CLONING OF CDNA CODING FOR DIHYDROFLAVONOL-4-REDUCTASE (DFR) AND CHARACTERIZATION OF DFR EXPRESSION IN THE COROLLAS OF GERBERA-HYBRIDA VAR REGINA (COMPOSITAE)

We are approaching corolla differentiation in Compositae by studying t he regulation of flavonoid pathway genes during inflorescence developm ent in gerbera. We have cloned a dfr cDNA from a ray floret corolla cD NA library of Gerbera hybrida var. Regina by a PCR technique based on homologies found in genes isolated from other plant species. The funct ionality of the clone was tested in vivo by complementing the dihydrok aempferol accumulating petunia mutant line RL01. By Southern blot anal ysis, G. hybrida var. Regina was shown to harbour a small family of df r genes, one member of which was deduced to be mainly responsible for the DFR activity in corolla. Dfr expression in corolla correlates with the anthocyanin accumulation pattern: it is basipetally induced, epid ermally specific and restricted to the ligular part of corolla. By com paring the dfr expression in different floret types during inflorescen ce development, we could see that dfr expression reflects developmenta l schemes of the outermost ray and trans florets, contrasted with that of the disc florets.