Identification of QTLs for Grain Quality on a RIL Population Derived from a Cross between Japonica Rices

A recombinant inbred lines (RILs) consisting of 231 lines, derived from a japonica (Suweon365) and a japonica (Chucheongbyeo) rice, was used to investigate the genetic factors affecting cooking and eating quality of rice. Alkali digestion value (ADV), amylose content (AMY), protein content (PRO) and glossiness of cooked rice (GCR) were measured by quantitative trait loci (QTLs) analysis over 2 years. A total of 10 QTLs for the four traits were detected, of which two for ADV, two for AMY, two for PRO and four for GCR. QTL-by-environment interactions were observed by comparing QTL mapping of the same population grown in 2 years. For each trait, one to two QTL were found, which were repeatedly detected in 2 years at five loci on chromosomes 1, 6, 7 and 8. Two QTLs for GCR on chromosomes 7 and 8 were closely linked with QTLs for PRO. To confirm the QTLs for GCR, the RILs harboring desirable QTL alleles of Chucheongbyeo were successively backcrossed with Suweon365 by marker assisted selection (MAS). In BC3F2 generation, the lines homozygous for Chucheongbyeo allele had the allele effect of 2.35 for qGCR-7, 2.25 for qGCR-8, and 1.25 for qGCR-11. These results would be useful in MAS breeding for the improvement of rice eating quality and pyramiding of desirable QTLs.