Xanthomonas Threats

Xanthomonas includes diverse, widespread and damaging bacterial plant pathogens

Bacteria of the genus Xanthomonas can cause disease in more than 350 plant species including many economically important crops. For example, black rot, caused by Xanthomonas campestris pv. campestris (Xcc), is a major disease of brassicas like cabbage and cauliflower in the UK. Climate change and plant imports are increasing the threat posed by other Xanthomonas species. Although currently absent or rare, diseases like bacterial leaf streak of maize (caused by X. vasicola pv. vasculorum), angular leaf spot of strawberry (caused by X. fragariae), and black rot of watercress (caused by X. nasturtii) are of significant concern to the UK.

Accurate diagnostics are essential for informed disease and biosecurity management. Large-scale whole genome sequencing of diverse Xanthomonas isolates can facilitate development of species, pathovar and even race-specific genetic markers. It can also identify novel species and aid taxonomic reclassification. For brassica improvement, genetically mapping black rot resistance can support breeding programmes.

Find out more about black rot caused by Xanthomonas campestris pv. campestris

Our research used genetic sequencing and imaging to better understand Xanthomonas infections and screened for disease resistance in brassicas, strawberry and maize

Whole-genome sequencing of ~1000 Xanthomonas isolates enabled detailed classification of relationships in the Xanthomonas genus. We identified novel species, made taxonomic reclassifications, and developed highly specific diagnostic markers which can discriminate species, pathovars or races. Screening unique lines of Brassica oleracea (cabbage species) and Brassica napus (rapeseed and swede species) lines identified useful sources of resistance to Xcc. We also screened two Xanthomonas species considered to represent a real biosecurity threat to the UK; X. fragariae on strawberry varieties and X. vasicola pv. vasculorum on
some popular maize varieties.

To find out more about this project contact Murray Grant.

PhytoBacExplorer

As a side project, the Xanthomonas Threats team have also been developing PhytoBacExplorer. It is a powerful, user-friendly online resource for analysing and visualising genomic variation within plant-pathogenic bacteria. All the Xanthomonas strains sequenced for this project (and many more) are now available on the database.

Meet the Xanthomonas Threats Team