Fungal pathogens use secreted effector proteins to suppress immunity and support their infection, but effector proteins have also been reported in fungi, which engage in nutritional symbioses with plants. Sequence based effector comparisons between pathogens and symbiotic arbuscular mycorrhizal (AM) fungi are hampered by the huge diversity of effector sequences, even within closely related microbes.  In this presentation, I will introduce how we overcame this limitation through the use of a comprehensive secretome-wide structural prediction of the AM symbiotic fungus R. irregularis, followed by a comparison of the structural models with fungal pathogen effectors. Specifically, I will focus on the pathogenic FOLD effector family, demonstrating its conservation and diversification in AM fungi. Additionally, I will discuss how our approach might reshape our understanding of the strategies employed by AM fungi to colonize their host plants.