Biological Control Of Diseases Research Articles

Compatibility of Trichoderma harzianum with commercial herbicides

Biological disease control has become popular in recent years and has established itself as a viable alternative to chemical control. However, the efficiency of biological control can be limited by the application technology. Thus, the objective of this work was to evaluate the compatibility of Trichoderma harzianum with three commercial herbicides. The fungus was incubated in culture medium supplemented with doses of three commercial herbicides and incubated for 4 days. The CI50 (concentration capable of inhibiting 50% of the mycelial growth of the fungus) was determined for each herbicide and compared with the recommended doses for field application. All herbicides tested reduced mycelial growth, with CI50 lower than the recommended doses. The data suggest low compatibility between T. harzianum and the tested herbicides.

Screening and Identification of Streptomyces lavendulae against Walnut Rot Disease Cytospora chrysosperma

Streptomyces is a biocontrol agent capable of protecting walnut from stem rot disease caused by the fungal pathogen Cytospora chrysosperma. Antagonistic strains were selected from walnut rhizosphere soil for biocontrol of the disease. The strains were screened using C. chrysosperma as the target pathogen. Using dilution coating plate separation method, plate confrontation method, growth rate method and in vitro branch protection experiment, screening the antagonistic actinobacteria with inhibitory effect and control effect on walnut tree rot disease. Strains were identified based on their morphological, physiological, and biochemical characteristics, 16S rDNA sequencing, and phylogenetic analysis. The strain F-02 was identified as Streptomyces Lavendulae. Plate confrontation method tests showed that the inhibition rates of the Streptomyces strain F-02 on the pathogens were approximately 80.30%. Further study showed that the filtrate of strain F-02 couldinhibit the C.chrysosperma, and the widths of their inhibition zone reached 1.24±0.15 mm, the prevention effect of 71.03%. For the first time, S.lavendulae was used for the biological control of walnut tree rot. It provides strain resources for the development of walnut rot agents. It has potential applications for biological control of walnut tree rot disease.

Characterization of Two Novel Single-Stranded RNA Viruses from Agroathelia rolfsii, the Causal Agent of Peanut Stem Rot.

Peanut stem rot is a soil-borne disease caused by Agroathelia rolfsii. It occurs widely and seriously affects the peanut yield in most peanut-producing areas. The mycoviruses that induce the hypovirulence of some plant pathogenic fungi are potential resources for the biological control of fungal diseases in plants. Thus far, few mycoviruses have been found in A. rolfsii. In this study, two mitoviruses, namely, Agroathelia rolfsii mitovirus 1 (ArMV1) and Agroathelia rolfsii mitovirus 2 (ArMV2), were identified from the weakly virulent A. rolfsii strain GP3-1, and they were also found in other A. rolfsii isolates. High amounts of ArMV1 and ArMV2in the mycelium could reduce the virulence of A. rolfsii strains. This is the first report on the existence of mitoviruses in A. rolfsii. The results of this study may provide insights into the classification and evolution of mitoviruses in A. rolfsii and enable the exploration of the use of mycoviruses as biocontrol agents for the control of peanut stem rot.

The Growth-Promoting and Colonization of the Pine Endophytic Pseudomonas abietaniphila for Pine Wilt Disease Control.

In this study, we focused on evaluating the impact of Pseudomonas abietaniphila BHJ04 on the growth of Pinus massoniana seedlings and its biocontrol efficacy against pine wilt disease (PWD). Additionally, the colonization dynamics of P. abietaniphila BHJ04 on P. massoniana were examined. The growth promotion experiment showed that P. abietaniphila BHJ04 significantly promoted the growth of the branches and roots of P. massoniana. Pot control experiments indicated that strain BHJ04 significantly inhibited the spread of PWD. There were significant changes in the expression of several genes related to pine wood nematode defense in P. massoniana, including chitinase, nicotinamide synthetase, and triangular tetrapeptide-like superfamily protein isoform 9. Furthermore, our results revealed significant upregulation of genes associated with the water stress response (dehydration-responsive proteins), genetic material replication (DNA/RNA polymerase superfamily proteins), cell wall hydrolase, and detoxification (cytochrome P450 and cytochrome P450 monooxygenase superfamily genes) in the self-regulation of P. massoniana. Colonization experiments demonstrated that strain BHJ04 can colonize the roots, shoots, and leaves of P. massoniana, and the colonization amount on the leaves was the greatest, reaching 160,000 on the 15th day. However, colonization of the stems lasted longer, with the highest level of colonization observed after 45 d. This study provides a preliminary exploration of the growth-promoting and disease-preventing mechanisms of P. abietaniphila BHJ04 and its ability to colonize pines, thus providing a new biocontrol microbial resource for the biological control of plant diseases.

