Pseudomonas jiyuanensis JY2025 and application thereof

Abstract

The present application belongs to the technical field of microorganisms, and relates to a Pseudomonas jessenii JY2025 and application thereof. Pseudomonas piscicola The biological preservation number of the Pseudomonas jessenii (P. jessenii) JY2025 is CGMCC No. 37283. The strain provided by the present application has broad-spectrum antifungal activity, can significantly inhibit the growth of various plant pathogenic fungi, and has the abilities of salt and alkali tolerance, inorganic phosphorus degradation, protease secretion, siderophore secretion and indole acetic acid production, which are helpful to promote crop growth and improve soil fertility.

Description

Technical Field

[0001] This invention belongs to the field of microbial technology and relates to a strain of Pseudomonas quassioides JY2025 and its applications. Background Technology

[0002] The information disclosed in this background section is intended only to enhance understanding of the overall background of the invention and is not necessarily to be construed as an admission or in any way implying that such information constitutes prior art known to those skilled in the art.

[0003] Saline-alkali land is one of the important obstacle soil types in my country, severely restricting crop growth and yield. Traditional chemical improvement methods are costly and prone to environmental pollution. Therefore, the development of salt-tolerant microbial agents with growth-promoting and biocontrol functions has become a current research hotspot.

[0004] Microorganisms secrete proteases to solve the problem of obtaining nitrogen and carbon sources. Proteins in the environment are large and complex molecules that cannot directly cross cell membranes. By secreting proteases, microorganisms act like "molecular scissors," cutting proteins into absorbable amino acids and small peptides. This process not only provides essential nutrients for their own growth but is also crucial for many pathogenic microorganisms to attack their hosts. The secretion of siderophores, on the other hand, addresses another essential but extremely difficult-to-obtain resource—iron. In oxygen-rich environments, iron exists primarily in the insoluble ferric (Fe3+) form, which is almost unusable by organisms. Microbial siderophores act as "molecular traps," possessing a high affinity for ferric iron, capable of "stealing" it from environmental or host molecules to form a complex. Subsequently, the microbial cell recognizes and absorbs this complex through specific receptors, reducing the iron to usable ferrous (Fe2+) within the cell.

[0005] Currently, although many salt-tolerant or growth-promoting strains have been reported, a multifunctional strain that combines salt tolerance with multiple growth-promoting characteristics such as inorganic phosphorus degradation, protease secretion, siderophoresis, and the plant hormone indoleacetic acid, while also exhibiting significant biocontrol functions, has not yet been systematically reported. Summary of the Invention

[0006] To address the aforementioned problems, this invention provides a strain of *Pseudomonas quassioides* JY2025 and its applications. This strain exhibits significant growth-promoting, biocontrol, and salt-alkali tolerance capabilities, and can be used for crop growth and disease control in saline-alkali land.

[0007] To achieve the above objectives, the technical solution provided by this invention is as follows: In a first aspect, the present invention provides a strain of *Pseudomonas quassioides* (… Pseudomonas piscicolaJY2025 was deposited on January 5, 2026, at the China General Microbiological Culture Collection Center (CGMCC); Address: No. 3, Courtyard 1, Beichen West Road, Chaoyang District, Beijing, Institute of Microbiology, Chinese Academy of Sciences; Accession number: CGMCC No. 37283.

[0008] The *Pseudomonas urticaria* provided by this invention ( Pseudomonas piscicola JY2025 is a multifunctional pseudomonad strain with broad-spectrum antifungal activity. It can significantly inhibit the growth of various plant pathogenic fungi, and also has salt and alkali tolerance, as well as the ability to produce the plant hormone indoleacetic acid (IAA), degrade inorganic phosphorus, secrete siderophores, and secrete proteases. It is suitable for the biological control of plant diseases and the promotion of crop growth.

[0009] Secondly, the present invention provides the *Pseudomonas urticaria* described in the first aspect (…). Pseudomonas fish Application of JY2025 in inhibiting plant pathogens.

[0010] Thirdly, the present invention provides the *Pseudomonas urticaria* described in the first aspect (… Pseudomonas fish The use of JY2025 in the preparation of compositions that inhibit plant pathogens, said compositions comprising *Pseudomonas aeruginosa* as described in the first aspect (…). Pseudomonas piscicola JY2025 or its derivatives.

[0011] Furthermore, the derivative is selected from the *Pseudomonas urticaria* (…). Pseudomonas piscicola At least one of the following: culture, extract, lysate, metabolite or inactivation product of JY2025.

