Transgenes consisting of a dsRNA of an RNAi suppressor plus the 3' UTR provide resistance to Citrus tristeza virus sequences in Nicotiana benthamiana but not in citrus.
In an attempt to utilize post-transcriptional gene silencing (PTGS) as a means to impart resistance against Citrus tristeza virus (CTV) into citrus plants, the p23 + 3'UTR sequence (p23U) of the VT strain of CTV was engineered to fold into a double-stranded (ds) RNA structure. The resulting construct (p23UI) was introduced into Nicotiana benthamiana and Alemow (Citrus macrophylla) plants by Agrobacterium-mediated transformation. Transgenic p23UI- N. benthamiana were resistant to infection with a viral vector made of Grapevine virus A (GVA) + p23U (GVA-p23U), as indicated by the absence of the chimeric virus from inoculated plants. Inoculation of transgenic p23UI Alemow plants with CTV resulted in delayed appearance of symptoms in 9 out of the 70 transgenic plants. However, none of the plants showed durable resistance, as indicated by the obtaining of similar Northern hybridization signals from both transgenic and non-transgenic citrus plants. The possible causes for the failure of transgenic citrus plants to confer durable resistance to CTV are discussed.
Batuman
Ozgur
O
The S. Tolkowsky laboratory, The Virology Department, ARO, The Volcani Center, Bet Dagan, 50250, Israel.
Mawassi
Munir
M
Bar-Joseph
Moshe
M
D020413:3' Untranslated Regions / Q000235:genetics*; D002957:Citrus / Q000378:metabolism / Q000821:virology*; D017790:Closterovirus / Q000235:genetics; D007113:Immunity, Innate / Q000235:genetics*; D010935:Plant Diseases / Q000821:virology*; D018515:Plant Leaves / Q000821:virology; D030821:Plants, Genetically Modified; D034622:RNA Interference; D012330:RNA, Double-Stranded / Q000235:genetics*; D012367:RNA, Viral / Q000032:analysis / Q000235:genetics; D013045:Species Specificity; D014026:Nicotiana / Q000821:virology; D019076:Transgenes
D020413:3' Untranslated Regions; D012330:RNA, Double-Stranded; D012367:RNA, Viral