Genetics and cytology of a new male-sterile, female-fertile soybean mutant

Mutants affecting male sterility have potential applications in breeding me thodology studies and for commercialization of hybrids. Male-sterile, femal e-fertile soybean [Glycine max (L,) Merr.] plants were observed in an F-2 e ntry. Our objectives were to determine the inheritance, linkage, and alleli sm of the A91-JB-124 male-sterile, female-fertile mutant, and to conduct a detailed comparative microscopic study of microsporogenesis and microgameto genesis of fertile and sterile plants. The A94-JB-124 male-sterile, female- fertile mutant is a single recessive gene, allelic to ms6, and is linked to the W1 (flower color locus) with 4.3 +/- 0.3% recombination value based on 988 F-2 plants in the coupling linkage phase. A comparative microscopic st udy of microsporogenesis and microgametogenesis of fertile and sterile plan ts was conducted. The expression of the male-sterile gene is associated wit h rapid degenerative changes both in the tapetum and the parietal layer, Th ese changes are initiated at the late sporogenous mass stage. The A91-JB-12 4 mutant a as assigned gene symbol Ms6 ms6 (Ames 2) and Genetic Type Collec tion number T354H. The T295H Ms6 ms6 mutant is non designated Ms6 ms6 (Ames 1), T354H will be useful in the Cosegregation Method to produce hybrid soy bean seed.