Forest tree seedlings, ornamentals and seedlings for home gardening, shipping pallets, and even firewood can cross thousands of miles and international borders before reaching their final destination, and all can carry an invisible community with them, pathogens and mutualists alike. As long as they don’t cause economic or human-visible ecological problems, these microscopic associates are generally ignored. Our work looks at the fungal communities that accompany imported plants, tracking their establishment (or lack of it), the changes in the communities around them, and the health of their hosts.
The poplar-poplar rust pathosystem is a near-model system in forest pathology, in which years of breeding for resistance have seen each qualitative resistance type deployed overcome in due course by pathogen evolution. Working with the INRA Tree-Microbe Interactions group, I studied rapid changes in the poplar rust fungus (Melampsora larici-populina) in response to breeding for quantitative resistance in its host, testing whether new types of resistance-by-degree will be more durable to rust evolution.
As a doctoral student and postdoc at UC Berkeley, I developed genetic and genomic resources to study resistance to sudden oak death (Phytophthora ramorum) in one of its most susceptible hosts, the California endemic tanoak (Notholithocarpus densiflorus). Current research questions build on this, using trait assessments and modelling to ask whether resistance in wild trees can be enough to slow the disease, or if P. ramorum will evolve in response?
International collaboration and communication are recognised a key component of forward-looking plant health policy – the problem emerging in one corner of the world today is the big risk elsewhere, tomorrow. Botanic gardens can serve an important role, monitoring the effects of local pathogens on species originating from around the world.