Search Results (114)

Soybeans are highly susceptible to drought stress, which significantly impairs their growth and yield. Silicon (Si) supplementation has emerged as a promising strategy to mitigate drought-induced damage in plants. We investigated changes in the physiological and chloroplast proteomes in soybeans under drought stress, both with and without Si supplementation. Soybean plants were grown under controlled conditions and subjected to drought stress. The treatments included Si application (sodium silicate), sodium chloride control, and water control. Chloroplast proteins were extracted from control and Si-treated plants and analyzed using two-dimensional gel electrophoresis and mass spectrometry. Plants treated with Si showed improved drought tolerance, exhibiting reduced leaf rolling and wilting, while the control plants experienced significant wilting under drought conditions. Photosynthetic performance, measured by quantum efficiency of photosystem II and chlorophyll content, was better maintained in Si-supplemented plants under drought. However, stomatal conductance and transpiration were similarly reduced across all drought treatments. We detected 15 Si-responsive protein spots corresponding to 13 unique chloroplast proteins that were differentially expressed in response to Si supplementation. These identified proteins include those involved in photosynthesis, such as Rubisco activase isoforms, oxygen-evolving enhancer proteins, and PsbP domain-containing protein, as well as stress response proteins like dehydrin and 20 kDa chaperonin. Si treatment upregulated Rubisco activase isoforms, oxygen-evolving enhancer proteins, PsbP domain-containing protein, and 20 kDa chaperonin, which are typically reduced under drought. Si treatment maintained a higher glutamine synthetase level under drought stress. Gene ontology and KEGG pathway analyses revealed that Si-modulated proteins are associated with photosynthesis, energy metabolism, and nitrogen metabolism under drought stress. Our findings demonstrate that Si supplementation alleviates drought stress in soybean by preserving chloroplast function and enhancing the expression of photosynthetic proteins and enzymes, as well as key stress-responsive proteins. This research provides insights into the molecular mechanisms of Si-induced drought tolerance in soybeans and highlights potential targets for developing drought-resilient soybean cultivars. Full article

Cucumis sativus L., a salt-sensitive horticultural crop, is severely affected by soil salinity, which disrupts photosynthetic efficiency and metabolic homeostasis. This study quantified the effects of Plant Growth-Promoting Rhizobacteria (PGPR)—Pseudomonas paralactis, Bacillus cereus, Sinorhizobium meliloti, and Acinetobacter radioresistens—on key enzymatic indicators of cucumber seedlings exposed to 0, 50, 100, and 150 mM NaCl. PGPR inoculation significantly enhanced bacterial stress-mitigation and hormonal pathways, with ACC-deaminase activity increasing by up to 78.8% (A. radioresistens, 150 mM NaCl) and nitrilase activity by 50.5% (S. meliloti, 50 mM NaCl). Auxin-related pathways were strongly induced, as reflected by increases of up to 51.1% in the IAM pathway (P. paralactis) and 42.9% in the IPA pathway (A. radioresistens). In plant tissues, key metabolic enzymes exhibited high stability under salinity, with ProDH and NDPK activities increasing by up to 4.5% and 2.35%, respectively, while RuBisCO activity remained unaffected across treatments. These results demonstrate that PGPR function as effective bioestimulants by coordinating hormonal regulation and metabolic resilience, providing a sustainable biotechnological strategy to enhance cucumber tolerance to salinity stress. Full article

Copper (Cu) pollution poses environmental and health risks. Owing to its adaptability and potential for water purification, Nymphoides peltata (N. peltata) is being considered for use in the remediation of Cu pollution. However, the feasibility of using N. peltata for the remediation of Cu-polluted water bodies has not yet been assessed. Here, the physiological response of N. peltata to Cu stress was determined. N. peltata samples were exposed to varying Cu concentrations (0.2, 0.4, 0.6 and 0.8 mg∙L⁻¹), and the activities of glutamine synthetase (GS), nitrate reductase (NR), nitrite reductase (NiR), ribulose-1,5-diphosphate carboxylase (Rubisco), and glycolate oxidase (GO) were measured together with the concentrations of photosynthetic pigments. The results revealed that under Cu stress, NR and GS activities significantly decreased, while NiR activity significantly increased. Exposure to 0.2 mg∙L⁻¹ Cu promoted chlorophyll synthesis and enhanced Rubisco and GO activities; in contrast, exposure to Cu concentrations above 0.4 mg∙L⁻¹ significantly inhibited the aforementioned parameters. These findings indicate that Cu stress, regardless of concentration, significantly affects nitrogen metabolism in N. peltata by decelerating nitrate reduction and impairing the ammonification process. Meanwhile, only high Cu concentrations significantly affected photosynthesis. N. peltata can survive low Cu stress by regulating its photosynthetic enzymes. Therefore, N. peltata has potential for the ecological restoration of water bodies polluted with low Cu concentrations. Full article

