Search Results (110)

Sustaining rice productivity under the dual constraints of freshwater scarcity and low-temperature stress represents a pressing challenge for high-latitude japonica rice systems worldwide. There is an urgent need to develop coupled irrigation–agronomic management strategies that jointly safeguard yield stability and water use efficiency (WUE) in cold-region rice production. In this study, a two-year field experiment was conducted in 2024–2025 on albic soil (Albic Luvisols, WRB; θfc 38.2% v/v, pH 5.80, clayey texture with poor permeability and a propensity for subsurface waterlogging) in the Sanjiang Plain, Heilongjiang Province, China (47°15′ N, 133°28′ E), with nine coupled “irrigation regime × auxiliary practice” treatments, comprising conventional continuous flooding, four-level controlled irrigation (CI) at lower thresholds of 60%, 70%, 75%, and 80% θfc, and their combinations with film mulching (FM) or a humic-acid-based soil amendment (SA). An interpretable machine-learning diagnostic framework was developed, with elastic net (EN) as the primary analytical model and random forest (RF) as a nonlinear control, to simultaneously identify core yield predictors and outlier treatments. The principal findings were: (i) The soil-amendment-coupled 75% θfc CI treatment (SACI) increased grain yield by 12.3% and reduced water input by 17.0% relative to conventional continuous flooding, with WUE reaching 1.801 kg m⁻³, a 35.3% gain over the control (p < 0.05); these improvements were consistent across both individual years (year × treatment interaction: p = 0.601; inter-year rank correlation ρ = 0.967). Lowering the CI threshold below 75% θfc significantly reduced grain yield through diminished effective-panicle retention. (ii) Multi-method consensus analysis (Kendall’s W = 0.871, p < 0.01) identified root volume at the milk stage as the most strongly and consistently associated statistical predictor of yield formation, with convergent mechanistic support from independent rhizosphere evidence (Eh, TTC reductive activity). Definitive causal validation awaits isotope-tracing experiments. (iii) The film-mulching × continuous-flooding treatment (FMCG) was diagnosed as a yield-response outlier (permutation test p = 0.003), three in situ rhizosphere measurements (redox potential, root TTC-reducing activity, and rhizosphere temperature) supported the proposed mechanism of hot–anoxic rhizospheric inhibition. Methodologically, this study develops a four-level evidence convergence framework that integrates intra-model self-consistency, cross-model (EN vs. RF) consensus, independent rhizosphere evidence, and distribution-free permutation testing, with Jackknife+ conformal prediction and companion Monte Carlo simulations (1000 replicates) used to quantify the reliability boundaries under small-sample conditions (n = 27). These findings provide an evidence-based irrigation–soil co-management strategy for cold-region rice production in Northeast China, and the proposed diagnostic paradigm offers a generalizable, reliability-quantified methodological template for interpretable small-sample modeling in multifactorial coupled field experiments. Full article

The role of endogenous salicylic acid (SA), a major signaling molecule, was addressed in relation to the waterlogging (WL) stress response, including redox homeostasis and senescence. Wild-type and salicylate hydroxylase-expressing (NahG) tobacco plants were studied to reveal the stress-related effects of the transgene, which is known to deplete the endogenous SA pool. In control conditions, SA levels of the top leaves of NahG plants were moderately lower than those of wild-type, while SA was considerably reduced in the bottom leaves. WL conditions triggered a rise in H₂O₂ concentrations in young leaves, which was exaggerated in NahG plants, pointing to a mitigating effect of SA against the stress-associated oxidative burden. The NahG transgenic leaves displayed lower protein levels than their wild-type counterparts, indicating a role of SA in protein retention. In non-stressed NahG plants, young (top) leaves showed an increased level of protein nitration. WL treatment triggered decreased protein contents in the leaves of both genotypes. This coincided with the high H₂O₂ content of old leaves exceeding that of young leaves in most cases. The expression of the senescence marker gene Cysteine protease 1 was upregulated in WL-stressed bottom leaves. According to this marker, senescence progressed faster in NahG leaves. Links between SA, protein nitration, and leaf senescence were discussed. Additionally, a stimulating effect of the NahG transgene was confirmed on adventitious roots (AR) formation, which may have helped root functions and thus probably contributed to maintaining the growth of the WL-stressed plants. Our results have implications for how endogenous SA levels influence plants in a WL stress situation. According to our findings, the depletion of SA may trigger protein loss and tyrosine nitration, but at the same time accelerates AR formation in WL-stressed tobacco. Full article

