Anthocyanins in different Citrus species, an UHPLC-PDA-ESI/MS(n) -assisted qualitative and quantitative investigation

BACKGROUND
Anthocyanins are water-soluble pigments belonging to the flavonoid family. They are typically present in the flesh and peel in the blood orange cultivars. Although blood orange young shoots and flowers are not anthocyanin-colored, lemon, citron, rangpur lime, and Meyer lemon young shoots and flowers exhibit marked pigmentation due to anthocyanins, demonstrating that anthocyanin biosynthesis in the Citrus genus is tissue- and genotype-dependent. This study aimed to examine the qualitative and quantitative anthocyanin profile of fruit and other tissues from different Citrus species.

RESULTS
The presence of anthocyanin-pigmented stigmas in the young flowers of a blood orange tree (cv. 'Moro') was herein characterized and reported for the first time. The dominant pigments in blood orange fruits were cyanidin-3-glucoside and cyanidin-3-(6″-malonyl-glucoside), whereas different patterns were observed in the young shoots, flowers and peel tissues of different Citrus species.

CONCLUSION
This is the first study to report differentially expressed anthocyanin pigmentation patterns in different organs from several species of the genus Citrus. The obtained results could also represent a starting point for further investigations to better understand which regulatory genes are involved in anthocyanin biosynthesis in the fruits, shoots and floral tissues of different Citrus species.