Understanding the molecular mechanisms that regulate arbuscular mycorrhizal symbiosis

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Although sessile, plants are constantly interacting with their environment, including the living microorganisms (viruses, bacteria, fungi) that comprise their microbiome. Plant-microbe interactions represent one of the strongest determinants of plant health, with the potential to either positively or negatively influence agricultural productivity. Just as it is important to study disease-causing pathogens as a means of protecting crops from infection, so it is important to understand how beneficial microorganisms increase productivity as a means of enhancing these partnerships. Arbuscular mycorrhizal (AM) symbiosis is an ancient, beneficial interaction that occurs between approximately 80% of land plants on Earth, and a group of soil-dwelling fungi called Glomeromycota. The symbiosis is based on an exchange of carbon from the plant to the fungus, and in return, soil mineral nutrients from the fungus to its host. AM fungi naturally participate in beneficial symbioses with all globally important food crops, dramatically ameliorating the uptake of phosphorous and other nutrients from the soil. Plants that participate in AM symbiosis also show increased resistance against many stresses (including drought, salinity, and disease), further emphasizing the importance of this association. My long-term research objective is to understand the mechanisms by which AM fungi colonize plants. The first objective of this program seeks to identify novel proteins that are synthesized by the fungus during symbiosis and that act in the plant to promote root colonization by the fungus. The second objective focuses on characterizing the function of fungal proteins that are targeted to the nucleus of host plants during symbiosis to assess whether these fungal proteins alter host gene expression. Although it is well documented that AM fungi colonize a wide range of plants, how these fungi do so is largely unknown. My research program seeks to address these limitations. Achieving this goal is important because it may translate into ways by which we can further enhance protection of crops against disease-causing microbes, which may infect plants using similar mechanisms. Also, an understanding of how AM fungi actively promote symbiosis may identify avenues from which we can more effectively harness the potential of this ancient partnership. There is an ever increasing realization of the importance of agricultural research, particularly in an era where climate change and food security are issues that will strongly shape global development in the coming decades. Closely linked to food security, our current exploitation of soil mineral nutrients such as phosphorous is highly unsustainable. My research has a long-term goal of improving agriculture in a sustainable, environmentally-friendly way, aiding farmers in developing, and developed countries such as Canada, and supporting global society as a whole.