Coconut Biotechnology: Gene Discovery of Fatty Acid/Triglyceride Biosynthesis, Cocosin Promoter and Tissue Culture-Transformation In Corn As a Model System.

To prepare for the development of a genetically modified coconut with increased oil content and lauric acid, gene and promoter discoveries and the development of a tissue culture-based transformation system in corn as a model system were successfully done.

Gene discovery studies led to the RT-PCR-based cloning, molecular characterization, ontogenic expression and isoform occurrences of acetyl CoA carboxylase (ACCase), acyl carrier protein (ACP), β-ketoacyl synthase 3 (KAS3), acyl-ACP thioesterase (TE), lysophosphatidic acid acyltransferase (LPAAT), and  phosphatidic acid phosphatase (PAP).

Callus induction, somatic embryogenesis, shoot differentiation and plantlet regeneration were optimized for white corn inbred lines, Var 4 and P53, as a model system for transformation.  Transient expression of the reporter GUS gene was detected in both particle inflow gun (biolistic method) and Agrobacterium mediated transformed tissues of corn.

An endosperm-specific promoter of the cocosin gene was cloned, characterized, and tested for gene transcription in corn and papaya.  The 300-bp cloned cocosin promoter was transcriptionally active, and activity is similar or even stronger than the constitutive promoter 35S CaMV.