Chemical and Biological Technologies in Agriculture最新文献

Background

Hunan Province, a major rice-producing region in China, faces severe cadmium (Cd) contamination in rice grains. Cd, a heavy toxic metal, accumulates in rice through the soil–rice system, posing health risks via the food chain. Effective management relies on identifying pollution sources to guide targeted control and reduction strategies.

Results

Through the data collected over the past 5 years across four different regions, a multiple linear regression model was established to explore the effects of those factors influencing Cd accumulation in rice tissues, including the input fluxes of soil Cd, atmospheric deposition Cd (DICd), irrigation water Cd (IRCd), and fertilizer Cd (CFCd). Atmospheric deposition was identified as a major source of Cd input, with a higher annual average input flux than irrigation water and fertilizers. In the industrial and mining zone Zhuzhou, atmospheric deposition accounted for 96.42% of the total Cd input. In the regions with an increasing level of atmospheric deposition, Cd exhibited higher soil Cd concentrations but lower pH. Total soil Cd (TCd) concentrations demonstrated a significant positive correlation with both soil available Cd (ACd) concentrations and DICd. Additionally, TCd and DICd were determined to be the critical factors affecting the accumulation of Cd in rice tissues.

Conclusions

As indicated by the results, the spatial variation in rice Cd accumulation resulted from various sources of Cd input, highlighting the necessity to closely monitor Cd input fluxes across various regions. This study provides a benchmark for understanding the impact of atmospheric deposition on Cd accumulation in rice grains.

Graphical Abstract

Background

The antimicrobial peptide WMR-4, a myxinidin-derived sequence with Aib and D-amino acid substitutions, showed enhanced stability and strong antifungal activity against Fusarium oxysporum in vitro.

Results

Biophysical studies indicated a lytic mechanism via deep membrane insertion and leakage. However, free WMR-4 failed to block fungal penetration through cellulose barriers, revealing limits in complex systems. To overcome this, we developed supramolecular nanofibers functionalized with WMR-4 and the cell-penetrating peptide gH625. These nanofibers inhibited germ tube formation, partially reduced cellulose membrane penetration, and provided enhanced protection in biological contexts. Specifically, nanofibers limited opportunistic saprophytic colonization in apple tissues lacking epidermal barriers while preserving tissue integrity in intact tomato models, demonstrating barrier-specific therapeutic protection. SEM and AFM confirmed stable nanoscale coatings integrated into plant epidermal layers.

Conclusions

These results highlight WMR-4 as a potent antifungal candidate and demonstrate the potential of AMP-functionalized supramolecular nanostructures for agricultural applications.

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Walnut (Juglans regia L.) is an important oilseed crop, and salt stress threatens the growth of walnut tree. In this study, NO₃⁻ or NH₄⁺ was applied at three concentrations (4, 32, and 100 mM) to investigate the effect of NO₃⁻-N and NH₄⁺-N on walnut seedlings under 100 mM NaCl stress. Results showed that moderate (32 mM) NO₃⁻-N application alleviated the effect of salt stress. Moreover, plants treated with 32 mM NO₃⁻-N showed no significant morphological difference from those subjected to the nonstress treatment. The treatment of 32 mM NO₃⁻-N application enhanced plant growth, increased antioxidant enzyme activities (superoxide dismutase and catalase), and restricted Na⁺ and Cl⁻ uptake and transport. Additionally, it might induce beneficial shifts in the rhizosphere microbiome. Low-concentration (4 mM) NO₃⁻ or NH₄⁺ treatment individually induced the minor alleviation of salt stress. By contrast, 100 mM NO₃⁻ and all tested concentrations of NH₄⁺ further inhibited biomass and root growth, thereby exacerbating salt injury. Notably, 100 mM NH₄⁺ caused severe defoliation and seedling mortality. Furthermore, in contrast to its NO₃⁻ counterpart, 32 mM NH₄⁺ shifted the root microbiome and impaired microbial diversity, likely contributing to increased salt sensitivity. This study demonstrates that moderate NO₃⁻ application can effectively mitigate salt stress during walnut growth, offering a potential strategy for fertilizing walnut plantations under saline conditions.

