Assessment of Vegetative Growth and Genetic Integrity of Vanilla planifolia Regenerants after Cryopreservation

Vanilla planifolia Jacks. ex Andrews is the vanilla species with the most commercial and greatest economic importance. It has been used as a case study in different cryopreservation studies that involve three vitrification-based approaches: droplet-vitrification (D-V), V-cryoplate (V-Cp) and D-cryoplate (D-Cp). The aim of this study was to compare the impact of these cryogenic techniques on vegetative growth (survival, stem length and leaf number) between cryo-derived plants and in vitro-derived controls during 12 months of greenhouse growth. Genetic stability was also assessed using the inter-simple sequence repeat (ISSR) markers. There were no significant differences found in the survival and stem lengths of the in vitro-derived regenerants and cryo-derived plants. A significant increase in the number of leaves was only detected in cryo-derived plants when using the V-Cp method. The electrophoretic profiles, based on seven ISSR primers, detected low variability: 81 total bands and 27% polymorphism. This is the first report on the assessment of vegetative growth and genetic integrity in cryo-derived V. planifolia plants recovered under greenhouse conditions. Of the three cryogenic approaches, D-Cp appears to yield V. planifolia regenerants plants with more vigorous vegetative growth and a lower level of polymorphism. Future research should focus on the reproductive growth of vanilla regenerants.