University of Florida scientists Manjul Dutt and Jude Grosser are developing genetically engineered limes containing some similar genetic factors expressed in grape skin and blood orange pulp. These modified Mexican limes have a protein that induces anthocyanin biosynthesis, the process that creates the “red” in red wine, and causes the limes to develop a range of colors in the pulp from dark purple to fuchsia.
Anthocyanins also naturally occur in blood oranges. But blood oranges need cold temperatures to develop their trademark color. They grow and color well in the cooler climates of Spain and Italy, but do not exhibit the characteristic blood red color when grown in the subtropical climate of Florida.
These new limes were developed using genes isolated from the red grape Ruby Seedless and the blood orange Moro. Research on the utilization of these genes was conducted initially to develop a more consumer-friendly, alternative, plant-derived system. They are the first step toward Florida farmers producing blood oranges and (possibly) a new grapefruit cultivar.
In addition to changing the color of the fruit, the introduction of anthocyanins also change the color of leaves stems and flowers, and could lead to the creation of ornamental citrus plants. According to Dutt, flower color ranged from light pink to fuchsia.
Dutt and Grosser’s study will be published in the January edition of the American Society for Horticultural Science.