Identification of Armillaria nabsnona in gastrodia tubers.

The symbiosis between Armillaria species and an achlorophylous orchid Gastrodia elata BLUME has been reported. The main species described as a symbiont is Armillaria mellea (VAHL: FR.) KUMMER, known widely as a primary root rot pathogen.

Structural studies of zoospore attractants from Trachelospermum jasminoides var. pubescens: taxifolin 3-O-glycosides.

(2S, 3S)-Taxifolin 3-O-arabinoside, a new dihydroflavonol glycoside, together with the known substances, (2R 3R)-taxifolin 3-O-arabinoside, astragalin, isoquercitrin, and cosmosiin, were isolated from the leaves of Trachelospermum jasminoides var. pubescens. Structural elucidation was carried out by spectroscopic methods, and the absolute configurations of C-2 and C-3 in taxifolin 3-O-arabinosides were determined on the basis of circular dichroism.

Nicotinamide and structurally related compounds show halting activity against zoospores of the phytopathogenic fungus Aphanomyces cochlioides.

In a survey of plant secondary metabolites regulating the behavior of phytopathogenic Aphanomyces cochlioides zoospores, we found that leaf extracts of Amaranthus gangeticus and cotyledon extracts of pea (Pisum sativum) remarkably halted the motility of zoospores. Bioassay-directed fractionation of A. gangeticus and pea constituents revealed that the halting activity was dependent on a single chemical factor (halting factor).