Tomato is a world-wide cultivated and consumed vegetable crop that is appreciated for its high nutritional value. Tomato fruit yield and quality are often hampered by the limited availability of nutrients (e.g. phosphate) in the soil and by periods of drought. The application of arbuscular mycorrhizal fungi (AMF) provides a sustainable solution to these problems. However, a better understanding of the molecular cross-talk between the AMF and its host plant is crucial in order to reduce the variability that is currently observed upon AMF application in the field. In addition, efficient AMF spore production still presents a major bottleneck, limiting AMF research and making AMF an expensive alternative to chemical agricultural solutions. With this project, we aim at identifying important fungal effector proteins that are secreted into tomato root cells using novel proteome-wide approaches: laser capture microdissection (LCM) and isolation of nuclei tagged in specific cell types (INTACT) in combination with mass spectrometry. Next, we will seek the effector-interacting tomato proteins and elucidate the contribution of the AMF effector – tomato protein pairs in AMF dependent phosphate supply and drought resilience, as well as for spore production. As a result, we expect to find protein pairs that are important for efficient AMF symbioses and spore production, knowledge that will be used to increase tomato yield and -quality in a sustainable fashion.