Genetic relationship between grain yield and the contents of protein and fat in a recombinant inbred population of rice

To study the genetic relationship between grain yield and the nutrient contents in rice, 209 recombinant inbred lines derived from a cross between indica rice Xieqingzao B and Milyang 46 were used to determine quantitative trait loci (QTLs) affecting the yields and contents of the two major nutritional components in brown rice. Seven traits were analyzed, including brown rice recovery (BRR), protein content (PC), fat content (FC), grain yield (GYD), brown rice yield (BRYD), protein yield (PYD) and fat yield (FYD). The nutrient contents were significantly negatively correlated with BRR, GYD and BRYD, and the variations on nutrient yield were mainly ascribed to GYD. A total of 22 QTLs distributed on 10 regions of eight chromosomes were detected. Two QTL clusters were found on the short arm of chromosome 6 and the long arm of chromosome 10, respectively. The former was responsible for all the seven traits, and the latter for all the traits except BRR and FC. In both regions, the maternal alleles decreased nutrient contents, but they increased the yields of grain, brown rice, protein and fat. Implication of these results for the breeding of rice varieties with enhancing nutritional capacity is discussed.