Biological Control Of Diseases Research Articles

Biological control of Corynespora leaf fall disease in rubber by endophytic Trichoderma spp. under field conditions

Biological control of Corynespora leaf fall disease in rubber by endophytic Trichoderma spp. under field conditions

Characteristics and whole-genome analysis of a novel Pseudomonas syringae pv. tomato bacteriophage D6 isolated from a karst cave.

Pseudomonas syringae is a gram-negative plant pathogen that infects plants such as tomato and poses a threat to global crop production. In this study, a novel lytic phage infecting P. syringae pv. tomato DC3000, named phage D6, was isolated and characterized from sediments in a karst cave. The latent period of phage D6 was found to be 60min, with a burst size of 16 plaque-forming units per cell. Phage D6 was stable at temperatures between 4 and 40°C but lost infectivity when heated to 70°C. Its infectivity was unaffected at pH 6-10 but became inactivated at pH ≤ 5 or ≥ 12. The genome of phage D6 is a linear double-stranded DNA of 307,402bp with a G + C content of 48.43%. There is a codon preference between phage D6 and its host, and the translation of phage D6 gene may not be entirely dependent on the tRNA library provided by the host. A total of 410 open reading frames (ORFs) and 14 tRNAs were predicted in its genome, with 92 ORFs encoding proteins with predicted functions. Phage D6 showed low genomic similarity to known phage genomes in the GenBank and Viral sequence databases. Genomic and phylogenetic analyses revealed that phage D6 is a novel phage. The tomato plants were first injected with phage D6, and subsequently with Pst DC3000, using the foliar spraying and root drenching inoculum approach. Results obtained after 14days indicated that phage D6 inoculation decreased P. syringae-induced symptoms in tomato leaves and inhibited the pathogen's growth in the leaves. The amount of Pst DC3000 was reduced by 150- and 263-fold, respectively. In conclusion, the lytic phage D6 identified in this study belongs to a novel phage within the Caudoviricetes class and has potential for use in biological control of plant diseases.

Characterization of a broad-spectrum antifungal strain, Streptomyces graminearus STR-1, against Magnaporthe oryzae.

Fungal diseases such as the devastating rice blast pose severe threats to crop production worldwide. Biological control of crop diseases caused by fungal pathogens is an environment-friendly approach for safeguarding crop production. But the insufficient availability of microbial agents effective against various fungal diseases has hampered the development of green production in crops. In this study, we identified a broad-spectrum antifungal bacterium, Streptomyces graminearus STR-1, showing antagonistic activity to diverse fungal pathogens including Magnaporthe oryzae, Rhizoctonia solani, Fusarium graminearum, Ustilaginoidea virens, and Bipolaris maydis. Its antifungal activity was relatively stable and less affected by temperature and pH. Evaluation of the biocontrol activity of STR-1 revealed that STR-1 prevented and controlled rice blast disease via eliciting plant immunity and suppressing fungal infection-structure development. STR-1 broth extract inhibited spore germination, likely through inhibiting protein synthesis. Combining LC-MS and chromatography analysis of the antimicrobial compounds purified from STR-1 broth extract, together with decoding STR-1 genomic sequence, we identified 4-oxo-4-[(1-phenylethyl)amino]but-2-enoic acid, 1,3,5-Trimethylpyrazole and SMA-1 as the potential main STR-1 secondary metabolites associated with its antifungal effects. This study suggests that bacterial strain STR-1 could be used for identifying highly effective and broad-spectrum secondary metabolites for containing rice blast and other crop diseases. The application of the active compounds offers a promising measure to tackle fungal disease.

