Mapping and Interaction of QTLs for Thousand-Grain Weight and Percentage of Grains with Chalkiness in Rice

Abstract

Using a backcross inbred line (BIL) population derived from the cross between Koshihikari ( Oryza sativa subsp. japonica) and Kasalath ( O. sativa subsp. indica), the main-effect QTLs for thousand-grain weight (TGW) and percentage of grains with chalkiness (PGWC) in Nanjing in 2005 and 2006, and the epistatic effect and the QTL × environment interaction (QE) were analyzed. Correlation analysis showed that there was a significantly positive correlation ( r = 0.42 in 2005, and r = 0.35 in 2006, P<0.001) between TGW and PGWC in the BIL population. A total of 11 main-effect QTLs for TGW were identified, including 5 common QTLs in both years and 5 QTLs with significant QE effect. There were 8 pairs of epistatic effect for TGW, and 7 pairs of them with significant QE effect. Six main-effect QTLs and 9 epistatic effects for PGWC were identified, and 3 main-effect QTLs and 4 epistatic effects had QE effect. Three main-effect QTLs simultaneously controlled TGW and PGWC, and their alleles from the same parent increased TGW and PGWC. One epistatic effect had similar effects on both traits. Some main-effect QTLs, such as qTGW-3c, qTGW-4a, and qTGW-6b, only controlled TGW and could be used in breeding programs.