QTL mapping of grain weight in rice and the validation of the QTL qTGW3.2

Abstract

A recombinant inbred line (RIL) population bred from a cross between a javanica type (cv. D50) and an indica type (cv. HB277) rice was used to map seven quantitative trait loci (QTLs) for thousand grain weight (TGW). The loci were distributed on chromosomes 2, 3, 5, 6, 8 and 10. The chromosome 3 QTL qTGW3.2 was stably expressed over two years, and contributed 9-10% of the phenotypic variance. A residual heterozygous line (RHL) was selected from the RIL population and its selfed progeny was used to fine map qTGW3.2. In this "F2" population, the QTL explained about 23% of the variance, rising to nearly 33% in the subsequent "F2:3" generation. The physical location of qTGW3.2 was confined to a ~556 kb region flanked by the microsatellite loci RM16162 and RM16194. The region also contains other factors influencing certain yield-related traits, although it is also possible that qTGW3.2 affects these in a pleiotropic fashion.

Keywords: CIM; FLL; FLL/W; FLW; GL; GL/W; GW; HD; HN; HZ; Hainan; Hangzhou; MAS; Max; Min; PCR; PH; PL; PN; QTL; QTL mapping; R1–R9; R2; RHL; RHL-D; RHL-H; RIL; Rice; SF; SSR; TGW; TNSP; Thousand grain weight; composite interval mapping; flag leaf length; flag leaf length to width ratio; flag leaf width; grain length; grain width; heading date; marker-assisted selection; maximum; minimum; panicle length; panicle number per plant; panicles number per plant; plant height; polymerase chain reaction; quantitative trait locus; recombinant inbred line; recombinant individuals (1–9); residual heterozygous line; residual heterozygous line with D50 segment in the target region; residual heterozygous line with HB77 segment in the target region; simple sequence repeat; spikelet fertility; the phenotype variance explained by the QTL; the ratio of grain length to width; thousand grain weight; total number of spikelets formed per panicle.