The Role of Organic Farming in Sustainable Agriculture

Organic farming, as a sustainable alternative to conventional high-input practices reliant on synthetic fertilizers, fungicides, and pesticides, prioritizes the vitality of soil as a living ecosystem. Embracing practices such as crop rotation, animal manures, crop residues, green manures, and biological pest and disease control, organic agriculture aims to uphold soil health and productivity. By meeting present food demands in an environmentally conscientious manner, organic farming also safeguards the needs of future generations, thereby preserving and nurturing our ecosystem. Modern agriculture has detrimentally impacted the environment, leading to issues such as decreased soil fertility, elevated water hardness, insect resistance development, reduced genetic diversity in plants, heightened levels of toxic residues in the food chain and animal feed, contributing to health problems and environmental degradation. In contrast, organic farming nurtures plants with essential macronutrients and micronutrients while simultaneously enhancing soil physical, chemical, and biological characteristics. Guided by the ethos of sustainability, organic farming prioritizes mitigating health risks linked to synthetic inputs and cultivating a healthier ecosystem. The minimal environmental footprint of organic farming positions it as a practical solution for tackling urgent concerns like soil degradation, water pollution, and global ecological well-being. Essentially, organic farming stands out as a beacon of sustainable agriculture, paving the way to reconcile food production with environmental conservation. Moreover, organic farming's low environmental impact presents an opportunity to rehabilitate and enhance degraded agricultural lands.

Growth promotion and biological control of fungal diseases in tomato by a versatile rhizobacterium, Pseudomonas chlororaphis subsp. aureofaciens SPS-41

Pseudomonas chlororaphis subsp. aureofaciens SPS-41, a beneficial bacterium isolated from rhizosphere of sweet potato, has been explored as a biological control agent for the management of soil-borne diseases. In this study, its plant growth-promoting and antifungal properties against two major tomato fungal pathogens (Fusarium oxysporum and Botrytis cinerea) were evaluated using in vitro and in vivo experiments. Strain SPS-41 produced indole-3-acetic acid (IAA), siderophore, biofilm, protease, amylase, chitinase, and could solubilize phosphate. It also inhibited fungal mycelial growth, with an inhibition rate of more than 80% in dual culture assays. Volatile organic compounds (VOCs) produced by SPS-41 also exhibited strong antifungal activity. In addition, SPS-41 promoted the growth of tomato seedlings in greenhouse conditions, and the severity of wilt disease and grey mold decreased significantly with rhizospheric inoculation of cell suspension and VOC fumigation comparing to untreated controls. The composition of VOCs emitted by SPS-41 was analyzed, and 57 volatiles were identified by SPME/GC-MS. Of these, 2-tridecanone, 2-undecanone, 2-nonanone, 2-acetylthiazole, 9-decenyl acetate, 2-hexadecanol, α-farnesene, and nonanal were the major volatiles. Nonanal, 2-nonanone and 2-acetylthiazole were confirmed to inhibit the growth of all three pathogens. The complete genome of strain SPS-41 was sequenced and annotated. We identified a series of gene clusters responsible for the synthesis of active secondary metabolites with antimicrobial and biocontrol functions. Moreover, several genes related to plant growth promotion, such as nitrogen fixation and indole-3-acetic acid and siderophore biosynthesis were also identified. This research indicates that strain SPS-41 is a plant growth promoting bacterium with the potential for development as a new biocontrol agent for tomato fungal pathogens.

The Use of Rhizobacteria on White Rot Disease and Growth of Lettuce

White rot caused by Sclerotinia sclerotiorum [(Lib.) de Bary] is one of the most important diseases negatively affecting lettuce production. In this study, the effects of rhizobacteria containing different species on S. sclerotiorum were investigated. Also effect of rhizobacteria were determined on the growth of lettuce. Eight rhizobacteria strains (Enterobacter cloacae, E. aerogenes, Bacillus cereus, Microbacterium testaceum, Pseudomonas putida, P. chlororaphis, Acinetobacter calcoaceticus, and Burkholderia cepacia) were used in the study. Firstly, the in vitro effects of rhizobacteria strains were investigated on the mycelial growth and sclerotia viability of S. sclerotiorum. Then, pot experiments were carried out under controlled greenhouse conditions to determine the effect of selected strains on white rot disease and the growth of lettuce. The effect of tested bacteria on the mycelial growth of S. sclerotiorum ranged between 38.09-79.84%, and the P. putida strain had the highest impact. The bacterial strains were also effective on the sclerotia viability of S. sclerotiorum. The efficiency in the pot experiment was between 50-90% on white rot, and the highest effect was recorded in A. calcoaceticus strain. In the pot experiment rhizobacteria also increased plant growth. In particular, E. aerogenes was the most successful strain in plant growth. The results revealed that bacterial strains have different inhibitory effects in in vitro and in vivo experiments, while having the potential in the biological control of white rot disease and positive results on lettuce growth.