Plants adapt to abiotic stresses by a variety of physiological and molecular mechanisms, among which the root plays important roles via responding to underground and soilborne signals. Fructan is a polysaccharide involved in energy metabolism and stress adaptation. Orobanche cumana is a holo-parasitic plant that mainly attaches to the root of the host sunflower (Helianthus annuus). Oc6-FEH, a fructan 6-exohydrolase from O. cumana, is involved in both fructan metabolism and flooding responses. Expression of Oc6-FEH is induced by flooding and indole-3-acetic acid (IAA). Oc6-FEH possesses fructan catabolism activity and is associated with fructose release. Overexpression of Oc6-FEH in the host sunflower reduces malondialdehyde (MDA) and hydrogen peroxide (H₂O₂) accumulation, boosts the activities of antioxidant enzymes, including peroxidase (POD) and superoxide dismutase (SOD), and enhances photosynthetic performance. The expression level of Oc6-FEH was found to be positively associated with the flooding tolerance of invading O. cumana, which is connected to the host root. Furthermore, IAA treatment also improved the flooding tolerance of O. cumana. In summary, the metabolism of fructan and the activity of Oc6-FEH were demonstrated to ameliorate waterlogging stress. Oc6-FEH provides a promising genetic target for the improvement of flooding tolerance in crops. Full article

Precipitation is a fundamental element in terrestrial water circulation and ecosystem hydrological balance. The occurrence of concentrated precipitation is closely linked to vegetation growth and soil fertility rather than accumulated or averaged precipitation. Despite its importance, the characteristics of continuous precipitation and its specific effects on vegetation cover remain uncertain. In this study, we formulated a new continuous precipitation index system, including $C{P}_d$ (continuous precipitation days); $AC{P}_t$ (annual continuous precipitation times); $C{P}_a$ (continuous precipitation amount); and $FCP$ (frequency in different ranges of $AC{P}_a$). We utilized daily precipitation data from 467 meteorological stations across China, which were divided into eight vegetation type regions. We observed that the spatial distribution of continuous precipitation differed to varying degrees from accumulated precipitation. The national average of $MAC{P}_a$ for a single event was 16.7 mm, ranging from 3.8 mm in the temperate desert region to 37.1 mm in the tropical monsoon forest and rainforest region. Similarly, the national average of $MC{P}_d$ ($MMC{P}_d$) for a single event was approximately 2.3 or 9 days. At the regional level, the tropical monsoon forest and rainforest region experienced the longest $MMC{P}_d$. Furthermore, the national average of $MAC{P}_t$ occurrences for 1 year was 57.7 times, varying from 29.8 times in the temperate desert region to 77.9 times in the tropical monsoon forest and rainforest region. Vegetation responses to precipitation regimes exhibit significant regional heterogeneity across China. Our analysis reveals that $MAC{P}_t$ and $M{P}_a$ show markedly positive correlations with vegetation growth. In subtropical monsoon climate zones, particularly the Yunnan–Guizhou Plateau and Qinling Mountains, $MAC{P}_t$ demonstrates strong positive correlations (r = 0.6–1.0) with NDVI, where sustained rainfall provides stable moisture availability for vegetation. While a positive correlation between vegetation (NDVI) and mean annual consecutive precipitation is observed in some arid northern regions, in ecosystems such as the Loess Plateau (TG/TM), vegetation growth shows greater dependence on $M{P}_a$, highlighting the crucial role of total precipitation amount in water-limited ecosystems. Notably, extreme precipitation events display dual effects on vegetation dynamics. Prolonged heavy rainfall ($MMC{P}_d$/$MMC{P}_a$) exhibits significant negative impacts on NDVI (r = −1.0 to −0.6) in topographically complex regions, including the Hengduan Mountains and Yangtze River Basin (SE), likely due to induced soil erosion and waterlogging stress. Our findings underscore the importance of incorporating continuous precipitation indices to evaluate and forecast the influence of precipitation on ecosystem stability. This understanding is vital for developing informed conservation and management strategies to address current and future climate challenges. Full article

