Development and utilization of an InDel marker linked to the fertility restorer genes of CMS-D8 and CMS-D2 in cotton.

The cytoplasmic male sterility (CMS) system is a useful tool for commercial hybrid cotton seed production. Two main CMS systems, CMS-D8 and CMS-D2, have been recognized with Rf and Rf as the restorer genes, respectively. The development of molecular markers tightly linked with restorer genes can facilitate the breeding of restorer lines. In this study, the InDel-1892 marker was developed to distinguish Rf and Rf simultaneously. Sequence alignment implied that CMS-D8-Rf has a 32 bp insertion and that CMS-D2-Rf has a 186 bp insertion at the InDel-1892 locus. The codominant marker was co-segregated with Rf and Rf. Hence, this marker can be used for tracing Rf and Rf simultaneously and identifying the allele status at the restorer gene locus. The results of this study will facilitate efficient marker-assisted selection for restorer lines and hybrids of CMS systems.