Abstract
Virus-induced RNA silencing is involved in plant antiviral defense and requires key enzyme components, including RNA-dependent RNA polymerases (RDRs), Dicer-like RNase III enzymes (DCLs), and Argonaute proteins (AGOs). However, the transcriptional regulation of these critical components is largely unknown. In petunia (Petunia hybrida), an ethylene-responsive element binding factor, PhERF2, is induced by Tobacco rattle virus (TRV) infection. Inclusion of a PhERF2 fragment in a TRV silencing construct containing reporter fragments of phytoene desaturase (PDS) or chalcone synthase (CHS) substantially impaired silencing efficiency of both the PDS and CHS reporters. Silencing was also impaired in PhERF2- RNAi lines, where TRV-PhPDS infection did not show the expected silencing phenotype (photobleaching). In contrast, photobleaching in response to infiltration with the TRV-PhPDS construct was enhanced in plants overexpressing PhERF2 Transcript abundance of the RNA silencing-related genes RDR2, RDR6, DCL2, and AGO2 was lower in PhERF2-silenced plants but higher in PhERF2-overexpressing plants. Moreover, PhERF2-silenced lines showed higher susceptibility to Cucumber mosaic virus (CMV) than wild-type (WT) plants, while plants overexpressing PhERF2 exhibited increased resistance. Interestingly, growth and development of PhERF2-RNAi lines were substantially slower, whereas the overexpressing lines were more vigorous than the controls. Taken together, our results indicate that PhERF2 functions as a positive regulator in antiviral RNA silencing.
Highlights
Virus-induced gene silencing (VIGS) is a rapid and effective method for functional characterization of genes in a plant
An 802-bp EST corresponding to a putative ethyleneresponsive element binding factor 2 (ERF2) gene was identified among genes up-regulated during flower development in petunia from a microarray analysis (Wang et al, 2013)
The data presented here support our hypothesis that the ethylene-responsive element binding factor PhERF2 plays an important role in antiviral RNA silencing
Summary
Virus-induced gene silencing (VIGS) is a rapid and effective method for functional characterization of genes in a plant. A modified Tobacco rattle virus (TRV) vector has proved to be an excellent tool for VIGS, due to its wide host range and its ability to infect meristematic cells (Di Stilio et al, 2010). This system is composed of binary transformation plasmids, TRV1 and TRV2, with a region harboring. In petunia, silencing of phytoene desaturase (PDS) or chalcone synthase (CHS) provides useful phenotypical markers in VIGS studies for functional characterization of genes in leaf and floral tissues, respectively (Chen et al, 2004; Reid et al, 2009; Jiang et al, 2011)
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