Antagonistic Microorganisms Research Articles

Combination of atmospheric and room temperature plasma and ribosome engineering techniques to enhance the antifungal activity of Bacillus megaterium L2 against Sclerotium rolfsii.

Sclerotium rolfsii is an extremely destructive phytopathogenic fungus that causes significant economic losses. Biocontrol strategies utilizing antagonistic microorganisms present a promising alternative for controlling plant pathogens. Bacillus megaterium L2 has been identified as a potential microbial biocontrol agent in our previous study; however, its efficacy in controlling pathogens has yet to meet current demands. This study aims to enhance the antifungal activity of strain L2 against S. rolfsii R-67 through a two-round mutagenesis strategy and to preliminarily investigate the mutagenesis mechanism of the high antifungal activity mutant. We obtained mutant Dr-77 with the strongest antifungal activity against R-67, and its cell-free supernatant significantly reduced the infection potential of R-67 to Amorphophallus konjac corms, which may be attributed to the antimicrobial compound phenylacetic acid (PAA), and PAA content in Dr-77 (5.78 mg/mL) was 28.90 times higher than original strain L2. This compound exhibited strong antifungal ability against R-67, with a half maximal effective concentration (EC50) value of 0.475 mg/mL, significantly inhibiting mycelial growth and destroying the ultrastructure of R-67 at EC50 value. Notably, PAA also exhibited broad-spectrum antifungal activity against six phytopathogens at EC50 value. Moreover, genome analysis revealed nine different gene mutations, including those involved in PAA biosynthesis, and the activities of prephenate dehydratase (PheA) and phenylacetaldehyde dehydrogenase (ALDH) in PAA biosynthesis pathway were significantly increased. These results suggest that the elevated PAA content is a primary factor contributing to the enhanced antifungal activity of Dr-77, and that this mutagenesis strategy offers valuable guidance for the breeding of functional microbial resources. © 2024 Society of Chemical Industry.

In Vitro Antagonistic Activity of Plant Growth Promoting Rhizobacteria Against Aggressive Biotypes of the Green Mold.

During the cultivation of button mushrooms, the green mold epidemic, which causes a decrease in productivity, is a very important problem. The environmental harm of chemicals used in the control of such epidemics and the demand of consumers for organic products without chemicals have brought environmentally friendly biological control to the fore. Biological control can be achieved by the use of antagonistic microorganisms and their metabolites. In this study, the effectiveness of Bacillus spp. and Pseudomonas spp. for the biological control of the aggressive biotypes of the green mold disease agent Trichoderma aggressivum strains was examined in vitro. For this purpose, the antifungal effects of Bacillus spp. and Pseudomonas spp. against T. aggressivum strains were examined by in vitro dual culture test. Afterward, the antifungal activity of Bacillus spp. metabolites was assessed further using the agar well diffusion method. Then, it was determined whether the bacterial strains showing antifungal activity showed antagonistic activity against A. bisporus. Although none of the Pseudomonas spp. showed antifungal activity against T. aggressivum strains, most of the Bacillus spp. were found to have high activity. It has been concluded that Bacillus sp. Ö-4-82 may be potential biological control agent for button mushroom cultivation.

Plant defense compounds can enhance antagonistic effects against Alternaria brassicicola of seed-associated fungi isolated from wild Brassicaceae.

Plant microbiota appear more and more as potential sources of antagonistic microorganisms. However, the seed microbiota associated with wild plant species has rarely been explored. To identify fungal antagonists to the seed-borne pathogen Alternaria brassicicola, seeds were collected in natural populations of three Brassicaceae species, Arabidopsis thaliana, Capsella bursa-pastoris and Draba verna. A large number of fungal strains reduced the growth of A. brassicicola. The most antagonistic strains belonged to Alternaria, Apiospora, Trichoderma and Aspergillus. Seed-associated fungi tolerated host plant defenses and exhibited lower sensitivity compared to A. brassicicola to indolic compounds such as the phytoalexin camalexin and the glucosinolates (GLS)-breakdown compound indole-3-carbinol. By contrast, antagonistic strains were as inhibited as A. brassicicola in presence of allyl-isothiocyanates (ITC) derived from aliphatic GLS, and more inhibited by benzyl-ITC derived from aromatic GLS. However, all defense compounds could enhance the antagonistic effects of some of the isolated strains on A. brassicicola. The observed potential synergistic effects between defense compounds and seed-associated antagonistic strains emphasize the need for further studies to elucidate the molecular bases of the interactions. A better understanding of the interactions between host plants, pathogens and fungal endophytes is also needed to develop sustainable biocontrol strategies.

