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Down-regulation of lycopene ε-cyclase expression in transgenic sweetpotato plants increases the carotenoid content and tolerance to abiotic stress
- Ke, Qingbo, Kang, Le, Kim, Ho Soo, Xie, Tian, Liu, Chunjuan, Ji, Chang Yoon, Kim, Sun Ha, Park, Woo Sung, Ahn, Mi-Jeong, Wang, Shiwen, Li, Hongbing, Deng, Xiping, Kwak, Sang-Soo
- Plant science 2019 v.281 pp. 52-60
- 9-cis-epoxycarotenoid dioxygenase, RNA interference, abscisic acid, beta-carotene, biosynthesis, callus, catalytic activity, chlorophyll, genes, humans, leaves, lutein, lycopene, lycopene epsilon-cyclase, membrane permeability, nutritive value, oxygen, photosystem II, salt stress, stress response, stress tolerance, sweet potatoes, transgenic plants, water stress
- Carotenoids are required for many biological processes in plants and humans. Lycopene ε-cyclase (LCY-ε) catalyzes the conversion of lycopene into lutein via the α-branch carotenoid biosynthesis pathway. Down-regulation of IbLCY-ε by RNAi increases carotenoid accumulation and salt stress tolerance in transgenic sweetpotato calli. As the role of IbLCY-ε in carotenoid biosynthesis and environmental stress responses in whole plants is poorly understood, transgenic sweetpotato (RLE plants) with reduced expression of IbLCY-ε were developed. RLE plants contained higher levels of total carotenoid and β-carotene, due to an elevated β-carotene/lutein ratio rather than increased de novo biosynthesis. RLE plants showed high reactive oxygen species/radical-scavenging activity. They also exhibited an enhanced tolerance of both salt and drought stress, which was associated with lower membrane permeability and a higher photosynthetic rate, respectively. Elevated carotenoid accumulation in RLE plants mitigated the reductions in leaf photosystem II efficiency and chlorophyll induced by abiotic stress. Expression of the carotenoid cleavage genes 9-cis-epoxycarotenoid dioxygenase, carotenoid cleavage dioxygenase 1 (CCD1) and CCD4 was higher in RLE plants, as was abscisic acid accumulation. IbLCY-ε silencing thus offers an effective approach for developing sweetpotato plants with increased tolerance to abiotic stress that will grow on global marginal lands with no reduction in nutritional value.