Masson Pine (Pinus massoniana), an important afforestation species in southern China, is severely threatened by pine wilt disease caused by pine wood nematode (Bursaphelenchus xylophilus, PWN). To differentiate mortality induced by B. xylophilus from that caused by abiotic environmental factors, hyperspectral imaging and needle chlorophyll content were measured and analyzed for the early detection physiological changes in Masson pine seedlings under various environmental stressors. Four-year-old Masson pine seedlings were subjected to PWN inoculation, mechanical injury, drought, and waterlogging treatments. Hyperspectral reflectance and needle chlorophyll content of Masson pine were measured concurrently at 7-day intervals. The results showed that hyperspectral imaging responses varied among the stressors. Both PWN and waterlogging stress induced rapid mortality, with spectral changes observed as early as the 3rd week and reaching statistical significance by the 5th week. Under PWN infection, hyperspectral reflectance increased markedly in the 405–580 nm range, accompanied by a pronounced blue-shift of the red edge position (680–750 nm), while needle chlorophyll content declined sharply from approximately 0.8 mg g⁻¹ to 0.48 mg g⁻¹. Waterlogging stress produced a uniform increase in reflectance within the 500–580 nm range, with the hyperspectral curve gradually flattening, and needle chlorophyll content decreasing from 0.75 mg g⁻¹ to 0.6 mg g⁻¹. Conversely, drought-stressed seedlings exhibited only minor hyperspectral changes and maintained relatively stable chlorophyll levels, demonstrating the inherent drought tolerance of Masson pine. The RF and XGBoost models performed best in fitting the entire process of pine wood nematode infection and waterlogging stress, with all R² values greater than 0.69. The distinct hyperspectral imaging patterns under nematode infection and water-related stresses provide a reliable basis for early diagnosis and monitoring pine wilt disease in Masson pine stands. Full article

Pyruvate decarboxylase (PDC) is an intracellular non-oxidizing enzyme that relies on thiamine pyrophosphate (TPP), which is important for plant survival under anaerobic conditions and increasingly recognized for its role in broader stress reaction. However, the PDC gene family of tomato (Solanum lycopersicum), an important waterlogging-sensitive agricultural product, has not yet been discovered. In this study, eight SlPDC genes were discovered within the tomato genome. Gene structure analysis revealed that SlPDC members exhibited varying intron–exon configurations, with SlPDC8 possessing the most complex structure containing seven introns. Promoter analysis revealed a multitude of cis-acting elements responsive to light, hormones, and various stresses. Particularly, the promoter of SlPDC8 contains both ABRE and TGACG/CGTCA-motif. Tissue-specific expression profiles showed that SlPDC8 was mainly highly expressed in the roots. Expression profiling demonstrated that SlPDC genes respond divergently to different abiotic stresses, including salt, hydrogen peroxide (H₂O₂), drought, waterlogging, cold, heat, darkness, and UV radiation stresses. Notably, SlPDC1, SlPDC7, and SlPDC8 were significantly upregulated by waterlogging, with SlPDC8 showing the most robust induction. Functional validation through VIGS proved that SlPDC8-silenced plants exhibited significantly impaired growth, decreased photosynthetic pigment content, severe leaf wilting, and poor root development under waterlogging conditions compared to control plants. Furthermore, silencing SlPDC8 led to increased malondialdehyde (MDA) levels and decreased antioxidant enzyme activities, indicating heightened oxidative damage under waterlogging stress. We conclusively demonstrate that SlPDC8 plays a critical positive regulatory role in waterlogging tolerance by maintaining cellular homeostasis and enhancing antioxidant capacity. Full article

