Five different populations have been recognized as sources of ms1 alleles. Genetic studies of male-sterile, female-fertile mutations conducted by Palmer et al. (1978) showed that ms1-North Carolina (T260), ms1-Urbana (T266), ms1-Tonica (T267), and ms1-Ames (T268) are independent mutations at the ms1 locus. Yee and Jian (1983) reported another mutation at the ms1 locus, designated Shennong Male-Sterile Soybean L-78-387.