Polymorphic and differentially expressed effector candidates can be linked to the virulence profiles of the PST 2013 field isolates. (a) Polymorphism analysis highlights cluster-specific effector candidates. Circles represent the number of genes with non-synonymous mutations in each category. (b) Differential expression analysis identifies cluster-specific differentially expressed effector candidates. Roman numerals represent population clusters. (c) PST130_08031 is a previously identified effector candidate that was significantly down-regulated by isolates in cluster III and had two amino acid substitutions that were specific and conserved among cluster I isolates. The five carboxy-terminal amino acids were not defined due to poor coverage.