Characterisation of a cyclin-dependent kinase (CDKA) gene expressed during somatic embryogenesis of coconut palm

The CDKA gene is linked to the cellular control. This gene was isolated from coconut palm (Cocos nucifera L) and a detailed expression analysis was done during somatic embryogenesis. Analysis of the deduced amino acid sequence showed the most important residues to be conserved. The highest homology was with Picea abies (96% similarity). Expression of the putative CnCDKA gene steadily increased during embryogenic callus formation phase when embryogenic competence is attained. In situ hybridization specified the localization of the transcripts as being mainly in a few cell layers within the meristematic centres in embryogenic calli at 90 day cultures. Analysis of CnCDKA expression at different somatic embryo formation stages showed that the expression was decreased progressively with the lowest expression in germinated somatic embryos.