Resistance to Grapevine leafroll associated virus-2 is conferred by post-transcriptional gene silencing in transgenic Nicotiana benthamiana.
Grapevine leafroll-associated virus-2 (GLRaV-2) is an important component of the leafroll disease complex in grapevine. We have previously sequenced the GLRaV-2 genome and identified the coat protein (CP) gene. The objective of this study is to test the concept of pathogen-derived resistance against a closterovirus associated with grapevine leafroll disease. Because GLRaV-2 is capable of infecting Nicotiana benthamiana, we decided to test the concept on this herbaceous host. Thirty-seven T(0) transgenic N. benthamiana plants expressing the GLRaV-2 CP gene were regenerated following Agrobacterium-mediated transformation. Disease resistance was evaluated in greenhouse-grown T(1) and T(2) plants by mechanical inoculation with GLRaV-2. Although all the inoculated non-transgenic plants showed symptoms 2-4 weeks post inoculation, various numbers of transgenic plants (16-100%) in 14 of 20 T(1) lines tested were not infected. In these resistant plants, GLRaV-2 was not detectable by enzyme linked immunosorbent assay. Although virus resistance was confirmed in T(2) progenies, the percentage of resistant plants was generally lower (0-63%) than that of the corresponding T(1) lines (0-100%). Northern blot and nuclear run-off results showed that virus resistance in the transgenic plants was consistently associated with the low level of transgene RNA transcript suggesting a post-transcriptional gene silencing. The success of pathogen-derived resistance to GLRaV-2 in transgenic N. benthamiana plants represents the first step towards eventual control of the leafroll disease in grapevines using this strategy.
Ling
Kai-Shu
KS
Department of Plant Pathology, NYSAES, Cornell University, Geneva, NY 14456, USA. kai.ling@ars.usda.gov
Zhu
Hai-Ying
HY
Gonsalves
Dennis
D
D000818:Animals; D036022:Capsid Proteins / Q000235:genetics* / Q000378:metabolism; D017790:Closterovirus / Q000145:classification / Q000235:genetics*; D007113:Immunity, Innate; D010935:Plant Diseases / Q000821:virology*; D030821:Plants, Genetically Modified / Q000235:genetics / Q000821:virology*; D034622:RNA Interference; D012231:Rhizobium; D014026:Nicotiana / Q000235:genetics* / Q000821:virology*; D014170:Transformation, Genetic; D019076:Transgenes / Q000502:physiology*
D036022:Capsid Proteins