words: rice, grain size, primary mapping, fine mapping, marker assisted selection (MAS)