Search Results (80)

A genomic analysis of the hydrocarbon-oxidizing strain R. qingshengii F2-2 was conducted to characterize the genes responsible for plant growth stimulation and phytopathogen biocontrol. Understanding these mechanisms is vital for developing effective phytoremediation approaches. It was shown that the F2-2 genome consists of a 6.3 Mb chromosome and three plasmids, two of which are linear—pLP156 (155 kb) and pLP337 (337 kb)—and one circular—pCP209 (210 kb). The genes responsible for biosynthesis of phytohormones (auxins, gibberellins, cytokinins), phosphate solubilization, and production of siderophores and antibiotic-active compounds (chloramphenicol and pristinamycin IA) were identified in the strain chromosome. Orthologous genes encoding phenazine antibiotics were found in the linear plasmid pLP156. The phytostimulating properties of the strain, associated with auxin production (2–4 μg/mL); the ability to effectively colonize rapeseed, mustard, and tobacco plants; and protective action against Fusarium spp. under artificial phytopathogenic background conditions, were experimentally confirmed. Thus, the discovered properties of the R. qingshengii F2-2 strain indicate its potential for the phytoremediation of oil-contaminated soils. Full article

Straw returning is a critical practice with profound strategic importance for sustainable agricultural development. However, within a comprehensive soil health evaluation framework, research analyzing the impact of tobacco straw returning on soil ecosystem health from the perspectives of microbial taxa and functional genes remains insufficient. To investigate the effects of tobacco straw returning on virulence factor genes (VFGs), methane-cycling genes (MCGs), nitrogen-cycling genes (NCGs), carbohydrate-active enzyme genes (CAZyGs), antibiotic resistance genes (ARGs), and their host microorganisms in soil, this study collected soil samples from a long-term tobacco-rice rotation field with continuous tobacco straw incorporation in Shaowu City, Fujian Province. Metagenomic high-throughput sequencing was performed on the samples. The results demonstrated that long-term tobacco straw returning influenced the diversity of soil VFGs, MCGs, NCGs, CAZyGs, ARGs, and their host microorganisms, with richness significantly increasing compared to the CK treatment (p < 0.05). In the microbially mediated methane cycle, long-term tobacco straw returning resulted in a significant decrease in the abundance of the key methanogenesis gene mttB and the methanogenic archaeon Methanosarcina, along with a reduced mtaB/pmoA functional gene abundance ratio compared to CK. This suggests enhanced CH₄ oxidation in the tobacco-rice rotation field under straw returning. Notably, the abundance of plant pathogens increased significantly under tobacco straw returning. Furthermore, a significantly higher norB/nosZ functional gene abundance ratio was observed, indicating a reduced capacity of soil microorganisms to convert N₂O in the tobacco-rice rotation field under straw amendment. Based on the observation that the full-rate tobacco straw returning treatment (JT2) resulted in the lowest abundances of functional genes prkC, stkP, mttB, and the highest abundances of nirK, norB, malZ, and bglX, it can be concluded that shifts in soil physicochemical properties and energy substrates drove a transition in microbial metabolic strategies. This transition is characterized by a decreased pathogenic potential of soil bacteria, alongside an enhanced potential for microbial denitrification and cellulose degradation. Non-parametric analysis of matrix correlations revealed that soil organic carbon, dissolved organic carbon, alkaline-hydrolyzable nitrogen, available phosphorus, and available potassium were significantly correlated with the composition of soil functional groups (p < 0.05). In conclusion, long-term tobacco straw returning may increase the risk of soil-borne diseases in tobacco-rice rotation systems while potentially elevating N₂O and reducing CH₄ greenhouse gas emission rates. Analysis of functional gene abundance changes identified the full-rate tobacco straw returning treatment as the most effective among all treatments. Full article