As climate change continues to alter rainfall patterns and precipitation regimes across the globe, waterlogging is emerging as a widespread and pressing issue that threatens agricultural productivity and food security. In this study, we investigated the potential of humic substances to mitigate waterlogging stress in cabbage (Brassica oleracea L.) seedlings. Specifically, humic acid and fulvic acid solutions were applied to the growth medium at weekly intervals both before and after a 10-day waterlogging period. The effects of humic acid and fulvic acid applications on waterlogging-induced stress were evaluated through various physiological and biochemical parameters, including shoot fresh weight, root fresh weight, shoot dry weight, root dry weight, plant height, stem diameter, chlorophyll a, chlorophyll b, total chlorophyll, proline, malondialdehyde, hydrogen peroxide, indole acetic acid, gibberellic acid, abscisic acid, and antioxidant enzyme activities including catalase, peroxidase, and superoxide dismutase. The results indicated that waterlogging stress significantly impaired plant growth parameters, but these adverse effects were mitigated by humic acid and fulvic acid applications. The humic substances contributed to stress tolerance by modulating key biochemical responses, including a shift in proline, hydrogen peroxide, malondialdehyde, abscisic acid, and antioxidant enzyme activity levels, which otherwise increased under stress conditions. Furthermore, the decline in indole acetic acid and gibberellic acid content due to waterlogging was alleviated by humic acid and fulvic acid treatments. Overall, the findings suggest that humic acid and fulvic acid can effectively reduce the detrimental effects of waterlogging stress in cabbage seedlings, demonstrating their potential as biostimulants with comparable protective effects. Full article

Plants living in wetland environments (hydrophytes) have developed metabolic adaptations to cope with hypoxia. However, the specific metabolic signatures underlying this adaptation in naturally occurring hydrophytes, compared to their mesophytic relatives, remain insufficiently explored. GC-MS was used to carry out a comparative metabolic profiling of leaves from two pairs of closely related species (the hydrophytes Iris pseudacorus and Comarum palustre versus the mesophytes I. sibirica and Argentina anserina). In total, approximately 260 compounds were detected, of which roughly 100 were annotated. Using Principal Component Analysis, we revealed that the primary source of metabolic variation was phylogenetic (genus/tribe affiliation), while a secondary gradient correlated with ecological adaptation to submergence. A common adaptive metabolic signature of hydrophytes was identified, including the accumulation of dicarboxylic acids from Krebs cycle (succinate, fumarate) and glycolytic metabolites (pyruvate), suggesting a restructuring of energy metabolism under oxygen deficiency. Furthermore, hydrophytes, particularly I. pseudacorus, accumulated higher levels of soluble sugars (sucrose, fructose, glucose) and amino acids, thereby supporting energy supply and alternative NAD(P)H reoxidation pathways. Species-specific differences in the accumulation of antioxidants (e.g., flavonoids, ascorbate) were also observed, indicating diverse strategies for managing oxidative stress. Our findings contribute to identifying a “metabolic fingerprint” associated with waterlogging tolerance. Full article

Water and nitrogen supply are key factors limiting the establishment of alpine plant seedlings and the efficiency of ecological restoration on the Tibetan Plateau. As an endemic shrub to Tibet, the morphological and physiological response mechanisms of Piptanthus nepalensis (Hook.) D. Don to coupled water and nitrogen stress remain poorly understood. This study employed a pot experiment with a completely randomized two-factor design, incorporating five water gradients (0–100% field capacity, FC) and five nitrogen levels (0–4 g·plant⁻¹ urea). The aim was to elucidate the regulatory mechanisms of water/nitrogen coupling on Piptanthus nepalensis growth, physiology, and morphogenesis. The results indicated the following: (1) A significant water/nitrogen coupling effect was observed, with optimal water/nitrogen combinations producing pronounced synergistic effects. Principal component analysis (PCA) revealed that the first two axes cumulatively explained 99.32% of the morphological variation. The W3N3 treatment (40–60% FC water + 2 g·plant⁻¹ nitrogen) exhibited optimal growth traits and maximum leaf elongation, establishing the optimal water and fertilizer management threshold for this species. (2) Confronted with two starkly contrasting stresses—drought (W4, W5) and waterlogging (W1)—plants adopted convergent “conservative” morphological adaptation strategies (significantly reduced leaf length and width) to lower metabolic expenditure. (3) Photosynthetic physiological analysis revealed that under extreme water deficiency (W5) or waterlogging (W1) stress, intercellular CO₂ concentration (Ci) paradoxically increased, indicating a shift in photosynthetic suppression mechanisms from stomatal limitation to non-stomatal limitation (metabolic injury). (4) The Mantel Test confirmed that photosynthetic physiological traits significantly drove morphological trait variation (p < 0.001), establishing a close feedback loop between “physiological function and morphological structure”. Conclusions: Moderate water deficit (40–60% FC) combined with moderate nitrogen fertilization (2 g·plant⁻¹) effectively alleviates non-stomatal limitation and releases morphological constraints, thereby promoting rapid growth in Piptanthus nepalensis. This study reveals the phenotypic plasticity and convergent adaptation mechanisms of Piptanthus nepalensis under water/nitrogen co-stress, providing precise water and fertilizer management guidelines for vegetation restoration in degraded ecosystems of Tibet. Full article

