Evidence for functional divergence in AM fungal communities from different montane altitudes

• Local AMF grew more profusely than the introduced fungi.
• Locally adapted AM associations were more mutualistic only at the low temperature.
• Plants consistently performed better with AMF inocula from the higher altitude.

A considerable amount of symbiotic functional variability has been demonstrated among arbuscular mycorrhizal fungal (AMF) species. However, little is known about the functional divergence in AMF communities from contrasting climates. Ecotypes of Pennisetum flaccidum were grown in growth chambers with AMF communities originating from two elevations (3 105 and 4 176 m asl) on Mount Segrila in Tibet. The combinations were grown under two temperature regimes (7–12 °C and 14–19 °C), equivalent to the mean temperatures during the growing season at the two elevations. AMF communities from different elevations showed different fungal performance at both temperatures. In most cases, AMF from cold habitats developed higher intraradical and extraradical colonization at 7–12 °C than AMF from the warmer habitat, and vice versa. For mycorrhizal growth responses (MGR), there was no consistent local versus foreign effect, but AMF inoculum from colder habitats consistently led to a higher MGR than the other inoculum. These results provide strong evidence for functional differences among AMF communities from contrasting climates.