Mapping of qGL7-2, a grain length QTL on chromosome 7 of rice.pdf

DOI: 10.1016/S1673-8527(09)60072-2 JOURNAL OF GENETICS AND GENOMICS J. Genet. Genomics 37 (2010) 523 531 Mapping of qGL7-2, a grain length QTL on chromosome 7 of rice Gaoneng Shao, Shaoqing Tang, Ju Luo, Guiai Jiao, Xiangjin Wei, Ao Tang, Jianli Wu, Jieyun Zhuang, Peisong Hu * State Key Laboratory of Rice Biology, China National Rice Research Institute, Hangzhou 310006, China Received for publication 23 February 2010; revised 17 April 2010; accepted 20 April 2010 Abstract A residual heterozygous line (RHL) carrying a heterozygous segment between two SSR loci RM11 and RM134 on the rice chromo- some 7 was selected from a set of recombinant inbred lines from the cross D50 (javanica)/HB277 (indica). The former parent produces much longer grains than the latter. Selfed progenies of this selection were analyzed genotypically (SSRs) and phenotypically (grain length). Grain length was discontinuously variable in the mapping populations, allowing for the placement of this QTL qGL7-2 within a ~4.8 cM interval defined by RM351 and RM234. A set of new markers within this region were developed, which narrowed the QTL to a 278 kb region defined by the markers Indel1 and RM21945. This region contains 49 predicted genes. The results also suggest that the novel allele for grain length will be used for the application of marker assisted selection for the improvement of grain length. Keywords: grain length; mapping; quantitative trait locus; residual heterozygous line; rice Introduction Rice (Oryza sativa L.) is a staple food crop for at least 65% of the population of China. As the population’s stan- dard of living improves, breeders’ priorities have begun to shift away from a sole focus on yield towards simultane- ously improving end-use quality. The grain’s length, width and the ratio are considered to be an important measure of quality in commerce, and together they represent the major components of grain shape. Co