Northeast Missouri State University
Purdue University

The Y1 gene codes for phytoene synthase
--Brent Buckner, Phillip San Miguel and Jeffrey L. Bennetzen

The Y1 gene is involved in the biosynthesis of carotenoids in maize. We have sequenced a 1.4Kb cDNA and approximately 6Kb of genomic DNA for a Y1 allele (a full length cDNA of the Y1 allele is expected to be approximately 1.8Kb in length). The cDNA sequence has good homology (64% identity, 75% similarity at the amino acid level) to the tomato gene pTOM5 which codes for phytoene synthase. Phytoene synthase is the enzyme that catalyzes the condensation of two molecules of geranylgeranyl pyrophosphate to yield phytoene, the first C40 carotenoid synthesized by plants. In addition, the deduced amino acid sequence of the Y1 gene product also exhibits good homology to the gene product of the crtB genes of Erwinia uredovora (31% identity and 48% similarity) and Rhodobacter capsulatus (29% identity and 52% similarity). The crtB gene product is also believed to be a phytoene synthase. Therefore, we conclude from these strong homologies that the Y1 gene of maize codes for phytoene synthase.
Please Note: Notes submitted to the Maize Genetics Cooperation Newsletter may be cited only with consent of the authors

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