Organic fertilizer granulation represents a promising strategy for modifying nitrogen (N) release from compost in soil. Nevertheless, there is a lack of large-scale field trials exploring its impact on tobacco production and soil N supply. This research conducted a preliminary study by employing ¹⁵N tracing technology to investigate the effects of granular compost on soil N transformation and supply; on the yield and quality of tobacco leaves; and on the distribution of granular compost-derived N among the different soil N pools and tobacco plant organs. The results revealed that the 2 cm diameter granule organic fertilizer treatment (G2) significantly increased tobacco leaf yield by 15% compared to conventional fertilization (CK). However, the 4 cm diameter granule organic fertilizer (G4) treatment resulted in a reduction in leaf yield. Notably, the quality of tobacco leaves remained unaffected compared to conventional fertilization treatment; the N content ranged from 15 to 25 g kg⁻¹, which was within the high-quality range. The results also indicated that direct N supply to the tobacco from granular compost was limited. The G2 and G4 treatments provided 2.8% and 2.2% of the N in the fertilizer to the tobacco plants, respectively, with more than 93% of the N in the tobacco plants derived from the soil. Therefore, both of these particle sizes of granular compost facilitated the absorption of soil N by tobacco plants. At the end of the growth period, the N content derived from the G4 granular fertilizer in the soil was significantly higher than that from the G2 fertilizer. This may be due to the slower nutrient release mechanism and longer release period of the G4 fertilizer compared to G2. Our results suggested that granulated compost fertilizer (both G2 and G4) has the potential to enhance soil N supply. Despite the elevated nitrogen levels observed in leaves treated with 4 cm diameter granular fertilizer, an integrated assessment of yield performance demonstrates that the 2 cm diameter granular organic fertilizer delivers superior economic benefits. However, G2 may also have a higher potential for N loss. Further investigations under field conditions are necessary to validate the applicability of granular fertilizer of different particle sizes and its specific mechanisms of impact. Full article

The usage of land on small farms in subtropical regions varies with climatic conditions. Agricultural cultivation typically occurs during the spring and summer (of the southern hemisphere), with tobacco being the primary crop on most small farms. During these seasons, livestock graze in pastures and woodlots. After the tobacco harvest (March), farmers plant winter cover crops, and by May, livestock is moved from the pastures to the agricultural areas. This study aimed to examine how grazing influences soil density, water infiltration rates, and animal behavior across different land types (pasture, native forest, eucalyptus reforestation, and agriculture) during the tobacco-growing season, and the off-season when grazing occurs on agricultural lands. It was found that forage availability and climatic conditions determined grazing duration in pastures and forests, under Integrated Crop–Livestock (ICL) systems. Higher forage volume in the agriculture area reduced grazing time and increased resting periods. Eucalyptus reforestation areas had the best soil conditions due to minimal grazing occurring there. An increase in soil bulk density and a decrease in water infiltration rates were observed at the end of the grazing period in both pasture and woodland areas. Year-round ICL systems appear to enhance soil quality through fallow periods, improving forage availability, soil moisture retention, and water infiltration as well. Full article

Oxybenzone (OBZ), an organic ultraviolet filter, is an emerging contaminant posing severe threats to ecosystem health. Using tobacco (Nicotiana tabacum) as a model plant, this study investigated the alleviation mechanisms of exogenous silicon (Na₂SiO₃, Si) and bamboo-based biochar (Bc) under OBZ stress. We systematically analyzed physiological and biochemical responses, including phenotypic parameters, reactive oxygen species metabolism, photosynthetic function, chlorophyll synthesis, and endogenous hormone levels. Results reveal that OBZ significantly inhibited tobacco growth and triggered a reactive oxygen species (ROS) burst. Additionally, OBZ disrupted antioxidant enzyme activities and hormonal balance. Exogenous Bc mitigated OBZ toxicity by adsorbing OBZ, directly scavenging ROS, and restoring the ascorbate-glutathione (AsA-GSH) cycle, thereby enhancing photosynthetic efficiency, while Si alleviated stress via cell wall silicification, preferential regulation of root development and hormonal signaling, and repair of chlorophyll biosynthesis precursor metabolism and PSII function. The mechanisms of the two stress mitigators were complementary, Bc primarily relied on physical adsorption and ROS scavenging, whereas Si emphasized metabolic regulation and structural reinforcement. These findings provide practical strategies for simultaneously mitigating organic UV filter pollution and enhancing plant resilience in contaminated soils. Full article

