Search Results (1,458)

The rhizosphere microbiome plays an important role in carbon- and nitrogen-cycling in soil and in the stress response of plants. It also affects the function of the ammonium transporter (AmtB) that senses nitrogen levels inside and outside the cells of the associative nitrogen-fixing bacterium GXGL-4A. However, the potential mechanism of the interaction between the AmtB deletion mutant of GXGL-4A (∆amtB) and microorganisms in the rhizosphere of plants under low-nitrogen stress is still unclear. As revealed by transcriptome analyses, mutation of the amtB gene in GXGL-4A resulted in a significant up-regulation of many functional genes associated with nitrogen fixation and transportation at transcription level. The application of ∆amtB changed the nitrogen level in the rhizosphere of cucumber seedlings and reshaped the microbial community structure in the rhizosphere, enriching the relative abundance of Actinobacteriota and Gemmatimonadota. Based on bacterial functional prediction analyses, the metabolic capacities of rhizobacteria were improved after inoculation of cucumber seedlings with the original strain GXGL-4A or the ∆amtB mutant, resulting in the enhancement of amino acids, lipids, and carbohydrates in the cucumber rhizosphere, which promoted the growth of cucumber plants under a low-nitrogen stress condition. The results contribute to understanding the biological function of gene amtB, revealing the regulatory role of the strain GXGL-4A on cucumber rhizosphere nitrogen metabolism and laying a theoretical foundation for the development of efficient nitrogen-fixing bacterial agents for sustainable agricultural production. Full article

Manganese (Mn) excess and low pH often coexist in some citrus orchard soils. Little information is known about the underlying mechanism by which raising pH reduces Mn toxicity in citrus plants. ‘Sour pummelo’ (Citrus grandis (L.) Osbeck) seedlings were treated with 2 (Mn2) or 500 (Mn500) μM Mn at a pH of 3 (P3) or 5 (P5) for 25 weeks. Raising pH mitigated Mn500-induced increases in Mn, iron, copper, and zinc concentrations in roots, stems, and leaves, as well as nitrogen, phosphorus, potassium, calcium, magnesium, sulfur, copper, iron, and zinc distributions in roots, but it mitigated Mn500-induced decreases in nitrogen, phosphorus, potassium, calcium, magnesium, sulfur, and boron concentrations in roots, stems, and leaves, as well as nutrient imbalance. Raising pH mitigated Mn500-induced necrotic spots on old leaves, yellowing of young leaves, decreases in seedling growth, leaf chlorophyll concentration, and CO₂ assimilation (A_CO2), increase in root dry weight (DW)/shoot DW, and alterations of leaf chlorophyll a fluorescence (OJIP) transients and related indexes. Further analysis indicated that raising pH ameliorated Mn500-induced impairment of nutrient homeostasis, leaf thylakoid structure by iron deficiency and competition of Mn with magnesium, and photosynthetic electron transport chain (PETC), thereby reducing Mn500-induced declines in A_CO2 and subsequent seedling growth. These results validated the hypothesis that raising pH reduced Mn toxicity in ‘Sour pummelo’ seedlings by (a) reducing Mn uptake, (b) efficient maintenance of nutrient homeostasis under Mn stress, (c) reducing Mn excess-induced impairment of thylakoid structure and PEPC and inhibition of chlorophyll biosynthesis, and (d) increasing A_CO2 and subsequent seedling growth under Mn excess. Full article

