Some aspects on the biotrophy of VAM fungi

Abstract

Hyphal growth from germinating spores of Gigaspora margarita was monitored under several conditions: with or without roots, root colonization, or removal of the spore. The results indicate that roots stimulate fungal growth by different mechanisms. Before colonization, roots provide inductive factors which promote fungal growth when the nutrients in spores are available. When colonization is completed, the roots also provide nutrients. The inductive action of roots probably involves root exudates and particularly gas balance, in which CO 2 appears to play key role. Any attempts to cultivate VAM fungi in pure culture should consider the nutritional and inductive role of roots.