How plants evolved a molecular switch to cope with heat

As climate change intensifies, plants face mounting challenges from increasingly frequent and severe heat waves. Researchers at VIB, Ghent University, and KU Leuven, along with global collaborators, have discovered a crucial molecular switch that enables plants to maintain their internal cooling system under high temperatures. Published in Nature Plants, the study reveals how plants regulate their stomata - tiny pores on leaf surfaces - to prevent overheating.

Unlike animals, plants cannot relocate to cooler areas, so they rely on innate mechanisms to avoid heat stress. Stomata open to allow water vapor to evaporate, releasing excess heat like sweating cools humans. While open stomata aid cooling, excessive opening can lead to water loss. Scientists have long recognized stomata's role in plant heat response, but the precise molecular processes have remained unclear.

Led by Professor Ive De Smet, the research team identified a novel pathway involving a protein called UBP24. High temperatures trigger a modification that stabilizes UBP24, stabilizing other proteins that maintain open stomata and the plant's cooling system. Understanding this mechanism is vital as temperatures continue to rise globally.

The newly discovered mechanism sheds light on how plants sustain leaf cooling during heat stress. De Smet emphasized the significance of this research in a warming world. The study revealed that a molecular switch enabling UBP24 to respond to heat appeared in vascular plants around the same time as the evolution of active stomatal regulation.

This seemingly minor change allowed plants to fine-tune their heat response. Moreover, the researchers discovered that a related protein in yeast follows a similar mechanism under heat stress, despite hundreds of millions of years of evolution separating the two organisms. This finding underscores the ancient and effective nature of this heat adaptation strategy across diverse life forms.

As climate change drives more frequent and intense heat waves, comprehending how plants naturally combat high temperatures becomes increasingly critical. This discovery unveils one of the ways plants have adapted to survive in a changing environment, potentially guiding efforts to cultivate crops better equipped for a warming world.