The Role of Fungal Microbiome Components on the Adaptation to Salinity of subsp. .

subsp. is a perennial grass that inhabits sea cliffs, a habitat where salinity and low nutrient availability occur. These plants have a rich fungal microbiome, and particularly common are their associations with in aboveground tissues and with and in roots. In this study, we hypothesized that these fungi could affect the performance of plants under salinity, being important complements for plant habitat adaptation. Two lines of , each one consisting of -infected and -free clones, were inoculated with the root endophytes ( and ) and subjected to a salinity treatment. Under salinity, plants symbiotic with had lower Na content than non-symbiotic plants, but this effect was not translated into plant growth. promoted leaf and root growth in the presence and absence of salinity, and promoted leaf and root growth in the presence and absence of salinity, plus a decrease in leaf Na content under salinity. The growth responses could be due to functions related to improved nutrient acquisition, while the reduction of Na content might be associated with salinity tolerance and plant survival in the long term. Each of these three components of the core mycobiome contributed with different functions, which are beneficial and complementary for plant adaptation to its habitat in sea cliffs. Although our results do not support an obvious role of itself in FRP salt tolerance, there is evidence that can interact with root endophytes, affecting host plant performance.