Fungal root colonization of Puccinellia frigida (Phil.) Johnston, a dominant grass species inhabiting the margins of high-altitude hypersaline Andean wetlands

• Diverse root fungal endophytes colonize the grass Puccinellia frigida in high Andean wetlands.
• Septate fungi and chytrids were observed in all root samples under extreme soil conditions.
• No variation in AM colonization was recorded between sampling seasons in two sites.
• In highly stressful sites AM fungi colonization was not was detected.
• Soil salinity and organic matter affect septate fungi and chytrids root colonization.

High-altitude hypersaline Andean wetlands are considered stressful environments by the prevalence of extreme abiotic conditions affecting both plant host and fungal root endophytes. Puccinellia frigida (Phil.) Johnston, a dominant plant species inhabiting the margins of these wetlands over 4000 m.a.s.l. in Northwest Argentina, is frequently colonized by fungal root endophytes. Here we examined the nature and dynamics of fungal root colonization on this plant species in three different wetlands (six sampling sites) and two growing seasons. Morphologically diverse septate fungi and chytrids were observed in root samples of P. frigida in all sampling sites, whereas arbuscular mycorrhizal fungi were found only in two sites. The level of colonization of chytrids and septate fungi differed significantly both between sites and seasons. Soil organic matter and electrical conductivity were the only habitat parameters significantly related to the observed differences. The widespread occurrence of non-destructive fungal associations suggest an important role for plant survival in extreme environments.