Transcriptional Profiling of Three <i>Pseudomonas syringae</i> pv. <i>actinidiae</i> Biovars Reveals Different Responses to Apoplast-Like Conditions Related to Strain Virulence on the Host

Pseudomonas syringae pv. actinidiae is a phytopathogen that causes devastating bacterial canker in kiwifruit. Among five biovars defined by genetic, biochemical, and virulence traits, P. biovar 3 (Psa3) the most aggressive responsible for recent reported outbreaks; however, molecular basis of its heightened unclear. Therefore, we designed first multistrain whole-genome microarray, encompassing Psa1, Psa2, Psa3 well-established model tomato, analyzed early responses to an apoplast-like minimal medium. Transcriptomic profiling revealed i) strong activation all hypersensitive reaction pathogenicity (hrp) hrp conserved (hrc) cluster genes, encoding components type III secretion system required involved environmental signals; ii) potential repression hrp/hrc Psa2; iii) flagellum-dependent cell motility chemotaxis genes Psa1. The detailed investigation three gene families upstream regulatory proteins (histidine kinases, their cognate response regulators, with diguanylate cyclase or phosphodiesterase domains) indicated cyclic di-GMP may be key regulator biovars. expression data were supported quantification biofilm formation. Our findings suggest diverse host apoplast, even among bacteria belonging same pathovar, can lead different strategies explain differing outcomes infections. Based on our structural analysis operons, also propose revision organization operon regulation syringae. [Formula: see text] Copyright © 2021 Author(s). This open access article distributed under CC BY-NC-ND 4.0 International license .