Five different populations have been recognized as a source of msl alleles. Genetics studies of male-sterile, female-fertile mutations conducted by Palmer et al. (1978) showed that msl (North Carolina) (T260), msl (Urbana) (T266), msl (Tonica) (T267), and msl (Ames) (T268) are independent mutations at the msl locus. Yee and Jian (1983) reported another mutation at the msl locus, designated Shennong Male-Sterile Soybean L-78-387.
Skorupska, Halina and Palmer, Reid G.
"Research Notes : United States : New independent mutation: msl (Ames 2),"
Soybean Genetics Newsletter: Vol. 14
, Article 43.
Available at: http://lib.dr.iastate.edu/soybeangenetics/vol14/iss1/43