Characterization and genetic mapping of a novel recessive genic male sterile gene ms305 in maize (Zea mays L.)

The male sterility system shows tremendous value for the long-term utilization of hybrid crop breeding. In this study, a male sterile mutant,K305ms, was derived from the M3progeny of maize (Zea maysL.) inbred line K305 exposed to60Co-γ irradiation. Male sterileK305msplants did not show any obvious differences from their sibling male fertile plants (K305F) during the vegetative stage, but failed to produce functional pollen at the reproductive stage. Microscopic observations determined that the dyads and tetrads from the pollen ofK305msplants developed abnormally, and subsequently the microspores were shriveled. Genetic analysis indicated that the male sterility ofK305mswas controlled by a single recessive genic gene. Gene mapping showed that the responsible gene was located between two simple sequence repeat markers on chromosome 2L in a region of 10.3 cM, bnlg469b and bnlg1940, with genetic distances of 2.9 and 7.4 cM, respectively. According to the microscopic and mapping characteristics, our results showed that this gene was distinguishable from all other reported male sterile genes in maize, and it is temporarily designated asms305. The linkage map in this study will provide a useful fundamental basis for molecular marker-assisted selection as well as for further map-based cloning ofms305.