The Department of Microbiology and Plant Pathology's weekly Plant Pathology 250 seminar series is presented this week by Neha Potnis, Associate Endowed Professor, Department of Entomology and Plant Pathology, Auburn University.

Seminar Title: "Monitoring fine-scale adaptations in plant pathogen populations that contribute towards recurring outbreaks and host jumps"

Abstract: Increased global trade and intensified monoculture in modern agricultural systems have predisposed agricultural production to a significant  challenge of recurring pathogen outbreaks compromising host resistance. A concern of emergence of novel pathogen genotypes, accompanied by host  shift, has been noted across different pathosystems. This challenge of host resistance erosion over time or host jump is not only due to emergence or  introduction of pathogen variants capable of overcoming the resistance but also due to environmental and anthropogenic factors that can alter evolution  of plant-pathogen interactions. Using Xanthomonas infecting tomato and pepper as a model system, we have investigated how intraspecific diversity  within Xanthomonas is structured by environmental parameters, host genotypes and growth dynamics of different pathogen genotypes. Strain-resolved  metagenomics allowed us to document differential abundance of pathogen lineages and associated virulence factors across temporal and spatial scales.  These dynamic communities showed seasonal  succession of two or more pathogen genotypes resulting in more homogeneous pathogen population  structure by the end of growing season. We speculate that Xanthomonas community dynamics results from the succession of strains with contrasting fitness strategies in response to climatic fluctuations, host defenses and competition with resident flora. Identifying the fine-scale adaptations in Xanthomonas lineages that have recently gained ability to infect pepper revealed that recent adaptation to pepper is a multigenic trait, not limited to typical  virulence factors, but also involved loci for carbohydrate and amino acid metabolism. This work will advance our understanding into investigation of adaptative traits in the genus Xanthomonas. 

Faculty Host: Caroline Roper; caroline.roper@ucr.edu