OENOPHILES will appreciate the subtlety of the discovery. The white and red grapes used in modern winemaking were produced by a mutation to a single gene.
The first varieties of Vitis vinifera, the most cultivated grape species, were black when ripe, a trait shared by most wild breeds, and which probably enticed birds and other animals to eat them and spread their seeds.
Now Shozo Kobayashi at the National Institute of Fruit Tree Science in Hiroshima, Japan, and colleagues report that at some point in the early evolution of grapes, a DNA element called a retrotransposon jumped from one part of the grape genome to another, blocking the expression of a gene called VvmybA1.
Advertisement
When two plants, each containing this altered gene, bred 鈥� or a single altered plant pollinated itself 鈥� the white grape was born. And the red grapes that are in use today came into being when a white grape plant鈥檚 altered gene lost its retrotransposon (Science, vol 304, p 982).
The discovery explains why white branches can arise on black grape vines and should help growers to produce even more new varieties, says grape-ripening expert Douglas Adams of the University of California, Davis. 鈥淚t suggests that a good starting point for breeding new red varieties might be some of the white grapes rather than the black ones.鈥