Conservation of Genes Required for Arbuscular Mycorrhizal Symbiosis.

Arbuscular mycorrhizal (AM) symbiosis is an ancient association that played a key role in the adaptation of plants to terrestrial environments. Originating over 400 million years ago at the dawn of land plants, this interaction depends on a core set of conserved genes that enable hosts to establish and maintain symbiotic relationships with AM fungi. The AM symbiotic program includes distinct genetic components for each stage of development, from signal perception to nutrient exchange. While AM-host plants have retained key genes dedicated to symbiosis, non-host lineages have independently lost these genes multiple times over evolutionary history. Recent studies in the liverwort Marchantia paleacea demonstrate that core mechanisms underlying AM symbiosis are conserved from bryophytes to angiosperms. Comparative genomic studies continue to uncover how symbiosis-specific genes are integrated with broadly conserved cellular machinery to sustain this interaction. Understanding these deeply conserved genetic modules is essential for uncovering the evolutionary foundations of plant-microbe associations and for harnessing their potential in sustainable agriculture.