Department of Cell & Systems Biology (CSB) Professor David Guttman has been recognized as a Highly Cited Researcher in 2022 by the science analytics firm Clarivate. This award is evidence that Guttman’s peers frequently refer to his work as they build toward improvements in plant and animal health. Dr. Guttman is highly cited across many fields of study through his work on understanding how bacteria adapt to and manipulate their hosts, the evolution of bacterial host specificity and virulence, and decoding the important role played by microbial communities (i.e., microbiomes) in maintaining the health of their hosts.
Dr. Guttman’s lab works in close collaboration with CSB Professor Darrell Desveaux. This collaboration unites expertise in evolutionary, comparative, and mechanistic biology to bring new perspectives to the study of host-pathogen interactions. The Guttman – Desveaux collaboration focuses on ‘effector’ proteins secreted by bacteria that can manipulate host cells and suppress immunity.
Importantly, these effectors can also be co-opted by hosts as signals of infection in a process known as effector-triggered immunity. Guttman must therefore consider the dual role of secreted pathogen effectors as both virulence factors and immune elicitors.
An important component of Dr. Guttman’s research is to assess the global genomic diversity of pathogens and their plant hosts by sequencing bacterial strains and plant varieties collected from across the globe. This ‘pan-genome’ analysis gives him a comprehensive view of the diversity of genetic factors involved in host-pathogen interactions and how these factors change through evolutionary time.
A highly cited paper from 2020, published in the journal Science, used comparative and functional approaches to classify effectors and assess their potential for eliciting effector-triggered immunity. While this study, “The pan-genome effector-triggered immunity landscape of a host-pathogen interaction” focused on a single ecotype of the model plant Arabidopsis thaliana, it still uncovered a surprising level of potential immune responses and two novel plant immune receptors.
More recent studies within brassicaceous crops related to Arabidopsis, within soybean, and within tomato are assessing how effectors suppress immunity in these crop plants and how this immunity has changed over the course of crop domestication.
Several exciting findings have already come out of this work, such as when Guttman and Desveaux turned their attention to tomatoes and their wild relatives, where they were “surprised and frustrated” by the lack of diversity in effector-mediated immune responses. They are currently pursuing this puzzling reduction in immune diversity with collaborators in Spain and Ontario.
A new paper in 2022 is a breakthrough in statistical analysis for probing the evolution of host-specificity and virulence in pathogenic bacteria. Dr. Ceda Bundalovic-Torma, a postdoc in the Guttman lab, developed a novel measure of evolutionary diversity that takes into account horizontal gene transfer.
Bacteria growing together in a microbiome can pass genetic material between evolutionarily divergent cells within a population through horizontal gene transfer. Existing diversity measures fail to consider this transfer, so Guttman’s researchers developed RecPD, an “interesting and fun” conceptual approach to computationally quantify genetic diversity.
Dr. Guttman’s expertise in genomic data science and microbiome analysis has enabled him to collaborate on a wide range of exciting, high-profile, and highly-cited human microbiome studies. His role as Director of the Centre for the Analysis of Genome Evolution & Function (CAGEF), a core facility that assists other research groups with their genomics and proteomics studies has also facilitated these collaborations. This work has led to important new insights into the role played by microbial communities in human health and disease.
Dr. Guttman’s experience makes him a valuable member of advisory boards for the Emerging & Pandemic Infections Consortium (EPIC), the Canadian Statistical Sciences Institute (CANSSI) Ontario, and the Data Sciences Institute (DSI). His work is leading to a better understanding of where the genetic potential for virulence originates, how this potential is maintained in bacterial populations, and how pathogen evolution impacts the fitness of their plant and animal hosts.
Congratulations, Dr Guttman!