Inhibition efficiency of wood vinegar on grey mould of table grapes

Physiological and Biochemical Mechanisms of Wood Vinegar-Induced Stress Response against Tomato Fusarium Wilt Disease

Wood vinegar, a by-product of charcoal biomass pyrolysis, has been used as a biofungicide in plant disease management because of its antimicrobial properties. However, the physiological and biochemical mechanisms through which wood vinegar alleviates biotic stress are poorly understood. In this study, pot experiments were conducted to investigate the resistance and regulation mechanism of wood vinegar prepared from different raw materials (ZM) and from a single raw material (SM) in controlling tomato (Solanum lycopersicum "Bonny Best") Fusarium wilt at different concentrations (0.3%, 0.6%, 0.9%, 1.2%, and 1.5%). The results showed that ZM and SM had significant control effects on tomato fusarium wilt under different concentrations in the same growth cycle. Under biotic stress, the two kinds of wood vinegar significantly increased the plant height, stem diameter, leaf area and yield of tomato under the concentration of 0.3%, 0.6%, 0.9% and 1.2%, and significantly reduced the content of malondialdehyde (MDA) and hydrogen peroxide (H2O2) in tomato leaves. The effect of 0.9% treatment was the most significant, ZM and SM significantly increased tomato yield by 122% and 74%, respectively, compared with CK under 0.9% treatment. However, the plant height, stem diameter and leaf area of tomato were significantly reduced under 1.5% treatment, but the content of soluble sugar, soluble protein and vitamin C in tomato fruit was the best. Compared with CK, ZM significantly increased by 14%, 193% and 67%, respectively, and SM significantly increased by 28%, 300% and 159%, respectively. Except for 0.3% treatment, both significantly increased the activities of catalase (CAT), peroxidase (POD) and superoxide dismutase (SOD) in tomato leaves. The response intensity of two kinds of wood vinegar-physiological and biochemical-to tomato disease resistance, growth and development, showed ZM > SM. The disease index of tomato showed highly significant negative correlation with plant height, stem thickness, leaf area and antioxidant physiology CAT, and highly significant positive correlation with MDA and H2O2 content. In conclusion, ZM was more effective than SM in enhancing tomato disease resistance by promoting tomato growth and development, decreasing leaf MDA and H2O2 content, and inducing antioxidant enzyme activity in leaves at moderate concentrations.

Quality assurance of postharvest grapes against Botrytis cinerea by terbinafine

Worldwide, fruit is an indispensable treasure house of nutrition for human beings, occupying a vital position of human diet. Postharvest fruit storage requires efficient antifungal agents to control Botrytis cinerea, which is a vital postharvest disease affecting fruit and leading to enormous losses. However, with the enormous abuse of existing antifungal drugs, the problem of drug-resistant fungi is imminent, making the controlling diseases caused by pathogenic fungi even more challenging. Drug repurposing is an efficient alternative method, we evaluated a well-known antifungal chemical, terbinafine, against the agricultural pathogen, B. cinerea in vitro, as a result, terbinafine showed strong antifungal activity. Furthermore, the in vivo antifungal activity of terbinafine was evaluated, the results showed that terbinafine could reduce the decay area on grapes. Terbinafine could disrupt the cell membrane integrity, increase cell membrane permeability, and eventual cell death of B. cinerea. In addition, terbinafine reduced decay incidence, and weight loss and maintained the soluble solids, titratable acidity, ascorbic acid, total phenolic, and malondialdehyde content during the storage period of grapes. Overall, terbinafine could be an antifungal preservative for postharvest table grapes fresh-keeping.

