Potential Biocontrol Research Articles

Bacillus amyloliquefaciens MZ895491: an endophytic bacterium as potential biocontrol agent in integrated pest management of fall armyworm in maize

ABSTRACT The fall armyworm, Spodoptera frugiperda is a major pest of maize crops and necessitates effective control measures. Excessive use of chemical pesticides often results in the development of resistant insect populations and environmental contamination, highlighting the need for environmentally friendly substitutes. This research aimed to estimate the potential of maize (COH6) apoplastic fluid bacterium Bacillus amyloliquefaciens (MZ895491), as a biocontrol agent against second instar S. frugiperda larvae under laboratory and pot culture conditions. The results suggest that the presence of B. amyloliquefaciens in the artificial diet could reduce the growth and development of S. frugiperda larvae. Metabolic profiling of extracellular components of B. amyloliquefaciens revealed the presence of numerous defensive and anti-feeding metabolites. A study conducted in pots demonstrated that foliar application of B. amyloliquefaciens to 5 d old maize resulted in a significant increase in antioxidant activity (83.3%), chlorophyll content (63.3%) and phenolic content (81.3%) in the leaves of 35 d old maize after 24 h of S. frugiperda infestation. Feeding bioassay further indicated significant reduction in the feeding capacity of S. frugiperda larvae on maize inoculated with B. amyloliquefaciens. The study observed that a metabolic modification in maize leaves likely led to reduced growth in larvae during the whole plant bioassay. This suggests that foliar application of B. amyloliquefaciens may effectively serve as one of the biocontrol agents against Spodoptera frugiperda. The application appears to alter the feeding behaviour of the larvae and modify maize leaf metabolism.

Optimization of Fermentation and Biocontrol Efficacy of Bacillus atrophaeus XHG-1-3m2

Biological control plays an increasingly important role in various aspects of modern agriculture and forestry. Identifying biocontrol strains with commercial potential for effective disease management is currently a focal point in biological control research. In this study, Bacillus atrophaeus XHG-1-3m2, a strain with significant biocontrol potential against Wilsonomyces carpophilus causing shot hole disease in wild apricots, was developed. The study determined the antibacterial activity of the fermentation broth, the optimal fermentation medium composition and conditions, and explored its effectiveness in controlling Wilsonomyces carpophilus. The optimal fermentation medium for strain XHG-1-3m2 comprises 12.5 g/L yeast extract, 12.5 g/L soy peptone, 10.0 g/L sodium chloride, 1 g/L ammonium chloride, 1 g/L potassium dihydrogen phosphate, 1 g/L disodium hydrogen phosphate, and 0.5 g/L magnesium sulfate heptahydrate. With an initial pH of 7.0, a liquid volume of 40%, an inoculum volume of 3%, and shaking incubation at 28 °C for 24 h, the viable cell count reached 14 × 109 CFU/mL. In vitro and in vivo tests on leaves revealed that the fermentation broth and the biocontrol biofertilizer derived from this strain inhibited the leaf lesions caused by Wilsonomyces carpophilus on wild apricots, achieving inhibition rates of 94.62% and 82.46%, respectively.

Characterisation of indigenous entomopathogenic nematode, Steinernema abbasi PN-1 Elawad and its biocontrol potential against major lepidopteran pests

Characterisation of indigenous entomopathogenic nematode, Steinernema abbasi PN-1 Elawad and its biocontrol potential against major lepidopteran pests

Characterization of Endophytic Streptomyces rhizosphaericola Ahn75 and Its Potential for Biocontrol against Rice Blast.

Plant endophyte Streptomyces are excellent candidates as biocontrol agents against the rice blast fungus, Magnaporthe oryzae. In this study, a novel strain Ahn75 with antifungal activity was isolated from healthy rice stem and identified as Streptomyces rhizosphaericola by phenotypic characterization and phylogenetic analysis based on 16S rRNA, multilocus and genome sequences. Inhibition test using culture filtrate showed that Ahn75 could effectively suppress M. oryzae, with mycelia growth inhibition rate of 80.88% and spore germination inhibition rate of 78.26%. Genome sequence analysis of strain Ahn75 showed 40 gene clusters of secondary metabolites and several genes related to plant growth promotion were predicted in the genome of Ahn75. Several antimicrobial compounds including valinomycin, tetrabutylammonium, and benzalkonium chloride, were also detected in the antifungal fraction from Ahn75 culture filtrate by liquid chromatography and high resolution mass spectrometry. Meanwhile, strain Ahn75 demonstrates UV tolerance under UV irradiation for 60 min, pH tolerance between pH6 and pH9, and a high halotolerance in 7% (w/v) of NaCl. Greenhouse experiments indicated that Ahn75 is able to colonize rice stems, roots, and leaves, which help rice to reduce the rice leaf blast incidence by 59.76%. All these findings suggest that strain Ahn75 could be a potential biocontrol agent for rice blast.

