COMPLEMENTATION OF THE TOMATO ANTHOCYANIN WITHOUT (AW) MUTANT USING THE DIHYDROFLAVONOL 4-REDUCTASE GENE

We isolated the dihydroflavonol 4-reductase (DFR) gene from tomato (Ly copersicon esculentum) using a previously characterized cDNA as probe. Earlier studies had indicated that the DFR gene is present in tomato as a single gene located on chromosome 2 near the locus anthocyanin wi thout (aw). Mutant alleles of the aw locus result in the complete abse nce of anthocyanin pigmentation throughout all stages of plant develop ment. When the genomic DFR clone was introduced by Agrobacterium-media ted transformation into plants bearing the aw mutation, primary transg enic seedlings accumulated anthocyanins that could be observed while t he plants were still in tissue culture and which continued to be obser ved as the plants matured. Progeny of self pollinated and backcrossed transgenic plants segregated for anthocyanin pigmentation, and Souther n hybridization analyses indicated the presence of the DFR transgene e xclusively in those plants with pigmentation. These data indicate that the aw locus likely corresponds to the structural gene for DFR and th at DFR can be used as a visual, nondestructive, plant-derived marker g ene for tomato.