Page 168 - Plant Canada 2024 Proceeding

PLANT CANADA 2024

owned candidate sites in 2021 and 2022, and then incorporated our data into a spreadsheet-based
decision tool we built to rank sites for Poweshiek skipperling reintroductions. Our efforts culminated in the
selection of an initial release site in the spring of 2023. We are hopeful our methods will be useful to other
conservation practitioners faced with similar decisions in the future.

*[O129b] CHARACTERIZING DEFENSE MECHANISMS IN ARABIDOPSIS THALIANA AGAINST
TETRANYCHUS URTICAE HERBIVORY. Jorden Maglov , Julia Pastor-Fernandez , Michele Antonacci ,
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Alexander Harrison , Emilie Widemann , Vladimir Zhurov , and Vojislava Grbic . Department of Biology,
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Western University, London, Ontario, Canada
Correspondence to: jmaglov@uwo.ca

Tetranychus urticae (two-spotted spider mite) is an extreme generalist herbivore with the ability to feed on
over 1100 plant species, including 150 of agricultural importance. The two-spotted spider mite’s
polyphagous nature is driven by rapid adaptation to plant defenses. However, the specific plant defense
compounds mites must overcome to achieve a host-adapted state are largely unknown. Arabidopsis
thaliana is a challenging and non-preferred host for T. urticae, making it an excellent model to study mite-
host adaptation. It has previously been shown that a class of tryptophan-derived compounds specific to
the Brassicaceae family, indole glucosinolates, contribute partially to the A. thaliana defense response.
The remaining phytochemicals that protect the plant against mite herbivory are unknown. We used
combined metabolomic and transcriptomic approaches to identify classes of plant compounds that are
induced upon mite feeding. HPLC-MS and RNA-seq revealed that both phenylpropanoids and flavonoids
increase in abundance in planta upon mite feeding. Next, we measured mite fecundity on mutant A.
thaliana plants defective in overall phenylpropanoid and flavonoid biosynthesis to assess mite
performance. We found that mite fecundity significantly increases on phenylpropanoid and flavonoid
mutants relative to wild-type plants, suggesting that compounds within these pathways are toxic to spider
mites. We next fed mites with these plant compounds and screened for resulting mite mortality levels to
confirm the toxicity of these compounds in vivo. This study identified phenylpropanoids and flavonoids as
novel defense compounds protecting A. thaliana against spider mite herbivory. Because many
phenylpropanoids and flavonoids are ubiquitous among plants, this study may shed light on mite
adaptation mechanisms to not only A. thaliana, but economically important plants as well. Additionally,
these findings may enable the development of novel pest control strategies through the identification of
toxic phytochemicals.

[O129c] BRAWLING WEEDS AND THE FIGHT FOR CROP SURVIVAL. Clarence Swanton, Sasan
Amirsadeghi, Nicole Berardi, William Kramer, and Andrew McKenzie-Gopsill. University of Guelph
Correspondence to: cswanton@uoguelph.ca

Direct competition for light, water, and nutrient resources is traditionally considered the driving variable of
plant competition. Recent research, however, has suggested that resource competition is not the primary
mechanism by which weeds induce crop yield loss. Crop-weed competition begins with plant
communication, the ability of the crop seedling to detect the presence of neighboring weed seedlings.
Once the crop seedling interprets this incoming communication, significant molecular and physiological
changes occur. Such changes include a rapid increase in cellular singlet oxygen, a decline in
photosynthesis, a loss in the crop plants' ability to defend against insect and disease damage, and a loss
in the crop seedlings' ability to assimilate nitrogen. These four novel competition mechanisms alter the
growth trajectory of the crop seedling contributing to a rapid decline in crop yield potential.

[O130] DECIPHERING THE ROLE OF ER-LOCALIZED HSP90 FAMILY HEAT SHOCK PROTEIN IN
PLANT DEVELOPMENT AND STRESS RESPONSES. Rongmin Zhao, Jenan Noureddine, and
Morvenley Mamenta. Department of Biological Sciences, University of Toronto Scarborough, and
Department of Cell & Systems Biology, University of Toronto, Toronto, Canada
Correspondence to: rongmin.zhao@utoronto.ca

Endoplasmic reticulum (ER) is the organelle for lipids biosynthesis and the entry point of numerous
proteins that are sorted through the cellular secretory pathway, therefore playing an important role in
many cellular processes. Proteins that get into the ER membrane or lumen must be properly folded and a
cohort of highly conserved molecular chaperones reside in ER to aid in the folding and subsequent

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