Exploring the Exo-Metabolomes and Volatile and Non-Volatile Compounds of Metarhizium Carneum and Lecanicillium Uredinophilum.

Efforts are intensifying to identify bioactive microbial metabolites from biocontrol agents to manage plant pathogens in critical crops. This study examined both volatile organic compounds (VOCs) and non-volatile compounds from Metarhizium carneum and Lecanicillium uredinophilum strains for their antimicrobial effects against various phytopathogens and analyzed their exo-metabolomes. M. carneum VOCs inhibited four bacterial and eight fungal species by up to 45.45 %, while L. uredinophilum VOCs inhibited five bacterial and eight fungal species by up to 50.91 %. Additionally, n-BuOH extracts from both biocontrol agents effectively targeted three fungi and five bacteria. The exo-metabolomes of M. carneum and L. uredinophilum included 125 and 102 spectrometric features, respectively, primarily consisting of polyketides, alkaloids, lipids, organic aromatic compounds, terpenoids, and peptides. Our findings revealed a correlation between the phylogenetic relationships of M. carneum strains, their bioactivity patterns against phytopathogens, and their metabolomic profiles. Notably, some compounds detected in both fungi previously demonstrated biological activity against plant pathogens, enhancing their biocontrol potential. This study not only evidences the antimicrobial properties of diffusible compounds from M. carneum and L. uredinophilum, but also documents the antimicrobial potential of their VOCs for the first time, supporting their use in sustainable agricultural practices, reducing reliance on chemical inputs.

Selection and application of methanol-utilizing bacteria from tomato leaves for biocontrol of gray mold.

Gray mold, caused by Botrytis cinerea, is a significant threat to tomato production. Traditional chemical control methods have become increasingly ineffective because of the development of resistance. This study aimed to isolate methanol-utilizing bacteria from tomato leaves and evaluate their biocontrol potential against gray mold. To obtain bacterial suspensions, tomato leaf samples were collected and washed. We analyzed the microbial communities of these samples using 16S rRNA amplicon sequencing and identified several methylotrophic strains. Among these, 405 isolated strains were cultivated on a solid low-nutrient inorganic salt medium containing methanol, and 7 strains exhibiting considerable antifungal activity against B. cinerea were identified. Greenhouse tests revealed that two strains-SY163 and SY183-significantly reduced the severity of gray mold on tomato leaves. Disease index scores and the area under the disease progress curve values confirmed the efficacy of these strains as biocontrol agents. Statistical analysis indicated the effectiveness of pre- and co-application of these strains with B. cinerea. Phylogenetic analysis identified Serratia rubidaea as the inhibitory strain. The biocontrol activity is likely mediated through the production of antifungal compounds and suppression of B. cinerea sporulation. This study provides the basis for developing a technology of gray mold suppression by controlling the abundance of S. rubidaea in plant microbial communities.

Comprehensive genomic analysis of Brevibacillus brevis BF19 reveals its biocontrol potential against bitter gourd wilt

Bitter gourd wilt, a severe vascular disease triggered by the soilborne pathogen Fusarium oxysporum f. sp. momordicae (FOM), markedly constrains bitter gourd yield. In this study, a novel strain BF19 of Brevibacillus brevis was isolated and identified, exhibiting strong antimicrobial activity against FOM through in vivo and in vitro experiments. To comprehensively assess the biocontrol potential of strain BF19, we conducted phenotypic, phylogenetic, and comparative genomics analyses. Phenotypic analysis revealed that BF19 exhibited 53.33% biocontrol efficacy and significantly increased the average plant height, root fresh weight, and dry weight. Whole-genome sequencing and comparative genomic analysis revealed numerous potential genes associated with biocontrol mechanisms in BF19. Importantly, the integration of metabolic cluster prediction with liquid chromatography‒tandem mass spectrometry (LC‒MS/MS) revealed the presence of a macrobrevin antibiotic, a product of polyketide synthases (PKSs), predominantly in BF19 fermentation products. The effectiveness of the Br. brevis strain BF19 and its crude extract against bitter gourd wilt has also been confirmed. This study provides a genetic framework for future investigations on PKSs and establishes a scientific basis for optimizing field applications of microbial biopesticides derived from Br. brevis BF19.

