Page 159 - PC2019 Program & Proceedings

PLANT CANADA 2019

S103. Flooding tolerance is regulated through the MiR156/SPL module in Medicago sativa
*1
4
2
3
Feyissa, B.A. ; Y. Papadopoulos ; S. Kohalmi ; A. Hannoufa
2
1 University of Western Ontario; Agriculture and Agri-Food Canada;
4
3 The University of Western Ontario; Agriculture and Agri-Food Canada
Climate change is expected to increase the mean annual temperature and precipitation resulting in
frequent flooding events. To select or generate flooding-tolerant plants, it is imperative to understand the
underlying tolerance mechanisms. microRNA156 (miR156) is highly conserved across plant species and
is reported to impart effects on plant development, chemical composition, and stress physiology. To
investigate whether miR156 affects the response of Medicago sativa (alfalfa) to flooding stress, we used
miR156 overexpressors, miR156-regulated SPL13RNAi, flooding- tolerant (AAC Trueman) and
sensitive (AC-caribou) cultivars, exposed to two weeks of flooding. Physiological analysis, hormone
profiling and global transcriptomic data illustrated the positive role of miR156 in flooding stress
tolerance. During flooding, moderate miR156 over-expressers, SPL13RNAi, and AAC Trueman alfalfa
plants maintained Vcmax and Jmax, maximum rate of rubisco carboxylase activity and photosynthetic
electron transport rate, as well photosynthetic assimilation rate. Global transcriptomic-based pathway
analysis revealed the enrichment of transcripts related to photosynthesis and secondary
metabolites pathways. Moreover, hormone profiling showed an increase in the abundance of total ABA
metabolites contributed mainly by increased ABAGE and Phaseic acid, a catabolite of ABA, in
flooding tolerant alfalfa genotypes. Together, our results suggest that the role of a miR156/SPL13 module
in regulating flooding response in alfalfa is mediated in part by ABA and other secondary metabolites.

Biruk A Feyissa (bfeyissa@uwo.ca)

S104. Identifying Brachypodium distachyon proteins interacting with histone deacetylase BdHD1
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1
Torrez, A. ; H.A.L. Henry ; L. Tian 2
1 The University of Western Ontario; Agriculture and Agri-Food Canada
2
Gene expression of stress-responsive genes can be regulated through epigenetic mechanisms which
include DNA methylation and histone modifications. Current evidence has elucidated the involvement of
histone deacetylases (HDACs) in plant stress responses. HDACs facilitate the removal of acetyl groups
from histone tails and cause a condense chromatin structure, thus leading to gene repression.
In Arabidopsis thaliana, HDA19, belonging to the RPD3/HDA1 class, can interact with many
transcription factors to form complexes to repress gene expression. HDAC research has mainly been
conducted within dicotyledons and research within monocotyledons is
limited. Brachypodium distachyon is used as a model plant to investigate questions unique to monocot
crops. BdHD1, the closest homologous gene of HDA19, has been identified in B. distachyon. This study
investigated potential protein-protein interactions between BdHD1 and each of BdMYB22,
BdWRKY24 and BdHOS15. The interactions were investigated using yeast two-hybrid assays (Y2H) and
bimolecular fluorescence complementation (BiFC). Y2H assay shows that BdHD1 strongly interacted
with WRKY transcription factor member BdWRKY24. This interaction was further confirmed via BiFC.
An interaction between BdHD1 and the SANT domain-containing protein BdMYB22 was identified via
Y2H and confirmed via BiFC. The SANT domain is involved in chromatin remodeling. No interactions
were observed with BdHOS15. This research provides an insight for further discovering BdHD1-
complexes in B. distachyon.

Alberto Torrez (atorrez@uwo.ca)

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