Mutual influence of soil basidiomycetes and white mustard plants on their enzymatic and catabolic activities

Abstract

Liquid and volatile emanations in interactions of soil basidiomycetes with herbs affect fungal oxidoreductases and stress-related plant peroxidases (PO). In this study, gnotobiotic co-cultures between 6 non-pathogenic saprobes and 2 ectomycorrhizal basidiomycetes with the non-host plant white mustard were established on glucose-salt medium with the respective controls. Determined were oxidoreductase activities for culture fluids and plant tissues at initial fungal idiophase and degradation rates of Remazol-BBR and 5 PAHs. In culture fluids of Agaricus arvensis, A. porphyrizon, Lepista nebularis, Stropharia rugoso-annulata, and Hypholoma fasciculare (group-5), the laccase-deficient plant enabled activity increases in fungal laccase (by 2300-fold), in extracellular (fungal and?) plant-derived peroxidases (by 21-fold), and in the dissipation of phenanthrene and anthracene. Oxidative activities in roots rose by 46000-fold during adsorption of fungal laccases. Increases in the stress-related shoot-PO (by 4.1-fold) were exclusively elicited by group-5 saprobes and correlated with plant-phenolic-mediated formations of Mn(III) and increases in Remazol BBR bleaching. Agaricus bisporus and the ectomycorrhizal Hebeloma crustuliniforme and Suillus granulatus did not respond to plant emanations with elevated laccase activities but solubilized apparently root-surface PO. They failed to elicit stress-related activity increases of PO in white mustard shoot and prevented Mn(III) formation in several tissues. It is concluded that white mustard emanations promoted the catabolic performance of the plant-stress eliciting group-5 saprobes but not of A. bisporus and the ectomycorrhizal fungi with their low stress-inducing potential. The nature of the plant-released stimuli and the classes of fungus-released stress agents discussed must be determined in further studies.