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

Abstract

In this study, quantitative trait loci (QTLs) controlling rice heading date were detected in a F2:3 population derived from a cross between an <em>indica</em> rice variety, Tarom Mahalli, with early heading date, and an <em>indica</em> 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 (<em>hd1</em>, <em>hd4 </em>and <em>hd9</em>) were identified on chromosomes 1, 4 and 9 and two minor genes (<em>hd2a</em> and <em>hd2b</em>) 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.