The ponkan (Citrus reticulata Blanco cv. Ponkan), an important citrus crop, is increasingly threatened by soil acidification. This study evaluated the efficacy of various soil amendments, including lime alone (L), lime with gypsum and organic fertilizer (LGOF), lime plus K₂CO₃ (LK), and lime with chicken manure ash (LCMA), in mitigating soil acidification and improving ponkan seedling growth. Surface-applied lime raised topsoil pH and acid buffering capacity while reducing exchangeable Al. However, combined amendments (LGOF, LK, LCMA) more effectively alleviated acidity throughout the soil profile. They significantly increased pH and buffering capacity, decreased exchangeable H and Al in the 20–40 cm layer, and elevated exchangeable base cations (K⁺, Ca²⁺, Mg²⁺). These changes reduced Al content in roots, stems, and leaves, promoted deeper root growth, and increased biomass and nutrient uptake (N, P, K). Physiologically, combined amendments enhanced photosynthetic performance (chlorophyll, Pn, ΦPSII) and increased activity of key metabolic enzymes (Rubisco, SS, SPS, NR, GS), promoting sucrose, starch, and protein accumulation. LK rapidly raised subsoil pH and potassium levels, ideal for K-deficient orchards. LGOF and LCMA improved overall fertility by supplying Ca and Mg, with LGOF additionally enhancing soil structure in poorly structured acidic soils. Full article

To explore the improvement effect of diversified crop rotation on soil quality in long-term continuous cotton fields (15 years), a field experiment was conducted in southern Xinjiang in 2024. With continuous cotton (C-C) as the control, four crop rotations, namely, cotton–maize (C-M), cotton–wheat (C-W), cotton–soybean (C-S), and cotton–peanut (C-P), were set up. The results showed that compared with C-C, the soil organic carbon (SOC) treated by C-P and C-S increased significantly by 11.76% and 3.38%, respectively, and the easily oxidized organic carbon (EOC) increased by 45.18% and 37.15%, respectively. The dissolved organic carbon (DOC) treated with C-S increased by 14.36%, while C-M decreased by 10.98%. The carbon pool index (CPI) of C-P was the highest in the 0–20 cm soil layer, which was 13.00% higher than that of C-C. The β-1, 4-glucosidase (BGL) activity of C-C at 0–20 cm and 20–40 cm was 144.70–387.26% and 48.01–71.32% higher than that of other treatments, respectively. The RuBisCo activity of C-P was 80.96% higher than that of C-C. The soil quality index was the highest for C-S, followed by C-P, which was 74.56% higher than that of C-C. In conclusion, the cotton–peanut rotation can effectively improve the soil quality of continuous cotton fields by increasing the organic carbon composition, enhancing the activity of carbon-fixing enzymes and bacterial diversity. Full article

