Heading date (or flowering time, HD) represents one of the fundamental developmental events in the life cycle of the rice plant. It is one of the most important traits that enable rice to adapt to seasonal differences and specific growth conditions in diverse growing regions.

Recently, scientists from China National Rice Research Institute (CNRRI), Chinese Academy of Agricultural Sciences successfully detected a novel major QTL with pleiotropism for yield-related traits in rice. In our study, a major-effect quantitative trait locus (QTL), qHD5, was resolved as a single Medelian factor that causes NIL(BG1) and NIL(XLJ) to have at a minimum of 10-day difference in HD under both long-day and short-day conditions in rice. qHD5 was initially mapped to a 309.52-kb genomic region in our previous study. Here, using an advanced BC4F3 population and map-based cloning, CNRRI’s scientists further narrowed the location of qHD5 to a 52.59-kb region between the H71 and RD502 markers. Sequence analysis revealed that Os05g03040, which putatively encodes an AP2 (APETALA2) transcription factor, has six single nucleotide polymorphisms (SNPs) between NIL(BG1) and NIL(XLJ). On this basis, this gene was concluded to be the most probable candidate gene for qHD5. The results also showed that Hd3a, RFT1, Hd1, Ehd1, and Ghd7 were differentially expressed in the two NILs. Moreover, qHD was found to affect yield-related traits such as flag leaf width, flag leaf length, branch number, and 1000-grain weight.

This work was supported by grants from the National Natural Science Foundation of China (Grants 31101209, 31221004, and 31501290) and the Agricultural Science and Technology Innovation Program of Chinese Academy of Agricultural Sciences (CAAS-ASTIP-2013-CNRRI). The research finding has been published in Theoretical and Applied Genetics online on September 27th 2016 (DOI: 10.1007/s00122-016-2787-y). More details are available on the links bellow: