A candidate gene approach identified phytoene synthase as the locus for mature fruit color in red pepper (Capsicum spp.)

The color of mature pepper fruit is determined by the composition of carotenoids. The fruit color of red pepper is genetically determined by three loci, y, cl, and c2. We have been developing agenetic map of hot pepper using RFLP and AFLP markers in the F-2 population of an interspecific cross between Capsicum annuum cv TF68 and Capsicnm chinense cv Habanero. The color of the ripe fruit of TF68 is red and Habanero is orange. The red color is dominant over orange in the F-1 and the locus controlling this character has been marked in our SNU Linkage Group 7. To identify the gene or markers tightly linked to the red/orange locus, several candidate genes involved in the carotenoid biosynthesis pathway, namely FPS, GGPS, PSY, PDS, LCY and CCS, were examined. One of the candidate genes, phytoene synthase, cosegregated completely with furit color in the F-2 population. QTL analysis of the pigment content of F-2 individuals quantified by HPLC also indicated that phytoene synthase is the locus responsible for the development of fruit color. The color, pigment content and genetic behavior of Habanero also suggest that phytoene synthase may be responsible for the c2 gene discriminating between red and orange cultivars.