Bede J C, Teal P E, Goodman W G, Tobe S S
Department of Zoology, University of Toronto, 25 Harbord Street, Toronto, Ontario, Canada M5S 3G5.
Plant Physiol. 2001 Oct;127(2):584-93.
In most insect species, juvenile hormones regulate critical physiological processes such as metamorphosis and reproduction. In insects, these sesquiterpenoids are synthesized by retrocerebral endocrine organs, the corpora allata, via the classical mevalonate (MVA) pathway. One of these compounds, juvenile hormone III (JH III), has also been identified in the sedge Cyperus iria. In higher plants, biosynthesis of the sesquiterpenoid backbone may proceed through two distinct pathways: the MVA pathway or the 2C-methyl erythritol 4-phosphate pathway or through a combination of both pathways. Cell suspension cultures of C. iria were used to elucidate the biosynthetic pathway of JH III in the plant. Enzyme inhibition and labeling studies conclusively demonstrated that the biosynthesis of the sesquiterpenoid backbone of JH III proceeds via the MVA pathway. Inhibitor and precursor feeding studies also suggest that later steps of JH III biosynthesis in C. iria are similar to the insect pathway and that the final enzymatic reaction in JH III biosynthesis is catalyzed by a cytochrome P(450) monooxygenase.
在大多数昆虫物种中，保幼激素调节着诸如变态和繁殖等关键生理过程。在昆虫体内，这些倍半萜类化合物是由脑后内分泌器官咽侧体通过经典的甲羟戊酸（MVA）途径合成的。其中一种化合物，保幼激素III（JH III），也已在莎草科植物碎米莎草中被鉴定出来。在高等植物中，倍半萜类骨架的生物合成可能通过两条不同的途径进行：MVA途径或2-C-甲基-D-赤藓糖醇-4-磷酸途径，或通过这两条途径的组合。利用碎米莎草的细胞悬浮培养物来阐明植物中JH III的生物合成途径。酶抑制和标记研究最终表明，JH III倍半萜类骨架的生物合成是通过MVA途径进行的。抑制剂和前体饲喂研究还表明，碎米莎草中JH III生物合成的后续步骤与昆虫途径相似，并且JH III生物合成中的最终酶促反应是由细胞色素P（450）单加氧酶催化的。
