Bacteria-responsive microRNAs regulate plant innate immunity by modulating plant hormone networks

Abstract

MicroRNAs (miRNAs) are key regulators of gene expression in development and stress responses in most eukaryotes. We globally profiled plant miRNAs in response to infection of bacterial pathogen Pseudomonas syringae pv. tomato (Pst). We sequenced 13 small-RNA libraries constructed from Arabidopsis at 6 and 14 h post infection of non-pathogenic, virulent and avirulent strains of Pst. We identified 15, 27 and 20 miRNA families being differentially expressed upon Pst DC3000 hrcC, Pst DC3000 EV and Pst DC3000 avrRpt2 infections, respectively. In particular, a group of bacteria-regulated miRNAs targets protein-coding genes that are involved in plant hormone biosynthesis and signaling pathways, including those in auxin, abscisic acid, and jasmonic acid pathways. Our results suggest important roles of miRNAs in plant defense signaling by regulating and fine-tuning multiple plant hormone pathways. In addition, we compared the results from sequencing-based profiling of a small set of miRNAs with the results from small RNA Northern blot and that from miRNA quantitative RT-PCR. Our results showed that although the deep-sequencing profiling results are highly reproducible across technical and biological replicates, the results from deep sequencing may not always be consistent with the results from Northern blot or miRNA quantitative RT-PCR. We discussed the procedural differences between these techniques that may cause the inconsistency.Electronic supplementary materialThe online version of this article (doi:10.1007/s11103-010-9710-8) contains supplementary material, which is available to authorized users.

Next-Generation Systemic Acquired Resistance

“…Since the ddc mutant is affected in RNA-directed DNA methylation (Kurihara et al, 2008), our results support a similar role by siRNAs during the onset of transgenerational SAR. PstDC3000 has recently been reported to trigger the accumulation of 27 RNA interference families in Arabidopsis (Zhang et al, 2011). Furthermore, micro-RNAs and siRNAs have both been implicated in the response of Arabidopsis to P. syringae pathogens (Li et al, 2011).…”

Botrytis small RNA Bc-siR37 suppresses plant defense genes by cross-kingdom RNAi

“…8,16,5 Small RNAs (sRNAs), such as small interfering RNAs (siRNAs) and microRNAs (miRNAs) that trigger RNA interference (RNAi) are important in regulation and fine-tuning of plant immunity genes. 26,19,35 Several plant endogenous siRNAs and miRNAs contribute to the regulation of PTI, such as Arabidopsis miR393, miR160, and miR167; 22,37 ETI, such as natural antisense (nat)-siR-NAATGB2, 20 Arabidopsis long-siRNA-1, 18 and miRNA863-3p 23 ; or both PTI and ETI, as in the case of miR393 Ã . 38 Even though the regulatory role of endogenous plant sRNAs in plant immunity has been well characterized, little is known about the role of pathogen-derived sRNAs in microbial pathogenicity and host adaptation.…”

Multiple Rice MicroRNAs Are Involved in Immunity against the Blast Fungus Magnaporthe oryzae

“…Both miRNAs and siRNAs are involved in the regulation of diverse biological processes, including development and responses to biotic and abiotic stresses (Katiyar-Agarwal and Jin, 2010;Chen, 2012;Khraiwesh et al, 2012). In Arabidopsis (Arabidopsis thaliana), a set of miRNAs were identified to be responsive to the PAMP molecule flg22 or to the infection of nonpathogenic strain Pseudomonas syringae DC3000 with mutation in hypersensitive response and pathogenicity conserved C (hrcC 2 ; Fahlgren et al, 2007;Li et al, 2010a;Zhang et al, 2011). The first identified PTI-related small RNA is miR393, which can be induced by the PAMP molecule flg22 and positively contributes to PTI by suppressing auxin signaling by silencing auxin receptors (Navarro et al, 2006).…”