Construction and Characterization of a cDNA Library from the Pulp of Coconut (Cocos nucifera L.)

To investigate the gene expression profile of endosperm development, a cDNA library was constructed and characterized from the pulp of coconut at different developmental stages. The constructed cDNA library incorporated approximately 1 × 107 clones in total, and the size of the insertion fragments ranged from 800 to 2 000 bp. Sequencing results of 100 randomly picked clones showed that the recombination rate was 96%. In subsequent sequence analysis, 41 clones (41%) were homologous to known function proteins, and 23 clones showed high amino acid identity (more than 80%) with the corresponding genes of different plants. Semi-quantitative RT-PCR indicated that oleosin and globulin genes are pulp-specific expression, and have differential expression level in different developmental stage. Clone 29, recognized as homologous to KIAA1239 protein (Homo sapiens), was observed to occur nine times, indicating that this gene may be over-expressed during the endosperm development stage. However, the homologous protein was found only in mammals, and the detailed function is still unknown. Elucidation of the functional characterization of these genes will be carried out immediately.