UBC Botanists Uncover Plants' 'Pause-Play' Growth Strategy Against Climate Stress
Researchers at the University of British Columbia (UBC) have revealed a fascinating adaptive mechanism in plants that allows them to temporarily halt root growth during harsh environmental conditions like cold snaps or salt floods, then seamlessly resume or even accelerate development once the stress subsides. This 'pause and play' response, governed by specific genes and cellular pathways, could revolutionize crop breeding for Canada's challenging climate.
Led by doctoral student Olivia Hazelwood and Assistant Professor Dr. Arif Ashraf in UBC's Department of Botany, the study published in New Phytologist demonstrates how plants prioritize survival over expansion during stress, conserving energy for post-stress recovery. This discovery is particularly timely as Canada's prairies face intensifying droughts, heatwaves, and coastal salinization due to climate change.
Decoding the Stress Responses: Pause, Push, and Fast-Forward
Plants encounter diverse climate stressors, each triggering unique growth adjustments. Under cold stress—simulating winter snaps—roots cease elongation as cell division proteins diminish. Salt stress, akin to coastal flooding, similarly induces a growth arrest. Remarkably, after an equal recovery period in optimal conditions, roots resume normal growth, with proteins rebounding within 24 hours.
- Cold and Salt Stress: Complete pause in root growth; full resume post-recovery.
- Drought (Osmotic Stress): Slower 'pause and push' recovery, requiring extended time to regain momentum.
- Heat Stress: Initial acceleration or 'fast-forward' followed by pause until cooling; detailed in a forthcoming paper.
These patterns were consistent across a model plant (Arabidopsis thaliana) and two wild crop-related grasses, indicating evolutionary conservation.
The Cellular Hero: Cyclin-Dependent Kinase A;1 (CDKA;1) Gene
At the heart of this resilience lies the CDKA;1 gene, a cyclin-dependent kinase essential for cell cycle progression. During stress, CDKA;1 activity drops, halting division. Inhibiting it experimentally blocked recovery, confirming its pivotal role. Proteins tied to cell division vanish from stressed cells but reappear rapidly in recovery, enabling roots to catch up.
"After counting thousands of cells for months, I saw that certain proteins were present in fewer cells when plants are under cold, drought and salt stress, but within about 24 hours of being put back into optimal growth conditions, their numbers returned to normal," Hazelwood explained.
From Lab Benchmarks to Field-Relevant Grasses
The UBC team applied controlled cold (4°C) and salt (150 mM NaCl) stresses to roots, measuring elongation over days. Fluorescent markers tracked dividing cells, revealing stress-induced arrest at the G2/M checkpoint. Extending to wild grasses like Setaria viridis and Panicum hallii—ancestors of crops such as foxtail millet and switchgrass—validated the mechanism's broad applicability.
This cross-species consistency suggests ancient evolutionary adaptations, now targetable for modern breeding.
Climate Stress Hits Canadian Crops Hard: The Stakes
Canada's agriculture, valued at $150 billion annually and employing 2.3 million, grapples with escalating extremes. Droughts in the Prairies slashed wheat yields by 12% in recent years, costing billions alongside U.S. partners. Heatwaves and floods threaten canola and barley, with probabilistic models forecasting further losses under RCP scenarios.
Salt intrusion from sea-level rise endangers coastal farms in B.C. and Atlantic provinces, while erratic winters impact root crops. UBC's findings offer a genetic toolkit to mitigate these, ensuring food security amid projections of more frequent events.
Government Backing for Resilient Farming in Canada
Agriculture and Agri-Food Canada (AAFC) leads with the $1.1 billion Agricultural Climate Solutions fund, promoting carbon-storing practices and resilient varieties. Genome Canada invests $30 million in climate-smart genomics, aligning with UBC's gene-editing potential. B.C.'s On-Farm Climate Action Fund supports adaptation, echoing calls for drought-tolerant wheat.Learn more on AAFC initiatives.
Path to CRISPR-Edited Wheat: UBC's Next Steps
Hazelwood's team eyes Canadian wheat varieties for CDKA;1 enhancements via CRISPR-Cas9 within 2-3 years. Prior UBC work on hard red spring wheat's drought responses via osmolyte accumulation complements this. "In two to three years, we hope to adjust these genetics of Canadian crop varieties and create our own CRISPR-edited lines," Hazelwood stated.
Success could boost yields post-stress, vital as Western Canada records harvests despite droughts through tech like better seeds.
Dr. Arif Ashraf's Vision: Engineering Survival
Senior author Dr. Ashraf, whose lab probes endosomal trafficking in stress, emphasizes practicality: "We can’t stop heatwaves or snow storms. So we’re pinpointing genes that can help plants recover from these events and still produce in time for harvest." His prior publications on cold-mediated auxin transport in Arabidopsis underpin this work.
Photo by Ludmila Uleva on Unsplash
UBC's Broader Plant Resilience Research
Complementing this, UBC studies show wild plants rapidly evolving drought tolerance and leaky water loss accelerating warming. Arctic tundra shrubs green earlier, but flowering lags. These integrate into national efforts for resilient agroecosystems.
Global and Canadian Food Security Outlook
By enhancing recovery genes, UBC paves the way for crops enduring Canada's variable weather—longer seasons offset by extremes. This supports net-zero goals while safeguarding $150B sector. Collaborative breeding could yield hybrids thriving in Prairies' droughts or B.C.'s salts, ensuring bountiful harvests.Read the full New Phytologist study.
As climate pressures mount, UBC's innovations promise a greener, more productive future for Canadian fields.
