Mycorrhizal status of some plants of the Araucaria forest and the Atlantic rainforest in Santa Catarina, Brazil

In Brazil, the Araucaria forest and the Atlantic rainforest are two threatened ecosystems, with 10% or less of their original areas presently existing. To assess the mycorrhizal status in these forests, roots of 29 native species, belonging to 19 families, were collected throughout the year from different regions of Santa Catarina, Brazil. Roots were washed, and then cut in a cryo-microtome to seek ectomycorrhizal colonization. Other roots were stained before being examined for vesicular-arbuscular mycorrhizas (VAM). Patterns of colonization were identified and photographed. All plants presented evidence of vesicular-arbuscular mycorrhizal colonization. No evidence of ectomycorrhizal colonization was found. Vesicular-arbuscular mycorrhizal colonization patterns varied from single intracellular aseptate hyphae, coils, and/or appressoria, to vesicles and/or arbuscules. Results confirmed that VAM hosts are predominant in South American forests while ectomycorrhizas are extremely rare even among genera known as ectomycorrhizal in other regions of the humid tropics.