Biocontrol potential of Burkholderia gladioli STPT16 on postharvest decay of litchi fruit caused by Peronophythora litchii and Colletotrichum fructicola

Litchi downy blight (LDB) caused by Peronophythora litchii and anthracnose (AD) caused by Colletotrichum species are major pre- and postharvest disease of litchi fruit. Biocontrol agents such as Burkholderia has been applied for controlling postharvest fruit decay. In this work, an endophytic strain SZPT16 isolated from health litchi branch was identified as Burkholderia gladioli and exhibited strong antagonistic activity against mycelial growth and conidia/sporangia germination of two postharvest pathogens. Dual incubation of pathogen and biocontrol agents caused alterations in hyphal and conidial/sporangial structures and severe cell morphology changes such as mycelia deformation, cell wall collapse and cellular disorganization. Cell-free culture filtrates (CF, diluted at 25-fold) of B. gladioli SZPT16 showed an efficient inhibition on postharvest litchi decay by preharvest application (74.77 % protection) and postharvest application (64.68 % and 71.14 % protection for LDB and AD, respectively). Furthermore, UPLC-MS/MS metabolomic analysis identified 41 up-regulated differential metabolites, which mainly included nucleosides, nucleotides, and analogues, organic acids and derivatives, organic oxygen compounds, and organoheterocyclic compounds. This study firstly reported the efficacy of CF of B. gladioli SZPT16 in protecting postharvest litchi fruit against natural and inoculated pathogen infections. The overall results provide a promising alternative to chemical fungicides to control litchi postharvest decay.

Whole-Genome Sequencing of the Entomopathogenic Fungus Fusarium solani KMZW-1 and Its Efficacy Against Bactrocera dorsalis.

Fusarium solani KMZW-1 is recognized for its potential as a biocontrol agent against agricultural and forestry pests, particularly due to its compatibility with integrated pest management (IPM) strategies. This study aimed to investigate the complete genome of F. solani KMZW-1 and assess its pathogenicity against Bactrocera dorsalis. Whole-genome sequencing revealed a genome size of 47,239,278 bp, comprising 27 contigs, with a GC content of 51.16% and fungus identified as F. solani KMZW-1. The genome completeness was assessed as 97.93% using BUSCO analysis, the DFVF sequence identifier was Fusarium 0G092560.1, and AntiSMASH analysis identified 35 gene clusters associated with secondary metabolite biosynthesis, providing insights into the genetic basis of its pathogenic mechanisms and biocontrol potential. Comparative genomic analysis found 269 unique genes for F. solani KMZW-1, and collinearity analysis exhibited a high degree of synteny with Fusarium solani-melongenae. The pathogenicity of F. solani KMZW-1 was assessed using concentrations ranging from 1 × 104 to 1 × 1011 conidia/mL. Higher concentrations (1 × 1010 to 1 × 1011 conidia/mL) resulted in significantly increased cumulative mortality rates of B. dorsalis adults compared to the control group. Notably, the pathogenicity was higher in male adults than in females. Probit analysis yielded LC50 (50% lethal concentration) values of 5.662 for female and 4.486 for male B. dorsalis adults. In summary, F. solani, KMZW-1 exhibits strong insecticidal activity against B. dorsalis and shows potential as a biocontrol agent with IPM strategies. These findings provide robust genomic evidence supporting the use of F. solani KMZW-1 in managing against B. dorsalis populations.

Biocontrol Efficacy of Pseudomonas Consortia Against Botrytis Blight in Petunias.

