IN VITRO PLANT REGENERATION AS A TOOL TO IMPROVE ORNAMENTAL CHARACTERS IN PASSIFLORA SPECIES

Abstract

The genus Passiflora, comprising about 500 species of vines, lianas and small trees, is the largest in the passion flower family (Passifloraceae). In the tropical and subtropical regions, several species are grown for their edible fruits (Passiflora edulis Sims.), while many others are cultivated in the warmer parts of the world, either outdoors or in the greenhouses, for their medicinal and ornamental value. Passiflora exhibits some unique floral traits, which are of particular interest to the floricultural market. With the aim to exploit the ornamental traits of some Passiflora species, a collection was settled at the CRA-FSO, in Sanremo. Tissue culture protocols were established for Passiflora hybrids 'Guglielmo Betto' and 'Manta', P. trifasciata Lemaire and P. foetida L. 'Hastata'. The in vitro regenerated plants were successfully acclimatized in the greenhouse. At flowering, P. 'Guglielmo Betto', P. 'Manta' and P. trifasciata plants, regenerated from tendrils, were similar to the mother plants concerning plant habit, flower shape, colour and form of leaves. P. foetida 'Hastata' plants which regenerated from immature-flowers showed morphological alterations in the flower and in the fruit involucral bracts. The reduced bracts left the fruit completely visible, conferring a new attractive phenotype. The modification is maintained in the cutting-derived plants.