Abstract

RNA silencing is an RNA-based network regulating gene expression and defense against invasive nucleic acids in most eukaryotes, including plants. Involvement of RNA silencing in viroid-host interaction became evident when viroid derived small RNAs (vd-sRNAs) of 21-24 nt, structurally similar to host microRNAs (miRNAs) and small-interfering RNAs (siRNAs), were detected in tissues infected by nuclear and chloroplast-replicating viroids. Based on these findings, it was proposed that vdsRNAs, similarly to miRNAs, might target host mRNAs for degradation (or translation inhibition), hus leading to symptom expression in the infected plants. In the last few years, the availability of high-throughput sequencing technologies is allowing in-depth characterization of vd-sRNAs accumulating in host tissues during infection, hence contributing significantly to further dissect possible functional rolesof RNA silencing in the plant-viroid interplay. Based on these technologies, we recently characterized vd-sRNAs derived from a chloroplast replicating viroid (Peach latent mosaic viroid, PLMVd). Moreover, by semi-quantitative RT-PCR and RNA ligase-mediated rapid amplification of cDNA ends, we have shown that two vd-sRNAs (containing the pathogenicity determinant strictly associated with an albinism) target for degradation a host mRNA, thus providing the first experimental evidence that vd-sRNAs indeed function like miRNAs. Interestingly, the targeted mRNA codes for a protein (cHSP90) involved in chloroplast biogenesis, which is the developmental pathway specifically compromised in the albino tissues infected by PLMVd variants generating the two vd-sRNAs (Navarro et al., Plant J. 2012). Altogether these data support involvement of RNA silencing in PLMVd pathogenesis and a possible more general role of vd-sRNAs in modulating host gene expression during viroid infection. To get a deeper insight into this question, we have integrated data from high-throughput sequencing of vd-sRNAs accumulating in tissues infected by chloroplast- and nuclear-replicating viroids with the respective degradome analyses. We will present data and discuss implications of the RNA degradation patterns potentially elicited by vd-sRNAs during viroid infection.

Autore Pugliese

• Navarro Ramirez Beatriz , Di Serio Francesco

Tutti gli autori

• Navarro B.; Gisel A.; Flores R.; Di Serio F.

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Anno di pubblicazione

2013

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