[0012] Furthermore, the culture refers to the product obtained by culturing a strain in a culture medium, selected from fermentation cultures, fermentation culture supernatants, volatile substances, or combinations thereof, and the product may include the strain itself.

[0013] The extract refers to the product obtained by solvent extraction or other treatments of the bacterial strain.

[0014] The lysate refers to the product obtained by treating the strain with enzymes, ultrasound, homogenization, etc.

[0015] The metabolites refer to substances produced by the strain through metabolism.

[0016] The inactivated product refers to the product obtained by treating the strain with heat, pressure, or drugs.

[0017] Furthermore, the plant pathogen is a fungus.

[0018] Furthermore, the fungi include *Fungiformis cibarius* (…). Bjerkandera scordata), powdery mildew ( Erysipelas chicory Fusarium solani () Fusarium solani Fusarium oxysporum ( Fusarium oxysporum Alternaria ( Alstroemeria Alternaria One or more of the following.

[0019] Fourthly, the present invention provides the *Pseudomonas urticae* strain described in the first aspect (…). Pseudomonas fish Application of JY2025 in crop growth promotion.

[0020] Fifthly, the present invention provides the *Pseudomonas urticae* strain described in the first aspect (…). Pseudomonas fish Application of JY2025 in soil improvement.

[0021] The *Pseudomonas urticaria* provided by this invention ( Pseudomonas piscicola JY2025, due to its stable survival in high saline-alkali environments, can be widely used for basic improvement of the physical and chemical properties of saline-alkali soils. It reduces soil salinity and alkalinity through mechanisms such as secreting organic acids. As a phosphorus-solubilizing strain, it can convert insoluble phosphorus in the soil that is difficult for crops to absorb into available phosphorus, thereby improving soil fertility and alleviating the nutrient deficiency problem that is common in saline-alkali lands. As a biocontrol strain, it can inhibit plant pathogens by producing antibacterial substances and competing for ecological niches, thereby reducing the disease pressure on crops under saline-alkali stress.

[0022] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. This invention isolates a salt-tolerant strain JY2025 from saline-alkali soil. It has strong salt tolerance and can withstand high salt stress. It also has significant abilities to degrade inorganic phosphorus, secrete proteases, secrete siderophores, and produce the plant hormone indoleacetic acid.

[0023] 2. In addition, this strain also has good biocontrol effects. Strain JY2025 showed certain inhibitory effects on a variety of plant pathogenic fungi through different treatment methods (bacterial suspension, supernatant, volatile substances). Attached Figure Description

[0024] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0025] Figure 1 This is a colony morphology diagram of strain JY2025 of the present invention; Figure 2 The phylogenetic tree of strain JY2025 of this invention is constructed based on the 16S rRNA sequence; Figure 3 The figures shown are experimental results of the growth-promoting characteristics of strain JY2025 of this invention; where A is the result of protease detection plate, B is the result of inorganic phosphorus degradation plate, and C is the result of CAS detection plate. Figure 4 This is a diagram showing the experimental results of the effects of strain JY2025 of this invention on some fungi; where A represents *Bacillus cibarius* (…). Bjerkandera scordata The control group diagram shows that B represents *Bacillus fumigatus* (a type of bacteria). Bjerkandera scordata ) Experimental group diagram, C is Alternaria ( Alstroemeria Alternaria The control group diagram shows that D represents Alternaria alternata (Alternaria). Alstroemeria Alternaria ) Experimental group diagram, E is Dinucleotidylcholine bacterium ( Ceratobasidium sp. The control group diagram shows that F represents Dinucleotidylcholine (BN) Ceratobasidium sp. ) Experimental group diagram, G is Fusarium equisetifolium ( Fusarium horsetail The control group diagram shows that H represents Fusarium equisetifolium (H). Fusarium horsetail Experimental group diagrams; Figure 5 The image shows the treatment results of a suspension of strain JY2025 of this invention on some fungi; where A represents Fusarium oxysporum (…). Fusarium oxysporum The control group diagram shows that B represents Fusarium oxysporum ( ). Fusarium oxysporum ) Experimental group diagram, C represents powdery mildew fungus ( Erysiphe cichoracea The control group diagram shows that D represents powdery mildew (…). Erysiphe cichoracea ) Experimental group diagram, E is Dinucleotidylcholine bacterium ( Ceratobasidium sp. The control group diagram shows that F represents Dinucleotidylcholine (BN) Ceratobasidium sp. Experimental group diagram, G is Trichoderma ( Trichoderma sp. The control group diagram shows that H represents Trichoderma (…). Trichoderma sp. ) Experimental group diagram, I is Fusarium solani ( Fusarium solani The control group diagram shows that J represents Fusarium solani (a type of fungus). Fusarium solani Experimental group diagram, K is Fusarium equisetifolium ( Fusarium horsetail The control group diagram shows that L represents Fusarium equisetifolium (…). Fusarium horsetail ) Experimental group diagram, M is *Bacillus cibarius* ( Bjerkandera scordata The control group diagram shows that N represents *Bacillus fumigatus* (a type of bacteria). Bjerkandera scorched Experimental group diagrams. Detailed Implementation

