Abstract
To examine the capacity for plant regeneration through somatic embryogenesis, Japanese soybean cultivars were investigated by 3-step-somatic embryogenesis: 1) induction of somatic embryos (SEs) from immature cotyledons, 2) proliferation of SEs in liquid medium and 3) differentiation of SEs into cotyledon-stage embryos. At each step, properties of the cultures varied among cultivars. Notably, significant differences were observed on 1) efficiencies of SE induction, 2) compactness of individual SEs during proliferation, and 3) yields of differentiated embryos (numbers of cotyledon-stage embryos differentiated from 100 mg globular SEs). We found that the compactness of SEs in liquid medium was very important factor for the recovery of well differentiated embryos. In fact, Yuuzuru and Yumeyutaka which indicated high ratios of compact SEs at proliferation step showed high yields of well differentiated embryos. The abilities of these Japanese cultivars to yield cotyledon-stage embryos were superior or comparable to North American cultivar ‘Jack’, which is used as one of the most preferable genotypes for somatic embryogenesis, indicating their high potentials for plant regeneration.
