This review discusses the mechanisms underlying beneficial plant-fungus interactions in mycorrhizal symbiosis. Mycorrhizal fungi, which associate with over 90% of plant species, have been studied using advanced molecular and genetic tools, revealing signaling pathways and nutrient transporters that underpin symbiosis. Both partners benefit: fungi improve nutrient and water uptake, while plants provide carbon and growth support. Mycorrhizal fungi are divided into two main groups: ectomycorrhizal (EM) and arbuscular mycorrhizal (AM). EM fungi colonize the root intercellular spaces, while AM fungi develop inside cells. AM fungi are the most widespread plant symbionts, associated with over 80% of land plants. They are obligate biotrophs, strictly dependent on their host for growth and reproduction. AM fungi have a unique biology, including asexual reproduction, syncytial mycelium, and a large number of nuclei in spores. They also host endobacteria, which may have been important in their evolutionary history. Despite these unique traits, AM fungi have been challenging to study due to their inability to be cultured outside their host. Recent advances in sequencing have provided insights into their genome and gene function, revealing their role in nutrient uptake and transport. AM fungi are crucial for plant nutrition, improving growth, stress resistance, and pathogen resistance. They also play a role in carbon cycling, though their role is less well understood. The review highlights the importance of mycorrhizal fungi in sustainable agriculture and food security, as they can enhance plant productivity and reduce the need for chemical fertilizers. However, challenges remain in understanding the molecular mechanisms of mycorrhizal symbiosis, particularly in AM fungi. Future research should focus on identifying the signaling molecules involved in the interaction between plants and fungi, as well as developing new strategies for mycorrhizal inoculation and crop improvement.This review discusses the mechanisms underlying beneficial plant-fungus interactions in mycorrhizal symbiosis. Mycorrhizal fungi, which associate with over 90% of plant species, have been studied using advanced molecular and genetic tools, revealing signaling pathways and nutrient transporters that underpin symbiosis. Both partners benefit: fungi improve nutrient and water uptake, while plants provide carbon and growth support. Mycorrhizal fungi are divided into two main groups: ectomycorrhizal (EM) and arbuscular mycorrhizal (AM). EM fungi colonize the root intercellular spaces, while AM fungi develop inside cells. AM fungi are the most widespread plant symbionts, associated with over 80% of land plants. They are obligate biotrophs, strictly dependent on their host for growth and reproduction. AM fungi have a unique biology, including asexual reproduction, syncytial mycelium, and a large number of nuclei in spores. They also host endobacteria, which may have been important in their evolutionary history. Despite these unique traits, AM fungi have been challenging to study due to their inability to be cultured outside their host. Recent advances in sequencing have provided insights into their genome and gene function, revealing their role in nutrient uptake and transport. AM fungi are crucial for plant nutrition, improving growth, stress resistance, and pathogen resistance. They also play a role in carbon cycling, though their role is less well understood. The review highlights the importance of mycorrhizal fungi in sustainable agriculture and food security, as they can enhance plant productivity and reduce the need for chemical fertilizers. However, challenges remain in understanding the molecular mechanisms of mycorrhizal symbiosis, particularly in AM fungi. Future research should focus on identifying the signaling molecules involved in the interaction between plants and fungi, as well as developing new strategies for mycorrhizal inoculation and crop improvement.