Differential resistance to Citrus psorosis virus in transgenic Nicotiana benthamiana plants expressing hairpin RNA derived from the coat protein and 54K protein genes

CARINA ANDREA REYES; EDUARDO JOSE PEÑA; MARIA CECILIA ZANEK; DANIELA VERONICA SANCHEZ; OSCAR GRAU; MARIA LAURA GARCIA

PLANT CELL REPORTS

SPRINGER

Año: 2009 p. 1 - 10

0721-7714

Citrus psorosis virus (CPsV), genus Ophiovi-rus, family Ophioviridae, is the causal agent of a seriousdisease affecting citrus trees in many countries. The viralgenome consists of three ssRNAs of negative polarity.Post-transcriptional gene silencing (PTGS), a mechanismof plant defence against viruses, can be induced by trans-genic expression of virus-derived sequences encodinghairpin RNAs. Since the production of transgenic citruslines and their evaluation would take years, a herbaceousmodel plant, Nicotiana benthamiana, was used to testhairpin constructs. The expression of self-complementaryhairpin RNA fragments from the coat protein (cp) and 54Kgenes of the Argentine CPsV 90-1-1 isolate conferredresistance on N. benthamiana plants, indicating that theseconstructs are good candidates for the transformation ofcitrus plants. The degree of resistance obtained varieddepending on the viral sequence chosen. The analysis ofthe levels of small interfering RNA accumulation and viralRNAs indicated that the construct derived from cp genewas better at inducing PTGS than that originating from the54K gene. The dependence of PTGS induction on thedegree of identity between the target and the inducertransgene sequences was tested using sequences derivedfrom CPV4, a more distant isolate of CPsV, as PTGS tar-gets. Efficient silencing induction was also obtained to thisisolate through the expression of the cp-derived hairpinThis is the first report of transgenic-resistant plants withithe context of this serious citrus disease.