Chemical and Biological Technologies in Agriculture最新文献

Background

Grape production generates substantial agricultural waste, particularly grape pomace, a by-product rich in bioactive compounds. Moreover, its reuse is strongly recommended to prevent environmental issues from improper disposal. This study explores the feasibility of using exhausted grape pomace, alone and in combination with anaerobic digestate, as substrates for Pleurotus mushroom cultivation. Grape pomace is rich in fiber, lipids, sugars, proteins, and phenolic compounds, which makes it a promising substrate for this purpose.

Results

Elemental analyses of this substrate revealed high carbon (46%) and nitrogen (2.5%) contents, along with greater levels of macro and microelements (P, Ca, Mg, Fe) compared to conventional substrates. Fourier Transformed Infrared (FTIR) spectroscopy identified aliphatic groups from seed fatty acids and polysaccharide bands, typical of the seedless part of grape pomace. Fatty acid evaluation confirmed the presence of partial glycerides with linoleic acid content exceeding 62%, while phenolic composition analysis highlighted a predominance of bound phenols. These chemical characteristics significantly increased mushroom production, with statistically significant increases in fresh weights observed upon the addition of grape pomace, resulting in variations exceeding 130% in some instances. The mixture with digestate exhibited the most promising results, probably due to improved pH values. FTIR and Surface Enhanced Raman Scattering (SERS) spectra of mushrooms grown on different matrices were similar, but with some differences likely related to substrate composition. In addition, SERS analysis identified ergothioneine, a significant fungal amino acid, which was not detectable in the FTIR spectra.

Conclusions

This study highlights grape pomace as an effective and sustainable substrate for mushroom cultivation, offering a viable alternative to conventional growth mediums. The high yield and consistent quality of mushrooms grown on grape pomace, particularly when mixed with anaerobic digestate, demonstrate its potential for commercial mushroom production. The findings support the broader goals of sustainable agriculture by promoting the recycling of agricultural by-products, minimizing waste, and adding economic value. This innovative approach to utilizing grape pomace contributes to improved environmental management and opens new opportunities for enhancing the efficiency and sustainability of mushroom cultivation practices.

Graphical Abstract

The soil health notion has been recently expanded to relate soil functions not only to soil fertility for a sustainable primary productivity, but also to the control of water cycling and of the soil carbon storage. Soil humus is fundamental to achieve the objectives of soil health, and it is therefore deemed necessary to enlarge the knowledge of its composition and dynamics, if a modern soil management was to be pursued. This review first describes the contemporary understanding of the supramolecular structure of soil humus and the derived modern method to identify the totality of humic components to an unprecedented extent in soils under different soil management and cropping systems. Then, it accounts on how humus, either native in soil or exogenous from sources rich in organic carbon such as lignite, compost, and lignocellulosic residues, improves the soil physical fertility, limits the risk of erosion, enhances the bioactivity of the rhizosphere microbiome, and directly stimulates plant growth. Moreover, it is highlighted the role played by humus in ecologically sound soil managements, such as in organic and biodynamic agricultural productions, which are progressively growing as alternative to conventional but environmentally unsafe practices.

Graphical Abstract

Histone acetylation is a key epigenetic modification involved in plant development. Although histone deacetylase inhibitors (HDACi) are commonly studied in human diseases, their role in regulating histone deacetylation in plants remains unclear. This study explores the function of Citronellol, a volatile small molecule, as a plant-derived HDACi using Arabidopsis thaliana (L.) Heynh (A. thaliana) as a model. Citronellol at concentrations of 3 and 6 mM enhanced both root development and aboveground growth. Enzyme activity assays, molecular docking, and molecular dynamics simulations showed that Citronellol binds to specific residues (PHE:64, ARG:65, MET:1, and ILE:214) of the histone deacetylase AtSRT1 in Arabidopsis, inhibiting its activity and elevating H3K9ac levels. Integrated RNA-seq and ChIP-seq analyses revealed that Citronellol increased the expression of genes linked to growth and development, including ATCTH, CPL3, IBR5, TCP4, and KUA1, through enhanced histone acetylation and activation of plant hormone signaling pathways. These findings provide new insights into the epigenetic regulation of plant growth by Citronellol, identifying it as a novel HDACi. Citronellol could serve as an effective plant growth regulator, offering valuable applications for agricultural development. 