Soil salinity poses a critical threat to global agricultural productivity, exacerbating food security challenges in arid and semi-arid regions. This review synthesizes current knowledge on the physiological and biochemical impacts of salinity stress in plants, with a focus on the role of gibberellic acid (GA₃) in mitigating these effects. Salinity disrupts ion homeostasis, induces osmotic stress, and generates reactive oxygen species (ROS), leading to reduced chlorophyll content, impaired photosynthesis, and stunted growth across all developmental stages, i.e., from seed germination to flowering. Excess sodium (Na⁺) and chloride (Cl⁻) accumulation disrupts nutrient uptake, destabilizes membranes, and inhibits enzymes critical for carbon fixation, such as Rubisco. GA₃ emerges as a key regulator of salinity resilience, enhancing stress tolerance through various mechanisms like scavenging ROS, stabilizing photosynthetic machinery, modulating stomatal conductance, and promoting osmotic adjustment via osmolyte accumulation (e.g., proline). Plant hormone’s interaction with DELLA proteins and cross-talk with abscisic acid, ethylene, and calcium signaling pathways further fine-tune stress responses. However, gaps persist in understanding GA₃-mediated floral induction under salinity and its precise role in restoring photosynthetic efficiency. While exogenous GA₃ application improves growth parameters, its efficacy depends on the concentration- and species-dependent, with lower doses often proving beneficial and optimum doses potentially inhibitory. Field validation of lab-based findings is critical, given variations in soil chemistry and irrigation practices. Future research must integrate biotechnological tools (CRISPR, transcriptomics) to unravel GA₃ signaling networks, optimize delivery methods, and develop climate-resilient crops. This review underscores the urgency of interdisciplinary approaches to harness GA₃’s potential in sustainable salinity management, ensuring food security and safety in the rapidly salinizing world. Full article

Lodging is one of the key limiting factors in achieving high wheat yield. The application of plant growth retardants (PGRts) is regarded as an effective practice to prevent lodging. For accurate PGRt selection and the establishment of stable, high-yield production plans, it is essential to make clear the regulation strategies for lodging resistance and yield in PGRts. Field experiments were conducted at two test sites. At the initial jointing stage of wheat, Chlormequat Chloride (CCC) or Uniconazole (S₃₃₀₇) was sprayed. Compared with the control (CK), spraying CCC or S₃₃₀₇ significantly reduced the culm lodging index (CLI) and decreased the lodging rate from 7.1% to 15.6%. CCC was more capable of adjusting plant morphology (reducing plant height and second internode length and increasing stem diameter), while S₃₃₀₇ was more effective in enhancing breaking strength. The contents of GA, IAA, and zeatin nucleoside (ZR) and the activities of lignin-related enzymes (TAL and CAD) were significantly correlated with different stem indicators and CLI. Compared with CK, the yield after spraying CCC or S₃₃₀₇ increased by 6.5% and 6.0%, respectively. CCC mainly enhanced the yield by increasing grain weight per spike and the SPAD value of leaves, while S₃₃₀₇ mainly did so by increasing the number of spikes and the effective leaf area. Moreover, carbon metabolism-related enzymes (Rubisco, SS, and SPS) were significantly positively correlated with the yield. The enzyme activity of CCC was higher at the heading stage, while that of S₃₃₀₇ was higher at the filling stage. Hence, spraying CCC or S₃₃₀₇ can significantly enhance lodging resistance and yield. The optimal PGRts should be selected based on the climate and the growth stage of the wheat. Full article

Rubisco activase (RCA) is an ATP-dependent enzyme that plays a crucial role in plant stress responses by regulating the catalytic activity of Rubisco. However, the alternative splicing and functional characteristics of the RCA gene exhibit notable species-specific diversity. The variable splice forms and functions of the RCA gene in mangrove plants remain poorly understood. Herein, we cloned the RCA cDNA in the leaves of mangrove plant Kandelia candel (L.) in response to combined flooding and salinity stress, and performed systematic expression analysis and functional validation. Our results demonstrated that the RCA gene undergoes alternative splicing to produce two isoforms, designated as KcRCA_l (GenBank accession: MG492021) and KcRCA_s (GenBank accession: MG492022), respectively. The KcRCA_l encodes a 440-amino acid protein (42.49 kDa) belonging to the β-isoforms, while KcRCA_s encodes a 474-amino acid protein (46.10 kDa) classified as the α-isoforms. Moreover, protein structure analysis revealed that both isoforms contain phosphorylation and lysine acetylation modification sites. Phylogenetic analysis indicated that KcRCA shares the closest evolutionary relationship with RCA from Cicer arietinum (chickpea) and Durio zibethinus (durian). Furthermore, RT-qPCR analysis revealed that the expression levels of KcRCA_l and KcRCA_s were significantly upregulated in K. Candel leaves under the combined stress condition. The following functional validation studies in transgenic Arabidopsis demonstrated that overexpression of the KcRCA cDNA enhances the plant’s tolerance to resist flooding and salinity stress while improving antioxidant capacity and increasing RCA and Rubisco activity, thereby maintaining photosynthetic efficiency under combined flooding and salinity stress. Our study not only provides new experimental evidence for understanding the molecular mechanisms of plant flooding and salinity stress, but also offers theoretical foundations for breeding flooding- and salinity-tolerant crops. Full article

