Page 135 - Plant Canada 2024 Proceeding

PLANT CANADA 2024

[O66] PAPERCLIP RNA STRUCTURES REDUCE DISEASE SYMPTOMS CAUSED BY SCLEROTINIA
SCLEROTIORUM THROUGH HOST INDUCED GENE SILENCING. Mark F Belmonte, Bliss M.
Beernink, and Steve Whyard. University of Manitoba, Department of Biological Sciences, 50 Sifton Road,
Winnipeg, Manitoba, Canada
Correspondence: mark.belmonte@umanitoba.ca

Sclerotinia sclerotiorum, the causal agent of white mold, infects over 600 species of plants worldwide.
Sclerotinia is a persistent problem for global food production that has traditionally been managed using
broad-spectrum fungicides. However, current fungicide strategies have proven less effective and crop
rotations fail due to the promiscuous host range of Sclerotinia and the formation of durable resting
structures known as sclerotia. Thus, there is an immediate need to manage Sclerotinia using novel
species-specific control methods. Our strategy exploits the inherent cellular defense process known as
RNA interference (RNAi). Upon encountering a double stranded RNA (dsRNA) molecule like a paper clip
(pc)RNA, the cell processes the pcRNA specifically targeting transcripts with sequence homology. Using
long dsRNAs and pcRNA structures produced in planta, we identified Sclerotinia-specific target genes
capable of host induced gene silencing via RNAi knockdown thus reducing the disease pressure of
Sclerotinia on transgenic Arabidopsis. These Sclerotinia gene targets and pcRNA structures shown to
work in Arabidopsis can be quickly translated into other plant species for improved fungal control in
economically important crops.
[O67] VOICES FROM BOTH SIDES: A MOLECULAR DIALOGUE BETWEEN TRANSCRIPTIONAL
ACTIVATORS AND REPRESSORS IN SEED AND SEEDLING DEVELOPMENT. Liang Song.
Department of Botany, University of British Columbia
Correspondence to: liang.song@botany.ubc.ca

High-quality seeds ensure successful seedling establishment and provide valuable nutrients to human
society. The phase switch from seed to seedling is crucial for plant survival and success. During seed
germination, the embryonic programs regulating storage reserve accumulation and dormancy must be
shut down, involving epigenetic modifications and feedback regulation among transcriptional regulators.
Recent works have reported Arabidopsis thaliana SEED DORMANCY 4-LIKE (AtSDR4L) and its homolog
Dynamic Influencer of Gene Expression 1 (DIG1) are targeted by ABA INSENSITIVE 3 (ABI3), a master
transcription factor in seed development. AtSDR4L and DIG1 function as transcriptional co-repressors of
the seed maturation programs during Arabidopsis seedling establishment. We established a link between
AtSDR4L/DIG1 and the Polycomb Repressive Complex (PRC)-associated protein VIVIPAROUS1/ABI3-
LIKE 2 (VAL2) by demonstrating their physical interactions and genome-wide binding similarities. We
present evidence that AtSDR4L and DIG1 likely use PRC2-mediated H3K27me3 deposition to regulate
target genes, including master regulators of seed maturation as well as AtSDR4L and its homologous
loci, to promote the embryonic-to-vegetative transition. Lastly, SDR4 and its orthologs appear to have
opposite functions in regulating seed germination in representative dicotyledonous and
monocotyledonous species, warranting further characterization of this family in various species.

*[O68] SOMETHING SWEET: SUGAR MEDIATED CHANGES IN CELL PROLIFERATION VIA TOR-
BRASSINOSTEROID SIGNALLING REQUIRE THE MICROTUBULE ASSOCIATED PROTEIN CLASP.
Sean P.A. Ritter, Dr. Laryssa Halat, and Dr. Geoffrey Wasteneys. The University of British Columbia
Correspondence to: sean.ritter@botany.ubc.ca

To survive, all organisms must coordinate energy intensive processes, such as growth, with
environmental conditions to prevent over-exertion in challenging situations. In plants, sugars are the
major energy source utilized to power cellular processes. Thus, plants must be able to both perceive and
enact appropriate cellular responses to sugar levels. TARGET OF RAPAMYCIN (TOR) is a conserved
protein kinase activated by growth factors and inactivated by energy deprivation, thereby acting as a
master regulator of metabolic pathways in all eukaryotes. In plants, TOR has been shown to alter
meristem activity, and thereby cell proliferation and growth, in response to changing light levels and sugar
availability. While numerous targets of TOR kinase activity have been identified, such as the
brassinosteroid (BR) responsive transcription factor BRASSINAZOLE RESTISTANT 1 (BZR1), how TOR
kinase activity is translated into altered growth at the cellular level is less clear. A candidate for one such
crucial link between TOR signaling and growth is the microtubule-associated protein CLIP-ASSOCIATED
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