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

• Published in: Virus genes Vol. 33; no. 3; pp. 319 - 327
• Main Authors: Batuman, Ozgur, Mawassi, Munir, Bar-Joseph, Moshe
• Format: Journal Article
• Language: English
• Published: United States Springer Nature B.V 01-12-2006
• Subjects: 3' Untranslated Regions - genetics; Citrus; Citrus - metabolism; Citrus - virology; Citrus tristeza virus; Closterovirus - genetics; Grapevine virus A; Immunity, Innate - genetics; Nicotiana - virology; Nicotiana benthamiana; Plant Diseases - virology; Plant Leaves - virology; Plants, Genetically Modified; RNA Interference; RNA, Double-Stranded - genetics; RNA, Viral - analysis; RNA, Viral - genetics; Species Specificity; Transgenes
• ISSN: 0920-8569; 1572-994X
• DOI: 10.1007/s11262-006-0071-y

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.