Page 180 - Plant Canada 2024 Proceeding

PLANT CANADA 2024

[O149] ADVANCEMENT OF B2-BASED DSRNA EXTRACTION METHOD: COST-EFFECTIVENESS
COMPARISON OF HTS-BASED VIRUS DETECTION METHODS. Mamadou L. Fall, Dong Xu, and
Pierre Lemoyne. Saint-Jean-sur-Richelieu Research and Development Centre, Agriculture and Agri-Food
Canada, Saint-Jean-sur-Richelieu, Quebec, Canada J3B 3E6
Correspondence to: mamadoulamine.fall@agr.gc.ca

Viral diseases pose a significant threat to global food production. Unlike bacterial or fungal infections,
treating virus-infected plants is impractical. Therefore, minimizing the impact of viruses on crop production
depends on our ability to monitor and anticipate outbreaks. Early detection is crucial for implementing
effective mitigation strategies. Virion-associated nucleic acid (VANA) and metagenomic sequencing are
commonly used to analyze the virome. VANA sequencing tends to favor DNA and enveloped RNA
viruses, while metagenomic sequencing is influenced by large-genome organisms and their prevalence.
We have developed a new method using dsRNA-binding proteins (B2-based) and compared its cost-
effectiveness with four existing methods using the Illumina MiSeq platform. The results indicate that
dsRNA sequencing surpasses metagenomics in terms of cost-effectiveness for detecting grapevine
viruses and for characterizing their genomes, regardless of genome type, size, or heterogeneity. Among
the tested methods, the DRB4-based dsRNA method (commercial kit) showed the highest accuracy,
followed by the cellulose-based method, and the B2-based dsRNA method. However, our B2-based
dsRNA method stood out as the most affordable and rapid option. In the broader context of One Health,
which involves monitoring both known and unknown viruses across various environments such as plants,
animals, insects, and soil, dsRNA sequencing offers a unique opportunity to enhance our ability to
monitor and predict viral outbreaks.

*[O150] PECTIN DYNAMICS DICTATES ANISOTROPIC CELL GROWTH DURING MESOPHYLL
MORPHOGENESIS. Diksha Bhola and Anja Geitmann. Department of Plant Science, Faculty of
Agricultural and Environmental Sciences, McGill University, Montreal, Canada
Correspondence to: Diksha.bhola@mail.mcgill.ca

Plants exhibit complex structure-function relationships showcased most eminently by the leaves. They
are the major sites for fundamental biophysical processes such as photosynthesis and respiration. The
efficiency of these processes is governed by the overall architecture of leaves, wherein each tissue layer
contributes in an additive manner.

Of critical importance for photosynthetic efficiency is the 3D arrangement of mesophyll cells and
intercellular spaces as it determines the diffusion of gases through the inner leaf tissue. Structural traits
such as mesophyll cell shape, area and volume, intercellular connectivity of air spaces between
mesophyll cells, mesophyll cell walls facing intercellular spaces, and porosity of the mesophyll tissue
affect mesophyll conductance and net photosynthetic capacity. Mesophyll morphogenesis is controlled by
cell wall polysaccharides that dictate non-uniform and anisotropic growth process and control cell
detachment resulting in a complex aerenchymatic tissue. The aim is to understand how mesophyll cells
develop their 3D shapes from the dense embryonic tissue and how the network of interconnected air
spaces is formed. Here we use Arabidopsis thaliana wildtype and mutants with altered pectin methyl
esterification to elucidate how cell wall polysaccharide composition correlates with tissue morphogenesis
and how altered cell wall properties affect leaf anatomy. Two complementary microscopic techniques are
employed to characterize mesophyll cell morphogenesis. Confocal laser scanning microscopy in
combination with immunohistochemistry is used to map various cell wall polysaccharides during
mesophyll development. Synchrotron-based X-ray microcomputed tomography (micro-CT) is used to
obtain cellular and tissue level information in non-destructive manner. Image analysis and processing is
done by MorphoGraphX and ImageJ software. We found that lowly esterified pectin are enriched in cell
wall segments that maintain continued cell-cell contact even during air space formation in the tissue.
Genetically modified enhanced levels of highly methyl esterified pectin causes higher degree of cell wall
expansion and bigger cells. Clearly, changes in pectin chemistry plays an important role in influencing the
growth of individual cells, their morphogenesis and cell-cell connectivity thereby affecting mesophyll
tissue porosity.

179