CRYOPRESERVATION AS A TOOL FOR THE MANAGEMENT OF COCONUT GERMPLASM
We present hereafter a review of different collaborative research studies carried out on the cryopreservation of coconut plumules excised from the zygotic embryo. Plumule (shoot apical meristem and leaf primordia) tissues have shown different degrees of success in cryopreservation depending on the combination of alginate encapsulation and osmotic or evaporative dehydration used. The percentage of regrowth was progressively improved from vitrification (0%), to osmoprotection (10%), and subsequently the encapsulation-dehydration technique allowed 20% regrowth level into leafy shoots. Addition of abscisic acid (20 to 40 μM) boosted recovery growth after freezing (up to 40%). Histological studies have clearly shown that the addition of lower amounts of ABA (10 μM) allows cells to maintain the structural characteristics of control cells for immersion into liquid nitrogen without dehydration. The effect of plant material conditioning, for transport from collecting site to laboratories, was studied to identify possible effects of uncontrolled factors on tissue tolerance to cryopreservation. Three conditioning methods [embryo set in endosperm core (ALB); embryo transferred onto of solidified agar (SW); embryo immersed into KCl solution (KCl)] were used. SW performance is clearly more efficient when combined with dehydration and freezing, giving 40% recovery. These results are interesting as they show that the medium surrounding the embryo (endosperm or medium supply) can be replaced by agar alone, without nutritive factors. This approach should also facilitate germplasm exchange. As a result of the absence of phloem vascular bundles in the plumular tissues, the approach described here should increase the scope for obtaining material free of pathogenic agents, an essential prerequisite for the conservation and exchange of germplasm. This approach should be a strong point in the fight against Lethal Yellowing Disease, the most serious disease affecting coconut plantations.
Malaurie, B., Tregear, J., N'Nan, O., Bandupriya, H.D.D., Borges, M. and Verdeil, J.-L. (2011). CRYOPRESERVATION AS A TOOL FOR THE MANAGEMENT OF COCONUT GERMPLASM. Acta Hortic. 908, 461-466
Cocos nucifera L., conservation and exchange of germplasm, encapsulation-dehydration, osmoprotection, plant growth recovery, plumule, zygotic embryo