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Transcriptional-metabolic networks in β-carotene-enriched potato tubers: The long and winding road to the golden phenotype

TitleTranscriptional-metabolic networks in β-carotene-enriched potato tubers: The long and winding road to the golden phenotype
Publication TypeArticolo su Rivista peer-reviewed
Year of Publication2010
AuthorsDiretto, Gianfranco, Al-Babili S., Tavazza Raffaela, Scossa F., Papacchioli V., Migliore M., Beyer P., and Giuliano Giovanni
JournalPlant Physiology
Keywordsarticle, Bacteria (microorganisms), beta carotene, biosynthesis, Chromatography, cluster analysis, gene regulatory network, Gene Regulatory Networks, Genetic, Genetically Modified, genetics, high performance liquid chromatography, High Pressure Liquid, Metabolic Networks and Pathways, metabolism, Oryza sativa, Phenotype, plant tuber, Plant Tubers, Plants, potato, promoter region, Promoter Regions, Solanum tuberosum, transgene, Transgenes, transgenic plant, Triticum aestivum, Zea mays

Vitamin A deficiency is a public health problem in a large number of countries. Biofortification of major staple crops (wheat [Triticum aestivum], rice [Oryza sativa], maize [Zea mays], and potato [Solanum tuberosum]) with β-carotene has the potential to alleviate this nutritional problem. Previously, we engineered transgenic "Golden" potato tubers overexpressing three bacterial genes for β-carotene synthesis (CrtB, CrtI, and CrtY, encoding phytoene synthase, phytoene desaturase, and lycopene β-cyclase, respectively) and accumulating the highest amount of β-carotene in the four aforementioned crops. Here, we report the systematic quantitation of carotenoid metabolites and transcripts in 24 lines carrying six different transgene combinations under the control of the 35S and Patatin (Pat) promoters. Low levels of B-I expression are sufficient for interfering with leaf carotenogenesis, but not for β-carotene accumulation in tubers and calli, which requires high expression levels of all three genes under the control of the Pat promoter. Tubers expressing the B-I transgenes show large perturbations in the transcription of endogenous carotenoid genes, with only minor changes in carotenoid content, while the opposite phenotype (low levels of transcriptional perturbation and high carotenoid levels) is observed in Golden (Y-B-I) tubers. We used hierarchical clustering and pairwise correlation analysis, together with a new method for network correlation analysis, developed for this purpose, to assess the perturbations in transcript and metabolite levels in transgenic leaves and tubers. Through a "guilt-by-profiling" approach, we identified several endogenous genes for carotenoid biosynthesis likely to play a key regulatory role in Golden tubers, which are candidates for manipulations aimed at the further optimization of tuber carotenoid content. © 2010 American Society of Plant Biologists.


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Citation KeyDiretto2010899