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  • Title: Caffeine biosynthesis and adenine metabolism in transgenic Coffea canephora plants with reduced expression of N-methyltransferase genes.
    Author: Ashihara H, Zheng XQ, Katahira R, Morimoto M, Ogita S, Sano H.
    Journal: Phytochemistry; 2006 May; 67(9):882-6. PubMed ID: 16624354.
    Abstract:
    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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