Botrytis cinerea, a fungal pathogen causing Botrytis blight, significantly impacts greenhouse crop management due to its broad host range and infection capabilities at various growth stages. Traditional control methods, primarily reliant on fungicides, are challenged by environmental concerns and the rise of fungicide-resistant strains. This study investigates the use of beneficial Pseudomonas bacteria as a sustainable alternative. We hypothesized that specific Pseudomonas consortia could provide more effective biocontrol of B. cinerea than individual strains. Our research investigated five Pseudomonas strains (14B11, AP54, 15H3, 94G2, and 89F1) known to reduce Botrytis blight in Petunia × hybrida. Compatibility for bacterial consortia was assessed through biofilm formation and direct bacterial inhibition assays. The biocontrol effects of the bacteria against B. cinerea were investigated in vitro using shared-air space dual culture assays and in planta by inoculating detached petunia flowers. We found strain 14B11 exhibited the highest biofilm formation, with consortia of 14B11 and 89F1 showing significant enhancement compared to individual cultures, while a slight, non-significant increase was observed in 14B11 and AP54 consortia. However, strain 14B11 efficacy was inhibited by strain 15H3. Genomic analyses identified antifungal compound-related gene clusters in 14B11 and AP54, contributing to their biocontrol potential. Trials with detached flowers of Petunia × hybrida 'Carpet Red Bright' confirmed significant disease severity reduction with 14B11, AP54, and their consortia. This research highlights strategic Pseudomonas consortia as promising, eco-friendly alternatives to chemical fungicides, promoting sustainable agriculture by enhancing our understanding of how microbial interactions can be used to manage Botrytis blight.

Bacillus velezensis B105-8, a potential and efficient biocontrol agent in control of maize stalk rot caused by Fusarium graminearum.

Maize stalk rot (MSR), caused by Fusarium graminearum, is the most serious soil borne disease in maize production, seriously affecting maize yield and quality worldwide. Microbial biocontrol agents are the best means of controlling MSR and reducing the use of chemical fungicides, such as Bacillus spp. In the study, a soil-isolated strain B105-8 was identified as B. velezensis (accession No. PP325775.1 and No. PP869695.1), demonstrated a broad spectrum against various pathogens causing maize diseases, which effectively controlled MSR, exhibited a high control efficacy of more than 60% and growth-promoting effect in the pot plant. B105-8 could effectively improve soil urease (S-UE), invertase (S-SC), and catalase (S-CAT) activities. S-NP activity showed an initial increase with a peak of 20,337 nmol/h/g, followed by a decrease, but activity remained significantly better than control treatment with chemical fungicides. The application of B105-8 repaired the damage caused by F. graminearum on soil activity. The antifungal compound B-1, extracted from B105-8, was purified using a protein purifier, revealing inhibitory effects against F. graminearum. Mass spectrometry analysis indicated the potential presence of C14 Bacillomycin, C15 Iturin, C15 Mycosubtilin, C17, and C15 fengycin in B-1. In pot experiments, a 5 μL/mL concentration of B-1 exhibited 69% control on MSR, enhancing maize root elongation, elevation, and fresh weight. At 10 μL/mL, B-1 showed 89.0 and 82.1% inhibition on spore production and mycelial growth, causing hyphal deformities. This study presents the innovative use of B. velezensis, isolated from maize rhizosphere in cold conditions to effectively control MSR caused by F. graminearum. The findings highlight the remarkable regional and adaptive characteristics of this strain, making it an excellent candidate to fight MSR in diverse environments. In conclusion, B. velezensis B105-8 demonstrated potential as a biocontrol agent for MSR.

Assessment of Trichoderma Species Isolated From Volcanic Soil of a Durian Field in Sisaket Province, Thailand for Plant Growth Promotion and Biocontrol Potential

Trichoderma species are ubiquitous saprophytic fungi commonly found in soil, with potential as fungal biocontrol agents for plant disease control and growth promotion. This research aimed to assess the attributes of Trichoderma sp. as plant growth promoters, focusing on nitrogen fixation, siderophore production, plant nutrient solubilization and indole-3-acetic acid production. Out of 19 isolates tested, 6 (T05, T19, T25, T27, T28 and T33) showed superior plant growth promotion abilities. These isolates were further evaluated for their capacity to enhance the germination of Khao Dawk Mali 105 rice seeds. Seeds were soaked in a suspension of conidia at a concentration of 1×1012 conidia/mL, and germination rates were measured. The germination rate ranged between 77.67 - 86.67 %, statistically significantly higher than the control rate of 33.33 %. Among the isolates, T05 exhibited the highest promotion of plant growth, evidenced by root length (7.27 cm), shoot length (8.50 cm), fresh weight (0.54 g) and dry weight (0.27 g), all significantly different from the control. Additionally, the potential of isolates to inhibit the fungal pathogen Colletotrichum sp. MN-3 was assessed using a dual culture method, with T35 showing the highest inhibition percentage (60.90 %). Morphological classification and nucleotide sequencing of the ITS1-5.8S-ITS2 region of rDNA gene identified the isolates as T. harzianum, T. reesei, T. asperellum and T. longibrachiatum. These findings underscore the effectiveness of Trichoderma sp. in promoting plant growth and suppressing plant pathogenic fungi. HIGHLIGHTSSix Trichoderma isolates (T05, T19, T25, T27, T28 and T33) exhibited superior plant growth promotion abilities. These isolates significantly enhanced germination rates of Khao Dawk Mali 105 rice seeds compared to the method. Among the isolates, T05 showed the greatest promotion of plant growth, as evidenced by root length, shoot length, fresh weight and dry weight. Trichoderma isolates demonstrated potential for inhibiting the fungal pathogen Colletotrichum sp. MN-3. Morphological classification divided the Trichoderma sp. into 4 groups, and species identification through nucleotide sequencing revealed T. harzianum, T. reesei, T. asperellum and T. longibrachiatum. GRAPHICAL ABSTRACT

