Metabolic engineering of ketocarotenoid formation in higher plants

• Published in: The Plant journal : for cell and molecular biology Vol. 39; no. 4; pp. 477 - 486
• Main Authors: Ralley, L, Enfissi, E.M.A, Misawa, N, Schuch, W, Bramley, P.M, Fraser, P.D
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Science Ltd 01-08-2004; Blackwell Science
• Subjects: 3,3'-hydroxylase; 4,4'-hydroxylase; Agrobacterium aurantiacum; astaxanthin; bacterial proteins; Bacterial Proteins - genetics; Bacterial Proteins - metabolism; biochemical pathways; Biological and medical sciences; biosynthesis; carotenoids; Carotenoids - biosynthesis; Carotenoids - genetics; Fundamental and applied biological sciences. Psychology; Gene Transfer Techniques; hydroxylase; ketocarotenoid; Lycopersicon esculentum; metabolic engineering; Metabolism; metabolite profiling; Models, Molecular; multi‐gene construct; Nicotiana - genetics; Nicotiana tabacum; oxygenase; oxygenases; Oxygenases - genetics; Oxygenases - metabolism; Paracoccus - genetics; Plant physiology and development; Plants, Genetically Modified; Plasmids; quantitative analysis; Restriction Mapping; Solanum lycopersicum - genetics; Solanum lycopersicum var. lycopersicum; Storage and secretion, pigments, phytochrome; tomatoes; transgenes; transgenic plants; oxygenase; Hydroxylation; carotenoids; Biosynthesis; hydroxylase; Ketolization; Gene; Dicotyledones; Angiospermae; Genetic improvement; Lycopersicon esculentum; Pigments; multi-gene construct; Genetic engineering; Spermatophyta; Transgenic plant; Solanaceae; metabolic engineering; Carotenoid; metabolite profiling
• ISSN: 0960-7412; 1365-313X
• DOI: 10.1111/j.1365-313x.2004.02151.x

Although higher plants synthesize carotenoids, they do not possess the ability to form ketocarotenoids. In order to generate higher plants capable of synthesizing combinations of ketolated and hydroxylated carotenoids the genes responsible for the carotene 4,4' oxygenase and 3,3' hydroxylase have been transformed into tomato and tobacco. The gene products were produced as a polyprotein. Subsequent cleavage of the polyprotein, targeting of the two enzymes to the plastid and enzyme activities have been shown for both gene products. Metabolite profiling has shown the formation of ketolated carotenoids from beta-carotene and its hydroxylated intermediates in tobacco and tomato leaf. In the nectary tissues of tobacco flowers a quantitative increase (10-fold) as well as compositional changes were evident, including the presence of astaxanthin, canthaxanthin and 4-ketozeaxanthin. Interestingly, in this tissue the newly formed carotenoids resided predominantly as esters. These data are discussed in terms of metabolic engineering of carotenoids and their sequestration in higher plant tissues.