Carrot Anthocyanin Diversity, Genetics, and Genomics

Purple carrots (Daucus carota ssp. sativus var. atrorubens Alef.) accumulate anthocyanins in their roots, petioles, and other plant parts. These flavonoid pigments represent an excellent dietary source of antioxidant and anti-inflammatory agents. In addition, carrot anthocyanins are also used as food dyes. Compositional variation in carrot root, mainly with regard to the content of acylated (AA) and non-acylated anthocyanins (NAA), strongly influences the bioavailability and chemical stability of these pigments, therefore conditioning their potential use as nutraceutical agents or as food colorants. In this context, genetic diversity analysis for root anthocyanin composition is relevant for selecting materials for either purpose. Also, knowledge on the genetic basis underlying anthocyanin biosynthesis and modification is expected to aid in the development of new varieties with high nutraceutical or for extracting food dyes. In the last decades, germplasm collections have been characterized for anthocyanin content and composition. Various simply inherited traits for root and petiole anthocyanin pigmentation and acylation, including P1, P3 and Raa1, and QTL for root anthocyanins, have been described and mapped to two regions of chromosome 3, in different genetic backgrounds. Recent advances in high-throughput sequencing and bioinformatic analyses have facilitated the discovery of candidate regulatory genes for root and petiole pigmentation associated with the P3 region in chromosome 3, as well as structural genes involved in anthocyanin glycosylation and acylation. In this chapter, we reviewed recent advances in diversity, genetic, and genomic studies related to carrot anthocyanin pigmentation.