Mango (Mangiferaindica L.) fruits are generally classified based on peel color into green, yellow, and red types. Mango peel turns from green to yellow or red or retain green colors during ripening. The carotenoids and anthocyanins are the important pigments responsible for the colors of fruits. In the present study, peels of different colored cultivars at three ripening stages were characterized for pigments, colors, and gene expression analysis. The yellow colored cultivar "Arka Anmol" showed higher carotenoid content, wherein β-carotene followed by violaxanthin were the major carotenoid compounds that increased during ripening. The red colored cultivars were characterized with higher anthocyanins with cyanidin-3-O-monoglucosides and peonidin-3-O-glucosides as the major anthocyanins. The gene expression analysis by qRT-PCR showed the higher expression of carotenoid biosynthetic genes viz. lycopene-β-cyclase and violaxanthin-de-epoxidase in yellow colored cv. Arka Anmol, and the expression was found to increase during ripening. However, in red colored cv. "Janardhan Pasand," there is increased regulation of all anthocyanin biosynthetic genes including transcription factors MYB and basic helix loop. This indicated the regulation of the anthocyanins by these genes in red mango peel. The results showed that the accumulation pattern of particular pigments and higher expression of specific biosynthetic genes in mango peel impart different colors.

Mango cultivars are broadly categorized into green, yellow, and red types based on their peel colors. Anthocyanins and carotenoids are the most important pigments responsible for the color of fruits. The information available on the composition of pigments on mango peel was scanty, and the exact role of anthocyanins and carotenoids in imparting peel color was not clear. The present study was aimed at profiling anthocyanin and carotenoid pigments in the peels of green ('Langra', 'Amrapali', 'Hamlet' and 'Bombay No. 1'), yellow ('Arka Anmol', 'Lazzat Baksh', 'Peach' and 'Banganapalli') and red ('Tommy Atkins', 'Lalmuni', 'Gulabi' and 'Janardhan Pasand') colored mango cultivars through liquid chromatography and mass spectrometry at different stages of ripening. The analysis helped in the identification of eight carotenoids and 24 anthocyanins in mango peel. Higher levels of carotenoids were observed in yellow colored cultivars, and major compounds were b-carotene and violaxanthin. Further, the red colored types were found to possess the higher anthocyanin content than green and yellow types. The major groups of anthocyanin compounds include cyanidin, peonidin, petunidin, delphinidin and pelargonidin. During fruit ripening, a significant increase in carotenoids content, and no or marginal rise in anthocyanin content was observed in mango peels. The results, show the status of carotenoids and anthocyanins in mango peel of different colored cultivars and their developmental pattern during ripening.

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