Infection by phytopathogenic bacteria triggers massive changes in plant gene expression, which are thought to be mostly a result of transcriptional reprogramming. However, evidence is accumulating that plants additionally use post-transcriptional regulation of immune-responsive mRNAsas a strategic weapon to shape the defense-related transcriptome. Cellular RNA-binding
proteins regulate RNA stability, splicing or mRNA export of immune-response transcripts. In particular, mutants defective in alternative splicing of resistance genes exhibit compromised
disease resistance. Furthermore, detection of bacterial pathogens induces the differential
expression of small non-coding RNAs including microRNAs that impact the host defense transcriptome. Phytopathogenic bacteria in turn have evolved effector proteins to inhibit
biogenesis and/or activity of cellular microRNAs. WhereasRNAsilencing has longbeenknownas
an antiviral defense response, recent findings also reveal a major role of this process in
antibacterial defense. Here we review the function of RNA-binding proteins and small RNAdirected post-transcriptional regulation in antibacterial defense.We mainly focus on studies that used the model system Arabidopsis thaliana and also discuss selected examples from other plants.
Dorothee Staiger, Christin Korneli, Martina Lummer and Lionel Navarro