Registration of two novel grain sorghum nuclear male sterile mutants: BTx623ms9‐1 and BTx623ms9‐3

Abstract

AbstractThe USDA‐ARS has released two new sorghum [Sorghum bicolor (L.) Moench] nuclear male sterile (NMS) mutants, BTx623ms9‐1 (Reg. no. GS‐791, PI 699654) and BTx623ms9‐3 (Reg. no. GS‐792, PI 699655). Both mutants were isolated from an ethylmethane sulfonate mutagenized population developed in the inbred line BTx623 and displayed stable male sterility across two environments tested. The homozygous BTx623ms9 panicle produces normal ovaries but small pale‐colored anthers with no pollen grains, making it easy to identify the sterile from the fertile panicles at the start of anthesis. Other than male sterility, the ms9 mutants are indistinctive from BTx623 wild type in morphology and development. Analyses indicate that the male sterility in BTx623ms9 mutants is controlled by recessive mutations on a single nuclear gene and differs from those that are available in currently known NMS lines (ms1, ms2, ms3, ms7, and ms8). The BTx623ms9‐1 and the BTx623ms9‐3 mutants harbor a nonsynonymous mutation (R218A) and a knockout mutation in the gene Sobic.002G221000, respectively. The causal mutations can be used to design molecular markers for efficient introduction of the Ms9 mutations into other sorghum lines. These two released NMS lines segregate for 50% pure male sterile and 50% fertile (Ms9/ms9) plants and can be maintained by pollinating sterile panicles with the pollen of the fertile plants. The two mutants can serve as female parents to create new mapping populations for genetic analysis and for evaluation of experimental hybrids.