Introgression between wild and cultivated soybeans of Japan revealed by RFLP analysis for chloroplast DNAs

Wild soybeans collected in Japan were surveyed for RFLPs of chloroplast DNA. Three haplotypes were detected in RFLPs with a cpDNA clone which contains a LSC region adjacent to the left member of IR. Most of the plants tested possessed haplotype III, and a few plants, collected mostly in southern Japan, had haplotype II. Haplotype I, which is the predominant form in modern cultivars, was detected at six sites from four widely separated regions. Our results indicate that haplotype III is predominant in wild soybean of Japan. Some of the plants having haplotype I were phenotypically intermediate between wild and cultivated soybeans, while the others possessed a seed morphology and plant architecture typical of ordinary wild soybean. The plants having haplotype I appear to be either derivatives of hybridization between wild and cultivated soybeans or relics of a direct progenitor of soybean cultivars with the haplotype I chloroplast genome.