Graphical Abstract

Background

The efficacy of biocontrol agents depends critically on their environmental adaptability, with nutrient availability being a key determinant of their success. In Trichoderma species, the mechanisms linking nutrient sensing to physiological responses remain poorly understood, despite their importance for biocontrol applications.

Results

This study reveals how different nitrogen sources fundamentally regulate the physiology and metabolism of Trichoderma harzianum through pH modulation. Under nutrient-rich conditions, T. harzianum exhibited a biphasic pH response characterized by initial acidification followed by alkalinization, which correlated with enhanced sporulation. Examining specific nitrogen sources, we found that sodium nitrate induced environmental alkalinization, while ammonium nitrate caused sustained acidification. These pH changes were linked to distinct physiological responses: alkaline conditions promoted sporulation, while acidic conditions enhanced mycelial growth and triggered specific metabolic responses. Notably, acidic conditions specifically induced the production of harzianic acid and related bioactive compounds, suggesting pH-dependent regulation of secondary metabolism. This nitrogen-dependent pH modulation pattern was conserved across Trichoderma species, as demonstrated by parallel responses in T. asperellum.

Conclusions

Our findings establish nitrogen source availability as a master regulator of Trichoderma physiology through pH-dependent mechanisms, controlling both development and secondary metabolism. This understanding provides new strategies for optimizing biocontrol formulations by manipulating nitrogen sources and pH conditions to enhance both fungal fitness and beneficial metabolite production.

Graphical Abstract

Background

Grape composition, characterized by mineral content, hormone levels, and antioxidant enzyme activities, fundamentally influences berry quality, nutritional value, and vine health. Various viticultural practices, particularly tillage methods and organic fertilization techniques, significantly impact these compositional parameters. This study investigates the effects of these agricultural practices on grape composition to establish optimal protocols for enhanced berry production and quality.

Methods

A three year study (2020–2022) evaluated the effects of soil management on grape quality in ‘Royal’ grapes (VIVC: 349). Using a Randomized Complete Block Design with four replicates of 12 vines, the study tested three tillage methods (chisel, disc harrow, and no-tillage) and four organic fertilizers (Antep radish, broccoli, olive blackwater, and a control). Treatments were analyzed for berry mineral content (macro and micronutrients), hormone levels (auxin, ABA, zeatin, SA, JA, cytokinin and GA), and antioxidant enzyme activities (SOD, POD, CAT, APX, GR, GST, G6PD and 6PGD).

Results

Based on our results, the disc harrow tillage method in conjunction with olive blackwater fertilizer demonstrated superior mineral accumulation, yielding peak concentrations of nitrogen (3.72%), phosphorus (0.40%), and magnesium (0.41 mg/kg) during the 2021 growing season. Endogenous hormone levels exhibited treatment-specific responses, with maximum indole-3-acetic acid (17.33 ng/g) accumulation observed under no tillage control conditions in 2022, while abscisic acid concentrations peaked (49,172.53 ng/g) under no tillage with broccoli fertilization. Antioxidant enzyme activities were significantly enhanced under chisel tillage combined with broccoli fertilizer treatment, leading to optimal superoxide dismutase (1426.54 EU) and peroxidase (14,936.81 EU) activities. Principal component analysis revealed that the first two components explained 51.35% of total variance, with distinct temporal clustering of treatment effects.

Conclusion

The optimal cultivation practice for ‘Royal’ grape variety was determined to be chisel tillage method combined with broccoli fertilization, which maximized both mineral nutrient content and hormone levels. These findings provide practical insights for viticulturists to optimize cultivation techniques for improved grape quality and nutritional value.

Graphical Abstract

Background

Plants have developed multiple chemical defence responses against pathogen attacks. The main mechanism of defence is based on a rapid transcriptional reprogramming of genes encoding biosynthetic enzymes that synthesize specific secondary metabolites. Increasing evidence indicates phenylamides (PAs) as an important group of bioactive compounds in food plants.