In chili cultivation, obstacles to continuous cropping significantly compromise crop yield and soil health, whereas crop rotation can enhance the microbial environment of the soil and reduce disease incidence. However, its effects on the diversity of rhizosphere soil microbial communities are not clear. In this study, we analyzed the composition and characteristics of rhizosphere soil microbial communities under chili continuous cropping (CC) and chili–cotton crop rotation (CR) using high-throughput sequencing technology. CR treatment reduced the alpha diversity indices (including Chao1, Observed_species, and Shannon index) of bacterial communities and had less of an effect on fungal community diversity. Principal component analysis (PCA) revealed distinct compositional differences in bacterial and fungal communities between the treatments. Compared with CC, CR treatment has altered the structure of the soil microbial community. In terms of bacterial communities, the relative abundance of Firmicutes increased from 12.89% to 17.97%, while the Proteobacteria increased by 6.8%. At the genus level, CR treatment significantly enriched beneficial genera such as RB41 (8.19%), Lactobacillus (4.56%), and Bacillus (1.50%) (p < 0.05). In contrast, the relative abundances of Alternaria and Fusarium in the fungal community decreased by 6.62% and 5.34%, respectively (p < 0.05). Venn diagrams and linear discriminant effect size analysis (LEfSe) further indicated that CR facilitated the enrichment of beneficial bacteria, such as Bacillus, whereas CC favored enrichment of pathogens, such as Firmicutes. Fusarium solani MG6 and F. oxysporum LG2 are the primary chili root-rot pathogens. Optimal growth occurs at 25 °C, pH 6: after 5 days, MG6 colonies reach 6.42 ± 0.04 cm, and LG2 5.33 ± 0.02 cm, peaking in sporulation (p < 0.05). In addition, there are significant differences in the utilization spectra of carbon and nitrogen sources between the two strains of fungi, suggesting their different ecological adaptability. Integrated analyses revealed that CR enhanced soil health and reduced the root rot incidence by optimizing the structure of soil microbial communities, increasing the proportion of beneficial bacteria, and suppressing pathogens, providing a scientific basis for microbial-based soil management strategies in chili cultivation. Full article

Wildfires can significantly alter soil physicochemical conditions and microbial communities in forest ecosystems. This study aimed to characterize the culturable soil fungal community and evaluate biological activity in Banco Totumo Bijibana, a protected dry tropical forest in Atlántico, Colombia, affected by a wildfire in 2014. Twenty soil samples were collected for microbiological (10 cm depth) and physicochemical (30 cm) analysis. Basal respiration was measured using Stotzky’s method, nitrogen mineralization via Rawls’ method, and fungal diversity through culture-based identification and colony-forming unit (CFU) counts. Diversity was assessed using Simpson, Shannon–Weaver, and ACE indices. The soils presented low organic matter (0.70%) and nitrogen content (0.035%), with reduced biological activity as indicated by basal respiration (0.12 kg C ha⁻¹ d⁻¹) and mineralized nitrogen (5.61 kg ha⁻¹). Four fungal morphotypes, likely from the genus Aspergillus, were identified. Simpson index indicated moderate dominance, while Shannon–Weaver values reflected low diversity. Correlation analysis showed Aspergillus-3 was positively associated with moisture, whereas Aspergillus-4 correlated negatively with pH and sand content. The species accumulation curve reached an asymptote, suggesting an adequate sampling effort. Although no control site was included, the findings provide a baseline characterization of post-fire soil microbial structure and function in a dry tropical ecosystem. Full article

This study investigates how phospholipid headgroups influence passive membrane penetration and structural impact of four nitrogen-, sulfur-, and oxygen-containing heterocycles (NSO-HETs)—N-methyl-2-pyrrolidone (PIR), 1,4-dioxane (DIOX), oxane (OXA), and phenol (PHE). Using all-atom molecular dynamics simulations combined with Accelerated Weight Histogram free energy calculations, the passive transport of NSO-HETs across DPPC, DPPE, DPPA, and DPPG bilayers was characterized. DPPG showed the highest membrane affinity, increasing permeability (logP_memb/bulk) by 27–64% compared to DPPE, associated with the lowest permeability and tightest lipid packing. Free energy barriers are also decreased in DPPG relative to DPPE; PIR’s central barrier dropped from 19.2 kJ/mol (DPPE) to 16.6 kJ/mol (DPPG), while DIOX’s barrier decreased from 7.2 to 5.2 kJ/mol. OXA exhibited the lowest central barriers (1.2–2.2 kJ/mol) and uniquely accumulated at higher concentrations in the bilayer center than in bulk water, with free energy ranging from −3.4 to −5.9 kJ/mol. PHE and OXA caused significant bilayer thinning (up to 11%) and reduced lipid tail order, especially in DPPE and DPPA. Concentration effects were most pronounced in DPPE, where high solute loading disrupted lipid order and altered free energy profiles. These results highlight the crucial role of headgroup identity in modulating NSO-HET membrane permeability and structural changes. Full article

