QTL Analysis for Traits Associated with Feeding Value of Straw in Rice (Oryza sativa L.)

Genetic improvement of the digestibility of rice straw for increasing the utilization of the whole rice plant as feedstuffs is an important way to solve the feedstuffs shortage in southeastern China. To elucidate the genetic basis of the traits affecting the digestibility of rice straw, a rice population of 111 recombinant inbred lines (RILs) derived from a cross of Nekken 2×Gaya was used to map the quantitative traits loci (QTLs) for in vitro dry matter digestion (IVDMD), the percentages of nonstructural carbohydrate (NSC) and acid detergent fiber (exclusive of residual ash, ADFom) in 2005 and 2006. IVDMD was positively correlated with NSC, and negatively correlated with ADFom. A total of 16 QTLs were detected in the two years, and the amounts of variation explained by individual QTLs ranged from 6.9% to 15.5%. Some QTLs for IVDMD and ADFom on chromosome 2 were detected in the two years. On chromosome 2, the interval RM475–RM3515 contained QTLs for IVDMD in the two years and for NSC in 2006 only, while the interval RM3874–RM5305 influenced ADFom in the two years and NSC in 2005 only. At those loci, Gaya contributed favorable alleles to IVDMD and NSC, while Nekken 2 contributed positive alleles to ADFom.