Understanding the multifunctionality of pyroligneous acid from waste biomass and the potential applications in agriculture

Efforts have been directed to the development of environmentally friendly processes and manufacturing of green products, use of renewable energy and more sustainable agricultural practices. Pyroligneous acid (PA) is a byproduct of biomass pyrolysis that consists of a complex mixture of bioactive substances. The complexity and richness of PA composition have opened a window for PA application in agriculture and mitigation of environmental pollution. This review brings a brief historical on the use of PA and regulatory policies adopted in Brazil, China, Japan and Thailand for PA application in agriculture. The composition and stability of PAs of several origins are presented, together with a discussion of the use of PA to boost plant growth and crop productivity, remove toxic metals from soil, inhibit soil ureases, mitigate the emission of greenhouse gases, control phytopathogen proliferation and weed dissemination. A great variety of biomass types are reported as feedstock to produce PA with distinct chemically diverse and active substances at wide-ranging concentrations. PA has been shown to successfully improve farming practices in a more sustainable fashion. The disclosure of the mechanisms of action that drive the PA's effects, together with the pursue of safety and efficacy data in a case-by-case way to address toxicity and shelf stability, will be valuable to expand the use of PA worldwide for food production.

Dynamic Modulation of SO2 Atmosphere for Enhanced Fresh-Keeping of Grapes Using a Novel Starch-Based Biodegradable Foam Packaging

To improve the fresh-keeping of highly perishable fruits with high commercial value, a novel starch-based foam packaging material was developed in this study. The foam incorporated the antiseptic ingredient Na₂S₂O₅, which chemically interacted with environmental moisture to release SO₂ as an antifungal agent. Scanning electron microscopy (SEM), moisture absorption and mechanical measurements were used to characterize the unique sandwich-like inner structure of the foam which allowed for the modulable release of SO₂. The starch-based foam exhibited sufficient resilience (~100%) to provide ideal cushioning to prevent physical damage to fresh fruits during transportation. When 25 g/m² of Na₂S₂O₅ was applied, the foam stably released over 100 ppm SO₂ and demonstrated satisfactory antifungal performance (inhibition over 60%) in terms of maintaining the appearance and nutritional values (such as soluble solids 14 vs. 11%, total acidity 0.45 vs. 0.30%, and Vitamin C 3.4 vs. 2.5 mg/100 g) of fresh grapes during a 21 day storage period. Additionally, the residual SO₂ (14 mg/kg) also meets the safety limits (<30 mg/kg). These research findings suggest great potential for the utilization of this novel foam in the food industry.

The Antifungal Effect of Pyroligneous Acid on the Phytopathogenic Fungus Botrytis cinerea

In recent years, climate change has intensified harsh periods of rain alternating with periods of drought, leading to an increase in the presence of phytopathogenic fungi. In this study, we want to analyse the antifungal properties of pyroligneous acid against the fungal phytopathogen Botrytis cinerea. Through the inhibition test, we observed that the application of different dilutions of pyroligneous acid rarefied the growth of the fungal mycelium. Furthermore, we have seen through the metabolic profile that B. cinerea is not able to use pyroligneous acid as a resource or even grow in close contact with this resource. Moreover, we observed that the pre-incubation of the fungus in pyroligneous acid leads to a reduction in biomass production. These results give us hope for the possible use of this natural substance as a possible substance to protect plantations from pathogen attacks.

Application of biostimulant products and biological control agents in sustainable viticulture: A review

Current and continuing climate change in the Anthropocene epoch requires sustainable agricultural practices. Additionally, due to changing consumer preferences, organic approaches to cultivation are gaining popularity. The global market for organic grapes, grape products, and wine is growing. Biostimulant and biocontrol products are often applied in organic vineyards and can reduce the synthetic fertilizer, pesticide, and fungicide requirements of a vineyard. Plant growth promotion following application is also observed under a variety of challenging conditions associated with global warming. This paper reviews different groups of biostimulants and their effects on viticulture, including microorganisms, protein hydrolysates, humic acids, pyrogenic materials, and seaweed extracts. Of special interest are biostimulants with utility in protecting plants against the effects of climate change, including drought and heat stress. While many beneficial effects have been reported following the application of these materials, most studies lack a mechanistic explanation, and important parameters are often undefined (e.g., soil characteristics and nutrient availability). We recommend an increased study of the underlying mechanisms of these products to enable the selection of proper biostimulants, application methods, and dosage in viticulture. A detailed understanding of processes dictating beneficial effects in vineyards following application may allow for biostimulants with increased efficacy, uptake, and sustainability.

