MOLECULAR CLONING of Elaeis guineensis PHYTOENE SYNTHASE (Egpsy) and ITS EXPRESSION in MESOCARP TISSUES

Abstract

Phytoene synthase (psy) gene is responsible for the synthesis of carotenoids in plants. In this study complimentary deoxyribonucleic acid (cDNA) and genomic sequences of psy were isolated by rapid amplification of cDNA ends and polymerase chain reaction (PCR) using ribonucleic acid (RNA) and DNA isolated from the mesocarp tissues of oil palm (Elaeis guineensis). The size of the full-length cDNA was 2233 bp. The open reading frame (ORF) was 1299 bp and encoded 433 deduced amino acid (AA) residues. The transcript profile revealed that psy was expressed at a maximum level at 12 weeks after anthesis (WAA). The lowest expression of psy was at 13 WAA, which was speculated as the transition of the leaf-like carotenoid to the formation of storage carotenoids. The AA sequence deduced from the cDNA was 70%-78% identical to PSY from other higher plants. The genomic sequence analysis revealed that the psy gene contains six exons and five introns. Southern blot analysis indicated that oil palm has only one copy of the psy gene in its genome.