Field trials were carried out over two tobacco cropping seasons (2020 and 2021) to assess the effectiveness of soil (PRE-T) and post-transplant (POST-T (OT)) herbicides in a tobacco crop, depending on rainfall and the type of soil. The effectiveness of PRE-T and POST-T (OT) herbicides alternated according to the presence of weeds, treatments, the region, and years. Unpredictable meteorological conditions throughout the two study years likely influenced the control of weeds. An unusually moist May in 2020 with a precipitation of 29 mm in the first WA PRE-T before the emergence of weeds generated the leaching of the PRE-T herbicide from the surface of the soil, which was likely the most probable reason for the reduced effectiveness of PRE-T-applied herbicides (less than 77%) in comparison to the POST-T (OT) application treatment in 2020 in the Prilep region. Conversely, the restricted rainfall after PRE-T and POST-T (OT) application may have caused the unsatisfactory efficacy of both PRE-T and POST-T (OT) herbicide treatments in the Titov Veles region in 2021 (less than 78 and 80%, respectively) in comparison with 2020. Excessive rain immediately after PRE-T and POST-T (OT) application resulted in the injury of tobacco plants in the Prilep region in 2020 and 2021, which was between 8 and 25%, and 7 and 22%, respectively, after seven DAHAs across both treatments. The injuries caused by pendimethalin and metolachlor were more serious. The yields of tobacco after both PRE-T and POST-T treatment in each region typically reflect the overall effectiveness of weed control and the extent of tobacco crop injury. Full article

Soil salinization threatens agriculture by inducing osmotic stress, ion toxicity, and oxidative damage. SnRK2 genes are involved in plant stress responses, but their roles in salt stress response regulation of tobacco remain unclear. Through genome-wide analysis, we identified 54 SnRK2 genes across four Nicotiana species (N. tabacum, N. benthamiana, N. sylvestris, and N. tomentosiformis). Phylogenetic reconstruction clustered these genes into five divergent groups, revealing lineage-specific expansion in diploid progenitors (N. tomentosiformis) versus polyploidy-driven gene loss in N. tabacum. In silico promoter analysis uncovered regulatory networks involving light, hormones, stress, and developmental signals, with prevalent ABA-responsive elements (ABREs) supporting conserved stress-adaptive roles. Structural analysis highlighted functional diversification through variations in intron–exon architecture and conserved kinase motifs. This study provides a genomic atlas of SnRK2 evolution in Nicotiana, offering a foundation for engineering salt-tolerant crops. Full article

Drought and soil salinization significantly constrain agricultural productivity, driving the need for molecular breeding strategies to enhance stress resistance. Zinc finger proteins play a critical role in plant response to abiotic stress. In this study, a gene encoding a C2H2-type zinc finger protein (AfZFP5) was cloned from Amorpha fruticosa, a species known for its strong adaptability. qRT-PCR analysis revealed that AfZFP5 expression is regulated by sorbitol, H₂O₂, NaCl, and NaHCO₃. And all four treatments can cause upregulation of AFZFP5 expression in the roots or leaves of Amorpha fruticosa within 48 h. Transgenic tobacco lines overexpressing AfZFP5 demonstrated enhanced tolerance to drought and salt–alkali stress at germination, seedling, and vegetative stages. Compared to wild-type plants, transgenic lines exhibited significantly higher germination rates, root lengths, and fresh weights when treated with sorbitol, NaCl, and NaHCO₃. Under natural drought and salt–alkali stress conditions, transgenic plants showed elevated activities of superoxide dismutase (SOD) and peroxidase (POD), and upregulated expression of oxidative stress-related kinase genes (NtSOD, NtPOD) during the vegetative stage. Additionally, transgenic tobacco displayed lower malondialdehyde (MDA) content and reduced staining levels with 3,3′diaminobenzidine (DAB) and Nitro blue tetrazolium (NBT), indicating enhanced reactive oxygen species (ROS) scavenging capacity by AfZFP5 upon salt–alkali stress. Under simulated drought with PEG6000 and salt–alkali stress, chlorophyll fluorescence intensity and Fv/Fm values in transgenic tobacco were significantly higher than in wild-type plants during the vegetative stage, suggesting that AfZFP5 mitigates stress-induced damage to the photosynthetic system. This study highlights the role of AfZFP5 in conferring drought and salt–alkali stress tolerance, providing genetic resources and a theoretical foundation for breeding stress-resistance crops. Full article

