SEMINAR: Plant Biology Research Seminar

Plant communities can be strongly influenced by their associated root microorganisms, such as mutualistic symbionts and soil-borne pathogens. I studied changes in arbuscular mycorrhizal (AM) and ectomycorrhizal (ECM) fungi associated with two plant species along a south-western Australian dune chronosequence representing two million years of soil and ecosystem development. Furthermore, I evaluated the role that native species of pathogenic Phytophthora and mutualistic ECM fungi may play in plant species coexistence in the Southwest Australian Biodiversity Hotspot. I found that AM fungal root colonisation declined with soil age, while ECM root colonisation increased. In addition, ECM fungal communities changed and became less diverse with soil age. These results were related mainly to pH and soil P. Finally, native Phytophthora reduced differences in competitive ability between Proteaceae and ECM plant species, likely contributing to their coexistence. I conclude that the importance of different symbionts and their communities is strongly associated with edaphic properties. Furthermore, I show that both mutualists and pathogens could play a role in maintaining plant diversity.