Pseudomonas spp HopA1 effectors interfere with post-transcriptional processes of defense-associated gene expressions

Horizontal acquisition of HopA1 effectors in Pseudomonas species has endowed expansion in their host range and increased infectivity potentials. HopA1s from P. syringae pv. syringae strain 61 (HopA1pss) but not from the tomato pathovar (HopA1pst) is recognized by Arabidopsis thaliana RESISTANCE TO PSEUDOMONAS SYRINGAE 6 (RPS6) to elicit effector-triggered immunity (ETI). To decipher detection and/or evasion modes in order to improve immunity in plants, we elucidated molecular mechanisms of HopA1 perception and its function in planta. Our studies demonstrated that HopA1pst is more potent in suppressing immunity than HopA1pss. ETI elicited against HopA1pss result from perturbations in mRNA processing/fate pathways. HopA1pss interactome in A. thaliana is enriched for proteins with regulatory roles in mRNA post-transcriptional and translational processes. Taken together with translational downregulation in vitro of a reporter gene activity by both HopA1s, our data suggest that this class of effector prevents defense-associated gene expressions. J. Mol. Sci. 2021, 22, 7440. (https://doi.org/10.3390/ijms22147440).