Heavy metal-contaminated soil poses a severe threat to environmental quality and human health, calling for eco-friendly and efficient remediation strategies. This study explored the use of biochar-immobilized copper-resistant Pseudomonas aeruginosa to remediate copper-contaminated soil and promote growth of Chinese milk vetch (Astragalus sinicus L.). Indoor pot experiments compared four groups: copper-contaminated soil (control), soil with biochar, soil with free bacteria, and soil with biochar-immobilized bacteria (IM). Results showed IM had the most significant effects on soil properties: it raised pH to 7.04, reduced bioavailable copper by 34.37%, and increased catalase (3.48%) and urease (78.95%) activities. IM also altered soil bacterial communities, decreasing their richness and evenness (alpha diversity) while shifting community composition. For Chinese milk vetch, IM reduced leaf malondialdehyde (a marker of oxidative stress) by 15%, increased total dry weight by 90%, and lowered copper accumulation in roots (18.62%) and shoots (60.33%). As a nitrogen-fixing plant, the vetch’s nitrogen fixation in roots and shoots rose by 82.70% and 57.08%, respectively, under IM. These findings demonstrate that biochar-immobilized Pseudomonas aeruginosa is a promising in situ amendment for remediating copper-contaminated soil and boosting plant growth. Full article

With climate change, the spatial and temporal patterns of precipitation are altered to a certain degree, which potentially affects the grey water footprint (GWF) of total nitrogen (TN) in agriculture, thereby threatening water security in the Yangtze River Basin (YRB), the largest river in China. The current study constructs an assessment framework for climate change impacts on the GWF of agricultural TN by coupling Shared Socioeconomic Pathways (SSPs) with the InVEST model. The framework consists of four components: (i) data collection and processing, (ii) simulating the two critical indicators (L_TN and W) in the GWF model based on the InVEST model, (iii) calculating the GWF and GWF index (GI) of TN, and (iv) calculating climate change impact index on GWF of agricultural TN (CI) under two SSPs. It is applied to the YRB, and the results show the following: (i) GWFs are 959.7 and 961.4 billion m³ under the SSP1-2.6 and SSP5-8.5 climate scenarios in 2030, respectively, which are both lower than that in 2020 (1067.1 billion m³). (ii) The GI values for TN in 2030 under SSP1-2.6 and SSP5-8.5 remain at “High” grade, with the values of 0.95 and 1.03, respectively. Regionally, the water pollution level of Taihu Lake is the highest, while that of Wujiang River is the lowest. (iii) The CI values of the YRB in 2030 under SSP1-2.6 and SSP5-8.5 scenarios are 0.507 and 0.527, respectively. And the CI values of the five regions in the YRB are greater than 0, indicating that the negative effects of climate change on GWFs increase. (iv) Compared with 2020, L_TN and W in YRB in 2030 under the two SSPs decrease, while the GI of TN in YRB rises from SSP1-2.6 to SSP5-8.5. The assessment framework can provide strategic recommendations for sustainable water resource management in the YRB and other regions globally under climate change. Full article

Suckling is crucial for piglet intestinal development and gut health, as it improves resilience during the challenging weaning phase and promotes subsequent growth. IPS, comprising Na⁺/K⁺ ions, whey protein, and glucose, has been shown to have positive effects on animal growth and intestinal health. The objectives of this study were to assess the impact of IPS consumption on the growth performance, immunity, intestinal growth and development, and microbiota structure of suckling piglets. A total of 160 newborn piglets were randomly divided into control and IPS groups, with IPS supplementation starting from 2 to 8 days after birth and continuing until 3 days before weaning. The findings revealed that IPS boosted the body weight at 24 days by 3.6% (p < 0.05) and improved the body weight gain from 16 to 24 days by 15.7% (p < 0.05). Additionally, the jejunal villus height and villus height to crypt depth ratio in the IPS group were notably increased to 1.08 and 1.31 times (p < 0.05), respectively, compared to the control group. Furthermore, IPS elevated the plasma levels of IgA and IgM, reduced the plasma levels of blood urea nitrogen (BUN), and enhanced the content of secretory immunoglobulin A (SIgA) in the jejunal mucosa of suckling piglets. Furthermore, IPS upregulated the mRNA expression of tight junction proteins GLP-2, ZO-1, and Claudin-1 in jejunal tissue, while downregulating the regulatory genes in the Toll-like pathway, including MyD88 and TLR-4 (p < 0.05). The analysis of gut microbiota indicated that IPS altered the relative abundance of gut microbes, with an increase in beneficial bacteria like Alloprevotella and Bacteroides. In conclusion, this study demonstrates that IPS supplementation enhances weaning weight, growth performance, immune function, and intestinal development in piglets, supporting the integration of IPS supplementation in the management of pre-weaning piglets. Full article

