Somatic Embryogenesis from Mature Zygotic Embryo Explants of Sorbus pohuashanensis Hedl

Somatic embryogenesis of Sorbus pohuashanensis Hedl was studied by taking intact mature zygotic embryo,zygotic embryo with 1 cotyledon and the cut cotyledon as explants.The basal induction and differentiation media were MS and MS1/2,respectively.The results showed that somatic embryo induction rate was the highest on intact mature zygotic embryo explant,which was 100%,and the best combination of plant growth regulators was 5 mg·L-1 NAA plus 2 mg·L-1 6-BA for induction of somatic embryos on MS medium.The concentrations of NAA and 6-BA and their interaction have significant effects on induction of callus and somatic embryos.Light environment with longer subculture interval were favorable to somatic embryogenesis.Stereomicroscope observation showed that there were two regeneration patterns(direct and indirect) and four development stages(globular,heart-shape,torpedo-shape and cotyledonary) for somatic embryogenesis of the species.Microscopic observation showed that the somatic embryos had bipolarity,and cotyledonary somatic embryos had fully-developed structure.