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Herein, a modified biogenic graphene oxide–mesoporous silica hybrid nanoparticle (GO–MSNs) was developed as a reliable and efficient nano-pesticide delivery system (nano-PDS) for the slow release of neem (Azadirachtin, Aza), which is known as an environmentally friendly biopesticide. For this purpose, GO–MSN-based nanocarrier (GO–MSNs) was synthesized using rice husk-derived silica and graphene precursors, followed by surface modification to obtain propyl amine-functionalized GO–MSNs nanocarrier (nano-PDS). The nano-PDS nanocarrier was then characterized and investigated for its potential as a nanoporous host for efficient loading and slow-release pattern of Aza to control the silverleaf whitefly (Bemisia tabaci). The nanostructure and porosity of the synthesized nanocarrier were fully characterized by X-ray diffraction (XRD), electron microscopy (SEM and TEM), thermogravimetric analysis (TGA), and surface area and pore analysis using the Brunauer–Emmett–Teller (BET) and Barrett–Joyner–Halenda (BJH) theories. The loading efficiency was found to depend on nanocarrier characteristics, such as surface area, pore size, functional group, and surface charge. Notably, the interaction between Aza and the amine functional groups found in the nano-PDS led to a more efficient slow-release profile compared to the bare GO–MSNs nanocarrier. The release rate of Aza was analyzed using a UV–visible spectrophotometer at 214 nm. The UV stability, thermal stability, and release behavior as paramount factors in developing a sustainable Aza delivery system were tuned by manipulating the nanocarrier surface. The organically modified biogenic GO–MSNs thus offers promising potential for slow-release and improved efficiency of Aza-based nanobiopesticide in the control of Bemisia tabaci.

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Background

Tomato (Solanum lycopersicum), a vital global crop rich in bioactive compounds, faces sustainability issues due to agrochemical overuse, necessitating eco-friendly biofertilizers like plant growth-promoting rhizobacteria (PGPR) for sustainable agriculture. This study aimed to identify superior PGPR strains with growth-enhancing volatile organic compounds (VOCs), characterize their VOC profiles, determine optimal VOC doses for growth promotion, and investigate their effects on root architecture, rhizosphere microbiome, and plant transcriptomics to elucidate mechanisms.

Results

Thirteen PGPR strains were screened for VOC-mediated tomato growth promotion. Key strains' VOCs were profiled using GC–MS. Dose-response assays tested core VOCs on growth and root architecture. Rhizosphere microbiome functional compartmentalization was analyzed, and transcriptomic profiling (KEGG pathway enrichment) of VOC-treated plants was performed. Three superior isolates (Pantoea ananatis D1-28, Burkholderia sp. D4-24, Burkholderia territorii D4-36) were identified, with D1-28 notably enhancing lateral roots and shoot biomass. GC–MS revealed strain-specific VOC profiles (31–37 compounds) sharing three core components: dimethyl disulfide (D), 2-nonanone (N), benzothiazole (B). Optimal doses profoundly remodeled root architecture and maximized growth: D (10⁻³ mmol/L), N (1 mmol/L), B (10⁻² mmol/L). VOCs drove rhizosphere functional compartmentalization, enriching specific taxa. Transcriptomics identified 132 differentially enriched KEGG pathways (130 conserved), primarily linked to auxin biosynthesis, sulfur/nitrogen metabolism, energy metabolism, and carbohydrate metabolism, indicating analogous mechanisms.

Conclusions

This study elucidates for the first time how P. ananatis VOCs coordinate plant hormone signaling, metabolic networks, and rhizosphere microecology to synergistically enhance tomato growth, providing a theoretical foundation for VOC-based green agricultural technologies.

Graphical Abstract

Background

The brown planthopper (Nilaparvata lugens) is a destructive rice pest in Asia, causing significant yield losses through sap feeding and virus transmission. We developed an eco-friendly nano-encapsulation system using chitosan nanoparticles (CS NPs) loaded with Litsea cubeba essential oil (Lc EO), a potent botanical insecticide. GC–MS analysis identified citral (48.5%) as the dominant component of Lc EO.

