Identification of major and minor genes associated with heading date in an indica × indica cross of rice (Oryza Sativa L.)

In this study, quantitative trait loci (QTLs) controlling rice heading date were detected in a F2:3 population derived from a cross between an indica rice variety, Tarom Mahalli, with early heading date, and an indica variety, Khazar, with late heading date. SSR linkage map was constructed using 74 polymorphic markers and 192 F2 individuals and covered a total of 1231.50 cM of rice genome. QTL mapping of heading date was performed by simple and composite interval mapping. Three major genes (hd1, hd4 and hd9) were identified on chromosomes 1, 4 and 9 and two minor genes (hd2a and hd2b) were mapped on chromosome 2. Major genes explained over 60% of total phenotypic variation and had negative additive effects for decreasing heading date. These results will be useful in marker-assisted breeding to improve rice genotype with early heading date.