Full Abstract Book - Wisconsin Union - University of Wisconsin ...

ICAR 2011
University of Wisconsin–Madison
defense similarly to the bon1 mutant. We found that cpr30 enhances the bon1 phenotype and the loss of SNC1 function suppressed cpr30
totally and cpr30 bon1 largely. The accumulation of SNC1 protein appears to be affected by the expression level of CPR30, suggesting
a regulation of the SNC1 protein stability by CPR30. We also identified sbo3, a suppressor of bon1 as a mutant of MOS1 (Modifier of
snc1-1). A few putative suppressors of bon1 were subsequently identified through analyzing MOS1 related genes. The identities of these
genes indicate that a transcriptional regulation of SNC1 at the chromatin level is critical for its activation and repression. Thus the activity
of SNC1 is under tight control at multiple levels.
235 Characterization of hybrid necrosis in Arabidopsis thaliana
Ben Hunter, Kathryn Solórzano-Lowell, Kirsten Bomblies
Harvard University, Cambridge, MA, USA
When plants are exposed to temperatures higher than those they are adapted to, a variety of responses are observed. One of these
is the inability to mount a proper response to pathogen attack. Hybrid necrosis is a type of postzygotic-incompatibility that has been
reported in many plant species, including Arabidopsis thaliana. Several studies of hybrid necrosis have demonstrated that it is the result
of epistatic interactions between genes associated with pathogen responses that spontaneously trigger an autoimmune response. Like many
pathogen responses, hybrid necrosis is suppressed at elevated temperatures. It is not known what mechanisms underlie this response.
Here we sought to understand the suppression of necrosis at elevated temperatures by identifying genetic modifiers in three different
cases in A. thaliana. We also characterised general suppressors of hybrid necrosis, as they rarely were common between the three studied
cases. Certain identified suppressors suggest that the temperature response is somewhat controlled by temperature-dependent changes in
chromatin. Disruption of the perception or production of certain hormones had different effects on hybrid necrosis. A lack of Salicylic
Acid appears to partially rescue some cases and a lack of Abscisic Acid enhances other cases. It has been shown elsewhere that a specific
point mutation in Resistance genes can suppress their temperature sensitivity. This mutation was tested in one case of hybrid necrosis but
did not appear to have similar effects. Overall, the suppression of hybrid necrosis does not appear to be controlled by one simple pathway,
instead it is more likely that many endogenous factors control the suppression as well as the threshold temperature at which it occurs.
236 Proteomic Analysis of the Plant-Pathogen Interface
Brenden Hurley 1 , Mike Wilton 1 , Yulu Liu 2 , Corinna Felsensteiner 1 , Stephane Angers 2,3 , David Guttman 1,4 , Darrell
Desveaux 1,4
1
Department of Cell and Systems Biology, University of Toronto, Toronto, Ontario, Canada, 2 Leslie Dan Faculty of
Pharmacy, University of Toronto, Toronto, Ontario, Canada, 3 Department of Biochemistry, University of Toronto,
Toronto, Ontario, Canada, 4 Centre for the Analysis of Genome Evolution and Function, University of Toronto,
Toronto, Ontario, Canada
Plants are constantly infiltrated by pathogens through natural openings and wounds.However, pathogenesis and virulence leading
to systemic disease is rare as plants possess an active immune system to detect microbes and trigger immune responses. A virulence
strategy employed by Pseudomonas syringae is the injection of type III secreted effectors (TTSE) directly into host cells via a molecular
syringe known as the type III secretion system (TTSS). While it is clear that TTSE interact with host proteins to disable plant immunity,
the precise targets of many TTSE remain unclear. One avenue of insight into host targets of TTSE is the proteomic identification of TTSE/
host protein complexes. Here we describe the purification of high molecular weight HopF2 Pto complexes from transgenic Arabidopsis via
gel-filtration and immuno-affinity chromatography. Liquid chromatography tandem mass spectrometry was subsequently used to identify
components of HopF2 Pto complexes revealing novel targets of HopF2 Pto in Arabidopsis.
237 The chs3-2D Mutation in the CHS3 LIM Domain Activates Constitutive Disease Resistance in
Arabidopsis
Kaeli Johnson 2 , Dongling Bi 1 , Yan Huang 2 , Zhaohai Zhu 1 , Xin Li 2 , Yuelin Zhang 1
1
National Institute of Biological Science, Beijing, P.R. China, 2 Michael Smith Laboratories and Department of
Botany, University of British Columbia, Vancouver, Canada
Plants possess a suite of Resistance (R) proteins which are essential for the activation of defense responses upon pathogen infection.
CHILLING SENSITIVE 3 (CHS3) is an R protein belonging to the TIR-NB-LRR class with a C-terminal zinc-binding LIM (Lin-11,
Isl-1, Mec-3) domain. Previous studies have implicated CHS3 in cold stress and defense response, although the role of the LIM domain
remains unclear. In this study, a dominant chs3 mutant (chs3-2D) isolated in a screen for NPR1-independent negative defense regulators
was characterized. The chs3-2D npr1-1 mutant displayed dwarfed, curled leaf morphology as well as elevated SA levels. The mutation
resulted in constitutive resistance to the virulent oomycete Hyaloperonospora arabidopsidis Noco2. Complementation experiments
showed that chs3-2D is a gain-of-function mutation. The nuclear localization of the protein was not affected by the mutation. Another chs3
mutant (chs3-3D) containing a mutation which appears to be in the LRR-LIM linker region was recently isolated in a mos4 suppressor
screen undertaken in our lab. Revertants of chs3-2D identified in a genetic screen will be presented. Analysis of these loss-of-function
and gain-of-function mutation sites will provide structural and functional details for the different domains of this R protein.
Poster: Biotic Interactions/Biotic Stress