The coupling of partial root-zone drying (PRD) with nitrogen forms exerts an interactive “water-promoted fertilization” effect, which enhances rice (Oryza sativa L.) growth and development, improves water use efficiency (WUE), mediates the expression of aquaporins (AQPs), and alters root water conductivity. In this study, gene cloning and CRISPR-Cas9 technologies were employed to construct overexpression and knockout vectors of the OsPIP2;1 gene, which were then transformed into rice (cv. Meixiangzhan 2). Three water treatments were set: normal irrigation (CK); partial root-zone drying (PRD); and 10% PEG-simulated water stress (PEG), combined with a nitrogen form ratio of ammonium nitrogen (NH₄⁺) to nitrate nitrogen (NO₃⁻) at 50:50 (A50/N50) for the coupled treatment of rice seedlings. The results showed that under the coupled treatment of PRD and the aforementioned nitrogen form, the expression level of the OsPIP2;1 gene in roots was upregulated by 0.62-fold on the seventh day, while its expression level in leaves was downregulated by 1.84-fold. Overexpression of OsPIP2;1 enabled Meixiangzhan 2 to maintain a higher abscisic acid (ABA) level under different water conditions, which helped rice reduce water potential and enhance water absorption. Compared with the CK treatment, overexpression of OsPIP2;1 increased the superoxide dismutase (SOD) activity of rice under PRD by 26.98%, effectively alleviating tissue damage caused by excessive accumulation of O₂⁻. The physiological and biochemical characteristics of OsPIP2;1-overexpressing rice showed correlations under PRD and A50/N50 nitrogen form conditions, with WUE exhibiting a significant positive correlation with transpiration rate, chlorophyll content, nitrogen content, and Rubisco enzyme activity. Overexpression of OsPIP2;1 could promote root growth and increase the total biomass of rice plants. The application of the OsPIP2;1 gene in rice genetic engineering modification holds great potential for improving important agricultural traits of crops. This study provides new insights into the mechanism by which the AQP family regulates water use in rice and has certain significance for exploring the role of AQP genes in rice growth and development as well as in response to water stress. Full article

Bacterial microcompartments (BMCs) are intracellular structures for compartmentalizing specific metabolic pathways in bacteria. As a unique type of BMCs, carboxysomes utilize protein shells to sequester ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) and carbonic anhydrase for efficient carbon dioxide (CO₂) fixation. This study aims to reconstruct an α-carboxysome in Saccharomyces cerevisiae and investigate its metabolic effects. Here, genes of the cso operon from Halothiobacillus neapolitanus, Calvin cycle-related enzyme phosphoribulokinase (PRK) from Spinacia oleracea, and two S. cerevisiae chaperone genes, HSP60 and HSP10, were introduced into S. cerevisiae. The engineered yeast strain demonstrated assembled and enzymatically active Rubisco, significant increase in ethanol production and reduction in the byproduct glycerol. Formation of the α-carboxysome structures was observed after purification by sucrose density gradient centrifugation. The engineered yeast strain harboring functional α-carboxysome has the potential for enhancing bioethanol production. Full article

