Ghent, 26 August 2026 — Plants cannot escape a heat wave, retreat into shade or move toward a cooler environment. Rooted in place, they must manage rising temperatures through physiological systems that balance cooling, water conservation and continued growth. A study led by researchers at the VIB-UGent Center for Plant Systems Biology, in collaboration with teams at VIB-KU Leuven, VIB-UGent and international institutions, has identified a molecular mechanism that helps plants keep this balance during heat stress. Published in Nature Plants, the research reveals how the protein UBP24 supports the opening of stomata, microscopic pores that allow leaves to release water vapour and lower their temperature.
Stomata are distributed across the surfaces of leaves and are controlled by pairs of specialised guard cells. When these cells take up ions and water, they become more pressurised and bend apart, opening the pore between them. This opening allows carbon dioxide to enter the leaf for photosynthesis, but it also permits water to escape through transpiration. Under hot conditions, that water loss can have a cooling effect: as water evaporates from internal leaf surfaces, it carries heat away, much as evaporation of sweat cools the human body. The process is useful but potentially costly, because excessive transpiration can deplete the plant’s water supply. Plants therefore need precise molecular control over when stomata open and close.
The new study identifies UBP24 as an important part of that control system. According to the researchers, high temperature triggers a molecular change that stabilises UBP24. In its more stable state, UBP24 helps preserve other proteins involved in maintaining stomatal opening, allowing the plant’s evaporative cooling system to remain active during heat stress. The findings add a previously unrecognised layer to the signalling network that connects temperature sensing with stomatal behaviour. Rather than functioning only as a passive response to water status, stomata can therefore be actively regulated to help leaves avoid overheating.
UBP24 belongs to a class of proteins associated with the removal or processing of ubiquitin-related molecular signals. Ubiquitin is a small protein that can be attached to other proteins to influence their stability, activity or fate inside the cell. By altering these molecular tags, cells can rapidly remodel their protein landscape in response to changing conditions. The researchers’ results indicate that the heat-responsive behaviour of UBP24 is linked to its molecular charge state, a property shaped by changes in the protein’s amino-acid chemistry. This charge-sensitive switch appears to influence how UBP24 behaves under high temperatures and how effectively it supports the stability of proteins controlling stomata.
The work was carried out by researchers led by Prof. Ive De Smet of VIB and Ghent University, with contributions from the laboratory of Prof. Kevin Verstrepen at the VIB-KU Leuven Center for Microbiology and the group of Prof. Kris Gevaert at the VIB-UGent Center for Medical Biotechnology. By combining plant physiology, molecular biology, biochemical analysis and evolutionary comparisons, the teams examined how UBP24 responds to heat and how that response affects the plant’s ability to regulate leaf pores. The experimental findings connected changes in the protein with the behaviour of stomata, providing evidence that the pathway is not merely correlated with heat tolerance but contributes directly to the plant’s cooling response.
The researchers then placed the mechanism in an evolutionary context by comparing UBP24-related proteins across dozens of plant species. Their analysis suggests that the molecular switch allowing UBP24 to respond to high temperature emerged in vascular plants around the same period that actively controlled stomatal opening and closing evolved. Vascular plants possess specialised tissues for transporting water and nutrients, and their emergence was accompanied by increasingly sophisticated ways of managing water movement and gas exchange. The appearance of this charge-sensitive feature may have provided an additional means of tuning stomata as plants expanded into environments where temperature, water availability and atmospheric conditions could fluctuate sharply.
This evolutionary timing is significant because stomata are more than simple openings in a leaf. They represent a central point of control between the plant and its environment. Opening them can improve carbon dioxide uptake and promote cooling, while closing them limits dehydration but may increase the risk of overheating and restrict photosynthesis. A regulatory mechanism that adjusts the stability and activity of key stomatal proteins could help plants make these trade-offs more precisely. The study suggests that the UBP24 switch became part of this sophisticated control architecture, helping plants coordinate cellular protein regulation with the physical demands imposed by heat.
The researchers also found that the underlying principle may extend beyond the plant kingdom. A related protein in yeast appears to rely on a similar molecular feature when cells experience elevated temperatures. Plants and yeast are separated by hundreds of millions of years of evolution and have very different lifestyles, yet both must protect proteins and cellular processes from heat-induced disruption. The parallel suggests that regulating protein behaviour through changes in molecular charge may represent an ancient cellular strategy for coping with thermal stress. In plants, that strategy has been integrated into the control of stomata; in yeast, it may support other aspects of cellular survival.
The discovery arrives as heat waves become more frequent and intense in many parts of the world. High temperatures can damage cellular membranes, destabilise proteins, disrupt photosynthesis and accelerate water loss, reducing plant growth and agricultural productivity. Crops exposed to prolonged heat may close their stomata to conserve water, but this can also limit carbon dioxide uptake and reduce photosynthetic performance. Understanding how plants naturally keep stomata open enough to cool their leaves could eventually help researchers identify targets for improving heat resilience. Any agricultural application would need to preserve the balance between cooling and water conservation, since a plant that transpires too freely could become vulnerable to drought.
The findings remain fundamental rather than immediately agricultural, and the researchers emphasise that much work is still required before the mechanism could be translated into crop improvement. Future studies will need to determine how UBP24 interacts with the full network of temperature, humidity, light and water signals that govern stomatal activity, and whether altering the pathway improves performance under realistic combinations of heat and drought. Nevertheless, the work provides a new molecular entry point for studying plant adaptation. By showing how an evolutionary change in a protein’s charge state can connect heat perception to stomatal regulation, the study offers a detailed example of how plants have developed cellular solutions to survive a warming world.
Subject of Research: Experimental study
Article Title: Evolutionary tuning of molecular charge state of UBP24 shapes responses to high temperature
News Publication Date: 26 August 2026
Web References: https://doi.org/10.1038/s41477-026-02345-1
References: Nature Plants, DOI: 10.1038/s41477-026-02345-1
Keywords: Plant heat stress, UBP24, stomata, transpiration, plant cooling, heat resilience, molecular charge state, protein stability, plant evolution, vascular plants, yeast, climate change, crop resilience, photosynthesis, cellular stress response
Tags: guard cell ion transportmolecular mechanisms in plantsmolecular switches in plant heat stressplant adaptation to rising temperaturesplant heat stress responseplant physiological responses to heatplant survival strategies under heat stressplant temperature regulationrole of stomata in plant temperature controlstomatal regulation and water losstranspiration and cooling in plantsUBP24 protein function in plants
