A pathogen-inducible endogenous siRNA in plant immunity. Proc Natl Acad Sci U S A

Department of Plant and Microbial Biology, University of California, Berkeley, Berkeley, California, United States
Proceedings of the National Academy of Sciences (Impact Factor: 9.67). 12/2006; 103(47):18002-7. DOI: 10.1073/pnas.0608258103
Source: PubMed


RNA interference, mediated by small interfering RNAs (siRNAs), is a conserved regulatory process that has evolved as an antiviral defense mechanism in plants and animals. It is not known whether host cells also use siRNAs as an antibacterial defense mechanism in eukaryotes. Here, we report the discovery of an endogenous siRNA, nat-siRNAATGB2, that is specifically induced by the bacterial pathogen Pseudomonas syringae carrying effector avrRpt2. We demonstrate that the biogenesis of this siRNA requires DCL1, HYL1, HEN1, RDR6, NRPD1A, and SGS3. Its induction also depends on the cognate host disease resistance gene RPS2 and the NDR1 gene that is required for RPS2-specified resistance. This siRNA contributes to RPS2-mediated race-specific disease resistance by repressing PPRL, a putative negative regulator of the RPS2 resistance pathway.

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Available from: Surekha Katiyar-Agarwal
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    • "In plants, nucleotide-binding site–leucine-rich repeat (NBS–LRR) proteins , which are structurally similar to NLRs, detect pathogens and can confer disease resistance [35]. Interestingly, two genetic examples of host disease resistance (R) genes in plants involve endogenous siRNA-mediated gene silencing and miRNA-mediated regulation of auxin signalling [36] . Corals and other cnidarians possess an unusually high diversity of NLRs compared to other invertebrates [37], but no direct evidence for their immune function has been reported until now. "
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    • "Under salt stress, the upregulation of SRO5 transcripts leads to accumulation of primary and secondary nat-siRNAs, which in turn suppress P5CDH transcripts , ultimately leading to the plant acquiring tolerance to salt stress (Borsani et al., 2005). Upon Pseudomonas syringae infection, the 22 nt nat-siRNAATGB2 down-regulates PPRL, which is a negative regulator of the host defense system (Katiyar-Agarwal et al., 2006). HTS has confirmed the bacterial-induced nat-siRNAATGB2 and characterized another phasing siRNA in addition to that (Zhou et al., 2009). "
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