36. 昆虫に含まれる内生インドール-3-酢酸の起源(口頭発表,植物化学調節学会第46回大会)

概要

論文の詳細を見る
We have reported in the last meeting that a gall-inducing sawfly on a willow tree (Salix japonica) and a gall midge on a mugwort (Artemisia princeps) contained high concentrations of indole-3-acetic acid (IAA), and both showed converting activity of tryptophan (Trp) to IAA. Afterward we found that IAA was contained not only in the gall-inducing insects but also in the non-gall-inducing insects, such as drosophila (Drosophila melanogaster) and silkworm, which (Bombyx mori) also converted Trp to IAA. Here we examined the origin of the converting enzymes and the biosynthetic pathway using silkworms. The regurgitant fluid (RF) of silkworms, which could contain saliva and contents of a foregut and a midgut, showed IAA producing activity. The activity was lost by heat treatment or pronase E treatment, suggesting the enzymatic conversion. In the feeding experiment, indoleacetamide (IAM) and indoleacetaldoxime (IAOx) have been so far detected as metabolites of labeled-Trp. We have concluded that the former was not the intermediate of IAA synthesis based on its non-enzymatic production from Trp and the failure of detecting IAA from JAM feed. The possibility that the symbiotic or contaminated bacteria are responsible for the IAA synthesis was eliminated by preparing sterile silkworm larvae, i.e., their RF showed activity to convert Trp both to IAOx and IAA. On the other hand, the silkworm bait composed of mulberry powder converted Trp to IAA.
2011-10-03