Is in vitro micrografting a possible valid alternative to traditional micropropagation in Cactaceae? Pelecyphora aselliformis as a case study

Abstract

Several taxa of Cactaceae are endangered by overcollection for commercial purposes, and most of the family is included in the Convention on International Trade in Endangered Species of Fauna and Flora (CITES). Micropropagation may play a key role to keep the pressure off wild populations and contribute to ex situ conservation of endangered taxa. One of the limits of micropropagation is the species-specific requirement of plant regulators for each taxon and sometimes even for different genotypes. With the micrografting technique the rootstock directly provides the scion with the necessary hormonal requirements. In this paper we present data on in vitro grafting of Pelecyphora aselliformis Ehrenberg, an Appendix I CITES listed species critically endangered and sought after by the horticultural trade, on micropropagated Opuntia ficus-indica Miller. Apical and sub-apical scions of P. aselliformis were used to perform micrografting with a successful rate of 97 and 81 % respectively. Survival rate after ex vivo transfer was 85 %. We hypothesize that this method could be applied to other endangered, slow growing taxa of Cactaceae thus contributing to the conservation of this endangered family.

Keywords: CITES; Ex situ conservation; In vitro grafting; Micropropagation; Succulent plants; Tissue culture.

Fig. 1

Different stages of micrografting procedures: a Seedling of Opuntia ficus-indica 30 days after sowing; b Opuntia ficus-indica subcultured and maintained as rootstock source indefinitely; c Seedlings of Pelecyphora aselliformis 60 days after sowing; d Freshly grafted sub-apical slice of Pelecyphora aselliformis on micropropagated Opuntia ficus-indica; e Micrografting of the apical part of Pelecyphora aselliformis after 20 days of cultivation. Arrow indicates new growth; f Micrografting of a sub-apical slice of Pelecyphora aselliformis after 20 days of cultivation. Arrows indicate new shoots arising from three different areoles