Elucidating the genetic basis underlying anthocyanin pigmentation in carrot

CAVAGNARO, P. F.; IORIZZO, M.; YILDIZ, M.; SENALIK, D.; PARSON, J.; WILLIS, D. K.; VAN DEYNZE, A.; SIMON, P. W.

Madison

Congreso; 36th International Carrot Conference; 2013

University of Wisconsin

Anthocyanins play a central role in the development of color, flavor and health attributes of numerous plant species. To date, research on anthocyanin genetics and biochemistry has mainly focused on anthocyanin-containing fruits, leaves and flowers of crop or model species. However, little is known about root anthocyanins. Purple or ?black? carrots accumulate relatively large quantities of anthocyanins in their roots (up to 17-18 mg/100 g fw), composed almost entirely of cyanidin glycosides with a predominance of acylated forms over non-acylated anthocyanins. This study investigated the genetic basis of anthocyanin accumulation in an F2 mapping population (N=450) derived from a cross between a purple and a non-purple (orange) rooted carrot. Root purple pigmentation segregated consistent with a two gene model for an F2, whereas leaves (petiole) purple pigmentation fitted a single dominant gene model. HPLC analysis on a subset of the F2 (N=184) revealed significant variation for all five anthocyanin pigments previously reported in carrot. A high resolution single nucleotide polymorphism (SNP) based map was constructed with this set of samples. Significant QTL were found for all anthocyanin pigments. QTL mapping revealed two regions in chromosome 3 with co-localized QTL for the different anthocyanin compounds. Leaf purple pigmentation, scored visually by the presence-absence of purple in the petioles- mapped to one of the two region with QTL for root anthocyanins, suggesting that this QTL may also control leaf pigmentation. Expression analysis of candidate genes that co-localized with the root anthocyanin QTL revealed differential expression -in purple versus non-purple rooted carrots- for 5 genes involved in anthocyanin biosynthesis. Comparative mapping with other purple segregating populations indicated that the genetic factors controlling purple pigmentation in this F2 are different than those reported previously in other genetic backgrounds. These results will contribute to our understanding of the genetic control underlying anthocyanin pigmentation in carrot and ?perhaps- other species.