Page 109 - PC2019 Program & Proceedings

PLANT CANADA 2019

S3. Strigolactone receptors from striga activate a latent Arabidopsis signaling pathway to bypass
the gibberellin requirement for germination
*
Bunsick, M. ; K. Nemrish; P. Sung; G. Ly; S. Lumba
University of Toronto

Parasitic plant infestations dramatically reduce the yield of major food crops in Sub-Saharan Africa and
pose a serious threat to food security. The first step of a successful parasitic infestation is host-dependent
germination. Seeds of the parasite Striga hermonthica detect hosts by sensing the plant hormone
strigolactone, which nearby crops emit. Despite its importance, we do not know how host-derived
strigolactones germinate parasitic plants. By expressing strigolactone receptors from Striga in different
genetic backgrounds of the model plant Arabidopsis thaliana, we show Striga receptors co-opt the
karrikin signaling pathway to germinate Arabidopsis seeds. Further, activation of this pathway
circumvents Arabidopsis’s requirement of the hormone gibberellin for seed germination. Our results
suggest that parasitic plant species evolved a pathway, latent in non-parasitic plants, to become its
dominant pathway for germination.

Michael Bunsick (michael.bunsick@mail.utoronto.ca)

S4. Early chemical priming persistently attenuates induced anthocyanin accumulation with broader
metabolic and possible systems-level impact
*1
Hiiback, K. ; M. Campbell 2
1 University of Toronto
2 University of Guelph

Priming is a general term for a phenomenon in which exposure to an early environmental stimulus results
in more rapid or vigorous response when the plant is exposed to subsequent challenges. Various
approaches to induce priming have been described including ‘seed priming’, a technique which
traditionally involves application of nutrients or endogenous plant molecules to seeds to improve crop
performance. Using a high-throughput approach, thousands of small molecules were screened to identify
compounds capable of ‘chemical priming’, specifically producing an altered response to subsequent
abiotic challenges when applied as seed priming treatments. Several novel molecules were identified in
this screen that had the persistent ability to reduce total anthocyanin accumulation in 7-18-day old
Arabidopsis thaliana seedlings induced by later chilling and low nitrogen treatments, even though
chemical exposure was limited to the developmental windows of seed imbibition and germination.
Untargeted metabolomic profiling revealed significant continued perturbations in the secondary
metabolism of chemically-primed plants including but not limited to the expected changes in
anthocyanins. Complementary transcriptional profiling of genes encoding flavonoid and anthocyanin
biosynthetic enzymes was completed to examine another systems level possibly linked to the persistent
effect. The presented research represents a proof-of-concept for the functional potential of seed priming
with novel compounds, and underscores the complexity of secondary metabolism as a component of plant
stress response.

Katrina Hiiback (k.hiiback@mail.utoronto.ca)

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