Mucoromycotina Fine Root Endophyte Fungi Form Nutritional Mutualisms with Vascular Plants

Fungi and plants have engaged in intimate symbioses that are globally widespread and have driven terrestrial biogeochemical processes since plant terrestrialisation >500 Mya. Recently, hitherto unknown nutritional mutualisms involving ancient lineages of fungi and non-vascular plants have been discovered although their extent and functional significance in vascular plants remains uncertain. Here, we provide first evidence of carbon-for-nitrogen exchange between an early-diverging vascular plant (Lycopodiaceae) and Mucoromycotina (Endogonales) fine root endophyte. Furthermore, we provide evidence that the same fungal symbionts colonize neighbouring non-vascular and flowering plants. These findings fundamentally change our understanding of the physiology, interrelationships and ecology of underground plant-fungal symbioses in modern terrestrial ecosystems by revealing the nutritional role of Mucoromycotina fungal symbionts in vascular plants.