Molecular genetic mapping of quantitative trait loci for milling quality in rice (Oryza sativa L.)

Abstract

Abstract Identification and mapping of genomic regions controlling quantitative trait loci (QTLs) was undertaken to determine the genomic regions associated with milling traits in rice to facilitate breeding of new rice varieties with high milling quality. The recombinant inbred (RI) population used was derived from cross of a japonica variety, ‘Asominori’, with an indica variety, ‘IR24’ through 289 RFLP markers. Three milling traits, namely, brown rice percentage (BRP), milled rice percentage (MRP), and milled head rice percentage (MHP), which are the main indicators of milling quality in rice, were estimated for each RI line and their parental varieties. Continuous distributions and transgressive segregations of three milling traits were observed in the RI population, showing that the three traits were quantitatively inherited. Two QTLs ( q BRP-9 and q BRP-10) for BRP were identified and mapped to chromosomes 9 and 10, and explained 7.2 and 21.3% of the total phenotype variation, respectively. Two QTLs ( q MRP-11 and q MRP-12) governing MRP were detected and mapped to chromosomes 11 and 12, accounted for 12.2 and 7.7% of total phenotype variation, respectively. In addition, three QTLs ( q MHP-1, q MHP-3 and q MHP-5) controlling MHP were observed and mapped to chromosomes 1, 3 and 5, and explained 16.0, 22.1 and 8.7% of the total phenotype variation, respectively. Among them, five QTLs ( q BRP-9, q BRP-10, q MRP-11, q MHP-3 and q MHP-5) from japonica parent, Asominori, and two QTLs ( q MRP-12, q MHP-1) from indica IR24 can improve milling quality in rice. The results and the tightly linked molecular markers that flank the QTL will be useful in breeding for improvement of milling quality in rice.