Vesicular Arbuscular Mycorrhizae Mohammad Reza Amerian April 2000

Introduction 4Mycorrhizae are mutualistic associations or symbiosis between soil fungi and plant roots that colonise the cortical tissue of roots. 4The host plant receives mineral nutrients and water while the fungus obtains photosynthetically derived carbon compounds.

Type of mycorrhizae and Taxonomy GLOMALES (ORDER) GIGASPORINAE Gigasporaceae Gigaspora Scutellospora GLOMINEAE Glomaceae Glomus Sclerocystis Acaulosporaceae Acaulospora Entrophospora èVesicular Arbuscular mycorrhizae (VAM or AM) èEctomycorrhizae (ECM) èEct-endo mycorrhizae èOrchid mycorrhizae èEricoid mycorrhizae

Arbuscules l Arbuscules are formed by repeated dichotomous branching and reductions in hyphal width. l Arbuscules start to form approximately 2 days after root penetration. l Arbuscules are considered the major site of exchange between the fungus and host.

Vesicles l Accumulate storage product l Intercellular l Intracellular l Function as propagules

External Hyphae D Type thick "runner" or they are different "distributive" hyphae as well as thin "absorptive" hyphae D Responsible for nutrient acquisition D Propagation of the association D Spore formation

Global perspective on mycorrhizae

Benefits Ascribed to Mycorrhiza èImproved nutrient uptake èIncrease tolerance of Drought Salts Heavy metals Pathogens èEnhanced soil stabilisation