Molecular Characterizations of Transgenic Nicotiana Benthamiana Plants Resistant to Red Clover Necrotic Mosaic Virus and Effects of Mixed Infections with Potato Virus Y on RNAi-Mediated Resistance

Persistent Link:
http://hdl.handle.net/10150/194799
Title:
Molecular Characterizations of Transgenic Nicotiana Benthamiana Plants Resistant to Red Clover Necrotic Mosaic Virus and Effects of Mixed Infections with Potato Virus Y on RNAi-Mediated Resistance
Author:
Solofoharivelo, Marie Chrystine
Issue Date:
2008
Publisher:
The University of Arizona.
Rights:
Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
Abstract:
Engineered resistance mediated by RNA interference to control viral diseases in plants has shown great promise. However, the discovery that most known plant viruses encode RNAi suppressors which interfere with RNAi raised the issue to whether this type of engineered resistance can be durable in the presence of heterologous viruses in mixed infection. The overall goal of this study was to investigate the mechanism of suppression of RNAi-mediated resistance in transgenic plants in the presence of a virus carrying a strong suppressor of RNAi. Nicotiana benthamiana plants were transformed with a 1.2 kb from the 5' end of RCNMV RNA-1. Transgenic resistant lines were obtained. Resistance in two different transgenic lines was shown to be mediated by two different types of RNAi: constitutive RNAi in D2 line induced by doubles-stranded (ds) transgene transcripts and virus-induced RNAi in B1 line. We demonstrated that PVY differentially affected RNAi-mediated resistance in the two lines. D2 line is completely immune to RCNMV infection. D2 line contained multiple copies of the 1.2 kb transgene which are rearranged and produced dsRNAs. PVY did not break the resistance in this transgenic line however data showed that PVY interfered with RNAi which correlated to an increase of the 1.2 kb transgene mRNA. In addition, PVY infection induced accumulation of 21 nt siRNAs and did not alter the transcription of the transgene. In contrast, PVY infection suppressed resistance mediated by virus-induced RNAi in B1 line. B1 contains a single copy of the1.2 kb transgene and is initially susceptible to RCNMV infection however became resistant to RCNMV in newly merging leaves after 14 days post inoculation. PVY infection did not affect the accumulation of the 1.2 kb transgene mRNA nor the accumulation of 21 nt siRNA corresponding to the transgene. The differential effect of PVY infection on the two RNAi-mediated resistances in the two transgenic lines suggests that properly designed resistant plants might withstand mixed virus infections and the presence of a strong suppressor of RNAi. In addition, the differential effect of PVY on RNAi suggests that parallel but distinct pathways are involved in dsRNA-induced, virus-induced, and sense RNAi.
Type:
text; Electronic Dissertation
Keywords:
RNA interference; resistance; RCNMV; PVY; mixed infections
Degree Name:
PhD
Degree Level:
doctoral
Degree Program:
Plant Pathology; Graduate College
Degree Grantor:
University of Arizona
Advisor:
Xiong, Zhongguo
Committee Chair:
Xiong, Zhongguo

Full metadata record

DC FieldValue Language
dc.language.isoENen_US
dc.titleMolecular Characterizations of Transgenic Nicotiana Benthamiana Plants Resistant to Red Clover Necrotic Mosaic Virus and Effects of Mixed Infections with Potato Virus Y on RNAi-Mediated Resistanceen_US
dc.creatorSolofoharivelo, Marie Chrystineen_US
dc.contributor.authorSolofoharivelo, Marie Chrystineen_US
dc.date.issued2008en_US
dc.publisherThe University of Arizona.en_US
dc.rightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.en_US
dc.description.abstractEngineered resistance mediated by RNA interference to control viral diseases in plants has shown great promise. However, the discovery that most known plant viruses encode RNAi suppressors which interfere with RNAi raised the issue to whether this type of engineered resistance can be durable in the presence of heterologous viruses in mixed infection. The overall goal of this study was to investigate the mechanism of suppression of RNAi-mediated resistance in transgenic plants in the presence of a virus carrying a strong suppressor of RNAi. Nicotiana benthamiana plants were transformed with a 1.2 kb from the 5' end of RCNMV RNA-1. Transgenic resistant lines were obtained. Resistance in two different transgenic lines was shown to be mediated by two different types of RNAi: constitutive RNAi in D2 line induced by doubles-stranded (ds) transgene transcripts and virus-induced RNAi in B1 line. We demonstrated that PVY differentially affected RNAi-mediated resistance in the two lines. D2 line is completely immune to RCNMV infection. D2 line contained multiple copies of the 1.2 kb transgene which are rearranged and produced dsRNAs. PVY did not break the resistance in this transgenic line however data showed that PVY interfered with RNAi which correlated to an increase of the 1.2 kb transgene mRNA. In addition, PVY infection induced accumulation of 21 nt siRNAs and did not alter the transcription of the transgene. In contrast, PVY infection suppressed resistance mediated by virus-induced RNAi in B1 line. B1 contains a single copy of the1.2 kb transgene and is initially susceptible to RCNMV infection however became resistant to RCNMV in newly merging leaves after 14 days post inoculation. PVY infection did not affect the accumulation of the 1.2 kb transgene mRNA nor the accumulation of 21 nt siRNA corresponding to the transgene. The differential effect of PVY infection on the two RNAi-mediated resistances in the two transgenic lines suggests that properly designed resistant plants might withstand mixed virus infections and the presence of a strong suppressor of RNAi. In addition, the differential effect of PVY on RNAi suggests that parallel but distinct pathways are involved in dsRNA-induced, virus-induced, and sense RNAi.en_US
dc.typetexten_US
dc.typeElectronic Dissertationen_US
dc.subjectRNA interferenceen_US
dc.subjectresistanceen_US
dc.subjectRCNMVen_US
dc.subjectPVYen_US
dc.subjectmixed infectionsen_US
thesis.degree.namePhDen_US
thesis.degree.leveldoctoralen_US
thesis.degree.disciplinePlant Pathologyen_US
thesis.degree.disciplineGraduate Collegeen_US
thesis.degree.grantorUniversity of Arizonaen_US
dc.contributor.advisorXiong, Zhongguoen_US
dc.contributor.chairXiong, Zhongguoen_US
dc.contributor.committeememberXiong, Zhongguoen_US
dc.contributor.committeememberVanEtten, Hansen_US
dc.contributor.committeememberPierson III, Leland S.en_US
dc.contributor.committeememberBrown, Judith K.en_US
dc.identifier.proquest2839en_US
dc.identifier.oclc659749908en_US
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