Dissection of qTGW1.2 to three QTLs for grain weight and grain size in rice (Oryza sativa L.)
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Dissection of qTGW1.2, a minor quantitative trait locus (QTL) for 1,000-grain weight located on the long arm of rice chromosome 1, was reported here. Six sets of near isogenic lines (NILs) were developed from six BC2F9 plants of the indica rice cross Zhenshan 973/Milyang 46, respectively, segregated in a sequential order covering the region for qTGW1.2. They were tested for 1,000-grain weight, grain length, grain width and heading date. The SAS procedure GLM was used to analyze the phenotype differences among three genotypic groups in each NIL set. The qTGW1.2 was separated into three QTLs, including qTGW1.2a located in the 933.6 kb interval RM11730–RM11762, qTGW1.2b in the 418.8 kb interval RM11781–RM11800, and qTGW1.2c in the 2.1 Mb interval RM11800–RM11885. While qTGW1.2a and qTGW1.2c displayed the genetic action mode of negatively partial dominance, qTGW1.2b appeared to have a positively dominance effect as large as its additive effect. In addition, the effects of the three QTLs were consistently detected in different NIL sets. It was also shown that the effects of qTGW1.2a and qTGW1.2b on grain weight were related more to grain length than grain width, and qTGW1.2c related more to grain width than grain length. Our results indicate that the effects of minor QTLs could be steadily detected in a highly isogenic background and suggest that dominance effects of minor QTLs might play an important role in the genetic control of heterosis in rice.
KeywordsRice (Oryza sativa L.) Quantitative trait locus Near isogenic line Grain weight Grain size Dominance effect
Near isogenic line
Quantitative trait locus
Simple sequence repeat
This work was supported by the Chinese 863 Program (2011AA10A101), the National Natural Science Foundation of China (31221004), and a project of the China National Rice Research Institute (2012RG002-3).