[0026] To enable those skilled in the art to better understand the technical solution of the present invention, the technical solution of the present invention will be described in detail below with reference to specific embodiments.

[0027] Indoleacetic acid (IAA) can regulate the growth, elongation, division, and differentiation of plant cells. In addition, studies have shown that the presence of IAA is beneficial to the growth of photosynthetic bacteria, which also reveals that the IAA secreted by the strains has a direct impact on the growth and development of plants.

[0028] Soil often contains a large amount of organic phosphorus, but it is fixed in organic matter or minerals and cannot be directly absorbed and utilized by plants. If ineffective organic phosphorus can be converted into available inorganic phosphorus, the soil's phosphorus supply capacity will be greatly improved. On the one hand, it can reduce the amount of chemical phosphate fertilizer used, thereby avoiding the environmental problems of heavy metal accumulation and eutrophication caused by excessive phosphate fertilizer. On the other hand, when plants obtain sufficient phosphorus, their root systems can develop more and their above-ground parts can be stronger, thus promoting plant growth.

[0029] Plants cannot directly absorb large protein molecules (organic nitrogen), but they can efficiently absorb amino acids and short peptides. If the abundant organic nitrogen in the soil can be converted into a readily available nitrogen source that plants can directly utilize, it will help reduce the use of nitrogen fertilizers.

[0030] In practical applications, protease-producing strains are often used in combination with phosphate-solubilizing strains and strains that secrete indoleacetic acid, and the three work synergistically to increase crop yield.

[0031] Iron is an essential micronutrient for plants to synthesize chlorophyll, perform photosynthesis, and respiration. However, in highly saline-alkali soils, iron is mainly present as insoluble ferric iron (Fe3+). 3+ Iron deficiency chlorosis occurs when iron exists in the form of hydroxides, which plants cannot absorb, leading to yellowing of new leaves (iron deficiency chlorosis), and in severe cases, reduced yield or even death. Siderophores can strongly chelate ferric iron in the soil, forming soluble iron-siderophore complexes. Plant roots can directly absorb these complexes through specific transport proteins (such as YSL family proteins), or first reduce ferric iron to ferrous iron before absorption, thus efficiently acquiring iron.

[0032] This invention isolated a newly discovered strain of *Pseudomonas urticaria* (…). Pseudomonas piscicola JY2025. This strain was confirmed as a new microbial resource through phylogenetic analysis, exhibiting good salt and alkali tolerance, phosphorus solubility, indoleacetic acid production, and biocontrol activity. In particular, under salt and alkali stress, its indoleacetic acid production significantly increased, converting organic phosphorus into inorganic phosphate ions that can be directly absorbed by plants, providing a new microbial strain resource and application approach for saline-alkali soil improvement and crop growth promotion.

[0033] In embodiments of the present invention, *Pseudomonas urticaria* (…) is provided. Pseudomonas piscicola JY2025, collection information is as follows: Preservation institution: China General Microbiological Culture Collection Center, China Committee on the Preservation and Management of Microbial Culture Collections; Address: No. 3, Courtyard 1, Beichen West Road, Chaoyang District, Beijing, Institute of Microbiology, Chinese Academy of Sciences; Deposit date: January 5, 2026; Accession number: CGMCC No. 37283; Classification: Pseudomonas urticae ( Pseudomonas piscicola ).

[0034] In embodiments of the present invention, *Pseudomonas urticaria* (also provided) is also provided. Pseudomonas piscicola The derivative of JY2025 refers to a product derived from the strain, which may be *Pseudomonas urticaria* provided in this embodiment. Pseudomonas piscicola At least one of the following: culture, extract, lysate, metabolite or inactivation product of JY2025.