Results

CS-Lc NPs (282 nm in diameter) were successfully synthesized via emulsion-ionic gelation, exhibiting enhanced thermal stability and sustained release. Bioassays showed significantly higher insecticidal activity in CS-Lc NPs with LC₅₀ values of 391.41 mg/L at 72 h and 229.14 mg/L at 120 h, compared to unloaded CS NPs (1034.54 mg/L at 72 h and 627.78 mg/L at 120 h). The nano-formulation caused severe damage to the midgut epithelium, as observed through histopathology, elevated salivary flange production, disrupting the activities of detoxification enzymes (POD, SOD, CAT, AChE, AKP, ACP). Molecular analysis confirmed the upregulation of key detoxification genes, with a significant increase in NlCYP6AY1v2 expression, highlighting the enhanced bioavailability and sustained insecticidal activity provided by nano-encapsulation.

Conclusion

CS-Lc NPs enhanced both the stability and bioavailability of Lc EO, significantly improving its efficacy against BPH. This approach offers a promising alternative to reduce reliance on chemical pesticides in rice farming.

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Whole corn silage (WCS) is susceptible to deterioration during storage. However, suitable supplements can enhance active metabolites, which preserve silage quality and feeding value. This study compared the metabolic responses of WCS treated with Lactobacillus buchneri (LB), plant-derived melatonin (ME), and their combination (LB + ME) by evaluating fermentation quality, antioxidant indices, and active metabolites. Compared with that in the control (CK) treatment (348.43 U/g FW), superoxide dismutase (SOD) activity in the LB treatment significantly (p < 0.05) increased to 536.78 U/g FW. Meanwhile, the catalase activity in the ME treatment reached 34.90 nmol/min/g FW, which was significantly (p < 0.05) higher than that in the CK, LB, and LB + ME treatments. Furthermore, 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging capacities increased to 7.89 and 7.36 μmol Trolox/g DM in the LB and ME treatments, respectively. Similarly, the ferric ion-reducing antioxidant power (FRAP) values increased to 10.50 and 9.30 μmol Trolox/g DM in the LB and ME treatments, respectively. Metabolomics analysis revealed 1449 secondary metabolites in WCS, with LB and ME promoting the synthesis of flavonoids, particularly sinapic acid, 1,2,5,7,8-pentahydroxy-3-methylanthracene-9,10-dione, and 2,4-dihydroxybenzoic acid. A positive correlation was observed between water-soluble carbohydrates, DPPH, FRAP, SOD, chrysoeriol, and kaempferide in LB-treated WCS. In conclusion, the LB treatment exhibited superior antioxidant activities, which ultimately promoted flavonoid synthesis. The findings of this study provide mechanistic insights into the influence of supplements on antioxidant pathways in WCS. The development of WCS additives also provides direction for the optimization of functional additive products.

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Bacterial wilt disease is an important bacterial soil-borne disease that poses a considerable threat to the sericulture and other crop industries. In China, mulberry bacterial wilt disease is caused by Ralstonia pseudosolanacearum Mori (RPM), while in other crops, this disease is caused by R. pseudosolanacearum. Establishing a rapid detection method for bacterial wilt disease in mulberry and other crops is highly relevant for controlling its spread and damages. In the present study, we targeted the RPM-specific transposase RpmTEs gene (GenBank accession number: SAMN37721522) and R. pseudosolanacearum virulence genes transcriptional regulator phcA gene (GenBank accession number: AL646052.1) for developing a specific duplex PCR (dPCR) assay. The dPCR assay primers were designed, and 198 strains of R. pseudosolanacearum from nine different hosts were used to optimize the reaction system and amplification program. In addition, the RPM-dPCR detection assay was established to test its specificity, sensitivity, and practicality. In terms of specificity, the results showed that the RPM-specific detection primers RpmTEs-1F/R had a 2.27% higher accuracy rate compared to the MG67-F/R primers reported in previous literature. While the primers phcA-1F/R had a 5% higher accuracy rate than the AU759f/AU760r primers reported in previous literature. RPM-dPCR showed a DNA detection sensitivity of 1 pg/µL (equivalent to 1 × 10⁴ CFU/mL) at RpmTEs-1F/R:phcA-1F/R = 0.25:0.5, an annealing temperature of 63 ℃ and 30 cycles. It was found to be highly specific, as it wasn’t affected by non-target bacteria. The RPM detection rate for mulberry bacterial wilt samples (125) was 64.8%, while R. pseudosolanacearum detection rate for other crops’ samples (143) was 46.9%. Compared to traditional isolation method, RPM and R. pseudosolanacearum detection rates were 56.8% and 44.1%, respectively. Traditional isolation methods had a 2.8–8.0% lower detection rate than RPM-dPCR assay. The established RPM-dPCR assay is simple, specific, sensitive, and efficient, as it can be simultaneously used for the rapid detection of bacterial wilt in mulberry and other crops.

