Arbuscular mycorrhizal fungal abundance in elevation belts of the hyperarid Atacama Desert

Arbuscular mycorrhizal (AM) fungi affect ecosystem processes improving plant tolerance in (hyper)arid/saline environments. However, there are no previous studies on the presence of AM fungi in the Atacama Desert (Northern Chile), the driest desert in the world. Here, we studied the root and rhizosphere in 111 samples of representative plants from three elevation gradients: (i) hyperarid desert (700–2000 m a.s.l.), (ii) pre-Puna (2000–3100 m a.s.l.) and (iii) Puna (3100–4500 m a.s.l.) elevation belts. Soil pH, electrical conductivity (EC), organic matter, cations and the AM colonization and fungal structures were determined. All plants showed colonization and fungal structures. Root colonization ranged from 3.5 to 87%, hyphae showed densities from 0.13 to 204 m g⁻¹, and spore densities between 20 and 45,500 per 100 g of soil. The highest fungal structure abundances were found in Prosopis tamarugo, Baccharis scandens, Werneria pinnatifida, Deyeuxia curvula and Festuca deserticola rhizospheres. In general, EC and cations showed strong relationship with fungal structure abundance. Here, we reported for the first time the widespread presence of AM symbiosis in all the elevation belts of the Atacama Desert, constituting a first step to understand the ecological role that AM fungi play under extreme aridity and salinity conditions.