Identification and functional characterization of RXLR effector proteins that are conserved between downy mildew pathogens and Phytophthora species

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dc.contributor.authorAnderson, Ryan Gabrielen
dc.contributor.committeechairMcDowell, John M.en
dc.contributor.committeememberWestwood, James H.en
dc.contributor.committeememberTyler, Brett M.en
dc.contributor.committeememberLawrence, Christopher B.en
dc.contributor.committeememberWinkel, Brenda S. J.en
dc.contributor.departmentPlant Pathology, Physiology, and Weed Scienceen
dc.date.accessioned2017-04-06T15:43:45Zen
dc.date.adate2011-10-13en
dc.date.available2017-04-06T15:43:45Zen
dc.date.issued2011-09-09en
dc.date.rdate2016-09-27en
dc.date.sdate2011-09-14en
dc.description.abstractDiverse pathogens secrete effector proteins into plant cells to manipulate host cellular processes. The genome of Hyaloperonospora arabidopsidis (Hpa), the causative agent of downy mildew of Arabidopsis, contains at least 134 candidate RXLR effector genes. These genes contain an RXLR motif required for effector entry into host cells. Only a small subset of these candidate effectors is conserved in related oomycetes. Here, we describe a comparative functional characterization of the Hpa RXLR effector HaRxL96 and a homologous gene, PsAvh163, from the soybean pathogen Phytophthora sojae. HaRxL96 and PsAvh163 are induced during early stages of infection and carry a functional RXLR motif that is sufficient for protein uptake into plant cells. Both effectors can suppress or activate immune responses in soybean, Nicotiana, and Arabidopsis. Several SA-responsive defense genes are suppressed in Arabidopsis Col:HaRxL96 and Col:PsAvh163 during an incompatible interaction with Hpa Emoy2. Both effectors are localized to the nucleus and cytoplasm of plant cells. Nuclear localization of both effectors is required for proper virulence functions, including suppression of basal resistance and RPP4-mediated immunity to virulent and avirulent Hpa, respectively. In addition, both effectors interact with plant U-box (PUB) proteins that are conserved between diverse plant species. The targeted PUB proteins are negative regulators of plant immunity in Arabidopsis. These experiments demonstrate that evolutionarily-conserved effectors from different oomycete species can suppress immunity in plant species that are divergent from the source pathogen's primary host.en
dc.description.degreePh. D.en
dc.identifier.otheretd-09142011-144211en
dc.identifier.sourceurlhttp://scholar.lib.vt.edu/theses/available/etd-09142011-144211/en
dc.identifier.urihttp://hdl.handle.net/10919/77204en
dc.language.isoen_USen
dc.publisherVirginia Techen
dc.rightsIn Copyrighten
dc.rights.urihttp://rightsstatements.org/vocab/InC/1.0/en
dc.subjectOomyceteen
dc.subjecteffectoren
dc.subjectRXLRen
dc.subjectplant immunityen
dc.subjectHyaloperonospora arabidopsidisen
dc.titleIdentification and functional characterization of RXLR effector proteins that are conserved between downy mildew pathogens and Phytophthora speciesen
dc.typeDissertationen
dc.type.dcmitypeTexten
thesis.degree.disciplinePlant Pathology, Physiology, and Weed Scienceen
thesis.degree.grantorVirginia Polytechnic Institute and State Universityen
thesis.degree.leveldoctoralen
thesis.degree.namePh. D.en

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