Mapping of QTL for Fertility Restoration of HL-type Cytoplasmic Male Sterility in Rice(Oryza sativa L.)

Honglian-type CMS(CMS-HL)is one of the most extensively used cytoplasms in hybrid rice of China.In order to map both major and minor QTL controlling fertility restoration for CMS-HL,a Honglian-type male sterility line(YTA)was test-crossed to the RILs derived from a cross between Lemont and Teqing.Composite interval mapping was conducted based on the data of spikelet fertility and pollen fertility in the test-cross population of YTA/RILs.Significant difference between the two parents Lemont and Teqing in fertility restoration was observed and Teqing showed a much stronger fertility restoration than Lemont.Totally,four QTL for spikelet fertility and pollen fertility were mapped to chromosomes 1,2 and 10 of all the twelve rice chromosomes,each explaining 5%-24% of the trait variation.Among these QTL,three QTL with their positive alleles were from the parent Teqing.QTL qRF-10-1,mapped onto the interval RM258-C16 of chromosome 10,produced the largest effects on both the two traits,accounting for 24% of the spikelet fertility variation and 17% of the pollen fertility variation.Comparatively,the other three QTL produced much small effects on the traits,each explaining less than 10% of the trait variation.These results indicated that the fertility restoration of the RILs was mainly controlled by the major QTL qRF-10-1 and was also modified by the other three minor QTL.This suggestion was further confirmed by the continuous binary frequency distribution of spikelet fertility in the test-cross population of YTA/RILs.QTL qRF-10-1 with the most closely linked SSR marker of RM258 could be used as a target to be manipulated in breeding restoration lines for HL-CMS.