Interventions based on alternative and sustainable strategies for postharvest control of anthracnose and maintain quality in tropical fruits.

Colletotrichum spp. is a phytopathogen causing anthracnose in a variety of tropical fruits. Strategies used to control postharvest diseases in tropical fruits typically rely on the use of synthetic fungicides, which have stimulated the emergence of resistant pathogens. Safer alternative strategies to control anthracnose in tropical fruits have been described in the literature. This review presents and discusses the main innovative interventions concerning the application of sustainable alternative strategies in the postharvest control of pathogenic Colletotrichum species in tropical fruits, with a particular emphasis on the studies published in the last 5 years. The available studies have shown the use of various methods, including physical barriers, natural antimicrobials, and biological control with antagonistic microorganisms, to reduce anthracnose lesion severity and incidence in tropical fruits. The available literature showed high inhibitory activity in vitro, reduced anthracnose incidence and lesion diameter, and total disease inhibition in tropical fruits. Most studies focused on the inhibition of Colletotrichum gloeosporioides on avocado, papaya, and mango, as well as of Colletotrichum musae on banana; however, the inhibition of other Colletotrichum species was also demonstrated. The application of emerging sustainable alternative methods, including natural antimicrobial substances, also stimulated the induction of defense systems in tropical fruits, including enzymatic activity, such as polyphenol oxidase, peroxidase, and phenylalanine ammonia-lyase. The retrieved data helped to understand the current state of the research field and reveal new perspectives on developing efficient and sustainable intervention strategies to control pathogenic Colletotrichum species and anthracnose development in tropical fruits.

Efficacy of slow sand filtration enriched with Trichoderma atroviride in the control of Rhizoctonia solani in soilless culture

Soilless cultivation is increasingly common, but the nutrient-rich drainage from substrate cultivation is often discarded. However, drainage can be safely reused if previously disinfected. Slow sand filtration (SSF) is a low-cost, ecological, and effective method for water disinfection, primarily through biological control. Enhancing SSF with antagonistic microorganisms is not well-studied. Additionally, SSF has not been tested to control Rhizoctonia solani, a phytopathogen that can be spread by irrigation water. Therefore, the objective of his work was to test the efficacy of a slow sand filter improved through the inoculation of the antagonistic fungus Trichoderma atroviride, evaluating its suppression capacity against Rhizoctonia solani spread by the irrigation water in a closed substrate cultivation of cucumber (Cucumis sativus). Five experiments were conducted, testing the presence and absence of a sand filter, T. atroviride, and R. solani in each trial. Median disease severity was expressed on a scale of 1–5. The improved SSF increased disease control percentage by 49% compared to SSF alone and by 86% compared to no disease control method. In some experiments, SSF with T. atroviride totally controlled R. solani. The results confirm that biologically enhanced SSF with T. atroviride can effectively disinfect drainage in closed soilless cultivation systems infected with R. solani.

Non-chemical management of fungal diseases in berries: A review

Abstract Organically grown berries are highly valued for their significant economic and nutritional benefits, playing a crucial role in fostering sustainable agriculture. However, meeting the escalating demand for organic berries while sustaining profitable yields of top-quality produce remains challenging, primarily due to the obstacles presented by plant diseases and significant insect pests acting as vectors. Globally, significant losses in organic berry agriculture stem from pathogenic organisms such as bacteria, viruses, fungi, oomycetes, nematodes, and parasitic plants. Although chemical pesticides have historically served as effective control measures, their high costs and potential environmental and health risks necessitate exploring alternative approaches. Consequently, there have been groundbreaking advancements in biological methods for disease management, driven by an enhanced understanding of the intricate interactions between plant pathogens and the plant immune system. This comprehensive analysis elucidates the common pests and diseases affecting organic berry crops, with particular emphasis on fungal pathogens posing the greatest risk. The review documents efficient management strategies to mitigate the harm caused by fungal infections, focusing on biological control using antagonistic microorganisms. Thanks to years of intensive research, numerous commercially available products showcasing the effectiveness of biological control in combating pathogenic threats in organic berry crops have emerged. Furthermore, our review provides insights into recent advancements in the diagnosis and detection of plant diseases, encompassing both time-tested approaches from the previous generations and important methods currently in use. Ultimately, this review aims to help organic berry growers implement successful eco-friendly management strategies to safeguard their crops and boost yields by offering an overview of the latest developments in disease management.

