Identification of candidate genes conditioning anthocyanin pigmentation in the phloem tissues of carrot (Daucus carota) roots

CARVAJAL, S.; BANNOUD, F.; GOMEZ TALQUENCA, S.; CAVAGNARO, P. F.

Congreso; XXXIII Argentinian Meeting of Plant Physiology; 2021

Sociedad Argentina de Fisiología Vegetal

Purple carrots can accumulate large quantities of anthocyanins in their roots, thereby providing color and antioxidant properties to this vegetable. Carrot anthocyanins are also used as food dyes. Thus, the concentration of these pigments in the carrot root is important for both purposes; increasing nutritional value and colorants production. Depending on the carrot genotype, anthocyanins can accumulate in the entire root, or they can be present in specific root tissues. Many purple carrot cultivars accumulate anthocyanins in the exterior of the root and in the root outer phloem (OP) tissues, (also called cortex), but not in the root inner phloem (IP). The genetic control of this tissue-specific pigmentation patter is not well understood. In this work, we investigated gene expression, by RT-qPCR analysis, of 19 anthocyanin-related genes, including transcription factors, anthocyanin structural genes, and genes involved in intracellular transport of anthocyanins, in purple OP (POP) versus non-purple IP (NPIP) tissues of two unrelated carrot backgrounds. Fourteen of the 19 genes were consistently upregulated in the POP in both genetic backgrounds, whereas two genes were upregulated in specific backgrounds. Altogether, our results suggest that two MYB transcription factors, DcMYB7 and DcMYB113, are the main candidates conditioning anthocyanin pigmentation in the POP tissues in one of the two carrot lines analyzed, whereas only DcMYB113 seem to control pigmentation in the other carrot line. These results increase our understanding on the complex genetic regulation underlying carrot tissue-specific anthocyanin pigmentation.