Evaluation of the control efficacy of antagonistic bacteria from V-Ti magnetite mine tailings on kiwifruit brown spots in pot and field experiments.

Seemingly barren heavy-metal-polluted vanadium (V) and titanium (Ti) magnetite mine tailings contain various functional microbes, yet it is unclear whether this includes microbial resources relevant to the biological control of plant diseases. Kiwifruit brown leaf spot disease, caused by Corynespora cassiicola, can seriously reduce kiwifruit yield. To discover effective control measures for kiwifruit leaf spot, 18 bacteria strains among 136 tailing-isolated bacteria from V-Ti magnetite mine tailings were identified as inhibiting C. cassiicola by the confrontation plate method, indicating that antagonistic bacteria surviving in the V-Ti magnetite mine tailings were present at a low level. The 18 antagonistic strains could be divided into two BOX-A1R clusters. The 13 representative strains that were selected for phylogenetic tree construction based on their 16S rRNA sequences belonged to the Bacillus genus. Five predominant strains exhibited different toxin-production times and intensities, with four of them initiating toxin production at 32 h. Among them, Bacillus sp. KT-10 displayed the highest bacteriostatic rate (100%), with a 37.5% growth inhibition rate and an antagonistic band of 3.2 cm against C. cassiicola. Bacillus sp. KT10 also showed a significant inhibitory effect against the expansion speed of kiwifruit brown spots in the pot. The relative control effect was 78.48 and 83.89% at 7 days after the first and last spraying of KT-10 dilution, respectively, confirming a good effect of KT-10 on kiwifruit brown leaf spots in the field. This study demonstrated for the first time that there are some antagonistic bacteria to pathogenic C. cassiicola in V-Ti magnetite mine tailings, and Bacillus sp. KT10 was found to have a good control effect on kiwifruit brown leaf spots in pots and fields, which provided an effective biological control measurement for kiwifruit brown leaf spots.

Flavonoids from Citrus reticulata: Inhibitory activity against pathogenic fungi and biocontrol potential

The risks of synthetic fungicides propel a shift to biological plant disease control. Attention has been focused on screening plant secondary metabolites for plant-derived pesticides. Flavonoids are abundant and structurally diverse in citrus peels. The co-cultivation of four fungal pathogens with flavonoid extracts from the peels of Citrus reticulata unveiled a substantial inhibitory effect of these compounds, with polymethoxyflavones identified as the primary contributors. The microencapsulated citrus flavonoids using sodium alginate and gelatin showed 60% efficiency against cucumber wilt in potted seedlings, highlighting the potential of citrus flavonoids for biocontrol in field applications.

Exploring the Mycovirus Sclerotinia sclerotiorum Hypovirulence-Associated DNA Virus 1 as a Biocontrol Agent of White Mold Caused by Sclerotinia sclerotiorum.

Sclerotinia sclerotiorum is a necrotrophic fungal pathogen causing white mold on many important economic crops. Recently, some mycoviruses such as S. sclerotiorum hypovirulence-associated DNA virus 1 (SsHADV-1) converted S. sclerotiorum into a beneficial symbiont that helps plants manage pathogens and other stresses. To explore the potential use of SsHADV-1 as a biocontrol agent in the United States and to test the efficacy of SsHADV-1-infected United States isolates in managing white mold and other crop diseases, SsHADV-1 was transferred from the Chinese strain DT-8 to United States isolates of S. sclerotiorum. SsHADV-1 is readily transmitted horizontally among United States isolates of S. sclerotiorum and consistently conferred hypovirulence to its host strains. Biopriming of dry bean seeds with hypovirulent S. sclerotiorum strains enhanced resistance to white mold, gray mold, and Rhizoctonia root rot. To investigate the underlying mechanisms, endophytic growth of hypovirulent S. sclerotiorum in dry beans was confirmed using PCR, and the expression of 12 plant defense-related genes were monitored before and after infection. The results indicated that the endophytic growth of SsHADV-1-infected strains in plants stimulated the expression of plant immunity pathway genes that assisted a rapid response from the plant to fungal infection. Finally, application of the seed biopriming technology with SsHADV-1-infected hypervirulent strain has promise for the biological control of several diseases of wheat, pea, and sunflower.

