Plants use sugar, produced through photosynthesis, as a key signal to detect and respond to heat during the day, which could lead to more resilient crops.
A recent study led by Professor Meng Chen at the University of California, Riverside, has revealed a new mechanism in plants for sensing heat during daylight. This discovery challenges previous ideas that focused primarily on nighttime sensors. The research highlights the crucial role of sugar in this process, offering a more complete picture of how plants adapt to their environment.
Scientists traditionally believed that proteins like phytochrome B and early flowering 3 (ELF3) were the main heat sensors, mostly active at night. However, these models didn't explain how plants reacted to heat during the day, when both light and temperature are high. To explore this, the team used Arabidopsis, a small flowering plant often used in genetic studies. They exposed the plants to different temperatures and light conditions, observing how their stems, called hypocotyls, grew in response to warmth.
The findings showed that phytochrome B's ability to detect heat decreased in bright light. Despite this, the plants still responded to heat, suggesting other sensors were at play. Further tests showed that plants could react to warmth in light, but not in the dark, when phytochrome B wasn't working. Adding sugar to the growing medium restored this response, indicating sugar acts as a signal for higher temperatures.
The study also found that higher temperatures cause starch in leaves to break down, releasing sucrose. This sugar stabilizes a protein called PIF4, which controls growth. Without sucrose, PIF4 degraded quickly; with it, the protein accumulated and became active when another sensor, ELF3, also responded to the heat. This dual mechanism, involving sugar and proteins, allows plants to adjust their growth in response to daytime heat. This discovery, published in Nature Communications in 2025, offers a more nuanced understanding of plant thermosensing.
Understanding how plants sense heat during the day is vital for creating agricultural practices that ensure food security in a changing climate. This research could help develop crops that are more resistant to extreme temperatures. This knowledge can be used to breed plants that can better withstand the effects of climate change, ensuring a stable food supply.