Factors affecting somatic embryogenesis in eight Italian grapevine cultivars and the genetic stability of embryo-derived regenerants as assessed by molecular markers

Embryogenic cultures have been used in cryopreservation, genetic transformation, propagation, virus elimination, induced mutagenesis and in many other biotechnological applications, providing excellent opportunities for biotechnology advances in grapevine. Unfortunately the efficiency of somatic embryo- genesis (SE) is genotype-dependent in addition to showing interaction with explant type used and the plant growth regulator (PGR) composition. In order to identify the interaction of these parameters in SE, we tested eight wine grapevine cultivars, three explant types (ovary, anther/filament and stigma/style) and four PGR combinations in a statistically designed experiment. The genotype was the major deter- mining factor, with embryogenic response varying from 0.1 to 5.1% (about 50-fold difference). For PGR composition of the medium, embryogenesis ranged between 0.5 and 3.3% (a ≈7-fold difference). The explant type was the least important factor with embryogenesis ranging between 0.8% (anther/filament) and 2.3% (ovary)—only a ≈3-fold change. Anther/filament, that had generally been considered to be the most promising explant, surprisingly gave the lowest embryogenesis percentage. Genetic homo- geneity of plants developed from in vitro SE was assessed in comparison to mother plants using six inter-simple sequence repeat and ten random amplified polymorphic DNA primers that produced repro- ducible and clear bands ranging from 150 to 3500 bp. The amplification products were monomorphic across all the regenerated plants and their respective mother plants confirming the genetic homogeneity of the regenerants and demonstrating the suitability of SE for in vitro grapevine germplasm conservation and propagation.