Almost all plants form intimate symbiotic associations with mycorrhizal fungi. Mycorrhizal fungi form extensive mycelial networks in the soil and forage effectively for minerals such as nitrogen and phosphorus that are delivered to the plant roots. Plants often benefit from infection by these fungi and show enhanced growth. Plants can obtain up to 80% of nitrogen and up to 90% of their phosphorus demand from mycorrhizal fungi. Mycorrhizal fungi in turn receive photosynthates from the plant and the result is an association between two completely different organisms. Our research focuses on arbuscular mycorrhizal fungi (AMF), the most common group of mycorrhizal fungi. In particular we investigate the agricultural and ecological significance of mycorrhizal fungi and mycorrhizal fungal diversity.