Page 318 - PC2019 Program & Proceedings

PLANT CANADA 2019

P209. Investigating the Role of Brachypodium distachyon Cellulose Synthase 8 in Gluconacetobacter
diazotrophicus Colonization
2
1
3
Yang, X. ; K. Hill ; R. Austin ; K. Vessey ; L. Tian 2
*1
1 The University of Western Ontario
2
Agriculture and Agri-Food Canada
Saint Mary's University
3

Alternatives to synthetic nitrogen fertilizer are needed to reduce the costs of crop production and offset
environmental damage. Nitrogen fixing bacterium Gluconacetobacter diazotrophicus has been proposed
as a possible biofertilizer for monocot crop production. However, the colonization of G. diazotrophicus in
most monocot crops is limited and deep understanding of the response of host plants to G. diazotrophicus
colonization is still lacking. In this research, experiments were conducted to study the role of host plant in
the G. diazotrophicus colonization establishment using a new monocot model plant, Brachypodium
distachyon. The gene expression profile of G. diazotrophicus colonized B. distachyon root tissues was
generated via next generation RNA sequencing and then investigated through gene ontology and
metabolic pathway analysis. The RNA sequencing results indicated that Brachypodium may be actively
involved in the establishment of G. diazotrophicus colonization via cell wall synthesis, and jasmonic acid,
ethylene, and giberrelin biosynthesis. Therefore, the genes in these biosynthesis pathways potentially play
important roles in the beneficial association between the plant and G. diazotrophicus. The loss of function
muta P2. nt for Brachypodium cellulose synthase 8 (BdCESA8) showed decreased cellulose content in
xylem and increased resistance to G. diazotrophicus colonization. This result suggested that the cellulose
synthesis of the secondary cell wall is involved in G. diazotrophicus colonization.

Xuan Yang (xyang323@uwo.ca)

P210. Interaction of Arabidopsis calmodulin-like proteins with the protein 2b, an RNA silencing
suppressor of cucumber mosaic virus
1
2
1
2
1
Nakahara, K. ; H. Teresinski ; M. Suto ; S. Jin ; W. Snedden
1 Hokkaido University
Queen's University
2

RNA silencing is one of major antiviral systems in plants and most plant viruses encode RNA silencing
suppressors (RSS) to facilitate their infection of plants by inhibiting the plant’s endogenous antiviral
RNA silencing machinery. Previously, a tobacco calmodulin-like protein (CML) has been reported to
interact with HC-Pro and 2b, which are RSSs encoded by members of the
genus Potyvirus and Cucumovirus, respectively. We have shown that the tobacco CML, which was
named rgs-CaM, counteractively functions as an antiviral defense factor to direct degradation of its
interacting RSS proteins via autophagy. Plants encode dozens of CMLs (50 and 32 CMLs
in Arabidopsisand rice, respectively). Several CMLs of tobacco and other plants are similar to rgs-CaM in
their amino acid sequences, suggesting possible binding to viral RSSs. Here, we examined whether 5
closely-related CMLs from Arabidopsis(CML37, CML38, CML39, CML40 and CML41) which are
similar to rgs-CaM bind to 2b of cucumber mosaic virus (CMV) within a yeast two-hybrid system. The
results suggest that all these 5 CMLs bind to 2b whereas unrelated CMLs do not.
When Arabidopsismutants lacking CML37, CML38 and CML39, singly or doubly, were inoculated with
CMV, viral genomic RNAs accumulated more in these mutants, especially in double mutants, suggesting
that these Arabidopsis CMLs collaboratively function to control CMV infection by interacting with 2b.

Kenji Nakahara (knakahar@res.agr.hokudai.ac.jp)

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