Cloning and characterization of a putative farnesoic acid O-methyltransferase gene from the brown planthopper, Nilaparvata lugens.

Juvenile hormone (JH) plays key roles in both metamorphosis and adult reproductive processes. Farnesoic acid O-methyltransferase (FAMeT) is thought to be an important enzyme in the JH biosynthetic pathway, catalyzing methylation of farnesoic acid (FA) to methyl farnesoate (MF). A full-length cDNA (NlFAMeT) encoding a 299 amino acid putative FAMeT was isolated from the brown planthopper, Nilaparvata lugens (Stal) (Hemiptera: Geometroidea), a major rice pest in many parts of Asia. NlFAMeT showed high amino acid identities (52-54%) with other insect FAMeTs. Although the NlFAMeT transcript was expressed highly in corpus allatum (CA) and brain (without CA), no correlation was found between NlFAMeT transcript and JH titers. Although only a low level of NlFAMeT transcript was detected in the ovary, a high level was found in the abdomen and should be in one or more tissues undefined in the abdomen. Also, NlFAMeT transcript had a positive change during the vitellogenesis in female adults. These data indicated that NlFAMeT might not be a key enzyme in JH synthesis in N. lugens, but that it may play an important role in the ovary development. It might also be important in some unknown process in a so-far unidentified tissue in the abdomen.