Current knowledge on mycorrhizal symbiosis and endophytes in northwest Patagonia, Argentina

Abstract

Along a precipitation gradient, we summarize the current knowledge on mycorrhizal associations in Andean and Extra-Andean northwest Patagonian subregions, including High-Andean environments, forests, steppes, and meadows. In the Andean region, arbuscular mycorrhiza (AM) are prevalent (number of plant species, dominance, and abundance), including plants of all environments – High-Andean plants, native conifers and other dominant forest trees (except Nothofagus spp.) and their understory species⎯. Nothofagus spp. is some of the few ectomycorrhizic Patagonian native species. In the Extra-Andean steppe plants AM are also abundant; however, the central zones of meadows (plenty of non-mycorrhizal/non-host plants) are an exception. Mycorrhizal status decreases from the forests to the meadows, but the number of soil AM spores and infective propagules shows an opposite trend. In general, mixed mycorrhizal infections are rarely seen, and a relatively low frequency of other mycorrhizal types has been observed. Ericoid mycorrhiza (ErM) is present in a small number of plant species, and it is formed predominantly not only by Sebacinales and other some typically Ascomycota fungi but also by the presence of other no-identified Basidiomycota. Rhizoscyphus ericae was only identified fungi from High-Andean Gaultheria and has been the first record in the South America. Cadophora finlandia and Meliniomyces variabilis were identified from Gaultheria (probable ErM) and also from Nothofagus ectomorphotypes (EcM forming?); this raises the question if some Helotiales could form both mycorrhizal types. Dark septate endophytes coexist with mycorrhiza; they occurred in almost all species/individuals analyzed, regardless of mycorrhizal status or environmental characteristics. We encourage further research so as to deepen global diversity patterns and their determining factors.