Researchers find mechanisms behind plant response to warming

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Last Updated08/10/2024

The researchers found that carbon dioxide sensors are a central player in the stomatal warming-cooling responses, and can detect when leaves undergo rapid warming.

Plants use stomata, microscopic pores on their leaves, to regulate water loss through transpiration and control the intake of carbon dioxide (CO₂) for photosynthesis. As global temperatures rise, plants must adapt their stomatal behavior to survive.
Recent research from the University of California San Diego, published in New Phytologist, provides a deeper understanding of how plants manage these processes under elevated temperatures.

Stomata play a crucial role in balancing water loss and CO₂ intake. As plants face heat stress, stomatal pores widen, enabling cooling through evaporation.
This opening also facilitates greater CO₂ intake, enhancing photosynthesis and growth.

The study uncovered two distinct mechanisms that plants use to regulate stomatal responses under heat:

CO₂ sensors in plant leaves detect warming, which boosts photosynthesis and reduces internal CO₂ levels.
In response, stomata open, allowing plants to increase CO₂ intake, maximizing photosynthesis and benefiting growth.

Under extreme heat, photosynthesis becomes stressed, leading to a decline. In these conditions, stomata use an alternative pathway, bypassing the CO₂ sensor system.
This second pathway activates a cooling response, similar to sweating, enabling the plant to cool down even when normal photosynthesis-driven responses falter.

For years, scientists struggled to clearly decipher the mechanisms governing stomatal behavior under rising temperatures. The complexity arises from difficulties in controlling vapor pressure differences (VPD) while increasing temperatures, making it hard to distinguish the effects of temperature and humidity.
The UC San Diego researchers tackled this issue by developing a novel method to maintain constant VPD levels during heat increases.
This allowed them to identify the genetic mechanisms responsible for stomatal temperature responses, including those influenced by drought hormones and temperature-sensitive proteins.

These findings provide valuable insights into how plants cope with rising temperatures. Understanding the genetic basis of these stomatal responses offers opportunities to engineer heat-resistant crops, which could be crucial for sustainable agriculture as climate change intensifies.