Integrated rice–crayfish (Oryza sativa–Procambarus clarkii) co-culture (RC) systems have gained prominence due to their economic benefits and ecological sustainability; however, the interactions between soil properties and microbial communities in such systems remain poorly understood. This study evaluated the effects of the RC systems on soil physicochemical characteristics and microbial dynamics in paddy fields of southern Henan Province, China, over the 2023 growing season and subsequent fallow period. Using a randomized complete design, rice monoculture (RM, as the control) and RC treatments were compared across replicated plots. Soil and water samples were collected post-harvest and pre-transplanting to assess soil properties, extracellular enzyme activity, and microbial community structure. Results showed that RC significantly enhanced soil moisture by up to 30.2%, increased soil porosity by 9.6%, and nearly tripled soil organic carbon compared to RM. The RC system consistently elevated nitrogen (N), phosphorus (P), and potassium (K) throughout both the rice growth and fallow stages, indicating improved nutrient availability and retention. Elevated extracellular enzyme activities linked to carbon, N, and P cycling were observed under RC, with enzymatic stoichiometry revealing increased microbial nutrient limitation intensity and a shift toward P limitation. Microbial community composition was significantly altered under RC, showing increased biomass, a higher fungi-to-bacteria ratio, and greater relative abundance of Gram-positive bacteria, reflecting enhanced soil biodiversity and ecosystem resilience. Further analyses using the Mantel test and Random Forest identified extracellular enzyme activities, PLFAs, soil moisture, and bulk density as major factors shaping microbial communities. Redundancy analysis (RDA) confirmed that total potassium (TK), vector length (VL), soil pH, and total nitrogen (TN) were the strongest environmental predictors of microbial variation, jointly explaining 74.57% of the total variation. Our findings indicated that RC improves soil physicochemical conditions and microbial function, thereby supporting sustainable nutrient cycling and offering a promising, environmentally sound strategy for enhancing productivity and soil health in rice-based agro-ecosystems. Full article

Small reservoirs have important functions, such as water resource guarantee, flood control and drought resistance, biological habitat and maintaining regional economic development. In order to better clarify the impact of agricultural activities on the nutritional status of water bodies in small reservoirs, zooplankton were quantitatively collected from four small reservoirs in the Jiuxianshan agricultural area of Qufu, Shandong Province, in March and October 2023, respectively. The physical and chemical parameters in sampling points were determined simultaneously. Meanwhile, water samples were collected for nutrient salt analysis, and the eutrophication of water bodies in four reservoirs was evaluated using the comprehensive nutrient status index method. The research found that the species richness of zooplankton after farming (100 species) was significantly higher than that before farming (81 species) (p < 0.05). On the contrary, the dominant species of zooplankton after farming (7 species) were significantly fewer than those before farming (11 species). The estimation results of the standing stock of zooplankton indicated that the abundance and biomass of zooplankton after farming (92.72 ind./L, 0.13 mg/L) were significantly higher than those before farming (32.51 ind./L, 0.40 mg/L) (p < 0.05). Community similarity analysis based on zooplankton abundance (ANOSIM) indicated that there were significant differences in zooplankton communities before and after farming (R = 0.329, p = 0.001). The results of multi-dimensional non-metric sorting (NMDS) showed that the communities of zooplankton could be clearly divided into two: pre-farming communities and after farming communities. The Monte Carlo test results are as follows (p < 0.05). Transparency (Trans), pH, permanganate index (COD_Mn), electrical conductivity (Cond) and chlorophyll a (Chl-a) had significant effects on the community structure of zooplankton before farming. Total nitrogen (TN), total phosphorus (TP) and electrical conductivity (Cond) had significant effects on the community structure of zooplankton after farming. The co-linearity network analysis based on zooplankton abundance showed that the zooplankton community before farming was more stable than that after farming. The water evaluation results based on the comprehensive nutritional status index method indicated that the water conditions of the reservoirs before farming were mostly in a mild eutrophic state, while the water conditions of the reservoirs after farming were all in a moderate eutrophic state. The results show that the nutritional status of small reservoirs in agricultural areas is significantly affected by agricultural activities. The zooplankton communities in small reservoirs underwent significant changes driven by alterations in the reservoir water environment and nutritional status. Based on the main results of this study, we suggested that the use of fertilizers and pesticides should be appropriately reduced in future agricultural activities. In order to better protect the water quality and aquatic ecology of the water reservoirs in the agricultural area. Full article

