Fig. 1

The global Pst population is highly diverse and largely consists of geographically isolated groups of distinct homogenous individuals. a The global Pst population analysed herein consisted of 14 distinct groups of individuals. Phylogenetic analysis was performed on a total of 280 transcriptomic and 21 genomic datasets from Pst isolates spanning 24 countries, using a maximum-likelihood model and 100 bootstraps. Scale indicates the mean number of nucleotide substitutions per site. Bootstrap values are provided in Additional file 3. b Multivariate discriminant analysis of principal components (DAPC) could further define subdivisions within the global Pst population. A list of 135,139 biallelic synonymous single nucleotide polymorphisms (SNPs) was used for DAPC analysis. Assessment of the Bayesian Information Criterion (BIC) supported initial division of the Pst isolates into five genetically related groups (left; C1–5). Due to the high level of diversity among the global Pst population, this initial analysis could not resolve Pst isolates with lower levels of within-group variation. Therefore, a second DAPC analysis was carried out on each of the five initial population groups (right). Bar charts represent DAPC analysis, with each bar representing estimated membership fractions for each individual. Roman numerals represent the successive K values for each DAPC analysis. Numbers in circles are reflective of those assigned to distinct groups in the phylogenetic analysis