Effects of light on terpene hydrocarbon synthesis in Pinus pinaster [conifers, monoterpene hydrocarbons, sesquiterpene hydrocarbons, leaves]
1980
Gleizes, M. | Pauly, G. | Bernard-Dagan, C. | Jaques, R. (Bordeaux Univ. (France). Lab. de Biologie Vegetale)
The biosynthesis of terpene hydrocarbons has been investigated in maritime pine (Pinus pinaster Ait.) seedling primary leaves under light and darkness and with different precursors. Impossible in darkness, the synthesis of monoterpenes (mainly aplha- and Beta-pinene) is strongly activated by light. Only ('14)C-carbonate and ('14)C-acetate can be incorporated into monoterpenes. Activation by light is comparatively much more effective for seedling leaves previously cultivated under short days than in leaves from seedlings given long days. The spectral bands which are efficient for the snythesis of monoterpenes are located around 480 and 685 nm with ('14)C-carbonate and 480 and 630 nm with 1-('14)C-acetate. Furthermore, this light activation does not occur if leaf pieces instead of whole leaves are used for the incorporation experiments. When 2-('14)C-mevalonic acid and 1-('14)C-isopentenyl pyrosphosphate are applied as precursors, no radioactivity is recorded in monoterpene hydrocarbons even after light exposures. In contrast, sesquiterpene hydrocarbons (carophyllene and humulene) are easily synthesized under light or darkness in intact or fragmented leaves from the different precursors of photosynthetic or exogenous origin. From these results the compartmentalization in the synthesis of C(,10) and C(,15) hydrocarbons appears clear. There is a metabolic cooperation between the photosynthetic tissues and the specific site of elaboration of C(,10) hydrocarbons, which site is located in the parts where the epithelial cells of resin ducts are functional. The synthesis of sesquiterpene hydrocarbons takes place in the whole leaf without activation by light
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