[0035] Among them, culture refers to the product obtained by culturing the strain in a culture medium, selected from fermentation culture, fermentation culture supernatant, volatile substances or combinations thereof, and the culture may include the strain itself; extract refers to the product obtained by the strain through solvent extraction or other treatments; lysate refers to the product obtained by the strain through enzyme, ultrasound, homogenization or other treatments; metabolite refers to the substance generated by the strain through metabolism; inactivation product refers to the product obtained by the strain through heating, pressurization or drug treatments.

[0036] In embodiments of the present invention, *Pseudomonas urticaria* ( Pseudomonas piscicola JY2025 and its derivatives can be used to prepare compositions. In some embodiments, the compositions further include excipients. The excipients include amino acids, proteins, glucose, sodium chloride, etc.

[0037] In embodiments of the present invention, *Pseudomonas urticaria* (…) is also provided. Pseudomonas piscicola Application of JY2025 in inhibiting plant pathogens.

[0038] In embodiments of the present invention, *Pseudomonas urticaria* (…) is also provided. Pseudomonas piscicola The application of JY2025 in the preparation of compositions that inhibit plant pathogens, said compositions comprising *Pseudomonas quassioides* (… Pseudomonas fish JY2025 or its derivatives.

[0039] The plant pathogen is a fungus, including *Bacillus citrinum* (…). Bjerkandera scordata ), powdery mildew ( Erysiphe cichoracea Fusarium solani (Fusarium solani Fusarium oxysporum ( Fusarium oxysporum Alternaria ( Alstroemeria Alternaria One or more of the following.

[0040] In embodiments of the present invention, *Pseudomonas urticaria* (…) is also provided. Pseudomonas piscicola Application of JY2025 in crop growth promotion.

[0041] In embodiments of the present invention, *Pseudomonas urticaria* (…) is also provided. Pseudomonas piscicola Application of JY2025 in soil improvement.

[0042] The above-mentioned applications include seed dressing, soil irrigation, foliar spraying, or soil basal application of microbial agents.

[0043] Example 1 1. Materials Experimental sample: Coastal saline-alkali land in Weifang City, Shandong Province.

[0044] Required reagents: LB medium, PDA medium, CAS detection medium, skim milk powder, agar, tryptophan, Salkowski colorimetric solution.

[0045] 2. Method 2.1 Isolation and culture of strains The resuspended soil sample solution was serially diluted in physiological saline and spread onto LB agar. It was incubated at 28°C for 48–72 h. The number of colonies on each medium was recorded. Based on growth characteristics such as colony color, size, elevation, transparency, firmness, and edge regularity, single colonies were picked and streaked three times on the corresponding medium. The cultured strain was purified three times to obtain a pure cultured strain, designated JY2025.

[0046] 2.2 Identification of strains Genomic DNA was extracted from strain JY2025, and a 16S rRNA fragment was amplified by PCR. The obtained fragment was then sequenced and aligned. Phylogenetic analysis (using MEGA software) and polymorphic taxonomic analysis revealed that strain JY2025 showed the highest similarity to the type strain *Pseudomonas yucca*, and it was named... Pseudomonas piscicola JY2025.

[0047] 2.3 Preservation of microbial strains Streak the purified strain JY2025, then add 50% sterile glycerol preservation solution to the culture preservation tube, mark it, and finally store the strain mixture in an ultra-low temperature freezer at -80℃ (at least 3 backups).

[0048] 2.4 Determination of bacterial salt and alkali tolerance A single colony was picked up with an inoculation loop and placed into LB liquid medium. The culture was incubated at 28°C and 170 rpm for 48 h to prepare a stock solution. This stock solution was then inoculated at 1% into yeast extract tryptone liquid medium at pH 7 with mixed saline-alkali concentrations (NaCl:Na₂SO₄:NaHCO₃:Na₂CO₃ = 1:9:9:1) of 0 mmol / L, 20 mmol / L, 40 mmol / L, 60 mmol / L, 80 mmol / L, and 100 mmol / L, respectively. An uninoculated control was used. The medium was incubated at 28°C and 170 rpm for 48 h on a shaker, and the OD was measured. 600nm This reflects the strain's tolerance to salt and alkali.