To ensure the year-round efficient production of high-quality cherry tomatoes, this study evaluated how four cherry tomato cultivars can enhance yield and quality through optimized nutrient solution and supplementary lighting. Nutrient solutions (N1 and N2) were adjusted, with EC at 1.6 dS/m (N1: nitrogen 10.7 me/L, phosphorus 2.7 me/L, potassium 5.3 me/L) during flowering stage, and 2.4 dS/m (N1: nitrogen 16 me/L, phosphorus 4 me/L, potassium 8 me/L; N2: nitrogen 10.7 me/L, phosphorus 5.4 me/L, potassium 10.8 me/L) from fruit setting to harvest. N1 used standard adjustments, while N2 was optimized by adding solely with KCl and KH₂PO₄. Lighting treatments included L1 (natural light) and L2 (supplemental red/blue light). The application of N2 effectively decreased nitrate levels while it significantly enhanced the content of soluble sugars, flavor, and overall palatability, especially fruit coloring in cherry tomatoes, irrespective of supplementary lighting conditions. However, such optimization also increased sourness or altered the sugar–acid ratio. Supplementary lighting generally promoted the accumulation of soluble sugars, sweetness, and tomato flavor, although its effects varied markedly among different fruit clusters. The combination of optimized nutrient solutions and supplementary lighting exhibited synergistic effects, improving the content of soluble sugars, vitamin C, proteins, and flavor. N1 combined with L2 achieved the highest plant yield. Among the cultivars, ‘Linglong’ showed the greatest overall quality improvement, followed by ‘Baiyu’, ‘Miying’, and ‘Moka’. In conclusion, supplementary lighting can enhance the effect of nitrogen on yield and amplify the influence of phosphorus and potassium on fruit quality improvement in cherry tomatoes. The findings of this study may serve as a theoretical basis for the development of year-round production techniques for high-quality cherry tomatoes. Full article

Plants are constantly exposed to environmental stressors such as drought, salinity, and extreme temperatures, which threaten their growth and productivity. To counter these challenges, they employ complex molecular defense systems, including epigenetic modifications that regulate gene expression without altering the underlying DNA sequence. This review comprehensively examines the emerging roles of reactive oxygen species (ROS) and reactive nitrogen species (RNS) as central signaling molecules orchestrating epigenetic changes in response to abiotic stress. In addition, biotic factors such as pathogen infection and microbial interactions are considered for their ability to trigger ROS/RNS generation and epigenetic remodeling. It explores how ROS and RNS influence DNA methylation, histone modifications, and small RNA pathways, thereby modulating chromatin structure and stress-responsive gene expression. Mechanistic insights into redox-mediated regulation of DNA methyltransferases, histone acetyltransferases, and microRNA expression are discussed in the context of plant stress resilience. The review also highlights cutting-edge epigenomic technologies such as whole-genome bisulfite sequencing (WGBS), chromatin immunoprecipitation sequencing (ChIP-seq), and small RNA sequencing, which are enabling precise mapping of stress-induced epigenetic landscapes. By integrating redox biology with epigenetics, this work provides a novel framework for engineering climate-resilient crops through the targeted manipulation of stress-responsive epigenomic signatures. Full article

