D3497: Biosynthesis of insect juvenile hormone in plants: An convergent evolution

Juvenile hormones (JHs) are a group of structurally related sesquiterpenoids that play criticalroles in regulating diverse developmental programs of insects. Because of their importance,synthetic analogs of JHs have been developed as insecticides. Interestingly, a few species ofplants also produce insect juvenile hormones, which have implicated or demonstrated tofunction as plant defense against insects. While the biosynthetic pathway leading to JHs ininsects have been elucidated, our understanding of the JH biosynthetic pathway in plants islimited, particularly at the molecular level. Here we used Cyperus iria as a model species tostudy the molecular mechanism of JH III biosynthesis in plants. In this paper, we report on theidentification and characterization of farnesoic acid methyltransferase (FAMT), which catalyzesthe conversion of farnesoic acid to methyl farnesoate. The latter is the immediate precursor ofJH. FAMT gene of C. iria is related to jasmonic acid methyltransferase, which is conserved inplants. This implies the evolution of FAMT from JMT. FAMT of C. iria has no sequence homologyto the FAMTs from insects, suggesting convergent evolution of the JH biosynthetic pathway inplants.