Molecular, phenotypic and biosynthetic stability in Dioscorea floribunda plants derived from cryopreserved shoot tips

Shoot tips of Dioscorea floribunda, a medicinal species of yam, were cryopreserved using the vitrification technique, resulting in 87% survival and 30% plant regeneration. Genetic stability of plants derived from cryopreserved shoot tips was evaluated using molecular, morphological and biochemical methods. The random amplified polymorphic DNA (RAPD) analysis of 60 cryopreserved-derived and 20 in vitro grown (control) plantlets showed that 10 primers produced 64 clear reproducible bands, with the amplification products being monomorphic for all the plantlets tested except 1. A total of 5120 bands obtained from this study exhibited no aberration in RAPD banding except I being polymorphic. The morphological analysis of plants, after regrowing in green house, revealed no significant difference between cryopreserved-derived and control plants. Eigtheen important morphological characters (based on descriptor list) were examined including length/breath ratio of leaf, number of primary stems, petiole length, internodal length and lamina/petiole ratio. The diosgenin contents of cryopreserved-derived plants, analyzed using high performance liquid chromatography, were found to be same as those of control plants. Thus, with the experimental conditions tested, the D. floribunda plants derived after cryopreservation were found to be genetically stable at the molecular, phenotypic and biosynthetic levels. (C) 2002 Elsevier Science Ireland Ltd. All rights reserved.