Evaluating Native Bacillus Strains as Potential Biocontrol Agents against Tea Anthracnose Caused by Colletotrichum fructicola

Anthracnose of the tea plant (Camellia sinensis), caused by Colletotrichum spp., poses a significant threat to both the yield and quality of tea production. To address this challenge, researchers have looked to the application of endophytic bacteria as a natural alternative to the use chemical pesticides, offering potential for enhancing disease resistance and abiotic stress tolerance in tea plants. This study focused on identifying effective microbial agents to combat tea anthracnose caused by Colletotrichum fructicola. A total of 38 Bacillus-like strains were isolated from the tea rhizosphere, with 8 isolates showing substantial inhibitory effects against the mycelial growth of C. fructicola, achieving an average inhibition rate of 60.68%. Among these, strain T3 was particularly effective, with a 69.86% inhibition rate. Through morphological, physiological, and biochemical characterization, along with 16S rRNA gene phylogenetics analysis, these strains were identified as B. inaquosorum (T1 and T2), B. tequilensis (T3, T5, T7, T8, and T19), and B. spizizenii (T6). Biological and molecular assays confirmed that these strains could induce the expression of genes associated with antimicrobial compounds like iturin, fengycin, subtilosin, and alkaline protease, which effectively reduced the disease index of tea anthracnose and enhanced tea plant growth. In conclusion, this study demonstrates that B. inaquosorum, B. tequilensis, and B. spizizenii strains are promising biocontrol agents for managing tea anthracnose.

Eco-friendly formulation preparation of fungal biopesticide Metarhizium anisopliae and its impact on the viability, insecticidal activity and pesticidal compatibility

Aim: The present investigation evaluated the effect of various formulations on the viability, pesticide compatibility and biocontrol potential of fungal biopesticidal agent Metarhizium anisopliae under laboratory conditions. Methodology: Soil isolate of M. anisopliae biomass was formulated with different oils like sunflower, groundnut, neem oil, water and diesel using green principles. Results: Sunflower oil recorded maximum viability among the formulations, revealing 91.4% formulation efficacy, followed by groundnut oil, which showed 87.2% efficacy. The viability of the fungal isolate was found to be low in diesel formulation, which showed 69.2% formulation efficacy. A compatibility study revealed that sunflower oil formulation showed high tolerance to all the tested pesticides. Sunflower oil formulation also showed a high rate of mortality against S. litura. Interpretation: The present study suggests using oil formulation as an effective carrier for the fungal biopesticide Metarhizium anisopliae with high compatibility and viability. Key words: Biopesticide, Fungal strains, Metarhizium anisopliae, Sunflower oil

A potential biocontrol and growth-promoting agent Streptomyces luteoverticillatus B4 for managing cabbage Fusarium wilt and cucumber Alternaria leaf blight

Cabbage Fusarium wilt and cucumber Alternaria leaf blight are two widespread diseases caused by Fusarium oxysporum and Alternaria cucumerina that severely affect cabbage and cucumber output across the world. However, very few biocontrol actinomycete resources have been identified for these two diseases. An antagonistic actinomycete B4 was isolated and identified as Streptomyces luteoverticillatus. It is effective against a wide range of plant pathogens. The purpose of this study was to look into the inhibitory impact of S. luteoverticillatus B4 on F. oxysporum and A. cucumerina, as well as to create the theoretical groundwork and research technologies for the use of B4 as a biopesticide. It was found that B4 has the ability to detoxify organic phosphorus and produce siderophores, IAA, and glucoamylase. In the greenhouse pot test, B4 had a control efficiency of 56 % against F. oxysporum and 76 % against A. cucumerina. Further investigation into the inhibitory mechanism indicated that once the B4 fermentation broth operated on the two pathogens, their mycelial morphology was altered, and mycelial growth was suppressed, particularly for F. oxysporum. B4 could create volatile organic compounds that may have an inhibiting impact. In addition, B4 fermentation broth dramatically increased seed germination and seedling development in both cabbage and cucumber. S. luteoverticillatus B4 is a possible biocontrol agent that inhibits F. oxysporum and A. cucumerina while also encouraging cabbage and cucumber development.