Biocontrol of black rot of sweetpotato by Pichia pastoris recombinant strain expressing chitinase IbChiA

Black rot disease, caused by Ceratocystis fimbriata, is highly destructive to sweetpotato (Ipomoea batatas). IbChiA is a chitinase identified from sweetpotato with strong antifungal activity against C. fimbriata. The recombinant yeast X33/pGAPZαA-IbChiA was obtained by transforming IbChiA into Pichia pastoris using the constitutive secretory expression vector pGAPZαA. IbChiA was stably expressed and secreted into the extracellular space without an inducer. The recombinant yeast X33/pGAPZαA-IbChiA could not only distinctly inhibit the conidium germination and mycelial growth of C. fimbriata, but also exhibit excellent colonization ability on the tuberous root wounds of sweetpotato. Biocontrol experiments further revealed that recombinant yeast X33/pGAPZαA-IbChiA could effectively limit the expansion of lesions and reduce the severity of black rot in sweetpotato. The findings present a novel approach for the biological control of black rot disease in postharvest sweetpotato.

Endophytic Stenotrophomonas geniculata KJ-6 via producing antifungal volatile organic compounds effectively control Lanzhou lily postharvest diseases

The endophytic bacterial Stenotrophomonas geniculata KJ-6, was isolated from Arisaematis rhizoma. This strain has the ability to control three postharvest pathogenic fungi of Lanzhou lily (Trichoderma lixii F-2, Talaromyces tumuli F-3, and Fusarium annulatum F-6) by releasing volatile organic compounds (VOCs). The experiment utilized the double-layer sealed bottom plate method. The results demonstrate that KJ-6 effectively inhibits the mycelial growth of F-2, F-3, and F-6, with inhibition rates of 81.59%, 79.87%, and 84.7%, respectively. Moreover, scanning electron microscopy (SEM) revealed abnormal mycelium morphology in the test pathogenic fungi treated with KJ-6 VOCs, characterized by multiple wrinkles, cracks, and distortions. Using five common phytopathogenic fungi as controls, our results demonstrated that the VOCs from KJ-6 exhibited broad-spectrum antifungal effects. Analysis using headspace gas chromatography-ion mobility spectrometry identified three components of the VOCs produced by KJ-6, including 1-propanethiol, isoamyl acetate, and 2-methyl-1-butanol. Antifungal tests revealed that 1-propanethiol plays a crucial role in the inhibitory activity of VOCs. It exhibited inhibitory rates of 64.17%, 72.73%, and 26.71% on the mycelium growth of F-2, F-3, and F-6, respectively. In vivo experiments further confirmed that VOCs can significantly reduce the disease index and decay rate of Lanzhou lily bulbs during storage. Moreover, KJ-6 treatment led to a significant reduction in the degree of browning of lily bulbs. Additionally, it enhanced the activity of defense-related enzymes, improved disease resistance, and extended the shelf life of lily bulbs. As a result, this study offers a theoretical foundation for the biological control of postharvest diseases in Lanzhou lily.

Importance, challenges and perspectives of using fungi in the biological control of plant diseases for Brazilian agriculture

Importance, challenges and perspectives of using fungi in the biological control of plant diseases for Brazilian agriculture

Characterisation of New Foxunavirus Phage Murka with the Potential of Xanthomonas campestris pv. campestris Control.