Trichoderma-Bioenriched Vermicompost Induces Defense Response and Promotes Plant Growth in Thai Rice Variety "Chor Khing".

Vermicompost (VC) produced by African nightcrawler earthworms (Eudrilus eugeniae) is a natural fertilizer with a rich microbial community. Trichoderma asperelloides PSU-P1 is an effective antagonistic microorganism with multifaceted activity mechanisms. This research aimed to develop Trichoderma-bioenriched vermicompost (TBVC) to promote plant growth and induce the defense response in the Thai rice variety "Chor Khing". T. asperelloides PSU-P1 was tested against Rhizoctonia solani, the pathogen of sheath blight disease, using a dual-culture assay. The results showed that T. asperelloides PSU-P1 effectively inhibited R. solani in vitro growth by 70.48%. The TBVC was prepared by adding a conidial suspension (108 conidia/mL) to vermicompost. The viability of Trichoderma persisted in the vermicompost for 6 months and ranged from 1.2 to 2.8 × 107 CFU/mL. Vermicompost water extracts significantly enhanced seed germination, root length, and shoot length compared to a control group (p < 0.05). Plants that received the TBVC displayed significantly longer shoot and root lengths and higher total chlorophyll content than control plants (p < 0.05). The TBVC induced defense response by increasing the enzyme activity of peroxidase (POD) and polyphenol oxidase (PPO) in comparison with control plants. Rice grown in the TBVC had a significantly reduced incidence of sheath blight caused by R. solani in comparison with control rice (p < 0.05). Furthermore, the fungal community of rice plants was analyzed via the high-throughput next-generation sequencing of the internal transcribed spacer (ITS). The fungal community in the TBVC had greater alpha diversity than the community in the VC. Phylum Ascomycota was dominant in both samples, and a heat map showed that Trichoderma was more prevalent in the TBVC than in the VC. Our results indicate that the enrichment of VC with Trichoderma increases growth, enhances the defense response, and reduces the incidence of sheath blight disease in the Thai rice variety "Chor Khing".

Analysis of microbial communities in wheat, alfalfa, and oat crops after Tilletia laevis Kühn infection.

Common bunt caused by Tilletia laevis Kühn is one of the most serious fungal diseases of wheat. The root-microbial associations play key roles in protecting plants against biotic and abiotic factors. Managing these associations offers a platform for improving the sustainability and efficiency of agriculture production. Here, by using high throughput sequencing, we aimed to identify the bacterial and fungal associations in wheat, alfalfa, and oat crops cultivated in different years in the Gansu province of China. Soil samples (0-6 cm below the surface) from infected wheat by T. laevis had significantly more bacterial and fungal richness than control samples as per the Chao1 analysis. We found some dominant fungi and bacterial phyla in infected wheat by T. laevis, such as Proteobacteria, Acidobacteria, Actinobacteria, Chloroflexi, Ascomycota, Basidiomycota, and Mortierello mycota. We also analyzed the chemical and enzymatic properties of soil samples after T. laevis inoculation. The total nitrogen, total kalium (TK), ammonium nitrogen, available kalium, organic carbon, invertase, phosphatase, and catalase were more in T. laevis-infected samples as compared to the control samples, while pH, total phosphorus, nitrate nitrogen, available phosphorus, and urease were more in control samples compared to T. laevis-infected samples. The results of this study will contribute to the control of wheat common bunt by candidate antagonistic microorganisms and adverse properties of soil.