Antibacterial Effect of Eugenol on Shigella flexneri and Its Mechanism

Shigella flexneri (Sh. flexneri), which can be found in food and the environment, is a widespread food-borne pathogen that causes human diarrhea termed “shigellosis”. In this study, eugenol, a natural active substance, was investigated for its antibacterial activity against Sh. flexneri. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of eugenol against Sh. flexneri ATCC 12022 was 0.5 and 0.8 mg/mL. The growth curves and inhibitory effect in LB broth, PBS, vegetable juice, and minced pork showed that eugenol had a good activity against Sh. flexneri. Research findings indicated the superoxide dismutase activity of Sh. flexneri was inhibited after eugenol treatment, resulting in concentrations of intracellular reactive oxygen species and an increase in malondialdehyde. The flow cytometry analysis and field emission scanning electron microscopy results revealed obvious damage to cell membrane integrity and changes in the morphology of Sh. flexneri. In addition, the intracellular ATP concentration leaked from 0.5 μM to below 0.05 μM and the membrane potential showed a concentration-dependent depolarization after eugenol treatment. In summary, eugenol exerted strong antibacterial activity and has the potential to control Sh. flexneri in the food industry.

Exogenous Melatonin Treatment Induces Disease Resistance against Botrytis cinerea on Post-Harvest Grapes by Activating Defence Responses

Botrytis cinerea seriously affects the value of post-harvest grapes. Melatonin can act as an exogenous regulator in the resistance of exogenous pathogens due to its antioxidant activity. An artificial inoculation trial was conducted to research the induced resistance mechanism of melatonin treatment using the table grape “Muscat Hamburg” (Vitis vinifera L. cv). Grapes were immersed with 0.02, 0.2, and 2 mmol/L melatonin, followed by B. cinerea suspension injections after 48 h. The results showed that the mycelial growth and spore germination of B. cinerea was not significantly inhibited by melatonin at different concentrations (0.02–2 mmol/L). However, post-harvest melatonin treatment inhibited the increase of disease incidence and severity of grey mould, induced the synthesis and accumulation of total phenols and flavonoids, reduced malondialdehyde generation, and inhibited an increase in cell membrane permeability. Meanwhile, defensive enzyme activities, including superoxide dismutase (SOD), peroxidize (POD), catalase (CAT), phenylalanine ammonia-lyase (PAL), polyphenol oxidase (PPO), chitinase (CHI), and β-1,3-glucanase, were significantly increased in fruits treated with exogenous melatonin. These results suggested that exogenous melatonin treatment could activate defence responses to combat the infection of B. cinerea in post-harvest grapes.

Foliar Application of Wood Distillate Alleviates Ozone-Induced Damage in Lettuce (Lactuca sativa L.)

This study examined whether foliar applications of wood distillate (WD) have a protective effect on photosynthesis and the antioxidant power of lettuce when exposed to an ecologically relevant O₃ concentration. Seedlings of lettuce (Lactuca sativa L.) were fumigated daily with 60 ppb of O₃ for 30 days, five hours per day. Once per week, 50% of the fumigated plants were treated with foliar applications of 0.2% WD, while control plants were treated with water. The results clearly showed the ability of WD to protect lettuce plants from ozone-induced damage. Specifically, WD-treated plants exhibited lower damage to the photosynthetic machinery, assessed through a series of chlorophyll fluorescence parameters, a higher chlorophyll content, higher antioxidant power, as well as antioxidant molecules, i.e., caffeic acid and quercetin, and higher biomass. Counteracting the overproduction of ozone-generated reactive oxygen species (ROS) is speculated to be the main mechanism by which WD protects the plant from ozone-induced damage.