Читать книгу Biotechnology of Fruit and Nut Crops - Группа авторов - Страница 149

Barcelos et al. (2015) noted that currently utilized oil palm planting materials yield three times more than the material used decades ago. Genetic resources are maintained in ex situ field plots, and as in vitro storage methods, which can be used to conserve large numbers of materials, provide protection from diseases and low cost maintenance. Ex situ and in vitro storage provide complementary means for effective long-term conservation of the oil palm genetic materials (Ithnin et al., 2017).

The long-term observation of plants that originated from control and cryopreserved stabilized polyembryonic cultures (SPCs) of six elite oil palm clones was reported by Konan et al. (2007b). SPCs are able to propagate indefinitely at a steady growth rate when subcultured on the same plant growth regulator-free medium. Survival of plantlets in the nursery was monitored, and a series of vegetative and floral characteristics of >440 palms were studied for up to 12 years after transfer to the field in Côte d’Ivoire. The six clones tested showed an average recovery of 34% after cryopreservation in liquid nitrogen according to Dumet et al. (1993). Abnormal palms were observed in one clone only; the percentage of abnormal palms from cryopreserved SPCs was significantly lower (5%) than that measured for palms that originated from control SPCs (29%).

Beulé et al. (2018) assessed the efficiency of cryopreservation for somatic embryos with respect to regeneration and long-term storage capacity. To test the survival and recovery of 29 clones of oil palm somatic embryos cryostored for 20 years, clumps of somatic embryos were initially cultured for 7 days on medium containing 0.75 M sucrose, then dehydrated in air-tight containers containing silica gel until the moisture content was between 19% and 35% fresh weight, and finally immersed directly into liquid nitrogen and stored for 20 years. Survival rate of somatic embryos following cryopreservation and rewarming was 19.1% for the 29 clones tested, while survival of somatic embryos after 20 years of cryostorage was significantly higher, with an average of 33.2% for the 28 surviving clones. Out of these 28 surviving clones, three were lost due to contamination or regrowth decline, six produced only shoots and the remaining material was able to proliferate. This study demonstrated that it is possible to cryostore oil palm somatic embryos for extended periods and to regenerate proliferating cultures and plantlets from the cryopreserved material. Therefore, it is possible to use this procedure to store oil palm germplasm and to manage large-scale production in commercial micropropagation laboratories.