Abstract
BackgroundPotato is a major staple food, and modification of its provitamin content is a possible means for alleviating nutritional deficiencies. beta-carotene is the main dietary precursor of vitamin A. Potato tubers contain low levels of carotenoids, composed mainly of the xanthophylls lutein, antheraxanthin, violaxanthin, and of xanthophyll esters. None of these carotenoids have provitamin A activity.ResultsWe silenced the first dedicated step in the beta-epsilon- branch of carotenoid biosynthesis, lycopene epsilon cyclase (LCY-e), by introducing, via Agrobacterium-mediated transformation, an antisense fragment of this gene under the control of the patatin promoter. Real Time measurements confirmed the tuber-specific silencing of Lcy-e. Antisense tubers showed significant increases in beta-beta-carotenoid levels, with beta-carotene showing the maximum increase (up to 14-fold). Total carotenoids increased up to 2.5-fold. These changes were not accompanied by a decrease in lutein, suggesting that LCY-e is not rate-limiting for lutein accumulation. Tuber-specific changes in expression of several genes in the pathway were observed.ConclusionThe data suggest that epsilon-cyclization of lycopene is a key regulatory step in potato tuber carotenogenesis. Upon tuber-specific silencing of the corresponding gene, beta-beta-carotenoid and total carotenoid levels are increased, and expression of several other genes in the pathway is modified.
Highlights
Potato is a major staple food, and modification of its provitamin content is a possible means for alleviating nutritional deficiencies. beta-carotene is the main dietary precursor of vitamin A
Vitamin A is ingested by humans in two forms: preformed vitamin A, found in foods of animal origin, and β-carotene, found in dark green vegetables like spinach, in palm oil, and in orange vegetables like yams or carrots
We present the phenotypic analysis of transgenic potato plants in which the first biosynthetic step in the branch leading to lutein, lycopene ε-cyclase (Figure 1), has been inhibited through a tuber-specific antisense approach
Summary
Potato is a major staple food, and modification of its provitamin content is a possible means for alleviating nutritional deficiencies. beta-carotene is the main dietary precursor of vitamin A. Potato is a major staple food, and modification of its provitamin content is a possible means for alleviating nutritional deficiencies. Potato tubers contain low levels of carotenoids, composed mainly of the xanthophylls lutein, antheraxanthin, violaxanthin, and of xanthophyll esters. None of these carotenoids have provitamin A activity. The nutritional improvement of potato is of paramount importance to help eradicate nutritional deficiencies. Vitamin A deficiency affects several hundred million people worldwide [2]. Vitamin A is ingested by humans in two forms: preformed vitamin A (retinol), found in foods of animal origin, and β-carotene (provitamin A), found in dark green vegetables like spinach, in palm oil, and in orange vegetables like yams or carrots
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