Phages of phytopathogenic bacteria are considered to be promising agents for the biological control of bacterial diseases in plants. This paper reports on the isolation and characterisation of a new Xanthomonas campestris pv. campestris phage, Murka. Phage morphology and basic kinetic characteristics of the infection were determined, and a phylogenomic analysis was performed. The phage was able to lyse a reasonably broad range (64%, 9 of the 14 of the Xanthomonas campestris pv. campestris strains used in the study) of circulating strains of the cabbage black rot pathogen. This lytic myovirus has a DNA genome of 44,044 bp and contains 83 predicted genes. Taxonomically, it belongs to the genus Foxunavirus. This bacteriophage is promising for use as a possible means of biological control of cabbage black rot.

The Effectiveness of The Inhibition of Local Bacterial Isolate From The Rhizosphere of Oil Palm Plant on Leaf Spot Disease in Purple Eggplant (Solanum melongena L.)

Longterm use of pesticides can cause side effects on the environment and human health. PGPR is an environmentally friendly solution for biological control of leaf spot disease. This research aims to obtain bacterial isolates from the rhizosphere of oil palm plants which have the potential as biological agents to control fungal leaf spot diseases in eggplant plants. The research was carried out using 10 treatments, namely giving 9 samples of different bacterial isolates and 1 control and repeated 2 times, bringing the total to 20 plant samples. The results showed that there were 4 bacterial isolates from the rhizosphere of oil palm plants that had great potential to inhibit the growth of leaf spot fungi, namely isolate R5 (99.35%), isolate R2 (98.1%), isolate R6 (94.69%) and isolate R10 (94.29%). The bacterial isolates that were able to reduce the percentage of disease attacks compared to the first week of observation to the fourth week were isolates R4, R2 and R10, with a reduction in the percentage of disease attacks respectively of 15.15%, 7.14% and 1.98%. Based on the data, it can be seen that the R2 bacterial isolate is an isolate that has the potential to inhibit fungal isolates and reduce the percentage of leaf spot disease attacks on eggplant plants.

The potentiality of Wickerhamomyces anomalus against postharvest black spot disease in cherry tomatoes and insights into the defense mechanisms involved

Our previous study revealed that Wickerhamomyces anomalus effectively inhibited Botrytis cinerea disease in cherry tomatoes. However, the potentiality of W. anomalus against black spot disease in cherry tomatoes as well as possible mechanisms related to this efficacy remain unclear. In our current study, we investigated the efficacy of W. anomalus against black spot disease in cherry tomatoes, and the molecular mechanisms related to disease-resistance response of W. anomalus treated cherry tomatoes were also investigated by transcriptome analysis. The results exhibited that W. anomalus successfully controlled postharvest black spot disease of cherry tomatoes caused by Alternaria alternata. Furthermore, W. anomalus vigorously controlled the spore germination and reduced the germ tube elongation of A. alternata. The physiological mechanisms by which W. anomalus inhibited the black spot decay in cherry tomatoes mainly through enhancing the ascorbate peroxidase (APX) and chitinase (CHI), and reducing the content of malondialdehyde (MDA). In addition, based on transcriptome technology, W. anomalus could up-regulate genes involved in several important KEGG pathways, including amino sugar and nucleotide sugar metabolism pathway, selenocompound metabolism pathway, linoleic acid metabolism pathway, and galactose metabolism pathway. These genes may help the fruit to enhance the enzyme activities and nutritional values of cherry tomatoes, synthesize the regulatory molecules in plant disease response as well as plant growth and development, increase the defense and oxidation resistance of the fruit during and after harvesting, and trigger ROS induced resistance in cherry tomatoes. Ultimately, W. anomalus has been proved as a biocontrol agent which could effectively control black spot disease in cherry tomatoes caused by A. alternata. This study can provide theoretical reference for the practical application of antagonistic yeasts in the biological control of postharvest diseases of cherry tomatoes.

