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Article Addendum

The phytoene synthase gene family in the Grasses: Subfunctionalization provides tissue-specific control of carotenogenesis

Faqiang Li, Oren Tzfadia and Eleanore T. Wurtzel

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Carotenoids are a complex class of isoprenoid pigments playing diverse roles in plants and providing nutritional value. Metabolic engineering of the biosynthetic pathway has been of interest to specifically address global vitamin A deficiency by breeding cereal crop staples in the Poaceae (Grass family) for elevated levels of provitamin A carotenoids. However, there remain open questions about the rate-controlling steps that limit predictability of metabolic engineering in plants, whether by transgenic or nontransgenic means. We decided to focus on the first committed biosynthetic step which is mediated by phytoene synthase. Our studies revealed that in the Grasses, PSY is encoded by three genes. Maize transcript profiling, together with carotenoid and ABA analysis, revealed that the three PSY copies have subfunctionalized and provide the Grasses with a fine tine control of carotenogenesis in response to various developmental and external cues. Promoter analysis supports subfunctionalization; cis-element analysis of maize PSY1 alleles and comparison with Grass orthologs suggests that man’s selection of yellow maize endosperm has occurred at the expense of a change of gene regulation in photosynthetic tissue as compared to the progenitor white endosperm PSY1 allele.

Addendum to: Li F, Vallabhaneni R, Wurtzel ET. PSY3, a new member of the phytoene synthase gene family conserved in the Poaceae and regulator of abiotic stress-induced root carotenogenesis. Plant Physiol 2008; 146:1333-45; PMID: 18162592; DOI: 10.1104/pp.107.111120.
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Li F, Vallabhaneni R, Yu J, Rocheford T, Wurtzel ET. The maize phytoene synthase gene family: overlapping roles for carotenogenesis in endosperm, photomorphogenesis, and thermal stress tolerance. Plant Physiol 20

Authors

Faqiang Li

Department of Biological Sciences; Lehman College; The City University of New York; Bronx, New York USA; The Graduate School and University Center-CUNY; New York, New York USA

Oren Tzfadia

Department of Biological Sciences; Lehman College; The City University of New York; Bronx, New York USA; The Graduate School and University Center-CUNY; New York, New York USA

Eleanore T. Wurtzel Corresponding author: wurtzel@lehman.cuny.edu

Department of Biological Sciences; Lehman College; The City University of New York; Bronx, New York USA; The Graduate School and University Center-CUNY; New York, New York USA

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