Synergistic biocontrol mixture: free-cell extract with β-glucanase activity and chitosan against Thielaviopsis paradoxa, Colletotrichum gloeosporioides, and Rhizopus stolonifer

Biocontrol, which uses antagonistic microorganisms to manage plant diseases, holds promise for reducing postharvest losses but faces challenges due to varied pathogen responses. In response, biocontrol mixtures were proposed to enhance the antagonistic effect. This study evaluates the efficacy of chitosan and extracellular glucanase (EG) from Wickerhamomyces anomalus, both individually and combined, against Thielaviopsis paradoxa, Colletotrichum gloeosporioides, and Rhizopus stolonifer. The maximum inhibition of mycelial growth by chitosan for these fungi was 90.25% at 3 mg/mL, 14.2% at 5 mg/mL, and 56.28% at 3 mg/mL, respectively. Additionally, chitosan significantly inhibited spore germination across all fungi. While W. anomalus cells prevented mycelial filament association, EG alone had minimal impact on mycelial development but inhibited spore germination in a concentration-dependent manner. Combining EG with chitosan enhanced spore germination inhibition, notably achieving 98.18%. The biocontrol mixture effectively protected fruit under laboratory-controlled conditions, suggesting a robust biocontrol strategy for postharvest fungal disease management.

ПОЧВЕННЫЕ БАКТЕРИИ ИЗ АВТОХТОННЫХ МИКРОБНЫХ СООБЩЕСТВ ЦЕНТРАЛЬНОЙ СИБИРИ В БИОЛОГИЧЕСКОЙ ЗАЩИТЕ ПШЕНИЦЫ ОТ ALTERNARIA TENUISSIMA

The most powerful soil bacteria from autochthonous microbial communities of Central Siberia against phytopathogenic fungi Alternaria tenuissima were selected. Isolation from soil samples and cultivation of bacterial isolates were performed on the artificial nutrient medium for bacteria PD-agar. Antagonistic activity was measured on GRM Saburo. In this case, Alternaria tenuissima was sown in a dish on GRM Saburo, and the selected bacterial strains were sown around the micromycete. As a result of joint growth of the test culture and soil bacteria, the most powerful antagonists in the suppression zone of Alternaria tenuissima were identified. The most powerful bacteria-antagonists in reducing the intensity and prevalence of root rot were identified by the method of artificial infection of Alternaria tenuissima. Before infection with micromycete, bacterization of spring wheat seeds Novosibirskaya-15 with the studied bacterial isolates was carried out. Mathematical processing of the obtained results was fulfilled by one-way variance analysis and two-sample F-test for variance. The results of the study on the use of soil autochthonous antagonist microorganisms in biological protection of spring wheat from the causative agents of root rot Alternaria tenuissima showed that the studied bacterial isolates statistically significantly (p &lt; 0.01) reduced the intensity and prevalence of this disease. The maximum effect in reducing the intensity and prevalence of the disease was shown by isolates B2 and B4 (according to preliminary identification of Bacillus sp.). Also, the studied bacterial strains showed a positive effect on the length of sprouts. At the same time, isolate B2 showed a statistically significant (p &lt; 0.001) effect on the length of spring wheat sprouts. The stimulating effect was manifested in an increase in the length of sprouts compared to the control. Therefore, this strain can be recommended not only for protection against Alternaria tenuissima, but also for stimulating wheat growth.

Controlling Soil-Borne Fungus Aspergillus niger in Groundnut By Optimizing The Function of Isolated Bacillus Bacteria

Collar rot is a devastating disease caused by the soil-borne pathogen Aspergillus niger that greatly affects groundnut production worldwide. The long-term persistence of the fungus in the soil can reduce the effectiveness of synthetic fungicides. Recently, significant attention has been raised to the use of the biological control method such as the application of antagonistic microorganisms, which potentially decline the number of spores and eradicated A. niger from the soil. In the present study, three Bacillus strains (Bacillus siamensis 101, B. siamensis 112 and B. velezensis 137) isolated from the rhizosphere soil of groundnut cultivation farms were found to inhibit the growth of A. niger mycelia by 53.6% to 60.8% in vitro. In pot experiments, the supplementation of this mixture of three bacterial strains (namely BAZ04) strongly reduced the collar rot symptoms of groundnut with a biocontrol efficacy of 100% compared to nil (no treatment). Field trials demonstrated the efficiency of BAZ04 in controlling collar rot disease, which increased the yield by 20.5–22.7% compared to the untreated plots. These results suggest that BAZ04 is a potential biocontrol agent for collar rot disease.

