Hot and Hungry: High temperatures induce changes in leaf carbohydrate dynamics and sugar isotope fingerprints

Hot and Hungry: High temperatures induce changes in leaf carbohydrate dynamics and sugar isotope fingerprints | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Hot and Hungry: High temperatures induce changes in leaf carbohydrate dynamics and sugar isotope fingerprints Philipp Schuler, Margaux Didion-Gency, Valentina Vitali, Matthias Saurer, and 5 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-5509630/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 30 Nov, 2025 Read the published version in npj Science of Plants → Version 1 posted 14 You are reading this latest preprint version Abstract Accurate predictions of vegetation responses to global warming require a precise understanding of physiological temperature responses. We investigated the effects of air temperature (10°C to 40°C) under constant low vapour pressure deficit and sufficient water supply on leaf-level gas exchange, chlorophyll fluorescence, non-structural carbohydrate (NSC) concentrations, and the hydrogen (δ 2 H) and oxygen (δ 18 O) isotopic composition of leaf water and leaf sugar in C 3 trees, forbs, grasses, and one C 4 grass. Rising temperatures significantly altered leaf physiology, NSC composition, and the leaf sugar isotopic composition. We observed a shift from starch to sugar above 30°C, indicating a preference for a more readily available carbohydrate, with a concomitant shift in the hydrogen isotopic composition of leaf sugar. Furthermore, we demonstrate for the first time the close relationship between carbohydrate metabolism and stable isotope fractionation, with 2 H enrichment in leaf sugar with increasing temperature. Our results suggest that C 3 plants may experience shifts in their carbon metabolism at temperatures above 30°C, which can be detected by δ 2 H of leaf sugar. Such carbon imbalances may reduce the resilience of C 3 plants in an increasingly warming world. Earth and environmental sciences/Environmental sciences Biological sciences/Plant sciences/Plant physiology Biological sciences/Plant sciences/Plant stress responses/Heat Leaf gas exchange stable isotopes isotope fractionation carbon balance VPD leaf water Full Text Additional Declarations No competing interests reported. Supplementary Files HotandHungrySupplementaryFiguresandTablesnpjScienceofPlants.pdf Cite Share Download PDF Status: Published Journal Publication published 30 Nov, 2025 Read the published version in npj Science of Plants → Version 1 posted Editorial decision: Revision requested 06 Jul, 2025 Reviews received at journal 30 Jun, 2025 Reviewers agreed at journal 23 May, 2025 Reviewers agreed at journal 06 Apr, 2025 Reviews received at journal 06 Apr, 2025 Reviewers agreed at journal 11 Mar, 2025 Reviewers agreed at journal 11 Mar, 2025 Reviews received at journal 07 Feb, 2025 Reviewers agreed at journal 20 Jan, 2025 Reviewers agreed at journal 05 Dec, 2024 Reviewers invited by journal 05 Dec, 2024 Editor assigned by journal 05 Dec, 2024 Submission checks completed at journal 04 Dec, 2024 First submitted to journal 23 Nov, 2024 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-5509630","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":389203566,"identity":"af1b4fce-379f-40c3-957e-5d614bbe210a","order_by":0,"name":"Philipp 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