New insights in plant response to high temperatures and drought
Vlaams Instituut voor Biotechnologie
Ghent, 29 November 2024 – We are increasingly confronted with the impacts of climate change, with failed harvests being only one example. Addressing these challenges requires multifaceted approaches, including making plants more resilient. An international research team led by researchers at VIB-UGent has unraveled how the opening and closing of stomata - tiny pores on leaves – is regulated in response to high temperatures and drought. These new insights, published in Nature Plants, pave the way for developing climate change-ready crops.
Global climate change affects more and more people, with extreme weather conditions steadily becoming the norm. Beyond the immediate impacts like floods and severe droughts, it also significantly affects our natural ecosystems and crops, making it challenging in many regions to grow the food we rely on or to identify the right climate-adapted plants.
Prof. Ive De Smet (VIB-UGent Center for Plant Systems Biology): “For years our research has focused on the impact of extreme weather conditions on plants. The molecular insights we gain can lead to solutions to enhance plant resilience. In essence, we learn from the natural mechanisms that plants themselves deploy. For instance, how stomata on leaves play a crucial role in the plant’s interaction with the environment. This makes insights into their activation mechanisms highly valuable.”
Conflicting responses in stomata, the ‘sweat glands’ of plants
Plants respond to changing environmental conditions among others via opening or closing little pores in their epidermis. These so-called stomata regulate gas and water vapor exchange with the environment, function as entry points for pathogens, and are pivotal in shielding plants against abiotic stress. When temperatures are high, the stomata open to cool down, in dry conditions they close to prevent water loss. So, when conditions are dry and hot, this may evoke conflicting – and therefore less efficient - stomatal responses. The VIB-UGent team of Prof. Ive De Smet joined forces with research teams from the universities of Utrecht (NL), Valencia (Spain), and Wageningen (NL) and set out to unravel the underlying cellular mechanisms.
A well-regulated signaling axis
Dr. Xiangyu Xu (VIB-UGent), first author of the study: “Opening and closing of stomata are rapid responses that require switch-like signaling mechanisms. We know that phosphorylation-encoded switches within protein networks are reversible and tend to be faster than genetic switches. That’s why we studied the role of kinase-mediated phosphorylation relays in stomata opening and closing.”
Xu and his colleagues succeeded in identifying and characterizing a novel phosphorylation-dependent signaling axis that regulates stomatal aperture under high temperature and/or drought conditions. They demonstrated that TOT3, a high temperature-associated kinase, controls stomatal opening under high-temperature conditions, and that OST1, which regulates stomatal closure during drought stress, directly inactivates TOT3 through phosphorylation. This specific phosphorylation-mediated control of TOT3 activity acts as a switch to mediate stomatal aperture under high temperature and/or drought conditions.
Dr. Lam Dai Vu (VIB-UGent): “As a researcher, it is rewarding to unravel a new signaling axis that coordinates stomatal opening and closing in response to various stress signals. More importantly, in the context of global climate change, understanding these mechanisms holds potential for developing crops that are resilient to climate challenges.”
Journal
Nature Plants
Method of Research
Experimental study
Article Title
High temperature-mediated stomatal opening is regulated by the OST1-regulated TOT3-AHA1 module
Article Publication Date
29-Nov-2024
How fungi colonize plant roots
In nature, plant roots are always colonized by fungi. This interaction can be either mutualistic, benefiting both the plant and the fungus, or pathogenic, where the fungus harms the host plant. A research group led by Professor Dr Alga Zuccaro at the CEPLAS Cluster of Excellence has now deciphered how the beneficial root fungus Serendipita indica successfully colonizes plant roots of the model plant Arabidopsis thaliana. Initially, the fungus colonizes living root cells. Subsequently, limited cell death is triggered in the host plant, facilitating successful colonization without causing significant harm. The mechanisms controlling this host cell death are largely unknown. The team discovered now that Serendipita indica secretes two enzymes, NucA and E5NT, which produce the molecule deoxyadenosine (dAdo). This molecule activates a regulated cell death in plants, enabling the fungus to colonize the root system. The study ‘A nucleoside signal generated by fungal endophyte regulates host cell death and promotes root colonization’ was published in Cell Host & Microbe.
The researchers show that dAdo is initially produced in the apoplast, an extracellular space outside the host cells. In a subsequent step, dAdo enters the plant cell through the membrane transporter ENT3, where it hijacks the host’s immune system to induce cell death. This phenomenon, as described by Professor Zuccaro’s team, is not limited to plants. A similar process occurs in human patients during interactions between the pathogenic bacterium Staphylococcus aureus and human immune cells.
‘We found that the beneficial root fungus Serendipita indica uses two enzymes to produce dAdo, much like S. aureus, to induce cell death and enable successful colonization. This demonstrates that the mechanism is conserved across different microbes and lifestyles,’ said Professor Alga Zuccaro. The findings underscore the crucial interplay between microbial colonization and the host’s immune metabolism, paving the way for new strategies in medicine and agriculture. ‘By understanding these shared mechanisms, we can develop more effective approaches to manage both harmful and beneficial microbes in human health and crop production.’
Journal
Cell Host & Microbe
Method of Research
Experimental study
Subject of Research
Not applicable
Article Title
A nucleoside signal generated by a fungal endophyte regulates host cell death and promotes root colonization
Article Publication Date
26-Nov-2024
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