Enhancement of germination, hyperhydricity control and in vitro shoot formation of Vasconcellea stipulata Badillo

Vasconcellea stipulata has great commercial importance because of its enzymatic activity and as a source for genetic improvement of papaya since it is resistant to the papaya ringspot virus. However, due to its low regeneration by seeds and limited knowledge of its genetic and pharmaceutical properties, this species is not widely cultivated. For propagation, in vitro culture of seeds has been used to address this problem, but hyperhydricity, a physiological disorder, mainly expressed in the developing embryonic axis and specifically associated with this species, is a significant constraint. In order to obtain elite material for culture of V. stipulata, the aim of this work was to increase germination, to control hyperhydricity in embryos and to evaluate the potential to induce morphogenic responses, i.e., shoot formation. Our results showed that it is possible to increase germination up to 53% under in vitro conditions within a short period in the presence of hydrogen peroxide. In addition, hyperhydricity was significantly reduced (50%) in vitro when gibberellic acid concentrations were included on a 1/2 Nitsch and Nitsch nutrient medium, resulting in approximately 80% recovery of viable seedlings. Finally, other plant growth regulators were evaluated and found to trigger shoot formation in axillary buds as well as induce the formation of callus in leaf sections derived of seedlings.