Somatic embryogenesis from immature zygotic embryos and monitoring the genetic fidelity of regenerated plants in grapevine

Abstract

Somatic embryogenesis and plant regeneration were successfully established on Nitsch and Nitsch (NN) medium from immature zygotic embryos of six genotypes of grapevine (Vitis vinifera). The optimum hormone combinations were 1.0 mg dm-3 2,4-dichlorophenoxyacetic acid (2,4-D) for callus induction and 1.0 mg dm-3 α-naphthalene acetic acid (NAA) + 0.5 mg dm-3 6-benzyladenine (BA) for embryos production and 0.03 mg dm-3 NAA + 0.5 mg dm-3 BA for embryos conversion and plant regeneration. The frequency of somatic embryogenesis varied from 10.5 to 37.5 % among six genotypes and 15.5-42.1 % of somatic embryos converted into normal plantlets. The analysis of DNA content determined by flow cytometry and chromosome counting of the regenerated plantlets clearly indicated that no ploidy changes were induced during somatic embryogenesis and plant regeneration, the nuclear DNA content and ploidy levels of the regenerated plants were stable and homogeneous to those of the donor plants. RAPD markers were also used to evaluate the genetic fidelity of plants regenerated from somatic embryos. All RAPD profiles from regenerated plants were monomorphic and similar to those of the field grown donor plants. We conclude that somaclonal variation is almost absent in our grapevine plant regeneration system.