GENETIC DIFFERENTIATION BETWEEN SUMMER AND AUTUMN MATURING CULTIVARS OF SOYBEAN (GLYCINE-MAX (L) MERRILL) IN KYUSHU DISTRICT OF JAPAN

135 soybean landraces and pure line selections from Kyushu district of Japan were assayed for isozyme and seed protein loci in order to dete rmine the genetic structure of the groups of summer and autumn maturin g cultivars. Out of the 16 tested loci, Dial, Enp, Estl, and Ti exhibi ted a marked difference in allelic frequency between both groups. The summer cultivar group had a high frequency for Dial-b, Enp-b, Estl-a a nd Ti-b, whereas Dial-a, Enp-a, Estl-b and Ti-a were predominant in th e autumn group. The analysis of multi-locus genotypes revealed that bo th groups mostly consisted of different multi-locus genotypes. The all elic combination of Dial-b Enp-b Estl-a Ti-b was most frequently obser ved in the summer cultivars, whereas four genotypes, Dial-a Enp-a Estl -a Ti-a, Dial-a Enp-a Estl-b Ti-a, Dial-a Enp-b Estl-b Ti-a and Dial-a Enp-a Estl-b Ti-b, occupied most of the autumn cultivars. These resul ts indicated that both groups were appreciably differentiated from eac h other. The summer cultivar group also included a few accessions havi ng the multi-locus genotypes observed predominantly in the autumn grou p or Acol-b characteristic of the landraces native to northern Japan. It seems likely that the summer cultivar group was not phyletically de rived from a single common ancestor, but partly involves the landraces with early maturity derived from northern Japan. Dial, Enp, Estl and Ti are useful genetic markers to trace the origin and dissemination pa ths of Japanese soybean landraces.