[0049] 2.5 Determination of the ability of bacteria to secrete the plant hormone indole-3-acetic acid (IAA) Add 1 mg / mL L-tryptophan to liquid LB medium, repeat in triplicate, inoculate 5% of the test strain, incubate at 28℃ for 48 h at 170 rpm, centrifuge at 4000 rpm for 10 min, aspirate 0.5 mL of the supernatant, add an equal volume of Salkowski colorimetric solution, incubate in the dark for 30 min, and observe the color change. The color change is the basis for qualitative judgment; a pink color, and the redder the color, the higher the IAA content. (OD...) 530nm The absorbance was measured using a UV spectrophotometer, and the obtained bacterial absorbance was substituted into the IAA standard curve to obtain the bacterial IAA yield.

[0050] 2.6 Other growth-promoting performance experiments Methods for detecting protease and siderophore production capacity: The bacterial suspension of strain JY2025 was spot-inoculated onto protease detection medium and CAS detection medium, respectively. Three spots were inoculated at equal intervals on each plate, with an inoculation volume of 1.5 μL at each spot. After inoculation, the plates were incubated upside down in a constant temperature incubator at 28℃ for 3 days and 5 days, respectively. The diameter of the ring (D) and the diameter of the culturable bacterial colony (d) were measured using the cross-cross method, and the D / d ratio was calculated to quantitatively evaluate the protease and CAS production capacity of the strain.

[0051] Method for detecting the ability to dissolve inorganic phosphorus: The bacterial suspension of strain JY2025 was inoculated into LB liquid medium and cultured at 28℃ and 170 r / min for 48 h. 10 μL of seed liquid was then inoculated onto solid inorganic phosphorus screening medium plates using the spot inoculation method and incubated statically in an incubator at 28℃ for 5 days.

[0052] 2.7 Biocontrol Activity Assay 2.7.1 Flat Standoff Method The inhibitory effect of strain JY2025 on different pathogenic fungi was determined using the plate confrontation method. A fungal disc was placed in the center of a PDA medium, and a suspension of strain JY2025 was inoculated 2.5 cm away from the disc. The medium was incubated at 28°C for 5–7 days. The diameter of the inhibition zone was measured, and the inhibition rate was calculated using the following formula: Inhibition rate (%) = [(control colony diameter - treated colony diameter) / control colony diameter] × 100%.

[0053] 2.7.2 Method of incorporating supernatant into culture medium The antibacterial activity of strain JY2025 was determined using the supernatant incorporation method. Strain JY2025 was first inoculated into LB liquid medium and cultured at 28°C with shaking for 48 h. The supernatant was then obtained by centrifugation and filtration through a membrane filter. The supernatant was mixed with PDA medium cooled to approximately 50°C at a 10% (v / v) ratio, poured into plates, and allowed to solidify. A fungal mycelium was inoculated in the center of the medium, and the plates were incubated at 28°C for 5–7 days. Using PDA medium without supernatant as a control, colony diameters were measured, and the inhibition rate was calculated.

[0054] 2.7.3 Volatile substance antibacterial method The antibacterial activity of volatile substances from strain JY2025 was determined using a double-layer plate method. The lower layer was LB medium, inoculated with a suspension of strain JY2025 and spread evenly, and pre-cultured at 28°C for 24 h. The upper layer was PDA medium without the strain; after solidification, a fungal disc was inoculated in the center. The upper and lower plates were aligned and sealed, and incubated at 28°C for 5–7 days. Using a double-layer plate without strain JY2025 as a control, colony diameter was measured, and the inhibition rate was calculated.

[0055] 3. Experimental Results The obtained strain was named *Pseudomonas urticaria* ( Pseudomonas piscicola Strain JY2025, referred to as strain JY2025 in this article, was deposited on January 5, 2026 at the China General Microbiological Culture Collection Center (CGMCC), located at No. 3, Courtyard 1, Beichen West Road, Chaoyang District, Beijing, Institute of Microbiology, Chinese Academy of Sciences, with the accession number CGMCC No. 37283.

[0056] 3.1 Morphological identification of strains After incubation at 28°C for 24 h on LB medium, single colonies of strain JY2025 were pale yellow, rough-surfaced, opaque, and small in diameter. Figure 1 As shown.

[0057] 3.2 Species identification of strain JY2025 16S rRNA sequencing yielded a 1438 bp gene sequence fragment. Sequence alignment showed that strain JY2025 had the highest similarity to the type strain *Pseudomonas yucca*. In the phylogenetic tree constructed based on the 16S rRNA sequence, as shown... Figure 2 As shown, this strain is related to the type strain *Pseudomonas quassinus* cluster, indicating that this strain belongs to *Pseudomonas quassinus*.

