Global climate change has increased the severity and frequency of abiotic stresses, posing significant challenges to the survival and growth of woody plants. Non-structural carbohydrates (NSCs), including starch and sugars, play a vital role in enabling plants to withstand these stresses, helping to stabilize cellular functions by buffering plant energy demands and facilitating recovery on the alleviation of stress. Despite the recognized multiple functions of NSCs, the contrasting effects of multiple abiotic stresses on NSCs dynamics in woody plants remain poorly understood. This review aims to explore the current knowledge of the contrasting effects of abiotic stress conditions including drought, salinity, heat, water logging, and cold on NSCs dynamics. The roles of NSCs in regulating stress-resilience responses in woody plants are also discussed, along with the challenges in NSC measurement, and options for future research directions are explored. This review is based on comprehensive literature research across different search engines like Scopus, Web of Science, and Google Scholar (2000–2024) using targeted keywords. This study compiles the current research on NSCs functions and provides insights into the adaptive strategies of woody plants in response to changing climate conditions, providing groundwork for future research to improve stress tolerance in woody plants.

Direct-seeded rice offers multiple advantages, including lower labour costs and a reduced CO2 footprint. However, the risk of flooding during germination and at the early seedling and vegetative stages is high. Therefore, the capacity for anaerobic germination in waterlogged soils, as well as tolerance to partial and complete submergence, are both essential. It remains unclear whether anaerobic germination and flood tolerance are linked or if they act independently in the environment. Therefore, it is timely to investigate the relationship between these two traits in the context of progressing climate change. We investigated the submergence tolerance of 4-week-old plants of three African landraces, which had previously been shown to possess anaerobic germination capacity. Additionally, we included one submergence-sensitive check and two tolerant checks. These six genotypes were evaluated at three time points: initially (prior to submergence), after three days of submergence, and at the time of desubmergence following 29 days of submergence. We measured survival, key photosynthetic traits (leaf gas films, underwater net photosynthesis, chlorophyll concentration), and carbohydrate reserves. We found that the African landraces tolerant to anaerobic germination all outlived the submergence-sensitive check, ‘IR42,’ during 29 days of complete submergence. Moreover, all tested genotypes exhibited significant declines over the 29 days of submergence in gas film thickness, underwater net photosynthesis, leaf chlorophyll concentration, and leaf water-soluble carbohydrates and starch. However, no significant differences were observed among the genotypes. The underlying mechanisms of anaerobic germination tolerance in the three African landraces remain unknown, as they do not possess the gene Anaerobic Germination 1 (AG1). Furthermore, it is unclear whether the three genotypes contain the gene Submergence 1 (SUB1); however, SUB1 confers submergence tolerance only and does not provide tolerance to anaerobic germination. Based on the present study, we cannot rule out the possibility that the novel anaerobic germination tolerance observed in the three African landraces is somehow linked to submergence tolerance as well. A thorough bioinformatic analysis is therefore needed to further characterize these landraces.

Plant roots are exposed to hypoxia in waterlogged soils, and they are further challenged by specific phytotoxins produced by microorganisms in such conditions. One such toxin is hexanoic acid (HxA), which, at toxic levels, causes a strong decline in root O₂ consumption. However, the mechanism underlying this process is still unknown. We treated pea (Pisum sativum L.) roots with 20 mM HxA at pH 5.0 and 6.0 for a short time (1 h) and measured leakage of key electrolytes such as metal cations, malate, citrate and nonstructural carbohydrates (NSC). After treatment, mitochondria were isolated to assess their functionality evaluated as electrical potential and O₂ consumption rate. HxA treatment resulted in root tissue extrusion of K⁺, malate, citrate and NSC, but only the leakage of the organic acids and NSC increased at pH 5.0, concomitantly with the inhibition of O₂ consumption. The activity of mitochondria isolated from treated roots was almost unaffected, showing just a slight decrease in oxygen consumption after treatment at pH 5.0. Similar results were obtained by treating the pea roots with another organic acid with a short carbon chain, that is, butyric acid. Based on these results, we propose a model in which HxA, in its undissociated form prevalent at acidic pH, stimulates the efflux of citrate, malate and NSC, which would, in turn, cause starvation of mitochondrial respiratory substrates of the Krebs cycle and a consequent decline in O₂ consumption. Cation extrusion would be a compensatory mechanism in order to restore plasma membrane potential.

Forest restoration programs are increasingly adopted to mitigate climate change-driven ecosystem degradation, yet the plant functional strategies underpinning successful tree establishment are not fully understood. We investigated the effect of vapour pressure deficit and soil conditions on the interplay between leaf gas exchange and carbon metabolism in three-year-old saplings of different species characterised by distinct functional strategies, as well as non-structural carbohydrate (NSC) partitioning at plant desiccation. We performed two complementary experiments to evaluate interspecific functional differences between Fraxinus ornus L., Quercus cerris L., and Quercus pubescens Willd. in a Mediterranean restored woodland and to compare them with fully irrigated nursery conspecifics. Stomatal sensitivity to closure was similar between species, whereas higher leaf gas exchange and reduced leaf shedding increased twig sugars, as in the case of F. ornus, likely contributing to its better establishment. Irrigation augmented gas exchange rates in potted saplings under moderate evaporative demand but overall did not increase NSCs compared with outplanted conspecifics, possibly because of different carbon demand. Desiccated saplings maintained substantial NSCs, but their reduced pools, especially starch, suggested that they were consumed as a response to drought. Overall, findings indicate that NSC allocation can help define proxies of plant performance in restoration programs.

Drought induces the accumulation of osmolytes, including soluble non‐structural carbohydrates (NSC), to support osmotic adjustment and hydraulic recovery. Bark has been proposed as a major site of sugar storage, with stem photosynthesis potentially contributing to NSC production and drought responses. Some species also accumulate polyols, such as mannitol, often linked to membrane protection. However, the allocation of carbon compounds among plant organs during drought and recovery remains unclear. In this study, Fraxinus ornus saplings were exposed to stem shading, followed by drought and recovery to investigate the single and combined effects of these factors on NSC allocation in bark, wood, and roots. Hydraulic parameters were measured alongside concentrations of glucose, fructose, sucrose, starch, and mannitol under well‐watered, drought, and recovery conditions. Stem shading increased xylem vulnerability to embolism and reduced glucose concentration in stems and roots, while other sugars and mannitol were unaffected. Drought triggered starch degradation and increased hydraulic conductance loss, regardless of light treatment. Sucrose concentration increased in bark and roots, especially in non‐shaded plants, whereas mannitol increased mainly under combined drought and shading. During recovery, sucrose declined, whereas mannitol remained elevated. Our results indicate that carbon partitioning in F. ornus is strongly affected by drought and influenced by stem shading. Root sucrose appears central to whole‐plant osmotic adjustment but is sensitive to shading. Mannitol, likely sustained by starch degradation, may instead support osmotic adjustment during recovery, representing a more carbon‐efficient osmolyte.