13.ストライガの接触によるミヤコグサでのファイトアレキシン生合成の誘導(口頭発表)

概要

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Lotus japonicus, incompatible to Striga hermonthica and compatible to Orobanche aegyptiaca, was employed to study host responses at early stages of parasitization. cDNA libraries enriched by suppression subtractive hybridization for transcripts up-regulated in L. japonicus root segments adjacent to the attachment points of S. hermonthica seedlings (Lj-Sh) and those adjacent to O. aegyptiaca tubercles have been established. Genes involved in the biosynthesis of vestitol, an isoflavan phytoalexin produced by Lotus and other leguminous genera, were exclusively found in Lj-Sh. Expression of genes related to vestitol biosynthesis was higher in the roots attached with S. hermonthica than those parasitized by O. aegyptiaca and non-inoculated control roots. Metabolites exuded from L. japonicus seedlings inoculated with S. hermonthica were collected and a chemical was isolated after separation by analytical HPLC. Chromatographic behavior on HPLC, molecular formula and fragmentation pattern in the EI-MS of the chemical were identical to those of authentic vestitol. Fluorescence similar to that of authentic vestitol was observed on the surface of L. japonicus roots attached with S. hermonthica. It is suggested that the host roots recognize incompatible S. hermonthica as an unfavorable intruder. Vestitol may function as a chemical barrier to prevent S. hermonthica invasion.
植物化学調節学会の論文
2008-10-06