RESUMO
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.
Assuntos
Cyperus/metabolismo , Eritritol/análogos & derivados , Eritritol/biossíntese , Fosfomicina/análogos & derivados , Insetos/metabolismo , Hormônios Juvenis/biossíntese , Ácido Mevalônico/metabolismo , Sesquiterpenos/metabolismo , Fosfatos Açúcares/biossíntese , Aldose-Cetose Isomerases/metabolismo , Animais , Radioisótopos de Carbono , Carotenoides/biossíntese , Células Cultivadas , Inibidores das Enzimas do Citocromo P-450 , Complexo IV da Cadeia de Transporte de Elétrons/metabolismo , Inibidores Enzimáticos/farmacologia , Fosfomicina/farmacologia , Hormônios Juvenis/classificação , Lovastatina/farmacologia , Miconazol/farmacologia , Modelos Biológicos , Modelos Químicos , Complexos Multienzimáticos/metabolismo , Oxirredutases/metabolismoRESUMO
Juvenile hormones (JHs) are sesquiterpenoids that regulate metamorphosis and reproduction in most insect species. There has been one report of an insect JH in plants: JH III, methyl-10R,11-epoxy-3,7,11-trimethyl 2E, 6E-dodecadienoate, has been identified in two sedge species, Cyperus iria L. and C. aromaticus (Ridley) Mattf and Kük. This is the first report of callus and cell suspension cultures derived from C. iria. Farnesol and methyl farnesoate, two biosynthetic intermediates of JH III in insects, as well as JH III have been identified in suspension culture cell extracts by gas chromatography-mass spectroscopy. These cultures thus provide a useful in vitro model to investigate the biosynthesis of JH III in the sedge, C. iria.