WRKY transcription factors play critical roles in plant growth, development, metabolism, and stress responses. In this study, we performed the first genome-wide characterization of the WRKY gene family in Bupleurum chinense, using a T2T-level assembly of the autotetraploid genome. A total of 303 BcWRKY genes were identified and found to be unevenly distributed across four subgenomes. Phylogenetic and structural analyses revealed that segmental duplications after polyploidization drove lineage-specific expansion of the family. Meta-transcriptome analysis demonstrated that BcWRKY genes exhibited tissue-specific expression patterns and dynamic responses to stress, suggesting functional diversification. Under drought, waterlogging, methyl jasmonate, and ABA treatments, the contents of saikosaponins A and D significantly increased. This increase was accompanied by transcriptional activation of multiple BcWRKY genes. Correlation analysis between ten BcWRKYs and ten saikosaponins biosynthetic associated genes (BcBASs, BcCYPs, and BcUGTs) identified BcWRKY22, BcWRKY33, and BcWRKY46 as potential regulators of saikosaponin metabolism under stress conditions. Our study provided a comprehensive framework for understanding BcWRKY gene evolution and secondary metabolic regulation in polyploid medicinal plants. It also offered candidate genes for breeding B. chinense cultivars with high saikosaponin content. Full article

Barley (Hordeum vulgare L.) is resistant to salt, drought and low temperature stress but sensitive to waterlogging stress. For now, little is known in waterlogging stress about the molecular mechanisms underlying the regulation of hormonal pathways in barley roots. In this study, the effects of waterlogging stress on 33 genotypes during the whole growth stages were comprehensively assessed. Then, the root morphology, hormone content and relative root development gene expressions were investigated in the most waterlogging-sensitive and -tolerant genotypes. We found waterlogging-tolerant genotypes (four representative genotypes) increased root length, forks, surface and project area traits at the early stage of waterlogging stress; meanwhile, these root traits were reduced in waterlogging-sensitive genotypes (four representative genotypes) because of ABA and ethylene inhibition. Furthermore, waterlogging-tolerant barley genotypes, respectively, induced and inhibited the positive (TCP20 and PLT2) and negative (SHY2 and PILS2) regulated gene’s expressions that controlled the meristem growth at the root tips to cope with waterlogging stress. In addition, our results were consistent with the hypothesis that waterlogging-tolerant barley genotypes can simultaneously upregulate GA levels and downregulate ethylene accumulation, which may induce the expression of SHR and SCR genes and enhance root growth under waterlogging stress. This research lays a foundation for the subsequent screening and breeding of waterlogging-tolerant genotypes and the exploration of waterlogging-tolerant mechanisms in barley. Full article

Waterlogging is a major abiotic stress that restricts plant growth, productivity, and survival by disrupting root aeration and altering hormonal homeostasis. To elucidate the physiological and molecular responses associated with flooding tolerance in Liriodendron hybrids (Liriodendron chinense × Liriodendron tulipifera), this study investigated its morphological, physiological, and transcriptomic changes under 0, 1, 3, and 6 days of waterlogging. Roots exhibited rapid decay, while leaves showed delayed chlorosis and reduced chlorophyll content. Changes in antioxidant enzyme activities reflected enhanced antioxidant capacity, with superoxide dismutase (SOD) activity decreasing and peroxidase (POD) and catalase (CAT) activities increasing. Hormone measurements indicated organ-specific patterns, including abscisic acid (ABA) accumulation in leaves and decreased indole-3-acetic acid (IAA) and gibberellin (GA) levels in both roots and leaves. Transcriptome profiling revealed extensive transcriptional adjustments in hormone biosynthesis, signaling, and stress-responsive pathways, including divergent regulation of ABA-associated genes in leaves and roots and broad downregulation of auxin- and gibberellin-related genes. Key ABA biosynthetic genes (NCED1, ABA2) and signaling components (PYL4, PP2C, ABF) were upregulated in leaves but downregulated in roots, whereas auxin (YUC6) and gibberellin (GA20ox) genes were generally suppressed. These coordinated physiological and molecular responses suggest organ-differentiated adaptation to waterlogging in Liriodendron hybrids, highlighting candidate pathways and genes for further investigation and providing insights for improving flooding tolerance in woody species. Full article

