Page 288 - PC2019 Program & Proceedings

PLANT CANADA 2019

P149. Investigating the role of a family of receptor-like-cytoplasmic kinases in immune signaling
*
Gonzalez-Ferrer, C. ; K. Siegal; J. Monaghan
Queen's University

Plant disease resistance requires a tightly-coordinated signalling network to prevent the spread of
infection. Cell surface-localized receptor protein kinases recognize danger signals such as microbial
molecules and trigger phosphorylation-mediated signaling cascades resulting in cellular reprogramming
and disease resistance. Several receptor-like cytoplasmic kinases (RLCKs) have demonstrated roles in
immune phospho-relay across various plant species, making them a family of interest in the study of
defense regulation. Here, we present our investigation of a family of RLCKs in Arabidopsis
thaliana with hypothesized roles in immune signal transduction. Our ongoing work involves the
functional analysis of mutant and overexpression lines, immune-induced activation, and protein-protein
interactions with known regulators of immunity. This project seeks to characterize these interactions in
order to place this family of RLCKs in immune signaling, which may be conserved in many
agriculturally-significant crops.

Carmen Gonzalez-Ferrer (18cgf@queensu.ca)

P150. Identification of determinants in the turnip mosaic virus coat protein that are critical for
viral cell-to-cell movement and virion assembly
*1
Dai, Z. ; M. Bernards ; A. Wang 3
2
1 Western University
2
The University of Western Ontario
3 Agriculture and Agri-Food Canada; University of Western Ontario
Potyviruses represent the largest group of plant viruses including many agriculturally important pests
such as Turnip mosaic virus (TuMV). TuMV coat proteins (CPs) form a protective shell for the viral
genome, but many aspects of their role remain undefined. Here, we constructed a green fluorescent and
mCherry fluorescent protein-tagged TuMV infectious clone and conducted a series of deletion and
mutation analyses to determine the domains and specific residues of TuMV CP required for viral cell-to-
cell movement and virion assembly. Our data indicate that the N-terminal amino acid residues 6 to 50 of
TuMV CP are dispensable for replication, cell-to-cell movement and assembly, but the core domain
residues 51 to 199, the C-terminal residues 200 to 288 or 265 to 274 are essential for cell-to-cell
movement, albeit not for replication. Furthermore, mutation of the charged residues (R178 and D222) in
the core domain of CP abolished cell-to-cell movement and prevented formation of virions in protoplasts.
An alanine scanning mutagenesis study of the C-terminal region of CP suggests that the point mutant
R269A exhibits a slow cell-to-cell movement phenotype with a delayed onset of systemic infection,
independent of virion assembly. Moreover, these mutated CPs seem unstable, likely due to rapid
proteasomal degradation. These data advance our understanding about the essential role of specific
residues and domains of CP in TuMV cell-to-cell movement which are potential targets for the control of
potyviruses.

Zhaoji Dai (zdai9@uwo.ca)

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