Resistance to CymMV and ORSV in artificial microRNA transgenic Nicotiana benthamiana plants.

Transgenic plants expressing artificial microRNAs (amiRNAs) have been shown to confer specific resistance to corresponding viruses. Here, we generated Nicotiana benthamiana transgenic lines containing Oryza sativa miR528 as backbone, expressing amiRNAs targeting RNA-dependent RNA polymerase (RdRp) gene of Cymbidium mosaic virus (CymMV) and Odontoglossum ringspot virus (ORSV). The amiRNA transgenic lines could express amiR-CymMV and confer high percentage resistance to CymMV, while lack of detectable level of amiR-ORSV expression in amiR-ORSV transgenic N. benthamiana plants led to weak resistance to ORSV infection. In this project, we provide the first report of CymMV-resistant transgenic N. benthamiana plants based on amiRNA strategy. We believe that this amiRNA approach can be extended to generate CymMV-resistant transgenic orchids.