Molecular mapping of 36 soybean male-sterile, female-sterile mutants.

Mutability of the w(4) flower color locus in soybean [Glycine max (L.) Merr.] is conditioned by an unstable allele designated w(4)-m. Germinal revertants, purple-flower plants, recovered among self-pollinated progeny of mutable flower plants were associated with the generation of necrotic root, chlorophyll-deficiency, and sterility mutations. Thirty-seven male-sterile, female-sterile mutant lines were generated from 37 independent reversion events at the w(4)-m locus. The first germinal revertant study had one male-sterile, female-sterile mutant (st8, T352), located on Molecular Linkage Group (MLG) J. The second study had 36 germinal-revertant derived sterility mutants descended from four mutable categories of w(4)-m. The mutable categories were designated; (1) low frequency of early excisions, (2) low frequency of late excisions, (3) high frequency of early excisions, and (4) high frequency of late excisions. The objectives of the present study were to; (1) molecularly map the 36 male-sterile, female-sterile mutants, and to (2) compare map locations of these mutants with T352 (st8), identified from the first germinal revertant study. Thirty-three of 36 male-sterile, female-sterile mutations were derived from germinal reversions that were classified in the late excision categories. Thirty-five male-sterile mutants mapped to the st8 region on MLG J. The only exception mapped to MLG G. Most likely mutants were generated through insertion of a putative transposon that was excised from the w(4) locus. The location of 36 of 37 mutations to a single chromosomal region suggests preference for sequence-dependent insertion.