Climate change may impose stimulations or constraints on the mycorrhizal symbiosis by increasing and fluctuating temperatures. We conducted a study to compare the soil temperature response curves (6, 12, 18, and 24 oC) of three isolates of Funneliformis mosseae from different regions and climates (Finland, Denmark, Spain), to test if the isolates from cold environments were able to grow better at lower temperatures and the isolates from warmer environments grew better at higher temperatures. The results provided clear evidence suggesting no adaptation to soil temperature in these AMF isolates. All isolates showed reduced development and very little external mycelium growth at 6 and 12 oC, and similar increased development with increasing soil temperature.  These results suggest that AMF have a narrow window to develop in cold regions where temperatures below 15 oC prevail.