Anna Simonsen

Area of Study / Keywords

microbial ecology and evolution plant symbiosis plant ecology genomics transcriptomics soil biogeochemistry metagenomics

About

My PhD research career began in my home city where I studied the mutualism between legumes and bacterial symbionts at University of Toronto. I found the biological system utterly captivating, and this ultimately drew me to Australia with its iconic and highly diverse Acacia legumes. In Australia, I took up a postdoc position at CSIRO studying the diversity of Acacia associated bacterial symbionts in South West Australia. This eventually led me to Canberra Australia, conducting research as an ARC Discovery Early Career Research Fellow in Justin Borevitz's lab at Australian National University. I became an Assistant Professor, setting up my own lab in the Department of Biological Sciences at Florida International University in Miami, USA. My current lab, at University of Alberta, continues expansive research in plant host microbiomes and soil microbe ecology and evolution.  

Research

My research program spans plant-microbe interactions, microbial ecology, microbial evolution, biogeography and plant ecology. I combine a range of empirical approaches and analytic techniques, including the analyses of genomic, metagenomic, metabolomic, biogeochemical data, as well as implementing advanced statistical models that combine omics, environmental and spatial data. 

Rhizobia and their Legumes Hosts 

i) Eco-evolutionary interplay between free-living and symbiosis stages in plant symbionts

I study nitrogen-fixing symbionts that associate with legume roots (a.k.a. rhizobia). Although microscopic, rhizobia play a major role in global nitrogen-cycles because both they and their plant hosts are so globally widespread. Rhizobia spend much of their time as free-living colonies in the soil so my goal is to understand how selective pressures from the soil environment impact how these symbionts associate with their hosts. For example, do more stressful soil environments lead to a stronger mutualistic relationship, or can it lead to a mutualism break down? How does the soil environment impact the dynamics of horizontally transferred genes, including genes that control symbiosis? I will be exploring these and other questions, moving towards the broader goal of understanding how we can leverage mutualistic relationships between plants and bacteria for various applications, such as regenerative agriculture and habitat restoration in a changing climate.    

i) Mechanisms of symbiont specialization to their plant hosts

Legumes are one of the most diverse plant families in the world that grow on every continent. Legumes have co- evolved highly specialised relationships with rhizobia, but these relationships are quite complex. We currently have a poor understanding of why some legume species form associations with lots of different rhizobia species, while other legume species have very narrow requirements. We are currently investigating patterns of specialization between legumes and rhizobia from multiple biomes. 

Microbes and their Soil Habitat

i) The evolution of the pangenome in microbial symbionts   

All cells contain a genome. The last two decades of research have shown that bacteria, even within the same species complex show remarkable variation in genome content among different strains. While all strains possess a "core" genome, many strains carry unique genes that are only present in a subset of strains in natural soil population. My lab's research in Bradyrhizobium (a commonly occurring rhizobia) genome evolution has shown that some populations can show as much as 10% difference in genome size. Key findings show that environmental stress leads to reductions in genome size, showing that the environment imposes evolutionary changes that alter structural variation in the genome.  

ii) Climate change impacts in microbial functions in soil and plants

Soil microbes are highly diverse spanning all domains of life, Bacteria, Archaea and Eukaryotes and perform vital ecosystem services that power our global carbon and nitrogen cycles. My lab studies nitrogen-fixation, a critical process of the nitrogen-cycle that converts inert atmospheric nitrogen into biologically usable nitrogen-based compounds (i.e. ammonia). Here, my lab investigates how soil warming impacts the diversity and function of microbes in the soil and near the root zone (called the rhizosphere), with a particular focus on how soil warming impacts the function of nitrogen-fixation in free-living and symbiotic bacteria. We are currently investigating how climate change impacts the losses and gains of microbial species in various ecosystems, and whether microbial adaptation to climate change is impacting their symbiosis and nitrogen-fixation functions.    

I am currently recruiting graduate students for the January 2027 or Fall 2027 intake.  Please email me to enquire about opportunities, applications processes and any queries about specific projects for NSERC graduate-level and postdoc-level applications. University of Alberta also offers many scholarships and awards to support your research. All queries at postdoc, graduate and undergraduate level are welcome.