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Metabolic engineering of potato carotenoid content through tuber-specific overexpression of a bacterial mini-pathway

TitleMetabolic engineering of potato carotenoid content through tuber-specific overexpression of a bacterial mini-pathway
Publication TypeArticolo su Rivista peer-reviewed
Year of Publication2007
AuthorsDiretto, Gianfranco, Al-Babili S., Tavazza Raffaela, Papacchioli V., Beyer P., and Giuliano Giovanni
JournalPLoS ONE
KeywordsAlkyl and Aryl Transferases, alpha carotene, article, Bacteria (microorganisms), Bacterial, bacterial gene, bacterial protein, bacterium transformation, beta carotene, Carotenoid, Carotenoids, controlled study, crop production, Erwinia, Gene expression, Genes, genetic analysis, Genetically Modified, genetics, geranylgeranyl pyrophosphate, Intramolecular Lyases, isomerase, lycopene beta cyclase, lycopene cyclase isomerase, lycopene cyclase-isomerase, metabolic engineering, metabolism, nonhuman, oxidoreductase, Oxidoreductases, Phenotype, phytoene dehydrogenase, Phytoene desaturase, Phytoene synthase, plant leaf, Plants, potato, promoter region, regulatory mechanism, Solanum tuberosum, transferase, Transformation, transgenic plant, Transgenics, Triticum aestivum, unclassified drug, Zea mays

Background. Since the creation of "Golden Rice", biofortification of plant-derived foods is a promising strategy for the alleviation of nutritional deficiencies. Potato is the most important staple food for mankind after the cereals rice, wheat and maize, and is extremely poor in provitamin A carotenoids. Methodology. We transformed potato with a mini-pathway of bacterial origin, driving the synthesis of beta-carotene (Provitamin A) from geranylgeranyl diphosphate. Three genes, encoding phytoene synthase (CrtB), phytoene desaturase (CrtI) and lycopene beta-cyclase (CrtY) from Erwinia, under tuber-specific or constitutive promoter control, were used. 86 independent transgenic lines, containing six different promoter/ gene combinations, were produced and analyzed. Extensive regulatory effects on the expression of endogenous genes for carotenoid biosynthesis are observed in transgenic lines. Constitutive expression of the CrtY and/or CrtI genes interferes with the establishment of transgenosis and with the accumulation of leaf carotenoids. Expression of all three genes, under tuber-specific promoter control, results in tubers with a deep yellow ("golden2") phenotype without any adverse leaf phenotypes. In these tubers, carotenoids increase approx. 20-fold, to 114 mcg/g dry weight and beta-carotene 3600-fold, to 47 mcg/ g dry weight. Conclusions. This is the highest carotenoid and beta-carotene content reported for biofortified potato as well as for any of the four major staple foods (the next best event being "Golden Rice 2", with 31 mcg/g dry weight beta-carotene). Assuming a beta-carotene to retinol conversion of 6:1, this is sufficient to provide 50% of the Recommended Daily Allowance of Vitamin A with 250 gms (fresh weight) of "golden" potatoes. © 2007 Diretto et al.


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Citation KeyDiretto2007