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 60 min, 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 307,402 bp 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 14 days 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

Brazil's economic growth and development have a strong relationship with agribusiness. Agribusiness is made up of a production chain. This chain can be influenced by several problems, which can compromise the entire production cycle, such as various diseases and pests that can affect crops and reduce productivity, generating economic losses for producers. The objective of this literature review, of an exploratory-descriptive nature, is to present an overview of the economic, social, and environmental importance of Brazilian agribusiness, focusing on the western region of Bahia, pointing out its main challenges, as well as discussing the use of biotechnological tools for controlling plant diseases.

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.

Rhizomicrobiomics

Abstract Rhizomicrobiomics is the study of plant-associated microbes as a strategy for achieving sustainable development goals. With the development of the concept of microbiomes of soil/plant systems, the history leading to this concept over more than a century is reviewed. Microbial growth and community dynamics are discussed from both laboratory and field perspectives. The first use of the term microbiome applied to biological control of plant diseases, but it now seems appropriate to use the specific term rhizomicrobiome to describe the myriads of microbial functions that influence soil health, food production, bioremediation, and climate change. The advance and implications of molecular biology and modern imaging, along with functional analysis of ecosystems from space, coupled with artificial intelligence and machine learning, are indicated as ways to investigate the application of rhizomicrobiomics in achieving the UN Sustainable Development Goals to generate a cleaner planet and secure the future supply of food.

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.

Integration of soil microbiology and metabolomics to elucidate the mechanism of the accelerated infestation of tobacco by the root-knot nematode.

Tobacco root-knot nematode (TRKN) disease is a soil-borne disease that presents a major hazard to the cultivation of tobacco, causing significant reduction in crop quality and yield, and affecting soil microbial diversity and metabolites. However, differences in rhizosphere soil microbial communities and metabolites between healthy tobacco soils and tobacco soils with varying degrees of TRKN infection remain unclear. In this study, diseased rhizosphere soils of tobacco infected with different degrees of TRKN [severally diseased (DH) soils, moderately diseased (DM) soils, and mildly diseased (DL) soils] and healthy (H) rhizosphere soils were collected. Here, we combined microbiology with metabolomics to investigate changes in rhizosphere microbial communities and metabolism in healthy and TRKN-infected tobacco using high-throughput sequencing and LC-MS/MS platforms. The results showed that the Chao1 and Shannon indices of bacterial communities in moderately and mildly diseased soils were significantly higher than healthy soils. The Proteobacteria, Actinobacteria, Ascomycota, Burkholderia, Bradyrhizobium and Dyella were enriched in the rhizosphere soil of healthy tobacco. Basidiomycota, Agaricales, Pseudeurotiaceae and Ralstonia were enriched in severally diseased soils. Besides, healthy soils exhibited a relatively complex and interconnected network of bacterial molecular ecologies, while in severally and moderately diseased soils the fungal molecular networks are relatively complex. Redundancy analysis showed that total nitrogen, nitrate nitrogen, available phosphorus, significantly affected the changes in microbial communities. In addition, metabolomics results indicated that rhizosphere soil metabolites were significantly altered after tobacco plants were infected with TRKNs. The relative abundance of organic acids was higher in severally diseased soils. Spearman's analyses showed that oleic acid, C16 sphinganine, 16-hydroxyhexadecanoic acid, D-erythro-3-methylmalate were positively correlated with Basidiomycota, Agaricales, Ralstonia. In conclusion, this study revealed the relationship between different levels of TRKN invasion of tobacco root systems with bacteria, fungi, metabolites and soil environmental factors, and provides a theoretical basis for the biological control of TRKN disease.