Biotechnologies et conservation des ressources phytogénétiques

Abstract

In vitro techniques have numerous applications in collecting, propagating and conserving plant biodiversity. In vitro collecting techniques make it possible to introduce in vitro explants under field conditions from recalcitrant seeds and vegetatively propagated species. In vitro culture techniques make production and large scale propagation of disease-free material possible. Utilising in vitro culture techniques is of high interest for conserving: 1) genetic resources of recalcitrant seeds and vegetatively propagated species; biotechnology products (elite genotypes, metabolite-producing cell lines, transformed material) and 3) rare and endangered plant species. Medium term conservation is performed by reducing growth of the plant material, thereby increasing intervals between subcultures. Slow growth storage protocols are employed for numerous temperate and tropical species. For long term storage, cryopreservation (liquid nitrogen -196 °C) makes it possible to store plant material without modification or alteration for extended periods, sheltered from contamination and with limited maintenance. Cryopreservation is well advanced for vegetatively propagated plant species. Research is less advanced for recalcitrant species due to certain characteristics including their sensitivity to desiccation, their structural complexity and heterogeneity in terms of developmental stages and their water content at maturity. However, various technical approaches exist in order to establish cryopreservation techniques for a larger number of recalcitrant species. Routine utilisation of cryopreservation is still limited. However, the number of examples for which it is used on a large scale is increasing steadily.