Carotenoid Content and Genetic Variations of Orange Peppers

Capsicum, commonly known as pepper, is one of the oldest and most popular vegetable and spice in the world probably because of its characteristic flavor, nutrition, and color. Ripe pepper fruits are rich in carotenoids, specifically beta-carotene, capsanthin, and capsorubin. Humans can transform beta-carotene into vitamin A, therefore capsicum can aid in preventing blindness of  vitamin A-deficient children worldwide. Thus, Ivette Guzmana of New Mexico State University and colleagues conducted a detailed study of seven orange pepper varieties, distinguishing six carotenoids and DNA sequences of four carotenoid biosynthetic genes to identify the metabolic and genetic variations among the pepper varieties.

The researchers used the Ultra Performance Liquid Chromatography (UPLC) to identify the chemical profiles of the seven orange varieties. They found out that the orange color can either be due to accumulation of beta-carotene or a combination of red and yellow carotenoids. Four carotenoid biosynthetic genes were cloned and sequenced from the varieties to test if specific carotenoid biosynthetic enzymes are related with certain carotenoid profiles in orange peppers. This led to the discovery of a new gene (Ccs) variant. When they selectively bred for high beta-carotene levels, the need for carotenoid chemical composition arose because phenotypic recurrent selection based on color was not sufficient. The results pinpointed specific forms of genes (Ccs-3) which can be potential molecular markers for selection of orange pepper lines with high beta-carotene levels, thus, high provitamin A levels.

The abstract of this study is available at http://dx.doi.org/10.1016/j.plantsci.2010.04.014.