Cloning, characterisation, and expression analysis of an oleosin gene in coconut (Cocos nucifera L.) pulp

Abstract

SummaryOleosins are structural proteins found in oil bodies, organelles found in the cells of plant tissues with a high oil content that undergo extreme desiccation as part of their maturation process. Oleosins stabilise oil bodies. In this paper, a full-length cDNA sequence homologous to oleosin, a seed-storage oil-body protein, from coconut (Cocos nucifera L.) was identified from cDNA libraries during fruit development and characterised. The gene, termed Coco-Ole, contained an open reading frame of 375 bp encoding a polypeptide of 125 amino acids. The predicted amino acid sequence of coconut oleosin had a molecular mass of 13.0 kDa, and showed 92% (AAF76238.1) and 67% (AAC02239.1) sequence similarity to oil palm (Elaeis guineensis Jacq.) and rice (Oryza sativa) oleosin proteins, respectively. The amino acid sequence clustered in the same branch as oil palm in the cladogram, but was distant from other species. The results of semi-quantitative RT-PCR indicated that the Coco-Ole gene was expressed only in the pulp, and its expression increased significantly during pulp development. Compared with fluctuations in oil content, expression of the Coco-Ole gene was consistent with the anabolism of oil during pulp development. The cloning and sequencing of the Coco-ole gene provides a new marker for studies on oil body biogenesis and fruit development in coconut.