Ex situ conservation of oil palm (Elaeis guineensis Jacq.) genetic resources using biotechnology

Oil palm seeds have been classified as intermediate with regards to their storage behaviour. Therefore, genetic resources of this species cannot be conserved in the form of dry seeds at low temperature, as is the common practice for orthodox seeds. At present, the traditional ex situ method to preserve genetic resources of oil palm is as whole plants in the field. The establishment of field collections is made easier by the perennial character of this species. However, field collections remain exposed to natural disasters and attacks by pests and pathogens. The advent of biotechnology allows improvements to be made for long-term ex situ conservation of this species, through the storage of zygotic and somatic embryos in liquid nitrogen (-196°C). Research performed at the GeneTrop laboratory (Montpellier, France) has shown that partially desiccated excised mature embryos and whole kernels can be successfully cryopreserved. This approach ensures the conservation of various populations provided that the fertilization is controlled. Another approach uses embryogenic tissues established from elite hybrids or genetically transformed material, thus allowing the conservation of genotypes. A protocol has been developed for the cryopreservation of polyembryonic cultures, which includes a pregrowth treatment of cultures on medium with high sucrose content followed by partial desiccation and rapid freezing. This protocol has been successfully applied to clones of 80 different genotypes, leading to the establishment of a cryobank of oil palm germplasm in the GeneTrop laboratory in 1995. More recently, cryopreservation of embryogenic cell suspensions and of single somatic embryos has been achieved, thus making it possible for the cryopreservation of materials from elite trees. These results illustrate the potential and feasibility of using biotechnology to improve the long-term ex situ conservation of oil palm genetic resources. (Résumé d'auteur)