Control of coptis root rot by combination of Bacillus cereus isolate Y9 and other antagonistic microorganisms

Root rot is a destructive soil-borne disease of Coptis chinensis, which depends on chemical control at present, and more attention should be paid to biocontrol of disease. In the present research, isolate Y9 isolated from healthy root samples of Coptis, was identified as Bacillus cereus. Further screening and pot experiments showed that B. cereus isolate Y9 inhibited the growth of the main causal agents of coptis root rot disease (Fusarium solani and F. avenaceum) and seven other phytopathogenic fungi. The application of B. cereus isolate Y9 and compatible Trichoderma harzianum, T. atroviride and B. amyloliquefaciens, singly and in combination were found to be effective against Fusarium root rot in vitro and in field experiments. In field experiments, combinations of T. harzianum + B. amyloliquefaciens + Y9 (HYJ, in ratio of 1:1:1) showed the highest control efficacy of 63.85%, which was higher than the expected value (53.18%), indicating synergistic effect on the control of coptis root rot. Therefore, B. cereus isolate Y9 may be a potential biological control agent, and combined use with T. harzianum and B. amyloquefaciens offered even greater potential. The long-term effects of isolate B. cereus Y9 and its combinations on C. chinensis should be assessed in different locations and seasons in the future.

Біологічний захист рослин в Європейському Союзі (на прикладі Німеччини)

The application of ecological plant protection products against diseases, pests, and weeds is relevant for modern science-provided crop production. Much attention is paid to this problem in the European Union, where the use of pesticides is strictly adjusted by the European Food Safety Authority. Great hopes are pinned on biological plant protection products. However, among the thousands of biological products included in the BioPesticide DataBase, only a small number are authorized for use in agriculture. The requirements for the use of biological protectants in organic farming are even more stringent, regulating not only the properties of the product but also the crops in which they can be used. The aim of the work was to present the main requirements for the safety of biopesticides in the EU countries and to give an overview of biopesticides authorized for use in traditional and organic farming using Germany as an example. Methods. Analysis of EU documents on the requirements for registration of active substances in biological products for plant protection, biopesticide databases, and the list of biopesticides approved for use in general and organic farming in Germany. Results. According to the EU requirements for biopesticide safety, registration of biological plant protection products based on bacteria, fungi, and viruses, individual microbial cellular components or metabolites, as well as insect predators, pheromones, and plant-origin substances is allowed. Among the biopesticides with bactericidal and fungicidal effects registered in Germany, the preparations based on microbial antagonizing plant pathogens are prevalent, as well as preparations elaborated on the fungus Aureobasidium pullulans, Trichoderma asperellum, Verticillium albo-atrum, Coniothyrium minitans, bacteria Pseudomonas chlororaphis, Bacillus amyloliquefaciens, and also the preventive drug Cerevisan based on the cell walls of Saccharomyces cerevisiae. The following bioformulations based on Bacillus thuringiensis, Beauveria bassiana, Cydia pomonella Granulovirus, avermectin antibiotic Abamectine A, herbal products Azadirachtin A and Piretrin, and Maltodextrin are registered as insecticides. A bioformulation based on Bacillus firmus is authorized for use as a nematocide. Conclusions. Registration of biological plant protection products in Germany is carried out in accordance with the EU requirements for the safety of biopesticides. The list includes preparations based on antagonistic microorganisms, predatory microorganisms, microbial metabolites with antibiotic activity, substances for stimulation in plants nonspecific resistance to infectious agents. The fungicidal products are the widest represented. The number of products to control bacterial and nematode infections as well as the bioinsecticides spectrum is very limited. These are the well promising areas for further research and development of biological products.

Saccharomyces cerevisiae NX2320 inhibit Aspergillus carbonarius by cell membrane disruption and oxidative stress-mediated autophagy in in vitro and during grape storage

Aspergillus carbonarius not only causes the decay of fresh fruit, but also produce the mycotoxin ochratoxin A. Biological control of pathogenic fungus by antagonistic microorganisms is a safe and effective method. However, information about the potential mechanism of antagonistic microorganisms to suppress A. carbonarius is limited. In this study, S. cerevisiae NX2320 inhibited the growth of A. carbonarius in PDA media and during grape storage. 2-phenylethanol (2-PE) produced by S. cerevisiae NX2320 may be the key substance for its antifungal mechanism. The result indicated that S. cerevisiae NX2320 and 2-PE inhibited OTA production, break the redox steady state, destroy membrane integrity, cause cell autophagy and control the production of mycotoxins. The results indicated that S. cerevisiae must be further investigated for potential application to control fungal and mycotoxin problems during grape storage.

