Types of Mycorrhizal Association

Abstract

The following types of mycorrhizas are distinguished: Ectomycorrhizas, which are characterized by a Hartig net and may or may not have a mantle Endomycorrhizas, which have no Hartig net and may or may not have a mantle but are characterized by undifferentiated coil-shaped intracellular hyphae Ectendomycorrhizas, which display a Hartig net with or without a mantle alongside various forms of intracellular coiled or spherical hyphae The type of mycorrhiza formed depends on the level of auxin secretion by the fungus and on the sensitivity of the plant root to auxin, whether endogenous or induced by phosphate level in the substrate. The microclimate also affects mycorrhizal architecture. For instance, when paired with the plant host Helianthemum almeriense, Terfezia claveryi produces endomycorrhizas outdoors but ectomycorrhizas in the greenhouse and in vitro (with or without a mantle). Moreover, Terfezia boudieri coupled with Helianthemum sessiliflorum produces endomycorrhizas in Tunisia but ectomycorrhizas in the Israeli desert. Yet the effect of climate on mycorrhizal type cannot be interpreted solely in terms of auxin level, and there is evidence that auxin acts in concert with other plant hormones or with plant metabolites.