The presence of plastics in the soil environment is an undeniable global reality. Biodegradable plastics (BPs) possess several key properties that make them more environmentally sustainable compared to other categories of plastics. However, their presence induces significant changes in soil systems health where they are found, due to a combination of environmental, soil, and climatic factors, as well as the simultaneous presence of other pollutants, both inorganic and organic. In the present work, a review has been conducted on published research findings regarding the impact of various types of BPs on the parameters that regulate and determine soil health. In particular, the study examined the effects of BPs on physical, chemical, and biological indices of soil quality, leading to several important conclusions. It was observed that silty and loamy soils were significantly affected, as their physical properties were altered. Moreover, significant changes in both chemical and microbiological indicators were observed with increasing environmental temperatures. The presence of all types of biodegradable microplastics led to a significant reduction in soil nitrogen content as temperature increased. This study highlights the profound effects of the climate crisis on the properties of soils already contaminated with plastics, as the effects of rising temperatures on soil properties appear to be amplified in the presence of plastics. On the other hand, higher temperatures also trigger a series of chemical reactions that accelerate the degradation of BPs, thereby reducing their volume and mass in the soil environment. These processes lead to increased emissions of gases and higher ambient temperatures, leading to global warming. The types and quantities of plastics present, along with the environmental changes in a study area, are critical factors that must be taken into account by policymakers in order to mitigate the impacts of climate change on soil health and productivity. Full article

This study investigates the effects of diffusion modeling and swirl intensity on flow fields and NO emissions in CH₄/NH₃ non-premixed swirling flames using large eddy simulations (LESs). Simulations are performed for a 50/50 ammonia–methane blend at three global equivalence ratios of 0.77, 0.54, and 0.46 and two swirl numbers of 8 and 12, comparing the unity Lewis number (ULN) and mixture-averaged diffusion (MAD) models against the experimental data includes OH-PLIF and ON-PLIF reported in a prior study by the KAUST group. Both models produce similar flow fields, but the MAD model alters the flame structure and species distributions due to differential diffusion (DD) and limitations in its Flamelet library. Notably, the MAD library lacks unstable flame branch solutions, leading to extensive interpolation between extinction and stable branches. This results in overpredicted progress variable source terms and reactive scalars, both within and beyond the flame zone. The ULN model better reproduces experimental OH profiles and localizes NO formation near the flame front, whereas the MAD model predicts broader NO distributions due to nitrogen species diffusion. Higher swirl intensities shorten the flame and shift NO production upstream. While a low equivalence ratio provides enough air for good mixing, lower ammonia and higher NO contents in exhaust gases, respectively. Full article

Volcanic ash from explosive eruptions can significantly alter lake water chemistry through ash–water interactions, potentially influencing primary productivity. Alkaline (soda) lakes, mostly found in volcanic regions, are particularly sensitive due to their unique geochemical properties. However, the effects of volcanic ash on the biogeochemistry and phytoplankton dynamics of soda lakes remain poorly understood. This study presents the first nutrient release experiments using natural alkaline water from Lake Van (Türkiye) and volcanic ash from four volcanoes (Hekla, Arenal, Sakurajima, Rabaul-Tavurvur) with different compositions. Sixteen abiotic leaching experiments were conducted over contact durations ranging from 1 to 24 h. Results show rapid increases in pH (~0.4–0.5 units), enhanced silica and phosphate concentrations, and elevated levels of Na, K, Ca, Sr, and S. Nitrate and Mg were generally depleted. The low N:P ratio (~0.06) in Lake Van water indicated nitrogen limitation, partially mitigated by ash-derived inputs. Cyanobacteria dominated the phytoplankton community (95%), consistent with nitrogen fixation under low-nitrate conditions. Elevated silica may promote diatom growth, while changes in Mg/Ca ratios suggest possible impacts on carbonate precipitation and microbialite development. These findings highlight the biogeochemical and ecological relevance of volcanic ash inputs to soda lakes. Full article