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Lycopene cyclases determine high α-/β-carotene ratio and increased carotenoids in bananas ripening at high temperatures
- Fu, Xiumin, Cheng, Sihua, Feng, Chao, Kang, Ming, Huang, Bingzhi, Jiang, Yueming, Duan, Xuewu, Grierson, Don, Yang, Ziyin
- Food chemistry 2019 v.283 pp. 131-140
- alpha-carotene, bananas, beta-carotene, biochemical pathways, biosynthesis, enzymes, gene expression regulation, genes, lycopene, messenger RNA, pulp, ripening, temperature, vitamin A, vitamin A deficiency
- Bananas are a recommended food source to alleviate vitamin A deficiency because they contain a high ratio of provitamin A precursors. The objective of this study was to investigate carotenoid accumulation pattern in banana fruits during postharvest ripening and the mechanisms regulating this process. Ripe banana pulp had an unusually high α-/β-carotene ratio (1.05), and the carotenoid contents increased (p ≤ 0.05) under light and high temperature. We analyzed the sequences, transcript levels, and functions of genes involved in carotenoid synthesis. The high ratio of α-/β-carotene in ripe banana fruit was explained by the high flux to the α-carotene biosynthetic pathway, as reflected by high transcript levels of LCYE, and the weak flux to the β-carotene branch of the biosynthetic pathway due to inactive MaLCYB1.2. High temperature during ripening up-regulated the transcript levels of genes involved in the α- and β-carotene biosynthesis pathways and the activities of their encoded enzymes.