Heading date QTL in rice derived from an analysis of chromosome segment substitution lines

Abstract

The inheritance of heading date (HD) in rice was investigated using a set of lines in which chromosome segments of the photoperiod-and temperature-sensitive male sterile line Peiai 64S had been incorporated into a genetic background of the cv. 9311. The flowering time of each line was contrasted with that of cv. 9311 in four distinct environments: natural long days (13.2-14.2 h photoperiod) and artificially shortened days (9 h photoperiod) at Nanjing; and natural (low) temperature and enhanced temperature at Hainan. A set of 21 heading date quantitative trait loci (QTL) was identified, covering eight of the 12 rice chromosomes, and their dependence on photoperiod and/or temperature was characterized. Two of the QTL were photoperiod-sensitive, and eight were insensitive; while two were temperature-sensitive and four insensitive; the remaining five QTL were independent of both temperature and photoperiod. Based on its segregation in an F 2 population bred from the cross CSSL C053 · cv. 9311, the temperature-and photoperiod-insensitive QTL qHd-8-4 was mapped within a segment of chromosome 8 flanked by the SSR marker RM22469 (1.9 cM) and RM72 (2.4 cM).

Alternative functions of Hd1 in repressing or promoting heading are determined by Ghd7 status under long-day conditions

“…Since 2000, many heading date-related QTLs have been mapped using different genetic populations and methods 3 – 11 . Several major heading date QTLs have been cloned to date using a map-based cloning strategy 12 – 19 .…”