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. 2016 Feb 1;6:20234. doi: 10.1038/srep20234

Figure 1. Two alternative principal pathways leading to synthesis of the major floral scent compound 2PE in roses and their activities in winter and summer flowers.

Figure 1

[2H8]-2PE and [2H7]-2PE from L-[2H8]Phe in rose petals, and a comparison of activities in winter and summer flowers. (a) Photo of a representative W-flower and S-flower (left) and individual petals (right). (b) Two alternative principal pathways leading to 2PE. In W-flowers (route a), [2H8]PAld is synthesized by AADC after a Schiff base formation, the release of carbon dioxide, and the retention of the α-deuterium of L-[2H8]Phe. In S-flowers (route b), RyAAAT3 forms a Schiff base and releases α-deuterium prior to decarboxylation; [2H7]PPA is then converted to [2H7]PAld by PPDC. In both routes, [2Hn, n = 7, 8]PAld is converted to 2PE by PAR. (c) Typical mass spectra of [2Hn, n = 7, 8]-2PE produced by rose protoplasts of W-flowers harvested in January (upper) and S-flowers harvested in August (lower). (d) Ratios of [2Hn, n = 7, 8]-2PE synthesized in the L-[2H8]Phe feeding experiments in protoplasts prepared in W-flower (left) and S-flower (right). The production ratios of [2H8]- and [2H7]-2PE were calculated according to the intensities of the molecular ions at m/z 130 and m/z 129 (upper diagram). The ratios for the benzyl cations (lower diagram) at m/z 98 and m/z 97 were used to determine the chemical structure of each isotopolog. Error bars represent the standard deviation (SD) (n = 3). (e) Kinetic parameters of RyPPDC. Mean ± SD (n = 5). PPA and PA indicate phenylpyruvic acid and pyruvic acid, respectively. (f) Comparison of transcript levels involved in the 2PE pathway in W-flowers and S-flowers. Transcript analysis of the biosynthetic enzyme genes for 2PE in W-flowers (white bars) and S-flowers (gray bars) was performed by real-time PCR. All of the genetic data were standardized to β-actin transcript levels and represent the relative transcript level. The transcript levels of W-flowers were set to 1.0. Error bars represent the standard error (SE) (n = 5); *indicates P < 0.05.