Maltose promotes somatic embryogenesis in Hevea brasiliensis
1998
Blanc, Géraldine | Carron, Marc-Philippe | Lardet, Ludovic | Michaux-Ferrière, Nicole | Teisson, Claude
In #Hevea brasiliensis# somatic embyogenesis is necessary for mass clonal propagation. The CIRAD team has developed a somatic embryogenesis process that has already been used to regenerate numerous #in vitro# plantlets, which are currently being tested in field trials and have given promising initial results. Friable callus lines from various genotypes are maintained in the laboratory on a gel medium. Regeneration is started on a medium containing reduced amounts of growth regulators and 234 mM of sucrose as the carbon source. After around one month of proliferation, the callus undergoes necrosis and somatic embryogenesis proper is initiated. However, few cells are involved in this phenomenon. Transferring the calli to a medium without growth regulators enables the development of somatic embryos and their subsequent germination. In order to improve the initiation of somatic embryogenesis, we replaced the sucrose in the first medium with hexose, another diholoside or a polyol at the same concentration. We also varied the time spent by the culture on this medium from 0 to 56 days. The best results were obtained with maltose and 28 days' culture. Histological observations showed maltose has a rapid and uniform effect on the initiation of somatic embryogenesis. It is particularly reflected in the development of a larger number of somatic embryos. Callus growth was measured. Callus carbon and mineral nutrition was monitored over time and other biochemical measurements (proteins, antioxidants) were taken, including a quantification of the enzymatic activities involved in oxidating stresses. All these measurements showed that the nature of the carbohydrate contained in the culture medium has an effect on the orientation of cell metabolism. (Résumé d'auteur)
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