A New Nonsense Mutation in Capsanthin/Capsorubin Synthase Controlling Orange Pepper Fruit

Abstract

Carotenoids are plant pigments that play a major role in conferring fruit color. Carotenoid content is often controlled by genetic variation in the biosynthetic genes. The color of mature pepper fruit is mainly classified as red, orange, and yellow. Orange and yellow fruit colors are determined by mutations in phytoene synthase (Psy) and capsanthin-capsorubin synthase (Ccs), respectively. In contrast to the current fruit color model, we hypothesized that genetic variation in Ccs also controls orange fruit color in pepper. Ripe fruit of Capsicum annuum ‘K146465’ is orange, and its carotenoid profile obtained by HPLC analysis showed a lack of the major pepper carotenoid capsanthin but an abundance of lutein, zeaxanthin, and β-carotene compared to red pepper. cDNA cloning and sequencing analysis detected a new nonsense mutation due to a T1026 insertion in the coding region of Ccs, but no DNA sequence variation in Psy. We developed a derived cleaved amplified polymorphic sequence (dCAPS) marker to distinguish the nonsense mutation in Ccs. Genetic analysis of the F2 population derived from C. annuum ‘Sweet Banana’ (red fruit color) × C. annuum ‘K146465’ revealed that orange fruit color is determined by a single recessive gene. The nonsense mutation in Ccs distinguished by the dCAPS marker co-segregated with orange fruit color in the F2 population. This germplasm, coupled with the dCAPS marker and carotenoid profiling, will facilitate marker-assisted breeding to select orange fruit color and improve lutein, zeaxanthin, and β-carotene levels in pepper.