Page 253 - Plant Canada 2024 Proceeding

PLANT CANADA 2024

*[P99] IDENTIFYING THE GENOMIC VARIABILITY OF DIVERSE WHITE MOULD (SCLEROTINIA
1
1
SCLEROTIORUM (LIB.) DE BARY) ISOLATES. Marysia Zaleski-Cox , Laura Esquivel-Garcia , and
Valerio Hoyos-Villegas . McGill University – Macdonald Campus, 21111 Lakeshore Rd, Sainte-Anne-de-
1 1
Bellevue, Quebec H9X 3V9
Correspondence to: marysia.zaleski-cox@mail.mcgill.ca

Sclerotinia sclerotiorum (Lib.) de Bary (Ss) is a cosmopolitan, fungal plant pathogen that can greatly
reduce the yield of important crops such as Phaseolus vulgaris L. (common bean, Pv). Pv’s resistance to
Ss is quantitative and no cultivar with complete resistance has been identified. Ss does not have a
universal effect on common bean, as some isolates are more aggressive than others and an isolate by
host cultivar interaction has been observed. Our objective is to characterize the genomic diversity of Ss
within a geographically diverse set of isolates and identify loci potentially linked to variable aggressivity.
This will be done using whole genome sequencing of Ss to identify subpopulations within the collected
isolates followed by inoculation of diverse common beans with a representative of each Ss subpopulation.
Inoculation will provide phenotypic aggressivity information. The collected genotypic and phenotypic data
will be linked with an analysis of polymorphisms within regions associated with Ss aggressivity and a
multi-trait genome wide association study (GWAS) of Ss resistance in Pv. Ss isolate collection,
sequencing and analysis of variance are underway. This work will improve standard Ss screening
procedures in breeding laboratories by identifying appropriately diverse Ss isolates to be used during
inoculation of new breeding material. Additionally, a multi-trait GWAS will help uncover pleiotropic
resistance determinants in Pv. Ultimately, this will facilitate the development of Pv lines harbouring
improved Ss resistance.

*[P100] BREAKING FREE: INSIGHTS INTO AUXIN AND ETHYLENE CONTROL OF ABSCISSION
ZONE PATTERNING IN ARABIDOPSIS. Risham Osahan and Shelley R. Hepworth . Department of
1
1 1
Biology and Institute of Biochemistry, Carleton University, 1125 Colonel By Drive, Ottawa, ON, Canada,
K1S 5B6
Correspondence to: rishamosahan@cmail.carleton.ca

Abscission is a critical developmental process that leads to the detachment of plant organs. In
Arabidopsis thaliana, pollination triggers the abscission of floral organs by signaling cell separation
responses in abscission zones (AZs) at the base of sepals, petals, and stamens. As abscission
approaches, AZ cells form a proximal separation layer that secretes hydrolytic enzymes and a distal
lignified layer that serves as a mechanical brace. Phytohormones auxin and ethylene play an important
role in regulating abscission by inhibiting and promoting organ detachment, respectively. How these
hormones influence AZ structure and differentiation has been unclear. Experiments in wild-type plants
showed that AZs form their distinct layered structure about one position before organs detach. By
manipulating hormone pathways, our findings reveal that auxin is essential in ordering the cellular
architecture of AZs. Exogenous application of auxin caused disorganized AZs and inhibited layer
differentiation, whereas the inhibition of auxin transport led to the earlier formation of AZ layers. By
contrast, ethylene influenced the timing of abscission and layer formation without changing AZ
morphology. In ethylene-treated plants, AZ layers formed in unopened flower buds suggesting that AZs
are responsive to ethylene before pollination. Our research highlights distinct roles for auxin and ethylene
in AZ differentiation. Future work will explore how boundary genes that define and organize AZ cell
structure interact with auxin and ethylene to control the timing of AZ layer differentiation.

[P101] THE PURIFICATION AND IDENTIFICATION OF MONOTERPENE INDOLE ALKALOIDS IN
ALSTONIA SCHOLARIS. Scott Mann and Dr. Yang Qu. University of New Brunswick
Correspondence to: smann@unb.ca

Monoterpene Indole Alkaloids (MIAs) are a class of metabolites found in many plant families including
Apocynaceae, Rubiaceae, and Nyssaceae. MIAs have become popular in pharmaceutical research due
to their wide range of bioactivities, stemming from their diverse structure. Although medicinally valuable,
the synthesis of MIAs has proven difficult due to their complex structures. Therefore, the elucidation of
MIAs biosynthetic pathways is a crucial step to making these metabolites a pharmaceutically viable
option. The first step in understanding these biosynthetic pathways is to purify and Identify MIAs from
plant extracts. Alstonia scholaris, a tree species native to southeast Asia, has been previously

252