Comparative Genomics of Barley-Infecting Xanthomonas translucens Shows Overall Genetic Similarity but Globally Distributed Virulence Factor Diversity

Abstract

Xanthomonas translucens pv. translucens (Xtt) is a global barley patho-gen and a concern for resistance breeding and regulation. Long-read whole genome sequences allow in-depth understanding of pathogen diversity. We have completed long-read PacBio sequencing of two Minnesotan Xtt strains and an in-depth analysis of available Xtt genomes. We found that average nucleotide identity (ANI)-based approaches organize Xtt strains different from the previous standard multilocus sequencing analysis approach. According to ANI, Xtt forms a separate clade from X. translucens pv. undulosa and consists of three main groups which are represented on multiple continents. Some virulence factors, such as 17 Type III-secreted effectors, are highly conserved and offer potential targets for the elicitation of broad resistance. However, there is a high degree of variation in virulence factors, meaning that germplasm should be screened for resistance with a diverse panel of Xtt.