Sympatric pairings of dryland grass populations, mycorrhizal fungi, and associated soil biota enhance mutualism and ameliorate drought stress

1. There is evidence that the distribution of ecotypes of plants and their symbiotic arbuscular mycorrhizal (AM) fungi and other associated soil biota may be structured by the availability of essential soil nutrients; and that locally adapted partnerships most successfully acquire limiting nutrients. This study tests the hypotheses that plant genotypes are adapted to the water availability of their local environment, and this adaptation involves associations with local soil biota, including AM fungi. 

2. We grew semi-arid Bouteloua gracilis ecotypes from relatively wet and dry sites, with either sympatric or allopatric soil inoculum under moderate and extreme soil drying treatments to examine 1) how varying degrees of water limitation influence grass responses to soil biota, and 2) the relationship between AM fungal structures and these responses. 

3. Under extreme soil drying, the dry-site ecotype tended to perform better than the wet-site ecotype. Both ecotypes performed best in...