Heavy metal pollution and soil salinization harm human health and the environment. Phytoremediation is a widely accepted soil decontamination method, with woody plants being particularly effective due to their large biomass and extensive root systems. In this study, we identified and cloned PsnMLP328 from Populus simonii × P. nigra and demonstrated its role in mitigating salt and cadmium stress. PsnMLP328 expression was up-regulated under both stress conditions, and its overexpression in tobacco enhanced resistance to these stresses, albeit through distinct mechanisms. Transgenic plants exhibited increased Cd²⁺ uptake and a higher biomass, alleviating Cd²⁺-induced growth inhibition. Additionally, PsnMLP328 boosted proline content, chlorophyll levels, and antioxidative enzyme activities (POD, SOD) under Cd²⁺ stress, likely by protecting cells from oxidative damage. Expression analysis revealed that PsnMLP328 down-regulated the cadmium transporter Nramp2 while up-regulating YSL2 (another cadmium transporter) and potassium channels (AKT1 and AKT2/3), suggesting its role in modulating K⁺ and Cd²⁺ homeostasis. These findings indicate that PsnMLP328 enhances tobacco resistance to salt and cadmium stress, particularly the latter. This study is the first to elucidate the function of poplar MLP family genes under salt and cadmium stress, advancing our understanding of MLP gene roles in heavy metal stress and offering new insights for remediating salinized and heavy metal-contaminated soils. Full article

Soil microbial communities contribute to the growth, health, and productivity of crops during agricultural production, and yet it is not clear how different fertilization practices affect the diversity, composition, and co-occurrence network of soil bacterial communities at different stages of growing tobacco. Here, we report the characteristics of changes in soil bacterial communities at different tobacco growth stages and fallow periods after fertilizer application by selecting long-term continuous crop tobacco fields with different fertilizers (control (CK), a cattle manure organic fertilizer (OM), a cattle manure organic fertilizer and chemical fertilizer mix (MNPK), a chemical fertilizer (NPK), and crushed straw (ST)) at the time of tobacco planting, combined with high-throughput sequencing technology and molecular ecological network methods. The results showed that soil bacterial diversity did not respond significantly to fertilizer application during the growing period of roasted tobacco, which only increased bacterial diversity in the fallow period. The key taxa of the co-occurrence network were lost during the peak and maturity periods of tobacco cultivation and were gradually recovered after fallowing. The choice of straw, chemical fertilizer, and cow manure organic fertilizer mixed with chemical fertilizer when planting tobacco can better feed the growth of roasted tobacco, and the choice of an organic matter fertilizer (straw and cow manure) as the base fertilizer can accelerate the repair of the bacterial co-occurrence network after the soil has been fallowed and improve the subhealth of the planted tobacco soil. Full article

Soybean is crucial to food processing and agricultural output. However, pests and diseases can easily impact soybeans, reducing their production. Soybean cyst nematode (SCN) is a soilborne pathogen that has a large geographic range, a long lifespan, and the potential to inflict substantial harm to the soybean industry. Persistent use of major resistance genes leads to a progressive loss of resistance; therefore, continuous identification of new soybean strains and genes is essential for continued sustainable soybean production. In this research, the SCN-resistant and SCN-sensitive germplasm DN-L10 and Heinong 37 were inoculated with SCN 3. After stress treatment, the stressed roots were collected for RNA-Seq analysis. The sequencing results screened out the differentially expressed gene GmbHLH18. The GmbHLH18 gene was cloned, and the overexpression vector pCAMBIA3300-GmbHLH18 was constructed. Agrobacterium infected soybean hairy roots and genetically modified the roots of DN50 soybeans, and transgenic root seedlings were obtained. The transgenically identified root seedlings were transplanted in soil infested with SCN 3, and resistance to root nematodes was determined by magenta staining. The secondary and tertiary structures of the protein, phosphorylation sites, as well as the hydrophilicity related to the GmbHLH18 gene were analyzed. Subsequently, the recombinant subcellular localization vector pCAMBIA1302-GmbHLH18 was employed. Agrobacterium was injected into tobacco leaves, and organelle-specific expression was observed. Finally, stress resistance-related indexes of the roots of overexpressing plants and WT plants under SCN 3 stress were measured. The results showed that overexpression and subcellular localization vectors were successfully constructed and transformed into Agrobacterium K599 and GV3101, respectively. The encoded protein had 1149 amino acids, a molecular weight of 95.76 kDa, an isoelectric point of 5.04, 60 phosphorylation sites, a tertiary structure of a-helix (36.39%), random coil (53.40%), extended chain (8.64%), and corner (1.57%), and was hydrophilic. The protein that the gene encoded was a nuclear-localized protein, according to the results of subcellular localization analysis. Moreover, the Agrobacterium-induced hairy root test revealed that the number of overexpressed pCAMBIA3300-GmbHLH18 transgenic roots in the unit area of DN50 was substantially lower than in the control group, which at first suggested that the gene had partial resistance to SCN 3. Stress resistance-related indexes suggest that the contents of POD, SOD, and proline in the overexpressing root significantly increase after SCN 3 stress, demonstrating that this gene can enhance the plant’s resistance to the SCN 3 pathogen. Future research could focus on further elucidating the molecular mechanism underlying the gene’s resistance to SCN 3 and exploring its potential application in breeding soybean varieties with enhanced resistance. Full article

