Repeated gain and loss of a single gene modulates the evolution of vascular plant pathogen lifestyles

Abstract

Vascular plant pathogens travel long distances through host veins, leading to life-threatening, systemic infections. In contrast, nonvascular pathogens remain restricted to infection sites, triggering localized symptom development. The contrasting features of vascular and nonvascular diseases suggest distinct etiologies, but the basis for each remains unclear. Here, we show that the hydrolase CbsA acts as a phenotypic switch between vascular and nonvascular plant pathogenesis. cbsA was enriched in genomes of vascular phytopathogenic bacteria in the family Xanthomonadaceae and absent in most nonvascular species. CbsA expression allowed nonvascular Xanthomonas to cause vascular blight, while cbsA mutagenesis resulted in reduction of vascular or enhanced nonvascular symptom development. Phylogenetic hypothesis testing further revealed that cbsA was lost in multiple nonvascular lineages and more recently gained by some vascular subgroups, suggesting that vascular pathogenesis is ancestral. Our results overall demonstrate how the gain and loss of single loci can facilitate the evolution of complex ecological traits.

Evidence of gene nucleotide composition favoring replication and growth in a fastidious plant pathogen

“…vascular tissue vs plant parenchyma) ( Niño-Liu et al 2006 ) . Gene gain/loss events have mediated the transition between vascular and non-vascular pathovars ( Gluck-Thaler et al 2020 ). Therefore, other genomic variables ( i.e.…”

Genomic insights advance the fight against black rot of crucifers

“…Heterologous expression of cbsA enabled strains from non-vascular Xanthomonas pathovars to cause vascular disease symptoms. When cbsA was knocked out in some vascular Xanthomonas pathovars, the pathogen was unable to move through the xylem (Gluck-Thaler et al 2020). While this study focused on Xanthomonas translucens, the findings suggest that the presence of this gene in Xcc and its absence from Xcr could be the reason the former is a vascular pathogen and the latter is not.…”

“…In a study of over 50 published Xanthomonas genomes representing vascular and non-vascular pathogens, presence of a hydrolase gene, cbsA, was strongly correlated with the ability to invade the vascular tissue (Gluck-Thaler et al 2020). Heterologous expression of cbsA enabled strains from non-vascular Xanthomonas pathovars to cause vascular disease symptoms.…”

Comparative genomics of Xylella fastidiosa suggests determinants of host-specificity and expands its mobile genetic elements repertoire

“…We found that the vast majority (90%; 63/70) of the CDSs listed in Table S2, which were identified or predicted to be virulence and pathogenicity factors for X. fastidiosa [10, 34,36,38,[81][82][83][84], belong either to the core or soft-core genomes. The lack of CDSs in some strains is mostly due to pseudogenization (data not shown).…”