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Coumarin is a natural product well-known for its pleasant sweet-herbaceous and cherry flower-like odor. Despite coumarin is widely found in the plant kingdom, its occurrence in tea leaves is very poorly characterized. In this work, the cultivars, "Shizu-7132", "Koushun" and "Tsuyuhikari" were found to have sweet-herbaceous odor from the 11 Japanese green teas by the sensory descriptive analysis. Application of the stable isotope dilution assay for the quantification of coumarin revealed that the levels of coumarin in these Japanese green tea products with sweet-herbaceous and cherry flower-like odor ranged from 0.26 to 0.88 µg/g of green tea product, whereas the concentrations were generally below 0.2 µg/g of common green tea products. The "Shizu-7132" was found as naturally coumarin-rich green tea. The natural level of

The isolated protoplasts of rose flowers were used to investigate the metabolic pathway in rose flower leading from shikimic acid or L-phenylalanine (L-Phe) to 2-phenylethanol (2PE), a dominant volatile compound in hybrid roses such as Rosa damascena Mill., R. 'Hoh-Jun', and R. 'Yves Piaget'. Deuterium-labeled L-Phe ([2H8]L-Phe) was supplied to the protoplasts isolated from R. 'Yves Piaget' petals. The volatile end products ([2Hn]-2PE, n=6-8) and their related intermediates ([2Hn]phenylacetaldehyde, n=6-8) were detected in the protoplasts by gas chromatography-mass spectrometry (GC-MS). In addition, we chemically synthesized [2,3,4,5,6-13C5]shikimic acid, a new stable isotopomer, to investigate the formation of 2PE from shikimic acid by GC-MS and nuclear magnetic resonance. We proposed the hypothetical biochemical pathway of 2PE from shikimic acid via chorismic acid, L-Phe, and phenylacetaldehyde. This protoplast system facilitates findings of metabolic intermediates and simplifies the complex branching biosynthetic pathways of floral scents to distinct individual events.