A field experiment was conducted in 2018 at Marciano della Chiana (Arezzo, AR, Central Italy) with the main aim of investigating the effect of soil amendment with organic fraction municipal solid waste (OFMSW) compost and legume green manuring (Vicia villosa Roth, cv. villana) on a tobacco crop (dark fire-cured Kentucky type, cv. Foiano) grown under both full (100% of ET_c) and deficit (70% of crop evapotranspiration, ET_c) irrigation. The treatments are hereafter reported as GM (vetch green manuring) and NGM (no vetch green manuring), FI (full irrigation) and DI (deficit irrigation), and C (compost soil amendment) and NC (no compost soil amendment). The following parameters were calculated: (i) yield of the cured product (CLY, Mg ha⁻¹) at a standard moisture content of 19%; (ii) irrigation water use efficiency (IWUE, kg of cured product m⁻³ seasonal irrigation volume), nitrogen (N) agronomic efficiency (NAE, kg of cured product kg⁻¹ mineral N by synthetic fertilizers). Dry biomass accumulated in the stem and leaves (Mg ha⁻¹) was also measured at 25, 57, 74, and 92 days after transplanting (DAT). The N recovery from the different plant parts (kg ha⁻¹) was determined at 57 and 74 DAT. The C/N ratio, NO₃-N (kg ha⁻¹), the soil organic matter (SOM, %), and the soil contents of P₂O₅ and K₂O (mg kg⁻¹) were also analytically determined at 43, 74, and 116 DAT. Water retention measurements were carried out on soil samples at 116 DAT at 0–0.3 and 0.3–0.6 soil depths. Overall, there was a negative effect of both compost amendment and green manuring on yield. Green manuring and compost soil amendment improved soil chemical characteristics (i.e., SOM and C/N), as well as the plant N recovery, the IWUE, and the NAE. They increased the water retention capacity of the soil when the tobacco crop was deficit-irrigated and appeared to be promising practices to support the deficit irrigation strategy, contributing to reaching good agronomic results, although under the conditions of water shortage, and showing synergistic action in those conditions. Full article

