Inheritance of resistance in lettuce to Plasmopara lactucae-radicis and expression of the beet curly top virus coat protein gene in transgenic tobacco.

Persistent Link:
http://hdl.handle.net/10150/185462
Title:
Inheritance of resistance in lettuce to Plasmopara lactucae-radicis and expression of the beet curly top virus coat protein gene in transgenic tobacco.
Author:
Vandemark, George Joseph, III.
Issue Date:
1991
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:
The research presented in this dissertation involves the study of two systems in order to analyze and develop resistance in plants to pathogens. The first study considered the interaction between lettuce (Lactuca sativa L.) and Plasmopara lactucae-radicis, a recently described casual agent of downy mildew. This unique fungus is the only known casual agent of downy mildew that is restricted to the roots of its host. Thirty-eight lettuce cultivars were screened for resistance to P. lactucae-radicis. Two-wk-old lettuce plants grown hydroponically were challenged with this fungus and evaluated 2 and 3 wk after inoculation for resistance. Root necrosis and production of sporangia on roots was considered a susceptible reaction. Five cultivars were determined to be resistant to this fungus. Resistant cultivars, however, were colonized by the fungus but did not support the production of sporangia on roots. Data from F2 and F3 progenies demonstrated that resistance was conferred by a single recessive allele (plr). Fungal infection of susceptible plants resulted in significant decreases in fresh root and shoot weights and leaf number compared to decreases associated with infection of resistant plants. RFLP probes have been identified for mapping the plr gene. The second topic of this dissertation dealt with the development of transgenic tobacco plants that express a chimeric gene that consisted of the 35-S promoter and the coat protein gene of Beet Curly Top Virus, a member of the geminivirus group. Expression of viral coat protein genes in plants has resulted in resistance to the virus from which the coat protein gene was obtained. This type of "coat protein-mediated" resistance has not been demonstrated for any geminivirus. Tobacco leaf discs were inoculated with an Agrobacterium tumefaciens line that contained the chimeric gene. Three transgenic lines were determined by Southern and Northern analysis, and ELISA, to express the chimeric gene and produce coat protein. Trials to determine the resistance of these plant lines to BCTV are pending federal approval.
Type:
text; Dissertation-Reproduction (electronic)
Keywords:
Dissertations, Academic; Plant-pathogen relationships.
Degree Name:
Ph.D.
Degree Level:
doctoral
Degree Program:
Plant Pathology; Graduate College
Degree Grantor:
University of Arizona
Advisor:
Stanghellini, Michael E.

Full metadata record

DC FieldValue Language
dc.language.isoenen_US
dc.titleInheritance of resistance in lettuce to Plasmopara lactucae-radicis and expression of the beet curly top virus coat protein gene in transgenic tobacco.en_US
dc.creatorVandemark, George Joseph, III.en_US
dc.contributor.authorVandemark, George Joseph, III.en_US
dc.date.issued1991en_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.abstractThe research presented in this dissertation involves the study of two systems in order to analyze and develop resistance in plants to pathogens. The first study considered the interaction between lettuce (Lactuca sativa L.) and Plasmopara lactucae-radicis, a recently described casual agent of downy mildew. This unique fungus is the only known casual agent of downy mildew that is restricted to the roots of its host. Thirty-eight lettuce cultivars were screened for resistance to P. lactucae-radicis. Two-wk-old lettuce plants grown hydroponically were challenged with this fungus and evaluated 2 and 3 wk after inoculation for resistance. Root necrosis and production of sporangia on roots was considered a susceptible reaction. Five cultivars were determined to be resistant to this fungus. Resistant cultivars, however, were colonized by the fungus but did not support the production of sporangia on roots. Data from F2 and F3 progenies demonstrated that resistance was conferred by a single recessive allele (plr). Fungal infection of susceptible plants resulted in significant decreases in fresh root and shoot weights and leaf number compared to decreases associated with infection of resistant plants. RFLP probes have been identified for mapping the plr gene. The second topic of this dissertation dealt with the development of transgenic tobacco plants that express a chimeric gene that consisted of the 35-S promoter and the coat protein gene of Beet Curly Top Virus, a member of the geminivirus group. Expression of viral coat protein genes in plants has resulted in resistance to the virus from which the coat protein gene was obtained. This type of "coat protein-mediated" resistance has not been demonstrated for any geminivirus. Tobacco leaf discs were inoculated with an Agrobacterium tumefaciens line that contained the chimeric gene. Three transgenic lines were determined by Southern and Northern analysis, and ELISA, to express the chimeric gene and produce coat protein. Trials to determine the resistance of these plant lines to BCTV are pending federal approval.en_US
dc.typetexten_US
dc.typeDissertation-Reproduction (electronic)en_US
dc.subjectDissertations, Academicen_US
dc.subjectPlant-pathogen relationships.en_US
thesis.degree.namePh.D.en_US
thesis.degree.leveldoctoralen_US
thesis.degree.disciplinePlant Pathologyen_US
thesis.degree.disciplineGraduate Collegeen_US
thesis.degree.grantorUniversity of Arizonaen_US
dc.contributor.advisorStanghellini, Michael E.en_US
dc.contributor.committeememberGilbertson, Robert L.en
dc.contributor.committeememberNelson, Merritten
dc.contributor.committeememberMisaghu, Iraj J.en
dc.contributor.committeememberSmith, Stevenen
dc.identifier.proquest9124168en_US
dc.identifier.oclc710357890en_US
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