Since the first plant gene essential for arbuscular mycorrhizal (AM) symbiosis was identified, more than 170 such genes have been discovered. However, these findings remain scattered across species, and a systematic synthesis is urgently needed to guide future functional studies and breeding applications. This review provides a systematic classification and contextual overview of the currently reported plant genes essential for AM symbiosis, covering leguminous species (e.g., Medicago truncatula, Lotus japonicus) and non-leguminous species (e.g., Oryza sativa, Solanum lycopersicum). We classify these genes into functional modules corresponding to key stages of AM symbiosis: SL-mediated pre-symbiotic signaling, chitin signal perception, activation of the common symbiosis signaling pathway (CSSP), calcium (Ca²⁺) oscillation generation, arbuscule development and maintenance, and nutrient exchange. Beyond classification, we highlight conserved genetic modules across plant lineages and discuss their implications for engineering AM symbiosis in non-host or poorly symbiotic crops. This synthesis establishes a foundational genetic resource for molecular breeding aimed at enhancing nutrient-use efficiency and sustainable crop production.