Results

We synthesized a small collection of ferulic acid-derived phenylamides by chemoenzymatic approaches. The compounds were tested against fungal and bacterial pathogens to assess their antimicrobial potential. The treatment with the synthesized phenylamides showed modest inhibition of the fungal growth (up to 25%) and had no significant influence on spore germination, whereas some of the compounds gave a considerable inhibition of Pyricularia oryzae appressorium formation, up to 94%. They also exhibited in vitro antibacterial activity against six foodborne bacterial pathogens. Monitoring of six growth parameters (taking into account growth rate, time and absorbance) measured during 24 h incubation showed that the synthesized molecules, assayed at four concentrations between 12.5 and 100 mg/L, produced a stronger average antimicrobial effect against Gram-positive pathogenic strains than against Gram-negative ones.

Conclusions

The obtained results evidenced that the effect of this class of compounds is mainly related to blocking fungal virulence mechanisms, mediated by a significant effect on appressorium maturation, rather than to mycelium growth inhibition. Together with the observed in vitro antibacterial activity against foodborne bacterial pathogens, we conclude that PAs are promising candidates for future developments in the agri-food sector.

Graphical Abstract

The worldwide distribution and the host range of the phytopathogenic bacterium Xylella fastidiosa (Xf) have significantly changed in the last decade with numerous outbreaks reported in the Old Continent. Among the different European isolates, those of the subspecies pauca have been ranked as highly pathogenic, being the causal agents of the olive quick decline decimating olive trees in southern Italy. Significant research investments have been devoted towards finding therapeutic approaches to mitigate the impact of the infections in highly susceptible host species. This study aimed to evaluate in vitro efficacy against Xylella fastidiosa subsp. pauca (Xfp) of different classes of products, including metal ions, micronutrients, antibiotics, and phenolic compounds. The slow and fastidious growth of the bacterium requires optimization of specific protocols to assess antibacterial activities and the effect on biofilm formation. The results showed a dose–response effect against Xf for most products. Notably, among micronutrients and phenolic compounds, CuSO₄·5H₂O, Dentamet®, pyrocatechol and 4-methylcatechol showed the highest bactericidal and antibiofilm activity. At the same time, antibiotics demonstrated substantial bacteriostatic activity effectively inhibiting biofilm formation. For metal ions, such as CoCl₂, K₂B₄O₇·4H₂O and MnSO₄·H₂O, significant effects on bacterial cell viability were recorded but were not able to completely kill the bacterium. Regarding the antibiofilm activity, some of them were able to inhibit biofilm formation, while others increased its formation. Ca(NO₃)₂·4H₂O and Na₂MoO₄ were found to promote the growth of Xf. The methodologies described proved to be useful for profiling the antimicrobial activity of a large panel of compounds and the data collected provide evidence of their in vitro effectiveness.

Graphical Abstract

Background

Polysaccharides are the main active components of Imperata cylindrica; however, research primarily targets its roots, with limited studies on flower-derived polysaccharides.

Results

Two polysaccharides, FIC-1 and FIC-2, were extracted from the flowers of Imperata cylindrica using water extraction and ethanol precipitation. They were characterized by FT-IR, HPGPC, and SEM, with FIC-1 undergoing additional methylation and NMR analysis. FIC-1 was a neutral polysaccharide with a molecular weight of 5.3 kDa, while FIC-2 was an acidic polysaccharide with a molecular weight of 23.3 kDa. The two polysaccharides had distinct surface morphologies: FIC-1 had a rough, flocculent structure, while FIC-2 was smooth and lamellar. FIC-1’s main chain consists of →4)-β-D-Glcp-(1→, α-D-Glcp-(1→, →3)-β-D-Galp-(1→, →5)-α-L-Araf-(1→, and →4,6)-α-D-Manp-(1→ linkages, with side chains mainly formed by α-L-Araf-(1→ linked at the O-4 position of →4,6)-α-D-Manp-(1→. Further analysis of FIC-1 indicated that it promoted M1 macrophage polarization, activated NF-κB signaling pathway, and enhanced glycolysis and phagocytosis. While FIC-1 did not directly kill cancer cells, the cytokine-rich medium from FIC-1-stimulated macrophages significantly inhibited the proliferation of LLC1, ID8, and Hepa1-6 cancer cells.