The spatiotemporal regulatory mechanism underlying silicon (Si)-mediated cadmium (Cd) detoxification in rice (Oryza sativa L.) was investigated using non-invasive micro-test technology (NMT), combined with physiological and biochemical analyses. The results revealed the following: (1) Si significantly inhibited Cd²⁺ influx into rice roots, with the most pronounced reductions in ion flux observed under moderate Cd stress (Cd50, 50 μmol·L⁻¹), reaching 35.57% at 7 days and 42.30% at 14 days. Cd accumulation in roots decreased by 34.03%, more substantially than the 28.27% reduction observed in leaves. (2) Si application enhanced photosynthetic performance, as evidenced by a 14.21% increase in net photosynthetic rate (Pn), a 32.14% increase in stomatal conductance (Gs), and a marked restoration of Rubisco activity. (3) Si mitigated oxidative damage, with malondialdehyde (MDA) and hydrogen peroxide (H₂O₂) levels reduced by 11.29–21.88%, through the upregulation of antioxidant enzyme activities (SOD, APX, CAT increased by 15.34–38.33%) and glutathione metabolism (GST activity and GSH content increased by 60.78% and 51.35%, respectively). (4) The mitigation effects of Si were found to be spatiotemporally specific, with stronger responses under Cd50 than Cd100 (100 μmol·L⁻¹), at 7 days (d) compared to 14 d, and in roots relative to leaves. Our study reveals a coordinated mechanism by which Si modulates Cd uptake, enhances photosynthetic capacity, and strengthens antioxidant defenses to alleviate Cd toxicity in rice. These findings provide a scientific basis for the application of Si in mitigating heavy metal stress in agricultural systems. Full article

Corky split vein (CSV) is a common physiological disease in citrus that can result from multiple types of stresses. Preliminary field investigation found that more severe CSV in citrus cultivated in orchards lacking both boron (B) and other photosynthesis-related nutrients, including manganese (Mn). In this study, two-year-old ‘Newhall’ navel orange seedlings were treated with control (CK), B deficiency (BD), Mn deficiency (MnD), and combined B and Mn deficiency (BD + MnD). After 31 weeks, typical CSV symptoms appeared on old leaves (OLs) and secondary new leaves (SLs) in BD, while BD + MnD symptoms were more severe. BD and BD + MnD significantly reduced B concentrations in all leaf types, but there were no significant differences between them. Except for OLs in MnD, the net photosynthetic rate (P_n) of all leaf types significantly decreased in all treatments, with BD + MnD showing significantly lower P_n values than BD. Compared with BD, BD + MnD significantly increased minimal fluorescence (F_o) of all leaves at the later stage and significantly decreased Y(II) of new leaves. BD significantly increased sucrose and starch contents in all type leaves, while the OL starch content was significantly higher in BD + MnD than that in BD. BD + MnD significantly decreased the enzyme activities of Rubisco, TK, and FBA in OLs, FBPase and NI in PLs, and Rubisco in SLs compared with BD, while the activities of NI and AI in OLs and SS in SLs were significantly increased. BD + MnD significantly enhanced lignin concentrations and the expression of key lignin synthesis genes in leaves compared with BD. In conclusion, Mn deficiency exacerbates B-deficiency-induced CSV not only by intensifying photosynthetic dysfunction and carbohydrate accumulation but also by promoting lignin biosynthesis. These findings highlight the synergistic nature of B and Mn deficiencies in impairing leaf function and structure, providing new insights into the physiological and molecular mechanisms underlying CSV development. Full article

The problems of excessive nitrogen fertilizer application and mismatch between varieties and planting density are common in potato production in the dryland farming areas of Loess Plateau, and it is of great significance to select suitable nitrogen application rates and planting densities for the green and sustainable production of dryland potatoes in this area. In this study, Longshu 16 was selected as the potato variety, and we investigated two nitrogen application rates: 200 kg·hm⁻² (N1), 300 kg·hm⁻² (N2); and three planting densities: 37,500 plants·hm⁻² (D1), 52,500 plants·hm⁻² (D2), 67,500 plants·hm⁻² (D3). The effects of different nitrogen fertilization rates and planting densities on photosynthetic characteristics, leaf carbon and nitrogen metabolism enzyme activities, and yield and quality of potato were measured and analyzed. The results showed that during the tuber swelling stage, the activity of ribose-1,5-diphosphate carboxylase oxygenase (Rubisco) in potato leaves was increased by 9.05%. During the starch accumulation stage, the activity of glutamine synthetase (GS) in potato leaves was increased by 3.02~22.34% in N1D2 treatment compared with other treatments, and the activity of glutamate synthase (GOGAT) was increased by 2.83~7.35% compared with other treatments. During the starch accumulation stage, the activity of ADP-glucose pyrophosphorylase (AGPase) in potato leaves was increased by 7.85~31.17% in N1D2 treatment compared with other treatments. The contents of protein, starch, vitamin C, and calcium in potato tubers in N1D2 treatment were the highest, and the yield was the highest in N1D2 treatment. In conclusion, the recommended nitrogen application rate of 200 kg·hm⁻² and planting density of 52,500 plants·hm⁻² in dry-fed potato production improved the yield and quality of potato by enhancing activities of GAPDH, GS, and AGPase. Full article

