NASA Astrobiology Institute (NAI)

During the 2007-2008 year significant progress has been made characterizing the ecological and evolutionary history of fungal symbionts in early land plants. To date, the fungal symbionts throughout the life cycle in early land plant lineages (Lycopodiaceae, Psilotales and Ophioglossales) have been identified using sequence data. In addition to studying the fungal symbionts within early land plants, we have identified the fungal symbionts in photosynthetic neighboring plants to place our data in a larger ecological and evolutionary framework. Based on our sequence data, subterranean phases of the life cycle in these early land plant lineages obtain fixed carbon through an extensive fungal network. Additionally, our analyses have identified five new clades of fungi that form associations with subterranean plants. Furthermore, based on the diversity of fungi that we have identified, it is apparent that multiple species of fungi and multiple species of plants have independently evolved the ability to form plant-fungal associations where the fungus provides the plant with fixed carbon. Our research suggests a new framework for studying the ecology and co-evolution of plant-fungal symbioses where carbon flow between separate plants in a community is potentially widespread through shared fungal networks.