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ARS Home » Northeast Area » Washington, D.C. » National Arboretum » Floral and Nursery Plants Research » Research » Publications at this Location » Publication #135105
Title: CLONING OF A CDNA ENCODING THE CRANBERRY DIHYDROFLAVONOL-4-REDUCTASE (DFR) AND EXPRESSION IN TRANSGENIC TOBACCO

Author
item POLASHOCK, JAMES - RUTGERS
item Griesbach, Robert
item SULLIVAN, RAYMOND - RUTGERS
item VORSA, NICHOLI - RUTGERS

Submitted to: Plant Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/17/2002
Publication Date: 5/28/2002
Citation: Polashock, J.J., Griesbach, R.J., Sullivan, R.F., Vorsa, N. 2002. CLONING OF A CDNA ENCODING THE CRANBERRY DIHYDROFLAVONOL-4-REDUCTASE (DFR) AND EXPRESSION IN TRANSGENIC TOBACCO. Plant Science. 163:241-251.

Interpretive Summary: The specific color of fruits and flowers is dependant upon anthocyanin pigmentation. There are several different anthocyanin molecules which have a distinct color. Anthocyanin pigments are a result of a complex biosynthetic pathway. The key step in the pathway involves the enzyme dihydroflavonol reductase (DFR). DFR converts one of three colorless precursor molecules into the corresponding pigmented anthocyanin molecule. The specificity of DFR determines which anthocyanin is produced. One way to study the DFR specificity involves isolating the DFR gene and introducing it into host plants. The resulting genetically engineered plants express DFR in a different chemical background of precursors than the host plant. In this study, the cranberry DFR gene was introduced into tobacco. The resulting plants showed that the cranberry DFR had a very limited substrate specificity. Only one precursor was used as a substrate.

Technical Abstract: A clone representing a fragment of the (dihydroflavonol-4-reductase) DFR gene from cranberry was isolated from a genomic DNA library using the tomato DFR gene as a probe. Sequence analysis of the clone confirmed homology to published DFR gene sequences. 3' and 5' RACE (rapid amplificatoin of cDNA ends) reactions from cranberry leaf total RNA were used to obtain the entire cDNA sequence. The sequence information was used to amplify a full-length clone by rt-PCR. Sequencing analysis to confirm the identify of the full-length DFR cDNA identified a putative second allele. Segregation analysis suggested that the two sequences are not allelic, but multi-locus. Nucleotide sequence homology of the full length clones was highest to published DFR sequence from Camellia sinensis (about 80 percent identity) followed by Forsythis x intermedia, Antirrhinum majus, Rosa hybrida and Petunia hybrida. When expressed using the CaMV 35S promoter, the corolla of flowers of transgenic tobacco plants were much darker pink than the controls. Some flower parts not normally highly pigmented, such as the filaments, were also dark pink. These data confirm the identity and function of the cranberry clones and further suggest that overexpression of the cranberry DFR could be used to increase anthocyanin production in transgenic plants.