Mapping of three QTLs for seed setting and analysis on the candidate gene forqSS-1 in rice (Oryza sativa L.)

The lower seed setting is one of the major hindrances which face grain yield in rice. One of the main reasons to cause low spikelet fertility (seed setting) is male sterility or polen abortion. Notably, polen abortion has been frequently observed in advanced progenies of rice. In the present study, 149 BC2F6 individuals with signiifcant segregation in spikelet fertility were generated from the cross between N040212 (indica) and Nipponbare (japonica) and used for primary gene mapping. Three QTLs,qSS-1, qSS-7 andqSS-9 at chromosomes 1, 7 and 9, respectively, were found to be associated with seed setting. The recombinant analysis and the physical mapping information from publicly available resources exhibited that theqSS-1, qSS-7 andqSS-9 loci were mapped to an interval of 188, 701 and 3741 kb, respectively. The seed setting re-sponsible for QTLqSS-1 was further ifne mapped to 93.5 kb by using BC2F7 population of 1849 individuals. There are 16 possible putative genes in this 93.5 kb region. Polen vitality tests and artiifcial polination indicated that the male gamete has abnormal polen while the female gamete was normal. These data showed that low seed setting rate relative toqSS-1 may be caused by abnormal polen grains. These results wil be useful for cloning, functional analysis of the target gene governing spikelet fertility (seed setting) and understanding the genetic bases of polen sterility.