Virtually complete conversion of lycopene into β-carotene in fruits of tomato plants transformed with the tomato lycopene β-cyclase (tlcy-b) cDNA

Tomato fruit is the most important accumulator of the carotenoid pigment lycopene, which can be readily cyclised to beta-carotene by the plant enzyme lycopene beta-cyclase (lcy-b). The aim of this study was the modulation via genetic engineering of carotenogenesis in tomato to induce beta-carotene accumulation in fruits. Using a transgene conveying the tomato lcy-b cDNA we produced transgenic tomato plants whose fruits contained high amounts of beta-carotene as a result of the almost complete cyclisation of lycopene. Deregulation of the carotenogenesis in the fruits affected neither the morphology nor the developmental phases of these tomato plants, which instead showed to possess an increased productivity both under normal and reduced water supply regimes. Results demonstrate the feasibility of engineering tomato to divert carotenoid metabolic flux toward a desired useful end-product. (C) 2003 Elsevier Ireland Ltd. All rights reserved.