Presence of endophytic fungi in cacao plantations (Theobroma cacao L.), in the state of Tabasco, Mexico

Objective: the present work was done with the objective of identifying endophytic fungi associated with Theobroma cacao L. in Centro, Cunduacán and Comalcalco, locations in the state of Tabasco, Mexico. The molecular identity used was the region of the Internal Transcribed Spaces (ITS), ITS 1 and ITS 4. Design/methodology/approach: the study identified 15 fungal strains, grouped into 13 different species, belonging to the Ascomycota phylum, distributed in three different classes: Dothideomycetes, Eurotiomicetos and Sordariomycetes. It is important to mention that it is the first record of Endomelanconiopsis endophytica and freycinetiae found in cacao in Tabasco. In addition, we also identified Aspergillus foetidus, fischeri, delicatus arcoverdensis; Thielaviopsis ethacetica, Cophinforma atrovirens, Neurospora udagawae, Diaporthe miriciae, Nodulisporium indicum, Cophinforma atrovirens; Colletotrichum tainanense y hebeiense. Findings/conclusions: Many of these endophytic fungi produce secondary metabolites and antioxidants that can be used in the medical industry or for biological control of phytopathogenic diseases, such as Moniliophthora roreri.

Microbial community and chemical composition of cigar tobacco (Nicotiana tabacum L.) leaves altered by tobacco wildfire disease

AbstractTobacco wildfire disease caused by Pseudomonas syringae pv. tabaci is one of the most destructive foliar bacterial diseases occurring worldwide. However, the effect of wildfire disease on cigar tobacco leaves has not been clarified in detail. In this study, the differences in microbiota and chemical factors between wildfire disease‐infected leaves and healthy leaves were characterized using high‐throughput Illumina sequencing and a continuous‐flow analytical system, respectively. The results demonstrated significant alterations in the structure of the phyllosphere microbial community in response to wildfire disease, and the infection of P. syringae pv. tabaci led to a decrease in bacterial richness and diversity. Furthermore, the content of nicotine, protein, total nitrogen, and Cl− in diseased leaves significantly increased by 47.86%, 17.46%, 20.08%, and 72.77% in comparison to healthy leaves, while the levels of total sugar and reducing sugar decreased by 59.59% and 70.0%, respectively. Notably, the wildfire disease had little effect on the content of starch and K+. Redundancy analysis revealed that Pseudomonas, Staphylococcus, Cladosporium, and Wallemia displayed positive correlations with nicotine, protein, total nitrogen, Cl− and K+ contents, while Pantoea, Erwinia, Sphingomonas, Terrisporobacter, Aspergillus, Alternaria, Sampaiozyma, and Didymella displayed positive correlations with total sugar and reducing sugar contents. Brevibacterium, Brachybacterium, and Janibacter were found to be enriched in diseased leaves, suggesting their potential role in disease suppression. Co‐occurrence network analysis indicated that positive correlations were prevalent in microbial networks, and the bacterial network of healthy tobacco leaves exhibited greater complexity compared to diseased tobacco leaves. This study revealed the impact of wildfire disease on the microbial community and chemical compositions of tobacco leaves and provides new insights for the biological control of tobacco wildfire disease.

The Prospect of Hydrolytic Enzymes from Bacillus Species in the Biological Control of Pests and Diseases in Forest and Fruit Tree Production.

Plant diseases and insect pest damage cause tremendous losses in forestry and fruit tree production. Even though chemical pesticides have been effective in the control of plant diseases and insect pests for several decades, they are increasingly becoming undesirable due to their toxic residues that affect human life, animals, and the environment, as well as the growing challenge of pesticide resistance. In this study, we review the potential of hydrolytic enzymes from Bacillus species such as chitinases, β-1,3-glucanases, proteases, lipases, amylases, and cellulases in the biological control of phytopathogens and insect pests, which could be a more sustainable alternative to chemical pesticides. This study highlights the application potential of the hydrolytic enzymes from different Bacillus sp. as effective biocontrol alternatives against phytopathogens/insect pests through the degradation of cell wall/insect cuticles, which are mainly composed of structural polysaccharides like chitins, β-glucans, glycoproteins, and lipids. This study demonstrates the prospects for applying hydrolytic enzymes from Bacillus sp. as effective biopesticides in forest and fruit tree production, their mode of biocidal activity and dual antimicrobial/insecticidal potential, which indicates a great prospect for the simultaneous biocontrol of pests/diseases. Further research should focus on optimizing the production of hydrolytic enzymes, and the antimicrobial/insecticidal synergism of different Bacillus sp. which could facilitate the simultaneous biocontrol of pests and diseases in forest and fruit tree production.

