Fine Mapping A Quantitative Trait Loci Dth12, Controlling Heading Date In Rice (Oryza Sativa L.)

Heading date (HD) determine the grown regions of rice cultivars. Heading date is mainly affected by three factors, i.e. duration of the basic vegetative growth (BVG), photoperiod-sensitivity (PS) and temperature-sensitivity (TS). After its growing phage changes from vegetative growth to reproduce growth in rice, the heading date is determined by photoperiod-sensitivity. QTL analysis of heading date was conducted using a recombinant inbred line (RIL) population and chromsome segment substitution line(CSSL) derived from the cross of Asominori (japonica) and IR24 (indica)(QTLs dates from Doc. Xu junfeng et al). Based analysis results of heading date, we built CSSL84×Asominori back cross F2 population and mapped QTL-dth12 on the short arm of chromosome12 in rice genome. Finally, the heading date QTL-dth12 was fine mapped making use of CSSL84×Asominori back cross F2:3 population. The main conclusions are as follows:1. In Nanjing nature long day condition, the heading date of CSSL84, which was replaced by the IR24 allele at QTL-dth12 in Asominori, was longer than Asominori.2. Under artificial short-day (9h light/15h dark, SD) and natural long-day (14h light/10h dark, ND) conditions in the field near Nanjing, We investigate the heading date of Asominori,IR24 and CSSL84, and find a photoperiod-sensitivity QTL controlling heading date on chromosome 12.3. Based on F2 populations derived from the cross of CSSL84 and Asonimori, QTL-dth12 was narrowed down to a candidate genomic region of 41 kb long defined by Indel markers w020 and w019 on the top position of chromosome12 short arm. Gene prediction analysis indicated that there were 15 open reading framesin this region, of which 5 encoding function proteins,8 encoding hypothetical proteins and 2 encoding unknown proteins. The study has laid a good foundation for further fine mapping, cloning and the molecular mechanism of QTL-dth12 study.