Return to search

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

Diverse 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. / Ph. D.

Identiferoai:union.ndltd.org:VTETD/oai:vtechworks.lib.vt.edu:10919/77204
Date13 October 2011
CreatorsAnderson, Ryan Gabriel
ContributorsPlant Pathology, Physiology, and Weed Science, McDowell, John M., Westwood, James H., Tyler, Brett M., Lawrence, Christopher B., Winkel, Brenda S. J.
PublisherVirginia Tech
Source SetsVirginia Tech Theses and Dissertation
Languageen_US
Detected LanguageEnglish
TypeDissertation, Text
Formatapplication/pdf
RightsIn Copyright, http://rightsstatements.org/vocab/InC/1.0/

Page generated in 0.0022 seconds