GENETIC MANIPULATION OF CRANBERRY FRUIT AND LEAF ANTHOCYANIN GLYCOSYLATION.

Authors: NICHOLI, VORSA - RUTGERS UNIV.; Polashock, James

Submitted to: Theoretical and Applied Genetics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/21/2005
Publication Date: 5/1/2005
Citation: Nicholi, V., Polashock, J.J. 2005. Genetic manipulation of cranberry fruit and leaf anthocyanin glycosylation.. Theoretical and Applied Genetics. 130(5):711-715

Interpretive Summary: Certain pigments of American cranberry (Vaccinium macrocarpon Ait.) fruit are beneficial for human health. When naturally combined, or conjugated, by the plant with sugars, these pigments are particularly beneficial, and pigments conjugated with glucose are especially beneficial. Unfortunately, in American cranberry fruit the pigments are conjugated mainly with the sugars arabinose and galactose, with less than 8% conjugated with glucose, and so it would be beneficial to increase the proportion of pigments conjugated with glucose. Luckily, the fruit of another cranberry species, V. oxycoccus were found to contain the same pigments conjugated with glucose. We have carried out plant breeding experiments and biochemical analyses with these two species of cranberries to see if the hybrids would have a greater proportion of pigments conjugated with glucose than the traditional American cranberry. The hybrids were in fact intermediate to their parents in the proportion of pigments conjugated with glucose. This means that standard breeding methods can improve the nutritional of quality cranberry fruit. Fruit from these crosses can only be produced for evaluation three years after the seed is sown, which would slow the breeding program. However, we also found that the proportion of glucose- conjugated pigments is the same in cranberry leaves and fruit. Because leaves of cranberry hybrids can be tested for pigment conjugates after only one year of growth, our breeding program can make progress more efficiently. This research is primarily useful to other researchers in the field and has potential benefits leading to more nutritious food products.

Technical Abstract: The flavonoids of American cranberry (Vaccinium macrocarpon Ait.) are reported to be beneficial for human health, with anthocyanin glycosides contributing to the antioxidant potential. The anthocyanin glycosides of V. macrocarpon fruit are mainly galactosides and arabinosides of the aglycones, cyanidin and peonidin, with less than 8% glucosides. Flavonoid glucose conjugates have been reported to be more bioavailable than other sugar conjugates. The fruit anthocyanins of another cranberry species, V. oxycoccus were found to be largely glucosides of cyanidin and peonidin. Leaf anthocyanin glycosylation was found to correspond to fruit glycosylation in the two species, except for the complete lack of peonidin derivatives. Interspecific hybrids between these two species, and BC1 (to V. macrocarpon) and F2 generations were produced. The interspecific hybrids were intermediate to the parental species in the proportion of both leaf and fruit anthocyanin glucosides. Segregation in the backcross and F2 populations supports a single locus incomplete dominance model for leaf and fruit anthocyanin glycosylation. Leaf and fruit glycosylation was consistent for 60 BC1 individuals suggesting the same locus or two highly linked loci (< 5% recombination) confers both leaf and fruit glycosylation. The lack of peonidin in leaves indicates anthocyanin methoxyltransferase is not expressed in the leaves. In this study, we demonstrate the genetic manipulation of anthocyanin glycosylation in cranberry using interspecific hybridization, resulting in dramatically increased glucose-conjugated anthocyanins.