In the preceding note, it was mentioned that the derivation of an abnormally short chromosome involved natural cross-pollination of a partially malesterile (msp msp) plant (A76-517-2) by pollen from G. soja, G. gracilis", or an introgression product of these species into G. max. The recessive allele for self seed coat color (i) and the allele(s) producing the dark seed coat pattern of G. soja and "G.-gracilis" were concomitantly transferred in the cross-pollination. Segregation in later generations and a few testcrosses indicate that the characteristically patterned seed coats of G. soja and "G. gracilis" are governed by an allele of the R locus; the allele appears to be dominant to r (brown), r^m (ring-pattern) and, perhaps, to R (black).
Stelly, David M. and Palmer, Reid G.
"Research notes: Seed coats of Glycine soja and "G. gracilis" --inheritance of
Soybean Genetics Newsletter: Vol. 6
, Article 25.
Available at: https://lib.dr.iastate.edu/soybeangenetics/vol6/iss1/25