Page 242 - Plant Canada 2024 Proceeding

PLANT CANADA 2024

[P77] INVESTIGATING MOLECULAR EFFECTS OF HUMALITE APPLICATION ON FIELD-GROWN
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WHEAT USING QUANTITATIVE PROTEOMICS. Lauren E. Grubb , Mohana Talasila , Maria Rodriquez
Gallo , Linda Gorim , and R. Glen Uhrig . Department of Biological Sciences, University of Alberta,
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Edmonton, AB, CAN; Department of Agriculture, Food and Nutritional Science, University of Alberta,
Edmonton, AB, CAN; and Department of Biochemistry, University of Alberta, Edmonton, AB, CAN
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Correspondence to: grubb1@ualberta.ca

An increasing global demand for food production has resulted in increased synthetic fertilizer application,
with negative impacts on the environment. Biostimulants such as humalite are currently being applied as
a strategy to increase nutrient use efficiency and minimize negative environmental effects in cropping
systems. Humalite is a naturally-occurring coal-like substance found in mines in southern Alberta.
Humalite deposits are unique, boasting exceptionally high ratios of humic acids (>70%) and
micronutrients due to their unique freshwater depositional environment. Recently, local growers in Alberta
have begun to apply humalite to their fields despite limited scientific data demonstrating the impacts of
this product on yield across diverse crops. Some recent work has shown positive impacts on plant growth,
yield and nutrient use, especially in dry years, with humalite application. However, there is a lack of
research on the impacts of humalite on crops at the molecular level. As part of a larger agronomic project,
we have taken a quantitative proteomics approach to identify systems-level molecular changes induced
by the addition of different humalite application rates in field-grown wheat using three urea fertilizer
application rates (zero, half and full recommended rate based on soil tests). Key results will be discussed
and contextualized to provide insights into the protein-level changes associated with humalite application
and its meaning for overall crop productivity.

[P78] CLASP-SORTING NEXIN 1 INTERACTION: A KEY DRIVER IN PLANT ADAPTATION TO
ABIOTIC STRESS? Yexin Han, Dr. Laryssa Halat, and Dr. Geoffrey Wasteneys. Department of Botany,
The University of British Columbia
Correspondence to: yexin.han@botany.ubc.ca

Microtubules form complex arrays in all eukaryotic cells, and are crucial for cell shape, the cell cycle, and
intracellular transport. In plant cells, microtubules reorganize in response to external stimuli to help plants
adapt to environmental changes. This process requires microtubule-associated proteins including
CLASP (CLIP-ASSOCIATED PROTEIN). Previous work in our lab established that CLASP in the model
plant Arabidopsis thaliana, like its homologues in other model eukaryotes, functions as a rescue factor,
preventing the rapid disassembly of microtubules (Ambrose et al. 2011 Nat. Comm). In addition, we
discovered that CLASP interacts directly with SORTING NEXIN 1 (SNX1), a protein associated with
endosomal complexes. By tethering SNX1-endosomes to cortical microtubules, CLASP sustains the
plasma membrane distribution of the auxin transporter PIN2 and the brassinosteroid receptor BRI1, which
would otherwise be degraded in the lytic vacuole (Ambrose et al. 2013 Dev. Cell, Yuan et al., 2018
Current Biol.). Thus, in addition to its conserved role in microtubule dynamics, plants CLASP is a key
player in mediating plant hormone signalling. Sequence analysis indicates that the CLASP-SNX1
interaction is plant-specific, and present in all land plant lineages, leading us to hypothesize that this
interaction mediates plant resilience to environmental stress. Consistent with this, total loss of either
CLASP or SNX1 expression results in hypersensitivity to salt and other abiotic stress, and the
upregulation of reactive oxygen species-related genes. This total gene knock-out approach, however, is
problematic because we cannot determine whether these effects are specific to CLASP’s function in
tethering SNX1 or its function in microtubule dynamics and organization. The objective of my project is to
modify CLASP’s SNX1-interaction motif to generate a version of CLASP that no longer interacts with
SNX1 but retains its other functions. Using BLAST searches across land plants, I have narrowed down a
16 amino motif in an intrinsically disordered region that is highly conserved and using generative AI
programs, I have been able to predict and model the structural interaction of CLASP and SNX1. Yeast 2-
Hybrid is being used as a first step to confirm which amino acid substitutions can eliminate SNX
interaction before engineering these changes in plant. By uncoupling CLASP-SNX1 interactions, this
project will lead to new insight into plant abiotic stress tolerance mechanisms.

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