Graphical Abstract

The majority of plant diseases are caused by pathogenic fungi, leading to huge losses in agriculture and forestry. Recently, the isolation and identification of antifungal compounds from actinomycetes have emerged as effective strategies for developing novel biological fungicides. In this study, the antagonistic strain TCS22-109 demonstrated broad-spectrum antifungal activity against six common pathogenic fungi and was identified as Streptomyces murinus based on morphological, physiological, and biochemical characteristics, as well as phylogenetic analysis of the 16S rRNA gene sequence. To tap into the bioactive potential of actinomycetes, an antifungal activity-guided isolation was performed on the fermentation extracts of strain TCS22-109. As a result, two antifungal compounds, actinomycin D and pentamycin, were isolated from TCS22-109, and their chemical structures were elucidated using NMR (nuclear magnetic resonance spectroscopy) and HR-MS (high-resolution mass spectrometry) analysis. Among these, pentamycin exhibited notable broad-spectrum antifungal properties, particularly against Rhizoctonia solani and Botrytis cinerea. Scanning electron microscopy (SEM) revealed that pentamycin inhibited the mycelial growth of B. cinerea and induced sporulation. Additionally, treatment with pentamycin led to ergosterol depletion and enhanced intracellular leakage in B. cinerea mycelium, indicating damage to cell membranes. Furthermore, pentamycin effectively protected postharvest fruit from gray mold caused by B. cinerea. These findings suggest that pentamycin derived from S. murinus TCS22-109 holds promise as a natural fungicide for managing plant and postharvest fruit diseases.

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Liquid manure storage contributes substantially to environmental emissions within manure management systems. This study evaluated Yucca schidigera extract (YE) as a sustainable microbial modulator for mitigating ammonia (NH₃) and greenhouse gas emissions during 60-day storage of liquid chicken manure. Three treatments were established: no additive (control, CK), 0.1% biological deodorant (positive control, BF), and 0.5% YE. The results demonstrated that both YE and BF significantly reduced electrical conductivity (EC) (YE: 38.35%; BF: 34.51%) and ammonium nitrogen (NH₄⁺-N) content (YE: 14.15%; BF: 20.21%) relative to CK, while elevating the C/N ratio by 9.97% (YE) and 18.63% (BF). Total nitrogen decreased by 23.88% (YE) and 26.34% (BF) from initial levels. In addition, the cumulative NH₃ emissions of YE and BF decreased significantly by 20.18% and 20.12% compared to CK. However, YE increased CH₄ emissions by 17.43%, elevating global warming potential, whereas BF exhibited no significant effect on CH₄. Neither additive influenced CO₂ or N₂O emissions. Microbial analysis revealed YE enriched Firmicutes (e.g., Fermentimonas), while BF enhanced Actinobacteriota (e.g., Corynebacterium) and Proteobacteria. Both additives suppressed ammonia-producing bacteria (e.g., Proteiniphilum). Mantel tests analysis indicated NH₃ emissions correlated positively with EC and NH₄⁺-N (P < 0.01), while CH₄ emissions correlated with organic matter (OM) content (P < 0.05). These findings elucidate the microbial mechanisms of YE in mitigating the NH₃ emission during liquid manure storage, whereas YE may induce trade-offs in CH₄ emission. In the future, the formulation of compound plant-derived additives will be necessary for the synergetic abatement of carbon and nitrogen gases.

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