CONICET | Buscador de Institutos y Recursos Humanos

Manuscrito en preparación Citrus psorosis virus (CPsV) is the causal agent of a serious disease affecting citrus trees in many countries. CPsV is the type member of genus Ophiovirus. The virus is tripartite and its genome consists of three ssRNAs of negative polarity. CPsV RNA 1 codifies for a polypeptide of unknown function (24K protein) and the putative RNA-depended RNA polymerase (RdRp) (280K protein). RNA 2 codes for a polypeptide of 54.7 kDa of unknown function (54K protein), and RNA 3 for the coat protein (48K protein or CP). Pathogen-derived resistance (PDR) has been used as a means to control viral diseases through incorporation of viral-derived sequences into transgenic plants. Post-transcriptional gene silencing (PTGS) is a mechanism involved in plant protection against virus, and it can be induced by transgenic expression of pathogen-derived sequences encoding hairpin RNAs (hpRNA). Since the production of transgenic citrus lines and its evaluation would take years, we chose the herbaceous Nicotiana benthamiana, a model plant o test the hairpin silencing inducing constructs. The expression of self-complementary hairpin RNA fragments from the cp and 54k genes of the Argentine CPsV 90-1-1 isolate confer resistance in N. benthamiana plants, indicating that these constructions can be likely used for transformation of citrus plants. The degree of resistance obtained varied depending of the homology of the target sequence, testing here sequences from two different isolates. The analysis of the level of siRNAs accumulation and viral RNA degradation indicate that the homologous target is an strong inducer of the PTGS making the plant more resistant to CPsV than the heterologous target, the more distant isolate CPV4. This is the first report of CPsV resistance plants against this important citrus disease