Cloning, characterization, and heterologous expression of a functional geranylgeranyl pyrophosphate synthase from sunflower (Helianthus annuus L.)

Geranylgeranyl pyrophosphate (GGPP) synthase is a key enzyme for the biosynthesis of terpenoid compounds that play vital roles in plant growth and development, and interactions between organisms. We have cloned and characterized a sunflower cDNA encoding GGPP synthase. Sequence analysis showed that the gene contained a 1 071-bp open reading frame coding for a peptide of 356 amino acid residues with a calculated molecular mass of 38.7 kDa. The predicted amino acid sequence of this sunflower GGPS has high similarity to other plant GGPP synthases (63–79% ). In vitro activity assay using recombinant protein and genetic complementation experiments have shown that the cDNA we cloned encodes for functional GGPP synthase. Gene expression studies using sunflower seedlings showed that the gene was expressed after two days of seed imbibition. Abscisic acid treatment down-regulated the expression of the gene.