Work

Hot and Hungry - High temperatures induce changes in leaf carbon dynamics and sugar isotope fingerprints

Year: 2025

Type: article

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.

Source: npj Science of Plants

DOI: 10.1038/s44383-025-00012-6