Identification and evaluation of an endophytic antagonistic yeast for the control of gray mold (Botrytis cinerea) in apple and mechanisms of action

Gray mold, caused by Botrytis cinerea, is a prevalent postharvest disease of apple that limits their shelf life, resulting in significant economic losses. The use of antagonistic microorganisms has been shown to be an effective approach for managing postharvest diseases of fruit. In the present study, an endophytic yeast strain PGY-2 was isolated from apples and evaluated for its biocontrol efficacy against gray mold and its mechanisms of action. Results indicated that strain PGY-2, identified as Bullera alba, reduced the occurrence of gray mold on apples and significantly inhibited lesion development in pathogen-inoculated wounds. Gray mold control increased with the use of increasing concentrations of PGY-2, with the best disease control observed at 108 cells/mL. Notably, Bullera alba PGY-2 did not inhibit the growth of Botrytis cinerea in vitro indicating that the yeast antagonist did not produce antimicrobial compounds. The rapid colonization and stable population of PGY-2 in apple wounds at 4 °C and 25 °C confirmed its ability to compete with pathogens for nutrients and space. PGY-2 also had a strong ability to form a biofilm and enhanced the activity of multiple defense-related enzymes (POD, PPO, APX, SOD, PAL) in host tissues. Our study is the first time to report the use of Bullera alba PGY-2 as a biocontrol agent for postharvest diseases of apple and provide evidence that Bullera alba PGY-2 represents an endophytic antagonistic yeast with promising biocontrol potential and alternative to the use of synthetic, chemical fungicides for the control of postharvest gray mold in apples.

Evaluation of Endophytic Microorganisms (Trichoderma hazianum and Bacillus subtilus) as Biofungicides against Bayoud Disease (Fusarium oxysporum f. sp. albedinis) on Date Palm (Phoenix dactylifera L.)

Backgraound: Date palm disease named Bayoud, is the major constraint caused by the soil fungus Fusarium oxysporum f. sp. albedinis (Foa) in Algeria. This work has the objective to in vivo biocontrol on bayoud disease incidence on three date palm varieties (Deglet-Nour, Feggous and H-mira), using two antagonistic microorganisms, one fungus (Trichoderma harzianum) and one bacterium (Bacillus subtilus). Methods: Foa strains obtained from isolation of the spines carrying the typical symptoms of Bayoud disease. Two strains used T. harzianum and B. subtilus, are isolated from rhizosphere soils of the date palm. Using the greenhouse screening test, the in vivo biocontrol test is carried out on 3-4 month-old date palm seedlings at the rate of 5 ml of inoculum suspension. Result: A significant (P less than 0.01), difference of date palm seedlings reactions against Foa isolate and antagonistic microorganisms was observed. All three date palm varieties present a high susceptibility against Foa until the total mortality of date palm seedlings. The biocontrol test showed that two antagonists showed different reaction, with the complete resistance of three varieties treated by T. harzianum, while, the antagonist B. subtilus protect just two varieties (Deglet-Nour and H-mira) and can’t protect Feggous variety when showed the susceptibility reaction by presentation of typical symptoms of bayoud disease. We can apply of these antagonistic microorganisms to protect our groves contaminated by Bayoud disease and contain just susceptible commercial cultivars of date palm.

Biocontrol agents modulate phyllosphere microbiota interactions against pathogen Pseudomonas syringae

The pathogen Pseudomonas syringae, responsible for a variety of diseases, poses a considerable threat to global crop yields. Emerging biocontrol strategies employ antagonistic microorganisms, utilizing phyllosphere microecology and systemic resistance to combat this disease. However, the interactions between phyllosphere microbial dynamics and the activation of the plant defense system remain poorly understood. Here we show significant alterations in phyllosphere microbiota structure and plant gene expression following the application of biocontrol agents. We reveal enhanced collaboration and integration of Sphingomonas and Methylobacterium within the microbial co-occurrence network. Notably, Sphingomonas inhibits P. syringae by disrupting pathogen chemotaxis and virulence. Additionally, both Sphingomonas and Methylobacterium activate plant defenses by upregulating pathogenesis-related gene expression through abscisic acid, ethylene, jasmonate acid, and salicylic acid signaling pathways. Our results highlighted that biocontrol agents promote plant health, from reconstructing beneficial microbial consortia to enhancing plant immunity. The findings enrich our comprehension of the synergistic interplays between phyllosphere microbiota and plant immunity, offering potential enhancements in biocontrol efficacy for crop protection.

