PHOTOAUTOTROPHIC MICROPROPAGATION AND ITS RELEVANCE IN THREATENED PLANT CONSERVATION

Abstract

The Global Strategy for Plant Conservation (GSPC) aims to halt the current loss of plant diversity by means of conservation measures, training and capacity building. To achieve the GSPC targets, it is very important to concentrate efforts in areas of the world rich in plant diversity. In the past, in vitro conservation measures have played an integral and successful part in this effort. However, for in vitro conservation by conservation practitioners to be increased in biodiversity hotspot countries, simplified, transferable and accessible methods will need to be developed. This should help to improve the success rate in re-introducing plants back into the wild and in ecological restoration programmes. Plants developed for repatriation and eventual reintroduction projects should be of the highest quality. Myoporum mauritianum and Trochetiopsis ebenus are threatened endemic plants from Mauritius and St Helena respectively. They were selected for a pilot study to investigate the effects of supporting systems and enriched CO 2 supply on their micropropagation. For both species, the photoautotrophic system improved the vigour and quality of the cultures. Plugs made of vermiculite and paper pulp (Florialite ® ) proved to be the better supporting system for both species compared to solidified agar medium. The fresh and dry weights of the roots were significantly higher in plants grown under photoautotrophic conditions with plugs as the supporting system and CO 2 enrichment. Similarly dry weights of the leaves of these two species were significantly better on plugs with CO 2 enrichment compared to mixotrophic cultures with agar as the supporting system. Simplifying in vitro culture and improving success rates are discussed in relation to conservation programmes dealing with recalcitrant plants that have high conservation rating according to the Red List of Threatened plants compiled by IUCN.