Insights into the RNA Virome of the Corn Leafhopper Dalbulus maidis, a Major Emergent Threat of Maize in Latin America

The maize leafhopper (Dalbulus maidis) is a significant threat to maize crops in tropical and subtropical regions, causing extensive economic losses. While its ecological interactions and control strategies are well studied, its associated viral diversity remains largely unexplored. Here, we employ high-throughput sequencing data mining to comprehensively characterize the D. maidis RNA virome, revealing novel and diverse RNA viruses. We characterized six new viral members belonging to distinct families, with evolutionary cues of beny-like viruses (Benyviridae), bunya-like viruses (Bunyaviridae) iflaviruses (Iflaviridae), orthomyxo-like viruses (Orthomyxoviridae), and rhabdoviruses (Rhabdoviridae). Phylogenetic analysis of the iflaviruses places them within the genus Iflavirus in affinity with other leafhopper-associated iflaviruses. The five-segmented and highly divergent orthomyxo-like virus showed a relationship with other insect associated orthomyxo-like viruses. The rhabdo virus is related to a leafhopper-associated rhabdo-like virus. Furthermore, the beny-like virus belonged to a cluster of insect-associated beny-like viruses, while the bi-segmented bunya-like virus was related with other bi-segmented insect-associated bunya-like viruses. These results highlight the existence of a complex virome linked to D. maidis and paves the way for future studies investigating the ecological roles, evolutionary dynamics, and potential biocontrol applications of these viruses on the D. maidis—maize pathosystem.

Bacteria as potential biocontrol agents for managing purple witchweed (Striga hermonthica) in grain sorghum

Abstract Purple witchweed [Striga hermonthica (Delile) Benth.], a highly destructive parasitic weed, poses a significant threat to sorghum [Sorghum bicolor (L.) Moench] cultivation. This hemiparasitic plant intrudes its root system into the host plant, leading to substantial yield losses, particularly in susceptible genotypes. In the pursuit of eco-friendly solutions, the biocontrol approach has gained attention as a potential management strategy for Striga. In this study, 13 bacterial strains belonging to the genera Bacillus, Gluconobacter, Pseudomonas, and Streptomyces were investigated in vitro for their efficiency in controlling the early-stage development of Striga. Among the tested strains, Streptomyces morookaensis NRRL B-12429 demonstrated significant inhibition of Striga seed germination and radicle elongation at 54.36% and 61.84%, respectively, when applied to preconditioned seeds with a synthetic germination stimulant. The effect of S. morookaensis on the inhibition of Striga seed germination was more pronounced in the presence of the host plant, sorghum, at 62.35%. However, biopriming of sorghum seeds with S. morookaensis did not enhance the inhibitory effects on Striga seed germination but resulted in a greater reduction in radicle elongation at 74.64% compared with non-primed seeds. Additionally, the biopriming with S. morookaensis promoted the growth of shoots and roots of germinating sorghum, regardless of the presence of Striga seeds. These findings highlight the potential of S. morookaensis strain NRRL B-12429 as a viable candidate for biocontrol agent applications in sorghum cultivation. Further exploration and investigation of its biocontrol capabilities can provide valuable insights for sustainable management practices against Striga infestations.

Biocontrol of Hemileia vastatrix, the Causal Agent of Coffee Leaf Rust, by Paenibacillus sp. NMA1017.

