Amrehn Evelyn, Aschenbrenner Anna-Katharina, Heller Annerose, Spring Otmar
Institute of Botany, University Hohenheim, Garbenstraße 30, 70599, Stuttgart, Germany.
Protoplasma. 2016 Mar;253(2):447-55. doi: 10.1007/s00709-015-0823-4. Epub 2015 May 9.
Capitate glandular trichomes (CGT) of sunflower, Helianthus annuus, synthesize bioactive sesquiterpene lactones (STLs) within a short period of only a few days during trichome development. In the current project, the subcellular localization of H. annuus germacrene A monooxygenase (HaGAO), a key enzyme of the STL biosynthesis in sunflower CGT, was investigated. A polyclonal antibody raised against this enzyme was used for immunolabelling. HaGAO was found in secretory and stalk cells of CGT. This correlated with the appearance of smooth endoplasmic reticulum in both cell types. Stalk cells and secretory cells differed in form, size and types of plastids, but both had structures necessary for secretion. No HaGAO-specific immunoreaction was found in sunflower leaf tissue outside of CGT or in developing CGT before the secretory phase had started. Our results indicated that not only secretory cells but also nearly all cells of the CGT were involved in the biosynthesis of STL and that this process was not linked to the presence or absence of a specific type of plastid.
向日葵（Helianthus annuus）的头状腺毛（CGT）在毛状体发育的短短几天内就能合成生物活性倍半萜内酯（STL）。在当前项目中，对向日葵CGT中STL生物合成的关键酶——向日葵牻牛儿烯A单加氧酶（HaGAO）进行了亚细胞定位研究。针对该酶制备的多克隆抗体用于免疫标记。在CGT的分泌细胞和柄细胞中发现了HaGAO。这与两种细胞类型中光滑内质网的出现相关。柄细胞和分泌细胞在质体的形态、大小和类型上有所不同，但两者都具有分泌所需的结构。在CGT之外的向日葵叶片组织中，或在分泌期开始之前发育中的CGT中，均未发现HaGAO特异性免疫反应。我们的结果表明，不仅分泌细胞，而且CGT的几乎所有细胞都参与了STL的生物合成，并且这一过程与特定类型质体的存在与否无关。
