Background and AimsGlobal climate change is intensifying the co-occurrence of abiotic stresses, particularly combined waterlogging/submergence and salinity, posing severe and escalating threats to woody plant ecosystems critical for biodiversity, carbon storage, and soil stabilization. Despite extensive research on herbaceous species, understanding of woody plant responses remains fragmented and disproportionately focused on specific groups like mangroves and halophytes. This review aims to synthesize and critically evaluate the current state of knowledge on the integrated physiological, morphological, and molecular responses of diverse woody plants to this challenging combined stress scenario.MethodsA comprehensive synthesis and analysis of existing scientific literature was conducted. This involved systematically examining empirical studies, comparative analyses, and theoretical frameworks related to the responses of various woody plant species to the concurrent application of waterlogging/submergence and salinity stress, drawing comparisons to single-stress effects and herbaceous model systems.ResultsThe majority of woody plants exhibit synergistic, more detrimental effects under combined stress compared to either stress alone. Key manifestations include significantly heightened inhibition of photosynthesis, severe disruption of ion (particularly Na+ and Cl-) homeostasis leading to toxicity, and exacerbated oxidative damage. Woody plants utilize core stress tolerance mechanisms analogous to herbaceous species, such as ion exclusion/compartmentalization, activation of enzymatic and non-enzymatic antioxidant systems, and osmotic adjustment via compatible solute accumulation. Crucially, they also deploy distinctive structural and long-term adaptive strategies, including the development of specialized organs (pneumatophores, hypertrophic lenticels), deep root systems for accessing less saline groundwater, and physiological acclimation processes leveraging their perennial nature. Nevertheless, critical knowledge gaps persist, particularly concerning the underlying molecular signaling networks, the mechanisms of long-term adaptation over years/decades, and the specific responses of mature trees in natural ecosystems.ConclusionSignificant gaps hinder a comprehensive understanding of how woody plants cope with combined waterlogging/submergence and salinity stress. To advance fundamental knowledge and inform effective ecological restoration strategies for climate-resilient landscapes, future research must prioritize the application of integrated multi-omics approaches (genomics, transcriptomics, proteomics, metabolomics), the development of high-efficiency genetic transformation techniques for recalcitrant woody species, the deployment of advanced high-throughput phenotyping platforms, and crucially, long-term field-based studies simulating realistic future stress scenarios.

Ascorbic acid (ASC) is a molecule naturally synthesized in plant cells, protecting against abiotic stresses by reducing reactive oxygen species (ROS), which cause oxidative damage. Aluminum (Al) toxicity is the major limiting factor on crop productivity in acidic soils, increasing ROS within cells and impairing the growth and development of plants. Exogenous antioxidant applications are an effective strategy to promote tolerance to abiotic stress. The objective was to evaluate the effect of foliar ASC applications (0, 50, 100, 200, and 400 mg L-1 ASC) and their interaction with Al toxicity (0, 400 mu M Al) in Star, an Al-sensitive cultivar of highbush blueberry. Significant increases of 1.6-fold in growth were observed in roots and leaves under treatment with 200 mg L-1 ASC. In the same treatment, increased pigments and antioxidant activity (similar to 1.2- to 2.3-fold) were observed concomitant with reduced lipid peroxidation. Positive correlations between organic acid exudation, the ASC/DHA ratio, and calcium levels were observed, whereas a negative correlation between lipid peroxidation and dehydroascorbate (DHA) was observed. Foliar ASC application also increased the ASC/DHA ratio in leaves and enhanced 2.2-fold organic acid exudation in the 200 mg L-1 ASC treatment. The results suggest that foliar ASC applications improved redox balance and underscore the potential of ASC as a practical solution to enhance resilience in Al-sensitive plants.

Woody plants have received considerable attention for the phytoremediation of heavy metal-contaminated soil. This study aimed to investigate the changes in antioxidant enzyme activity, macroelement uptake and microstructure of the woody plant Robinia pseudoacacia (black locust) for the phytoremediation of cadmium (Cd) and lead (Pb) co-contaminated soil based on dynamic sampling. The results show that black locust demonstrates strong tolerance in Cd and Pb co-contaminated soil. After 30-120 days of cultivation, the activities of superoxide dismutase, peroxidase and the macroelement (potassium [K] and calcium [Ca]) content in plant leaves significantly declined in response to Cd and Pb. However, after 160 d of cultivation, the antioxidant enzyme activities, chlorophyll, sulfhydryl and soluble protein contents, as well as Ca and magnesium content in plant leaves were returned to normal levels under the 40 mg kg(-1) Cd and 1000 mg kg(-1) Pb contaminated soil (CdPb3). Meanwhile, K content in plant leaves under the CdPb3 treatment was significantly (P < 0.05) increased by 68.9% compared with the control. Cadmium and Pb were primarily accumulated in black locust roots. Scanning electron microscope analysis indicated that the sieve tubes in the roots and stems of plant might block the transport of Cd and Pb. Transmission electron microscope analysis indicated that the number and volume of osmiophilic particles in plant leaves were increased and the cell walls were thickened in response to Cd and Pb stress. Path analysis further indicated that the growth of plant was related to macroelements uptake and physiological change (photosynthesis, antioxidant enzyme activity and chelation). Thus, black locust could effectively regulate the antioxidant defense system, macroelement absorption and microstructure to enhance plant tolerance to Cd and Pb stress. Moreover, black locust could maintain the normal urease, acid phosphatase and sucrase activities in the Cd and Pb co-contaminated soil. These findings suggest that black locust could be considered as a useful woody plant for the phytostabilization in Cd- and Pb-contaminated soil.

Belowground assemblages are closely related to the aboveground vegetation and edaphic properties, which are also driven by dominant plants due to direct and indirect influences. However, the effects of dominant woody plants on the belowground organisms along successional gradients remain poorly understood. Plant and soil samples were collected from an initial herbaceous stage (i.e. alpine meadows) and four stages dominated by woody species, beneath and between patches of the dominant woody plants, to assess the effects of dominant woody plants on the succession of microbial communities along a secondary successional gradient. We quantified herbaceous, edaphic, bacterial, and fungal dissimilarities between stages to explore how dominant woody plants affect bacterial and fungal dissimilarities between stages using structural equation modeling. We found that dominant woody plants generally increase the succession of microbial communities in early stages, but decrease it in late stages. Our results further suggest that the herbaceous dissimilarity between stages plays more important roles than the edaphic one in mediating the effect of dominant woody plants on both bacterial and fungal dissimilarities between stages. Our results provide insight into the relative role of direct and indirect influences on microbial dissimilarity between stages and highlight the importance of dominant woody plants in driving microbial succession. As woody encroachment increases in alpine meadows, the dominant woody plants may have strong consequences on the dynamic of microbial communities, thereby affecting ecosystem functioning.