Transient expression of artificial microRNAs confers resistance to grapevine virus A in Nicotiana benthamiana

MicroRNAs are post-transcriptional regulators of eukaryotic organisms that function through mRNA degradation or suppression of translation. Artificial microRNA (amiRNA) act in similar way and this technology has recently attracted much attention as a tool against plant virus infections. In this study, a construct assembled on the Vitis vinifera miR166f (vvi-miR166f) pre-miRNA was used to construct an amiRNA cassette by replacing the 21 nucleotides (nt) of the miR166f sequence with a 21 nt sequence from the Grapevine virus A (GVA) genome. Two amiRNAs cassettes were engineered with 21 nt sequences targeting GVA ORF1 and ORF5. Transient expression of these amiRNAs in Nicotiana benthamiana led to various levels of resistance indicating amiRNA technology as a potential tool for GVA control.