Pollution from heavy metals represents one of the most important threats to crops. Among these, Nickel (Ni) represents a dangerous element, strictly related to anthropic activity and easily accumulated in plants. In this study, effects of high levels (1 mM) of Ni²⁺ were investigated in barley (Hordeum vulgare L. cv. Nure) grown hydroponically, inducing a severe reduction in plant growth, as well as genotoxic damage. Moreover, stress affects photosynthesis, inducing a decrease in Fv/Fm and ΦPSII and an increase in D1 protein and RuBisCO (RbcL) abundance to compensate for the loss of photosynthetic efficiency. Changes were observed in carbon metabolism, with increases in phosphofructokinase, glyceraldehyde-3P dehydrogenase-NAD⁺, and pyruvate kinase expression confirmed by increased proteins and activities. Notably, there was an evident rise in PEP carboxylase activity, presence, and expression. This increase boosts the TCA cycle (increased fumarase) and supports photorespiration. Evident rises were observed also for glucose-6P dehydrogenase activity and presence. Ni²⁺ stress induced an evident increase in enzymes involved in nitrogen metabolism: particularly, the chloroplastic GS2/Fd-GOGAT cycle and N assimilation through the cytosolic glutamate dehydrogenase reaction were enhanced. These results design a specific stress-responsive metabolism by diverting the synthesis of N-compounds through alternative C/N assimilation pathways to counteract the effects of Ni²⁺ toxicity. This study depicts a diversion of the main C/N metabolism network towards an increase in leaf N assimilation, using carbon skeletons from dark CO₂ fixation under high Ni²⁺ stress. These results may provide possible targets for the improvement of heavy metal tolerance in cereals. Full article

Salt stress severely impairs photosynthesis and development in tomato seedlings. This study investigated the regulatory role of exogenous melatonin (MT) on photosynthetic performance under salt stress by determining chlorophyll content, chlorophyll a fluorescence parameters, Calvin cycle enzyme activities, and related gene expression. Results showed that salt stress significantly reduced chlorophyll content and impaired photosystem II (PSII) functionality, as evidenced by the increased minimum fluorescence (F_o) and decreased maximum quantum efficiency of PSII (F_v/F_m) and effective PSII quantum yield (Φ_PSII). MT application mitigated these negative effects, as reflected by higher F_v/F_m, increased chlorophyll content, and lower non-photochemical quenching (NPQ). In addition, MT-treated plants exhibited improved PSII electron transport and more efficient use of absorbed light energy, as shown by elevated Φ_PSII and qP values. These changes suggest improved PSII functional stability and reduced excess thermal energy dissipation. Furthermore, MT significantly enhanced both the activity and expression of key enzymes involved in the Calvin cycle, including ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco), Rubisco activase (RCA), phosphoglycerate kinase (PGK), glyceraldehyde-3-phosphate dehydrogenase (GAPDH), fructose-1,6-bisphosphatase (FBPase), fructose-bisphosphate aldolase (FBA), transketolase (TK), and sedoheptulose-1,7-bisphosphatase (SBPase), thereby promoting carbon fixation and ribulose-1,5-bisphosphate (RuBP) regeneration under salt stress. Conversely, inhibition of endogenous MT synthesis by p-CPA exacerbated salt stress damage, further confirming MT’s crucial role in salt tolerance. These findings demonstrate that exogenous MT enhances salt tolerance in tomato seedlings by simultaneously improving photosynthetic electron transport efficiency and upregulating the activity and gene expression of key Calvin cycle enzymes, thereby promoting the coordination between light reactions and carbon fixation processes. This study provides valuable insights into the comprehensive regulatory role of MT in maintaining photosynthetic performance under saline conditions. Full article