| Budget Amount *help |
¥3,700,000 (Direct Cost: ¥3,700,000)
Fiscal Year 2006: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 2005: ¥600,000 (Direct Cost: ¥600,000)
Fiscal Year 2004: ¥2,600,000 (Direct Cost: ¥2,600,000)
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| Research Abstract |
Caffeine and trigonelline are major nitrogenous compounds found in coffee seeds. Accumulation of these two alkaloids in Coffea arabica and Coffea canephora seeds was monitored. Growth stages are specified by letters, A to G Caffeine and trigonelline content increased at stages D and E. A high biosynthetic activity of caffeine was found in whole fruits (perisperm and pericarp) in stages B and C, and in developing seeds (endosperm) in stages D and E. The biosynthetic activities of caffeine were reduced in both pericarp and seeds in stages F and G. In both coffee fruits, the transcripts of CmXRSI, CTS2 and CCSI, three N-methyltransferase genes for caffeine biosynthesis were detected in every stage of growth, although the amounts of these transcripts were significantly less in stage a The pattern of expression of genes for caffeine synthesis during growth is roughly related to the in situ synthesis of caffeine from adenine nucleotides, although exceptions were found in the very early and later stages of fruit growth. The amounts of the transcripts of CmXRSI, CTS2 and CCSI, which encode three N-methyltransferases, were higher in seeds than in pericarp. Similarly, caffeine synthase (N3-methyltransferase) activity was also higher in seeds than in pericarp. Concentrations of trigonelline in ripe seeds (stage G) of C. arabica and C. canephora were ca. 1.3% and 1.4% of dry weight, respectively. High biosynthetic activity of trigonelline was found in young fruits (stages A-C) and in the pericarp of developing fruits (stage E). The biosynthetic activity was reduced markedly in seeds at stages F and G These results suggest that active trigonelline biosynthesis occurs in the pericarp of coffee fruits. Although the final concentration of caffeine and trigonelline varies in two coffee species, the patterns of fluctuations of the caffeine and trigonelline biosynthetic activity in all Coffea plants are all similar.
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