Arbuscular mycorrhizal fungi (AMF) promote plant growth through providing host plants with nutrients, in particular growth limiting nitrogen (N) and phosphorus (P). They can also induce plant resistance to biotic stress. There is however strong variation in plant benefit from the symbiosis depending on both the host and symbiont genotypes and environmental factors. Our goal is to identify genetic determinants (in both plants and fungi) and agricultural practices affecting the root associated AMF communities and the symbiotic responses in plants. We currently mainly focus on wheat.