2-Phenylethanol (2PE) is a prominent scent compound in roses. We have demonstrated that 2PE is produced without loss of the α-position hydrogen from L-[^2H_8]Phenylalanine (L-[^2H_8]Phe) by feeding experiments. In 2008-2011, we found [^2H_7]-2PE production in rose protoplast harvested from May to October. We, here aimed the functional characterization of novel 2PE biosynthetic pathway producing [^2H_7]-2PE. Feeding experiments of L-[^2H_8]Phe to rose protoplast revealed that [^2H_7]-2PE was hardly synthesized in the period from November to April. We characterized two enzymes (aminotransferase and decarboxylase) involving each step in the novel pathway. RNA interference on the biosynthetic enzyme reduced 2PE production. These results suggested that [^2H_7]-2PE is transformed from L-[^2H_8]Phe by the action of aminotransferase and decarboxylase.

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2-Phenylethanol (2PE) is a dominant floral scent compound in Damask and hybrid roses. We clarified 2PE biosynthesized from L-phenylalanine via phenylacetaldehyde (PAld) by aromatic L-amino acid decarboxylase and phenylacetaldehyde reductase. In the present study, we administered [^2H_8] L-Phe to protoplast from rose petal. The labeling pattern of [^2H_n]-2PE identified by GC-MS was not identical to those expected based on the known 2PE biosynthetic pathway in Rosa 'Yves Piaget'. Therefore the biosynthetic pathway was suggested to be present only in these rose. We tried to isolate genes and the enzymes involved in the biosynthetic pathway of 2PE.

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2-Phenylethanol (2PE), biosynthesized from L-phenylalanine (L-phe) via phenylacetaldehyde (PAld) by aromatic L-amino acid decarboxylase and phenylacetaldehyde reductase, is a dominant floral scent compound in Damask and hybrid roses. In the present study, we proposed the occurrence of changes in the biosynthetic pathway of 2PE in Rosa 'Yves Piaget' based on the environmental changes. To elucidate the changes in the biosynthetic pathways, we analyzed metabolites related to the biosynthetic pathway of 2PE in rose petals grown in different environment by capillary electrophoresis-time of flight mass spectrometry (CE-TOFMS). The CE-TOFMS analytical data revealed the difference in the amounts of metabolites related to shikimate pathway between the roses harvested in different environment. Moreover, we confirmed the increase in the amount of 2PE after feeding precursors of 2PE to isolated protoplasts from rose petals in different environment conditions. These results suggest that 2PE biosynthesis changes based upon the environment roses were grown. In addition, a new enzyme involved in biosynthesis of 2PE was identified; further purification and characterization of this new enzyme are underway.

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Flowers emit floral scent compounds throughout the initial unfurling till the senescence stages. Floral scent compounds serve as attractants for species-specific pollinators. Recent progress in elucidating the biosynthetic pathways, enzymes, and genes involved in the formation of floral scent compounds allowed the determination of their physiology and function rigorously investigated at the molecular and biochemical levels. We investigated the biosynthesis and the emission of floral scent compounds in the flowers of roses and Osmanthus flowers. During the course of our research, we employed feeding experiments of stable isotopes and investigated the biosynthetic pathways based on the molecular biological methodologies. In this paper, 1) We describe the involvement of 2-phenylethylβ-D-glucopyranoside in the emission of 2-phenylethaol in rose flowers. 2) Moreover, we have elucidated that 2-pheylethanol emitted from rose flowers was synthesized from L-phenylalanine by the action of two enzymes, an aromatic amino acid-decarboxylase and a phenylacetaldehyde reductase. 3) We have also observed the seasonal change in the biosynthetic pathways of 2-phenylethanol in the roses. 4) Furthermore, we have characterized o-Methyl transferase as one of the key enzymes involved in the formation of floral scent methoxy-phenol in Chinese roses. 5) We have also confirmed that CCD1 was clarified to be involved in the synthesis and rhythmic emission of α-, β-ionones from carotenoids in Osmanthus flowers grown under the 12h light-12h dark conditions.

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