Coffee leaf rust (CLR), caused by Hemileia vastatrix, is considered a highly important phytosanitary problem in Mexico. Currently, there are few microorganisms used as biocontrol alternatives to chemical control of CLR in organic coffee fields in Mexico. This study evaluates the use of Paenibacillus sp. NMA1017 as a biocontrol agent to inhibit the development of H. vastatrix in in vitro and in vivo (greenhouse) experiments. Hemileia vastatrix urediniospores were placed on water agar plates, and then Paenibacillus sp. NMA1017 was inoculated simultaneously or 8 h later. Urediniospores germination rate was reduced by 94% when the NMA1017 strain was inoculated simultaneously with the urediniospores and reduced by 38% when NMA1017 was inoculated 8 h later. Experiments with 8-month-old Bourbon coffee plants that were infected with H. vastatrix showed that disease incidence was reduced by 38, 90, and 50% when NMA1017 was applied 8 days before, simultaneously, or 8 days after the application of H. vastatrix, respectively. Paenibacillus sp. NMA1017 also reduced the severity of CLR on the leaves by up to 62%. The germination urediniospores of other rust pathogens such as Puccinia sorghi (maize leaf rust), Puccinia triticina (wheat leaf rust), Puccinia graminis f. sp. tritici (black stem rust of wheat), Uromyces striatus (alfalfa leaf rust), and Phragmidium sp. (rosebush leaf rust) were also inhibited. Use of the potential biocontrol agent Paenibacillus sp. NMA1017 might help reduce the application of chemical fungicides for the control of CLR, making coffee a more sustainable crop and providing management options for organic coffee growers.

Endophytic fungi from <i>Dichrocephala integrifolia</i>: Diversity, antifungal properties, enzymatic activities, and plant growth promotion

Dichrocephala integrifolia is a wild medicinal plant utilised in traditional healing and Ayurveda to cope up with several health issues by various groups of people around the world. Medicinal plants are associated with diverse fungal endophytes with potential bioactive properties. In this investigation, 26 fungal endophytes were isolated from D. integrifolia and three sterile forms using the Petri plate culture method. The endophytic isolation rate was highest for inflorescence (35.97%) and lowest for stem (15.61%). The highest colonization frequency was shown by F. solani (8.37%) and the lowest by Sterile morphotype 3 (1.36%). Out of the four plant parts, inflorescence was found to be highly infected, displaying an infection rate of 93.43% and the least infection occurred in the stem with 45%. The maximum number of isolated endophytic fungi belongs to the class Sordariomycetes, with a relative occurrence (%) of 71.72%. The Simpson’s diversity index reveals that the leaf endophytes were more diverse (0.94). Qualitative antifungal activity of the sporulating isolates against Curvularia lunata has shown that the maximum number of endophytes possessed Class 3 antagonism. Four isolates were selected based on screening of their antagonistic activity and their antifungal inhibition was calculated against nine fungal phytopathogens. Maximum inhibition (100%) was shown by Trichoderma sp. 2 (S2B2) against Alternaria alternata, A. brassicicola, Colletotrichum capsici, C. lunata, and Ustilaginoidea virens and least inhibition by Gliocladium sp. 1 (19.78%) against C. lunata. The four isolates were found to produce protease, lipase, amylase and cellulase enzymes. The isolates produced ammonia and hydrogen cyanide, but none of the isolates could solubilize phosphate. Potent biocontrol agents are much needed to replace synthetic chemicals and restore soil microflora.

Patulin inhibition of specific apple microbiome members uncovers Hanseniaspora uvarum as a potential biocontrol agent.

Penicillium expansum is a major postharvest pathogen of apples, causing loss in fruits through tissue damage, as well as in apple products due to contamination with the mycotoxin patulin. During infections, patulin is a cultivar-dependent virulence factor that facilitates apple lesion development. Patulin also has characterized antimicrobial activity and is important for inhibiting other competitive phytopathogens, but the role of this inhibitory activity has not been investigated in the context of the apple microbiome. In our current study, we isolated 68 apple microbiota and characterized their susceptibility to P. expansum extracts. We found Gram-negative bacteria and Basidiomycete yeast to demonstrate largely patulin-specific growth inhibition compared to Gram-positive and Ascomycete isolates. From co-cultures, we identified a Hanseniaspora and Gluconobacter pairing that reduced P. expansum biomass and found that Hanseniaspora uvarum alone is sufficient to reduce apple disease progression in vivo. We investigated possible mechanisms of H. uvarum biocontrol activity and found modest inhibition on apple puree plates, as well as a trend toward lower patulin levels at the wound site. Active biocontrol activity required live yeast, which also were effective in controlling Botrytis cinerea apple infections. Lastly, we explored the breadth of H. uvarum biocontrol activity with over 30 H. uvarum isolates and found consistent inhibition of P. expansum apple disease.