Submitted to: Citrograph
Publication Type: Trade Journal
Publication Acceptance Date: 2/25/2015
Publication Date: 5/22/2015
Citation: Thomson, J.G., Dasgupta, K., Thilmony, R.L. 2015. The development of novel Blood and Cara cara like citrus varieties. Citrograph. 6:3/65-69.
Technical Abstract: In 2012 the Citrus Research Board took a unique approach to developing novel citrus cultivars – a biotech approach. Blood and the Cara cara orange are special cultivars that are distinguished by their color and distinctive flavor. These cultivars offer variety in flavor, taste, health-benefits and are often in high demand when they are in season. Despite increasing consumer interest, production of these citrus varieties remains unreliable due largely to dependency on stringent growing conditions for full color and flavor formation. To offset this issue our lab proposed to generate Blood orange and Cara cara-like cultivars via genetic engineering by enhancing the expression of naturally occurring compounds in citrus and promoting their presence in the fruit using citrus genetic components. The compounds of interest are anthocyanin and/or lycopene. Anthocyanin are naturally occurring in Blood orange and many berry species such as raspberries, cherries and grape, while lycopene appear in Cara cara citrus cultivars along with tomato, cherries and strawberries. The required enzymes necessary for anthocyanin and lycopene production are characterized and the citrus genes responsible for producing these enzymes are known. Activation of a single gene (MybA) has been shown to turn on the anthocyanin pathway in many species, including citrus. Lycopene production on the other hand requires a minimal metabolic pathway of three genes for most plants and proper activation has shown increases in the metabolite’s production. This article describes the process of anthocyanin and lycopene cloning and testing to confirm enhancement of metabolic activity. It further demonstrates the isolation of citrus fruit specific promoters for controlled expression of the anthocyanin and/or lycopene enhancing genes. .