Norway spruce is a conifer storing large amounts of terpenoids in resin ducts of various tissues. Parts of the terpenoids stored in needles can be emitted together with de novo synthesized terpenoids. Since previous studies provided hints on xylem transported terpenoids as a third emission source, we tested if terpenoids are transported in xylem sap of Norway spruce. We further aimed at understanding if they might contribute to terpenoid emission from needles. We determined terpenoid content and composition in xylem sap, needles, bark, wood and roots of field grown trees, as well as terpenoid emissions from needles. We found considerable amounts of terpenoids—mainly oxygenated compounds—in xylem sap. The terpenoid concentration in xylem sap was relatively low compared with the content in other tissues, where terpenoids are stored in resin ducts. Importantly, the terpenoid composition in the xylem sap greatly differed from the composition in wood, bark or roots, suggesting that an internal transport of terpenoids takes place at the sites of xylem loading. Four terpenoids were identified in xylem sap and emissions, but not within needle tissue, suggesting that these compounds are likely derived from xylem sap. Our work gives hints that plant internal transport of terpenoids exists within conifers; studies on their functions should be a focus of future research.

中文翻译：

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萜类化合物在挪威云杉的木质部汁液中运输。

挪威云杉是一种针叶树，在各种组织的树脂导管中储存大量的萜类化合物。储存在针头中的部分萜类化合物可与de novo一起释放合成的萜类化合物。由于先前的研究提供了木质部转运的萜类化合物作为第三种排放源的暗示，因此我们测试了萜类化合物是否在挪威云杉的木质部汁液中运输。我们进一步旨在了解它们是否可能有助于从针头释放出萜类化合物。我们确定了木质部树液，针叶，树皮，木材和田间种植树木的根中的萜类化合物含量和组成，以及针叶中的萜类化合物排放。我们在木质部树液中发现了大量的萜类化合物（主要是含氧化合物）。与其他组织的含量相比，木质部汁液中的萜类化合物浓度相对较低，在其他组织中，萜类化合物存储在树脂导管中。重要的是，木质部树液中的萜类成分与木材，树皮或根中的成分大不相同，这表明萜类化合物的内部运输发生在木质部装载部位。在木质部汁液和排放物中鉴定出四个萜类化合物，但在针头组织中未发现，这表明这些化合物很可能源自木质部汁液。我们的工作提示针叶树内存在植物类萜的内部运输；关于它们的功能的研究应该是未来研究的重点。