CDNA cloning and endogenous expression of a flavonoid 3′5′-hydroxylase from petals of lisianthus ( Eustoma grandiflorum)

Abstract

A flavonoid 3′,5′-hydroxylase (F3′,5′-H) coding sequence was isolated from a lisianthus ( Eustoma grandiflorum Grise.) petal cDNA library using one of the petunia orthologues ( Hf1, pCGP602) as a probe. Hybridization analysis of lisianthus genomic DNA indicated the presence of a single gene coding for the F3′,5′-H. Comparison of deduced amino acid sequences with other F3′,5′-H sequences available showed 77.3% identity with the gentian, 71.9% identity with the eggplant, and 73.8 and 73.4% identity with the petunia Hf1 and Hf2 genes respectively. Northern RNA analysis showed that the F3′,5′-H mRNA is transcribed late in petal development, is concomitant with the appearance of coloured anthocyanins in petal tissue, and that the transcript is more abundant in the outer petal tissue when compared to the inner, deeply pigmented throat. A similar expression pattern has been described for the petunia Hf2 locus transcript suggesting the lisianthus F3′,5′-H and petunia Hf2 are homologous loci.