Aerial and underground organs display specific metabolic strategies to cope with water stress under rising atmospheric CO₂ in Fagus sylvatica L.

Abstract

Beech is known to be a moderately drought‐sensitive tree species, and future increases in atmospheric concentrations of CO2 ([CO2]) could influence its ecological interactions, also with changes at the metabolic level. The metabolome of leaves and roots of drought‐stressed beech seedlings grown under two different [CO2] (400 (aCO2) and 800 (eCO2) ppm) was analyzed together with gas exchange parameters and water status. Water stress estimated from predawn leaf water potential (Ψpd) was similar under both [CO2], although eCO2 had a positive impact on net photosynthesis and intrinsic water use efficiency. The aerial and underground organs showed different metabolomes. Leaves mainly stored C metabolites, while those of N and P accumulated differentially in roots. Drought triggered the proline and N‐rich amino acids biosynthesis in roots through the activation of arginine and proline pathways. Besides the TCA cycle, polyols and soluble sugar biosynthesis were activated in roots, with no clear pattern seen in the leaves, prioritizing the root functioning as metabolites sink. eCO2 slightly altered this metabolic acclimation to drought, reflecting mitigation of its effect. The leaves showed only minor changes, investing C surplus in secondary metabolites and malic acid. The TCA cycle metabolites and osmotically active substances increased in roots, but many other metabolites decreased as if the water stress was dampened. Above‐ and belowground plant metabolomes were differentially affected by two drivers of climate change, water scarcity and high [CO2], showing different chemical responsiveness that could modulate the tree adaptation to future climatic scenarios.

An outline on the chemical phenotype flexibility of forest species: an eco-metabolomics study of Pinus uncinata along an altitudinal gradient

“…The tricarboxylic acid (TCA) cycle is central and a mechanistic understanding of the impacts of abiotic stress, such as drought, on their regulation and dynamics is still deficiently described (Fàbregas and Fernie, 2019). We did not find clear increases of fumaric, malic, oxaloacetic, aconitic, and succinic acids in Low-pines, which have been commonly associated with drought stress (Ashrafi et al, 2018;Fernández de Simón et al, 2022;Sardans et al, 2020;Urano et al, 2009). Citric acid (CA), on the other hand, was found upregulated in Low-pines (Fig.…”

Water and Carbon Dynamics, Ecosystem Stability of Forest and Grassland in Response to Climate Change

“…Plants through newly absorbed C and stored NSC provide growth and other physiological functions such as respiration, osmoregulation, and defense mechanisms (Hartmann and Trumbore, 2016;Gersony et al, 2020;Trowbridge et al, 2021;. At the same time, NSC is an important reserve substance that can be used in stressful environments , such as drought, warming, and excessive CO 2 Fernańdez de Simoń et al, 2022). The NSC can reflect the C equilibrium status of the plants when grown in a negative environment.…”

Variations in Proline Content, Polyamine Profiles, and Antioxidant Capacities among Different Provenances of European Beech (Fagus sylvatica L.)

“…Due to its antioxidant potential and chaperone and osmoprotective activities, proline is undoubtedly one of the most studied osmolytes related to abiotic stress in plants [22,23]. Increased resistance to various abiotic stressors, including heat [24], drought [25], or a combination of heat and drought [26], or drought and rising CO 2 [27], as well as the presence of heavy metals [28,29] or xenobiotics [30] in various woody plant species, has been linked to increased endogenous proline levels. As a multifunctional amino acid, proline not only helps plants adapt to a variety of biotic and abiotic stressors, but it also functions as a signaling molecule that controls gene expression and plant development, modifies redox balance, and modulates defense against pathogens [23].…”