Research on the prevention and control of plant diseases by antagonistic microorganisms

Plant diseases, often caused by bacterial infections, pose significant challenges to human society due to their widespread and harmful consequences, resulting in substantial losses. Although traditional chemical prevention and control methods have shown effectiveness, they still pose serious environmental and other risks. Therefore, developing biological control is crucial for future plant disease prevention and management. In this study, we investigated the efficacy of antagonistic microorganisms. We conducted four related experiments and eventually reaffirmed the substantial inhibitory effect of antagonistic microorganisms on the growth of plant pathogens. Our findings are of great significance for further expanding the application scope and popularization of antagonistic bacteria and also enriching the specific application of antagonistic microorganisms for specific plant control.

Rhizospheric microbiota of suppressive soil protect plants against Fusarium solani infection.

Fusarium infection has caused huge economic losses in many crops. The study aimed to compare the microbial community of suppressive and conducive soils and relate to the reduction of Fusarium wilt. High-throughput sequencing and microbial network analysis were used to investigate the differences in the rhizosphere microbiota of the suppressive and conducive soils and to identify the beneficial keystone taxa. Plant pathogens were enriched in the conducive soil. Potential plant-beneficial microorganisms and antagonistic microorganisms were enriched in the suppressive soil. More positive interactions and keystone taxa existed in the suppressive soil network. Thirty-nine and 16 keystone taxa were identified in the suppressive and conducive soil networks, respectively. Sixteen fungal strains and 168 bacterial strains were isolated from suppressive soil, some of which exhibited plant growth-promotion traits. Thirty-nine bacterial strains and 10 fungal strains showed antagonistic activity against F. solani. Keystone taxa Bacillus and Trichoderma exhibited high antifungal activity. Lipopeptides produced by Bacillus sp. RB150 and chitinase from Trichoderma spp. inhibited the growth of F. solani. Microbial consortium I (Bacillus sp. RB150, Pseudomonas sp. RB70 and Trichoderma asperellum RF10) and II (Bacillus sp. RB196, Bacillus sp. RB150 and T. asperellum RF10) effectively controlled root rot disease, the spore number of F. solani was reduced by 94.2% and 83.3%. Rhizospheric microbiota of suppressive soil protects plants against F. solani infection. Antagonistic microorganisms in suppressive soil inhibit pathogen growth and infection. Microbial consortia consisted of keystone taxa well control root rot disease. These findings help control Fusarium wilt. © 2024 Society of Chemical Industry.

Effect of Co-Inoculation with Growth-Promoting Bacteria and Arbuscular Mycorrhizae on Growth of Persea americana Seedlings Infected with Phytophthora cinnamomi.

Avocado is one of the most in-demand fruits worldwide and the trend towards its sustainable production, regulated by international standards, is increasing. One of the most economically important diseases is root rot, caused by Phythopthora cinnamomi. Regarding this problem, antagonistic microorganism use is an interesting alternative due to their phytopathogen control efficiency. Therefore, the interaction of arbuscular mycorrhizal fungi of the phylum Glomeromycota, native to the Peruvian coast (GWI) and jungle (GFI), and avocado rhizospheric bacteria, Bacillus subtilis and Pseudomonas putida, was evaluated in terms of their biocontrol capacity against P. cinnamomi in the "Zutano" variety of avocado plants. The results showed that the GWI and Bacillus subtilis combination increased the root exploration surface by 466.36%. P. putida increased aerial biomass by 360.44% and B. subtilis increased root biomass by 433.85%. Likewise, P. putida rhizobacteria showed the highest nitrogen (24.60 mg ∙ g-1 DM) and sulfur (2.60 mg ∙ g-1 DM) concentrations at a foliar level. The combination of GWI and Bacillus subtilis was the treatment that presented the highest calcium (16.00 mg ∙ g-1 DM) and magnesium (8.80 mg ∙ g-1 DM) concentrations. The microorganisms' multifunctionality reduced disease severity by 85 to 90% due to the interaction between mycorrhizae and rhizobacteria. In conclusion, the use of growth promoting microorganisms that are antagonistic to P. cinnamomi represents a potential strategy for sustainable management of avocado cultivation.