Autophagy is an evolutionarily conserved cellular process that maintains homeostasis by degrading intracellular materials. Numerous studies have investigated the role of autophagy-related genes (ATGs) in plant adaptation to abiotic stresses. In plants, hypoxia (e.g., flooding events, oxygen supply during growth) rapidly activates the autophagy pathway as a protective mechanism for cell survival. Considering the moisture-loving yet waterlogging-sensitive nature of tea plants, this study explored the role of CsATG8f in the tea plant’s response to submergence. We found that overexpression of CsATG8f formed more autophagosomes than controls under submergence. Furthermore, CsATG8f was confirmed to physically interact with CsRAP2.12. Co-overexpression of both genes partially suppressed transcription of hypoxia-response genes while activating the antioxidant system, thereby enhancing tea plants’ resistance to submergence. Consistent with this, the opposite trend was observed in silenced plants, which attempted to mitigate stress damage by increasing GABA levels in vivo. In conclusion, our study reveals the crucial roles of CsATG8f and CsRAP2.12 in tea plant tolerance to submergence and provides new insights into potential regulatory networks governing tea plant adaptation to flooding. Full article

During the climate change era, plants are increasingly exposed to multiple environmental challenges occurring simultaneously or sequentially. Among these, salt stress and waterlogging are two major factors that severely constrain crop productivity worldwide and often occur together. To survive under such conditions, plants have evolved sophisticated systems to scavenge harmful levels of reactive oxygen species (ROS). Despite their cytotoxic potential, ROS also act as key signaling molecules that interact with nitric oxide (NO), Ca²⁺, protein kinases, ion homeostasis pathways, and plant hormones. These signaling and acclimatory mechanisms are closely associated with the functions of energy-regulating organelles—chloroplasts and mitochondria—which are major sources of ROS under both individual and combined stresses. While many of these responses are shared between salt stress, waterlogging and their combination, it is likely that specific signaling mechanisms are uniquely activated when both stresses occur together—mechanisms that cannot be inferred from responses to each stress alone. Such specificity may depend on precise coordination among organelle-derived signals and the tight regulation of their cross-communication. Within this network, ROS and NO likely serve as central hubs, fine-tuning the integration of multiple signaling pathways that enable plants to adapt to complex and fluctuating stress environments. Full article

The waterlogging tolerance of Lindera megaphylla, an evergreen species valued for ecological restoration and its role in landscapes, remains unclear, hindering its broader use in riparian green spaces and rain gardens. This study systematically assessed its physiological responses to simulated waterlogging stress (control/CK, mild/W1, moderate/W2, and severe/W3) and exogenous abscisic acid (ABA) applications (0, 1, and 3 μmol/L). The results showed that severe waterlogging (28 d) drastically reduced seedling survival to 30%, inhibited growth, induced significant reactive oxygen species (ROS) accumulation and membrane damage (malondialdehyde (MDA) +118.59%, relative conductivity (REC) +85.54%), and decreased photosynthetic pigments (Chla −41.60%, Chlb −40.02%, Car −34.33%). Exogenous ABA (3 μmol/L) substantially alleviated stress, increasing survival by 60.61% and enhancing tolerance through three integrated processes: (1) enhancing antioxidant defense (superoxide dismutase (SOD) +10.63%, peroxidase (POD) +9.33%) and reducing ROS; (2) stabilizing osmotic regulation (lower soluble sugars, proteins, and proline and increased leaf water content by +7.89%); (3) preserving photosynthetic integrity, evidenced by restored chlorophyll levels and significantly improved photosystem II and I efficiency. This study is the first comprehensive demonstration that ABA enhances L. megaphylla’s waterlogging tolerance by coordinating antioxidant, osmotic, and photosynthetic responses. Full article