Genetic mapping of anthocyanin pigment traits from specific tissues of the carrot root and leaves

BANNOUD, F.; ELLISON, S.; SENALIK, D.; FANZONE, ML; HOREJSI, T.; DA PEÑA HAMPARSOMIÁN, J.; IORIZZO, M.; SIMON, P. W.; CAVAGNARO, P. F.

Madison

Conferencia; 39th International Carrot Conference; 2018

University of Wisconsin-Madison

Purple carrots can accumulate large quantities of anthocyanins in their roots, as well as in other plant tissues and organs. The consumption of these water-soluble pigments is associated with reduced risk of cardiovascular disease, diabetes, arthritis and cancer, mainly due to their anti-oxidant and anti-inflammatory activities. In this study, we explored the genetic basis of anthocyanin pigmentation in different carrot root and leaf tissues. An F2 population (N=254) segregating for anthocyanin accumulation was used. Phenotypic data was obtained by scoring visually anthocyanin pigmentation in the root phloem and xylem, and in leaf petioles. Additionally, the content of the 5 major anthocyanin pigments in the root phloem and xylem, independently, was estimated by HPLC analysis. A linkage map was constructed using 1013 genotyping-by-sequencing (GBS) markers, which were distributed across the 9 carrot chromosomes. The entire map covered 911.9 cM, with an average marker spacing of 0.9 cM. Loci related to anthocyanin content in the different tissues were mapped using R/qtl. Mapping of traits with parametric distribution revealed 18 significant QTL for phloem anthocyanins on chromosomes 3, 4, 6 and 7, and 8 QTL for xylem anthocyanins mapped on chromosomes 3 and 7.Co-localized anthocyanin QTL with highest phenotypic explanatory power mapped to two regions of chromosome 3. These regions correspond to those of P1 and P3, the anthocyanin loci previously described. Leaf petiole pigmentation was mapped as a binary trait, and its map position co-localized with the region of P3. Ongoing transcriptome analysis (RNA-Seq) in purple and non-purple phloem tissues is expected to aid in delimiting the chromosome regions associated with phloem pigmentation and finding candidate genes for this trait.