Arbuscular mycorrhizal fungal diversity in high-altitude hypersaline Andean wetlands studied by 454-sequencing and morphological approaches

Abstract

The Laguna Brava Nature Reserve is a stressful habitat in the Andean Mountains (Argentina) dominated by extreme abiotic factors: high altitude and UVradiance, hypersalinity, alkalinity, and high concentrations of toxic elements in the soil. The sparse native vegetation that inhabits Laguna Brava and Mulas Muertas wetlands is frequently colonized by arbuscular mycorrhizal (AM) fungi. It is, however, unknown which AM species can survive in such a harsh environment and how those environmental conditions influence the AM communities. To answer these questions, 454-amplicon pyrosequencing and morphological (based on spore traits) approaches were used to assess fungal diversity. A total of 23molecular operational taxonomic units and 14 distinct morphospecies of AM fungi were identified. The morphological characterization of AM fungal communities in Laguna Brava and Mulas Muertas, supported by the molecular data, revealed that Glomeraceae and Claroideoglomeraceae were the dominant families, confirming the predominance of generalist and ruderal AM fungal taxa but with stresstolerant life history traits. Our results showed that the presence of AM fungi is strongly associated with local environmental variations in Laguna Brava (hypersalinity and high Na+, Sr, As and U contents in soils). The AM fungal communities in Laguna Brava and Mulas Muertas wetlands were similar according to the Simpson diversity index and the ecological distance estimated by Bray Curtis index. These results were also supported by the environmental parameters measured, as they did not vary between the studied sites. This study represents the first characterization of AM fungal community in a high-altitude Andean wetland in Argentina, improving our knowledge about these fungi from extreme environments.