LEVELS OF A TERPENOID GLYCOSIDE (BLUMENIN) AND CELL WALL-BOUND PHENOLICS IN SOME CEREAL MYCORRHIZAS

Four cereals, Hordeum vulgare (barley), Triticum aestivum (wheat), Sec ale cereale (rye), and Avena sativa (oat), were grown in a defined nut ritional medium with and without the arbuscular mycorrhizal fungus Glo mus intraradices. Levels of soluble and cell wall-bound secondary meta bolites in the roots of mycorrhizal and nonmycorrhizal plants were det ermined by high-performance liquid chromatography during the first 6 t o 8 weeks of plant development. Whereas there was no difference in the levels of the cell wall-bound hydroxycinnamic acids, 4-coumaric and f erulic acids, there was a fungus-induced change of the soluble seconda ry root metabolites. The most obvious effect observed in all four cere als was the induced accumulation of a terpenoid glycoside. This compou nd was isolated and identified by spectroscopic methods (nuclear magne tic resonance, mass spectrometry) to be a cyclohexenone derivative, i. e. blumenol C 9-O-(2'-O-beta-glucuronosyl)-beta-glucoside. The level o f this compound was found to be directly correlated with the degree of root colonization.