Candidate Gene Analysis Reveals That the Fruit Color Locus Corresponds to in Pepper ().

The diverse fruit colors of peppers ( spp.) are due to variations in carotenoid composition and content. Mature fruit color in peppers is regulated by three independent loci, , , and . and encode phytoene synthase (PSY1) and capsanthin-capsorubin synthase (CCS), respectively; however, the identity of the gene has been unknown. With the aim of identifying , we analyzed two pepper accessions with different fruit colors: AC08-045 and AC08-201, whose fruits are light yellow and white, respectively. Ultra-performance liquid chromatography showed that the total carotenoid content was six times higher in AC08-045 than in AC08-201 fruits, with similar composition of main carotenoids and slight difference in minor components. These results suggest that a genetic factor in AC08-201 may down-regulate overall carotenoid biosynthesis. Analyses of candidate genes related to carotenoid biosynthesis and plastid abundance revealed that both accessions carry non-functional alleles of , (), and However, a nonsense mutation (C2571T) in , a homolog of (), was present in only AC08-201. In a population derived from a cross between AC08-045 and AC08-201, a SNP marker based on the nonsense mutation co-segregated fully with fruit color, implying that the mutation in may cause the white color of AC08-201 fruits. Transmission electron microscopy (TEM) of AC08-201 fruit pericarp also showed less developed granum structure in chloroplast and smaller plastoglobule in chromoplast compared to those of AC08-045. Virus-induced gene silencing (VIGS) of significantly reduced carotenoid accumulation in 'Micropep Yellow', which carries non-functional mutations in both and . Furthermore, sequence analysis of , , and in other white pepper accessions of and showed that they commonly have non-functional alleles in , , and . Thus, our data demonstrate that the fruit color locus in spp. corresponds to the gene .