The presence of aluminum in arbuscular mycorrhizas of Clusia multiflora exposed to increased acidity

In this work, we present the results obtained after 9 months of watering with acidic solutions seedlings of Clusia multiflora, inoculated with arbuscular mycorrhizal fungi (AMF). The fungi were isolated from acid and neutral soil. C.multiflora is a tropical woody species that naturally grows on acid soils high in soluble Al. The research evaluated if arbuscular mycorrhizas (AM) could be responsible at least partially for the tolerance to acidity and to aluminum of C.multiflora and if an inoculum of AM fungi (AMF) coming from acid soils contributes more to the tolerance of acidity of C. multiflora than one coming from neutral soils. Results showed that in the absence of AMF (control treatment), the seedlings of C. multiflora did not grow, indicating that this species is highly dependent on AMF. When C. multiflora was exposed to a very acidic solution (pH 3), plants inoculated with AMF from acid soils were taller than those inoculated with AMF from neutral soils. Acidity affected root growth and root length. Plants inoculated with AMF from neutral soils showed thicker roots and lower shoot-root relationships than those inoculated with AMF from acid soils. Acidity did not affect root growth of C. multiflora inoculated with AMF from acid soils even when they were watered with solutions of pH 3. All plants accumulated high quantities of Al in roots (>10000 mg.kg ^–1), but plants inoculated with AMF from acid soils, accumulated less aluminum in roots than plants from the other treatments. A histochemical study of the distribution of Al in roots showed that in mycorrhizal plants, the aluminum was bound to the cell walls in the mycelium of the fungus, mainly in the vesicles or in auxiliary cells, a fact showed for the first time in this work.