Conclusions

These findings provide useful evidence that support the development and potential clinical application of polysaccharides derived from the flowers of Imperata cylindrica.

Graphical Abstract

Background

Scutellaria baicalensis roots contain root-specific flavones (baicalin, baicalein, and wogonin) exhibiting strong biological effects. Hence, this plant is considered the best plant material for hairy root system applications.

Results

In this study, we obtained hairy roots, which are considered natural genetically modified organisms, from S. baicalensis leaves in vitro using wild Agrobacterium rhizogenes (A. rhizogenes) R1000 and investigated the effects of postharvest wounding treatment on their flavone production and in vitro antimicrobial properties. Hairy roots were exposed to wounding stress, and the levels of baicalin, baicalein, and wogonin were determined using high-performance liquid chromatography (HPLC). We found that the levels of these flavones in S. baicalensis hairy roots increased after 6, 12, 24, 48, 72, and 96 h of exposure in a time-dependent manner. In particular, the highest production of three flavones was reported after exposure to 96 h of wounding stress. Furthermore, the expression levels of genes involved in root-specific flavone pathways (SbPAL1, SbPAL2, SbPAL3, SbCCL7, SbCHS2, SbCHI, SbFNS2-2, SbCYP82D1.1, and SbF8H) were determined at two time points (control and after 96 h of exposure). Expression levels of SbPAL1, SbCHS2, SbCHI, and SbCYP82D1.1 were significantly increased following exposure to wounding stress. Antimicrobials were observed with seven normal pathogens, two multidrug-resistant pathogens, and one pathogenic yeast. Moreover, the inhibition zone sizes of these bacteria were larger in the wounded S. baicalensis hairy roots with higher levels of baicalin, baicalein, and wogonin than in those with lower levels of these flavones. In addition to antimicrobial activities, the wounded hairy roots exhibited stronger anti-inflammatory and antioxidant activities than the controls.

Conclusions

Our results indicate that postharvest wounding treatment is a good strategy to increase flavone production and enhance the antibacterial activity of S. baicalensis hairy root cultures.

Graphic Abstract

Fusarium oxysporum-induced Fusarium wilt in bananas is a highly detrimental disease that significantly impedes the progress of the banana industry. In this study, Streptomyces aureoverticillatus HN6 was isolated from soil samples of Hainan Botanical Garden and showed a wide spectrum of bacterial inhibition and a substantial effect on the control of banana wilt disease. While the bacterium demonstrates high inhibitory activity, and the use of live strains is effective, there are limitations in the development and application of this particular strain, such as effective secondary metabolites are difficult to extract; unstable metabolites, and low sporulation rates. Consequently, the strain underwent electron beam mutagenesis, ⁶⁰Co-γ ray mutagenesis, two cycles of ultraviolet irradiation mutagenesis, and ethyl methanesulfonate (EMS) mutation to generate multiple mutant strains. The mutant strain Z20-1 exhibited resistance to elevated temperatures and enhanced enzymatic activities, specifically increased levels of both amylase and cellulase. Moreover, the fermentation broth of the mutant strain E95 substantially improved the bacterial inhibitory activity. Comparative genomic analysis revealed the presence of seven single-nucleotide polymorphisms (SNPs), one multiple nucleotide polymorphism (MNP), and three insertion-deletions when comparing the mutant strain E95 with the original strain HN6. Notably, the mutant strain E95 exhibited the highest expression of npmC, a core gene in the niphimycin C synthesis gene cluster. Through mutagenesis of the original strain HN6, several mutant strains with superior characteristics were successfully obtained. These findings serve as a valuable technical reference for the mutation breeding of Streptomyces.

Graphical Abstract