Whole genome sequencing provides evidence for Bacillus velezensis SH-1471 as a beneficial rhizosphere bacterium in plants

Bacillus is widely used in agriculture due to its diverse biological activities. We isolated a Bacillus velezensis SH-1471 from the rhizosphere soil of healthy tobacco, which has broad-spectrum antagonistic activity against a variety of plant pathogenic fungi such as Fusarium oxysporum, and can be colonized in the rhizosphere of a variety of plants. This study will further explore its mechanism by combining biological and molecular biology methods. SH-1471 contains a ring chromosome of 4,181,346 bp with a mean G + C content of 46.18%. We identified 14 homologous genes related to biosynthesis of resistant secondary metabolite, and three clusters encoded potential new antibacterial substances. It also contains a large number of genes from colonizing bacteria and genes related to plant bacterial interactions. It also contains genes related to environmental stress, as well as genes related to drug resistance. We also found that there are many metabolites in the strain that can inhibit the growth of pathogens. In addition, our indoor pot test found that SH-1471 has a good control effect on tomato wilt, and could significantly improve plant height, stem circumference, root length, root weight, and fresh weight and dry weight of the aboveground part of tomato seedlings. Therefore, SH-1471 is a potential biological control strain with important application value. The results of this study will help to further study the mechanism of SH-1471 in biological control of plant diseases and promote its application.

Biological control of anthracnose fruit rot disease (Colletotrichum spp.) and fruit yield improvement of jujube (Zizyphus jujuba Miller var. inermis Rehder) using Bacillus velezensis CE 100

Colletotrichum spp. are notorious phytopathogens that cause anthracnose rot disease in jujube fruits, have a complex lifestyle (with necrotrophic, hemibiotrophic, quiescent, and endophytic phases), they spread rapidly mainly through the production of spores and are increasingly becoming resistant to various fungicides which makes them difficult to control. This study investigated the inhibition of spore germination and mycelial growth of Colletotrichum spp. to suppress anthracnose rot disease in jujube fruits through the activity of cell wall degrading enzymes, and improvement of jujube fruit characteristics and yield via the production of indole-3-acetic acid (IAA) and gibberellin acid (GA3) by Bacillus velezensis CE 100. The bacterial culture broth exhibited a strong chitinase, β-1,3-glucanase and protease and the crude fraction suppressed the germination of spores by more than 95.0 % at a concentration of 100 µL/mL, and substantially reduced mycelial growth of Colletotrichum spp. The microscopic analysis revealed that the treatments degraded the cell walls and caused severe structural distortion of the spores and hyphae of Colletotrichum spp. Field application of B. velezensis CE 100 on the jujube tree crown and in the rhizosphere lowered the rate of anthracnose disease incidence by 2.8-fold and disease severity index (DSI) by 4.4-fold, compared to the control. In addition, B. velezensis CE 100 produced IAA (up to 15.6 mg/mL) and GA3 (up to 1.3 mg/mL), and the field application of the bacterial culture on the jujube tree crown and in the rhizosphere consequently improved the average fruit characteristics (fruit length, fruit diameter and fresh weight by 1.2-, 1.4- and 1.5-fold), chlorophyll index (photosynthetic rate by 1.1-fold), and fruit yield (by 2.1-fold) of jujube, compared to the control group. Thus, the inoculation of B. velezensis CE 100 has the potential effectiveness as a bio-fungicide against anthracnose rot disease in jujube fruits, and as a bio-fertilizer to improve fruit characteristics and yield.