Molybdenum (Mo) is widely used as a micronutrient fertilizer to improve plant growth and soil quality. However, the interactions between cell wall biosynthesis and molybdenum have not been explored sufficiently. This study thoroughly investigated the regulatory effects of different concentrations of Mo on tobacco cell wall biosynthesis from physiological and metabolomic aspects. The results indicate that Mo treatment increased the Mo content of tobacco variety K326. Moreover, it significantly up-regulated the gene expression levels of molybdases (NR, AO, SO, XDH) and molybdate transporters in tobacco, whereby the gene expression levels of NR were upregulated by 28.48%, 52.51%, 173.05%, and 246.21%, respectively; and MOT1 and MOT2 were upregulated by 21.49/8.67%, 66.05/30.44%, 93.05/93.26%, and 166.11/114.29%, respectively. Additionally, Mo treatment regulated the synthesis of related enzymes, effectively promoted plant growth, and significantly increased biomass and dry matter accumulation, with the biomass in the leaves increasing significantly by 30.73%, 40.72%, 46.34%, and 12.88%, respectively. The FT-NIR spectroscopy results indicate that after Mo was applied to the soil, the quantity of C-O-C, -COOH, C-H, and N-H functional groups increased. Concurrently, the contents of cellulose, hemicellulose, lignin, protopectin, and soluble pectin in the leaves significantly increased, wherein the content of soluble pectin and hemicellulose increased significantly by 31.01/288.82%, 40.69/343.43%, 69.93/241.73%, and 196.88/223.26%, respectively. Furthermore, the cell walls thickened, increasing the ability of the plant to withstand disturbances. The metabolic network diagrams indicate that Mo regulated galactose metabolism, and arginine and proline acid biosynthesis. The contents of carbohydrates, spermidine, proline, quinic acid, IAA, flavonoids, and other substances were increased, increasing the levels of polysaccharides and pectin within the cell wall, controlling lignin production, and successfully enhancing resistance to abiotic stress. These results offer important perspectives for further investigations into the role of trace elements. Full article

Cadmium (Cd) is a toxic metal primarily found as a by-product of zinc production. Cd was a proven carcinogen, and exposure to this metal has been linked to various adverse health effects, which were first reported in the mid-19th century and thoroughly investigated by the 20th century. The toxicokinetics and dynamics of Cd reveal its propensity for long biological retention and predominant storage in soft tissues. Until the 1950s, Cd pollution was caused by industrial activities, whereas nowadays, the main source is phosphate fertilizers, which strongly contaminate soil and water and affect human health and ecosystems. Cd enters the human body mainly through ingestion and inhalation, with food and tobacco smoke being the primary sources. It accumulates in various organs, particularly the kidney and liver, and is known to cause severe health problems, including renal dysfunction, bone diseases, cardiovascular problems, and many others. On a cellular level, Cd disrupts numerous biological processes, inducing oxidative stress generation and DNA damage. This comprehensive review explores Cd pollution, accumulation, distribution, and biological impacts on bacteria, fungi, edible mushrooms, plants, animals, and humans on a molecular level. Molecular aspects of carcinogenesis, apoptosis, autophagy, specific gene expression, stress protein synthesis, and ROS formation caused by Cd were discussed as well. This paper also summarizes how Cd is removed from contaminated environments and the human body. Full article

Soil remediation for cadmium (Cd) toxicity is essential for successful tobacco cultivation and production. Melatonin application can relieve heavy metal stress and promote plant growth; however, it remains somewhat unclear whether melatonin supplementation can remediate the effects of Cd toxicity on the growth and development of tobacco seedlings. Herein, we evaluated the effect of soil-applied melatonin on Cd accumulation in tobacco seedlings, as well as the responses in growth, physiological and biochemical parameters, and the expression of stress-responsive genes. Our results demonstrate that melatonin application mitigated Cd stress in tobacco, and thus promoted plant growth. It increased root fresh weight, dry weight, shoot fresh weight and dry weight by 58.40%, 163.80%, 34.70% and 84.09%, respectively, compared to the control. Physiological analyses also showed significant differences in photosynthetic rate and pigment formation among the treatments, with the highest improvements recorded for melatonin application. In addition, melatonin application alleviated Cd-induced oxidative damage by reducing MDA content and enhancing the activities of enzymatic antioxidants (CAT, SOD, POD and APX) as well as non-enzymatic antioxidants (GSH and AsA). Moreover, confocal microscopic imaging confirmed the effectiveness of melatonin application in sustaining cell integrity under Cd stress. Scanning Electron Microscopy (SEM) observations illustrated the alleviative role of melatonin on stomata and ultrastructural features under Cd toxicity. The qRT-PCR analysis revealed that melatonin application upregulated the expression of photosynthetic and antioxidant-related genes, including SNtChl, q-NtCSD1, NtPsy2 and QntFSD1, in tobacco leaves. Together, our results suggest that soil-applied melatonin can promote tobacco tolerance to Cd stress by modulating morpho-physiological and biochemical changes, as well as the expression of relevant genes. Full article