Endogenous small RNAs and antibacterial immunity in plants

Abstract

Small RNAs are non-coding regulatory RNA molecules that control gene expression by mediating mRNA degradation, translational inhibition, or chromatin modification. Virus-derived small RNAs induce silencing of viral RNAs and are essential for antiviral defense in both animal and plant systems. The role of host endogenous small RNAs on antibacterial immunity has only recently been recognized. Host disease resistance and defense responses are achieved by activation and repression of a large array of genes. Certain endogenous small RNAs in plants, including microRNAs (miRNAs) and small interfering RNAs (siRNAs), are induced or repressed in response to pathogen attack and subsequently regulate the expression of genes involved in disease resistance and defense responses by mediating transcriptional or post-transcriptional gene silencing. Thus, these small RNAs play an important role in gene expression reprogramming in plant disease resistance and defense responses. This review focuses on the recent findings of plant endogenous small RNAs in antibacterial immunity.

Fig. 1

Certain plant endogenous small RNAs (miRNAs and siRNAs) are up- or down-regulated by pathogen infection and target R genes or defense responses genes in plant immunity. These small RNAs contribute to gene expression reprogramming and fine-tuning in plant resistance and defense responses.

Fig. 2

Identified miRNAs and endogenous siRNAs that play a role in antibacterial PTI (A) and ETI (B) in Arabidopsis [–16,26]. The expression and putative function of miR167, miR160 and miR825 (A) were purely based on the deep sequencing data from Fahlgren et al. [16] and require further experimental validation. The putative function of AtlsiRNA-2, 3 and 5 (B) was based on Northern blot analysis and computational analysis and also requires further experimental validation.