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Phytochemistry. 2006 May;67(9):882-6. Epub 2006 Apr 18.

Caffeine biosynthesis and adenine metabolism in transgenic Coffea canephora plants with reduced expression of N-methyltransferase genes.

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Metabolic Biology Group, Department of Biology, Faculty of Science, Ochanomizu University, Bunkyo-ku, Tokyo, Japan.


In anti-sense and RNA interference transgenic plants of Coffea canephora in which the expression of CaMXMT1 was suppressed, caffeine biosynthesis from [8-(14)C]adenine was investigated, together with the overall metabolism of [8-(14)C]adenine. Compared with wild type control plants, total purine alkaloid biosynthesis from adenine and conversion of theobromine to caffeine were both reduced in the transgenic plants. As found previously, [8-(14)C]adenine was metabolised to salvage products (nucleotides and RNA), to degradation products (ureides and CO(2)) and to purine alkaloids (theobromine and caffeine). In the transgenic plants, metabolism of [8-(14)C]adenine shifted from purine alkaloid synthesis to purine catabolism or salvage for nucleotides. HPLC analysis revealed a significantly reduced caffeine content in the transgenic plants. A small quantity (less than 20 nmol g(-1) fresh weight) of xanthosine had accumulated in at least one of the transgenic plants.

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