[0058] The 16S rRNA sequence of strain JY2025 (SEQ ID NO: 1):

[0059] 3.3 Determination of bacterial salt and alkali tolerance As shown in Table 1, strain JY2025 exhibited a wide range of salt and alkali tolerance in the mixed salt and alkali culture medium, tolerating a maximum salt concentration of 100 mmol / L. Strain JY2025 maintained relatively stable activity at salt and alkali concentrations below 60 mmol / L, indicating that it could grow and function normally under these conditions. When the mixed salt and alkali concentration increased to above 60 mmol / L, bacterial activity decreased significantly, indicating that its growth and metabolic functions began to be significantly inhibited. In summary, this demonstrates that the strain possesses a highly efficient and stable salt and alkali tolerance physiological mechanism.

[0060] Table 1. OD of strains in mixed saline-alkali media of different concentrations 600 value

[0061] 3.4 Characterization of bacterial growth-promoting function The rhizosphere growth-promoting traits of strain JY2025 in various common plants were measured, and the results are shown in Table 2: Table 2. Growth-promoting results of the strains

[0062] The growth-promoting results of the strain are analyzed as follows: Inorganic phosphorus degradation ability: Phosphorus solubilization ability test showed that strain JY2025 produced obvious phosphorus-solubilizing transparent zones on the culture medium, with a diameter / colony diameter ratio of 1.39±0.12, confirming that it has the ability to promote the conversion of insoluble phosphate into available phosphorus, and is a highly efficient inorganic phosphorus-solubilizing bacterium.

[0063] Indole-3-Acetic Acid (IAA) production capacity: After cultivation in LB medium containing tryptophan, the IAA production was determined by the Salkowski colorimetric method to be 1.123±0.15 mg / L, indicating that it has the ability to synthesize plant growth hormones efficiently and stably.

[0064] Siderophore secretion capacity: When cultured on CAS test plates, the colonies formed a distinct orange halo, and the D / d ratio reached 1.99±0.17, confirming that it has siderophore secretion activity, which helps to improve iron nutrition in low iron environments.

[0065] Protease secretion capacity: After culturing in protease detection medium for 3 days, a clear and transparent hydrolysis zone appeared around the colony, with a D / d ratio of 1.3±0.16. This is because the extracellular protease secreted by the strain degraded the casein in the medium, proving that the strain has the growth-promoting characteristic of secreting extracellular protease. This strong hydrolysis capacity indicates that it has greater application potential in decomposing organic matter.

[0066] The growth-promoting functional spectrum of the strain shows that strain JY2025 mainly promotes plant growth by efficiently synthesizing auxin IAA, degrading inorganic phosphorus, and secreting siderophores and proteases, with clear and efficient functions.

[0067] 3.5 Biological defense capability like Figure 4 and Figure 5 As shown in the plate confrontation experiment, strain JY2025 exhibited differentiated inhibitory effects against various plant pathogenic fungi through different treatments (volatile substances, supernatant, and bacterial suspension), as detailed below: Volatile substance treatment: Its inhibitory effect showed significant fungal species specificity. For *Fungiformis* (… Bjerkandera scordata The inhibitory effect on Alternaria ( ) was most prominent, with an inhibition rate of 53.82%; against Alternaria ( ) Alternaria alstroemeria The inhibition rate of ) was as high as 74.35%; however, the inhibitory effect on some other pathogenic fungi was weak, or even no obvious inhibition was observed.

[0068] Fermentation supernatant treatment: It exhibits broad and stable inhibitory effects against various pathogenic fungi, especially *Rhizoctonia solani* (…). Ceratobasidium sp. The inhibition rate reached 8.54%, and it was effective against Fusarium equisetifolium (…). Fusarium horsetail The inhibition rate was 6.88%.

[0069] Bacterial suspension treatment: The most effective inhibitory agent is the powdery mildew fungus ( Erysiphe cichoracea The inhibition rate was as high as 53.24%, demonstrating very significant biocontrol potential. It also showed strong inhibition against *Fungiformis* (…). Bjerkandera scordata The inhibitory effect on *Rhizoctonia solani* was also remarkable, with an inhibition rate of 29.39%. It also showed significant inhibitory effects against *Rhizoctonia solani* (…). Ceratobasidium sp. ) and Fusarium equisetifolium ( Fusarium horsetail The inhibitory effects on *Fusarium oxysporum* were quite significant, with inhibition rates of 26.24% and 25.85%, respectively. Fusarium oxysporum Fusarium solani () Fusarium solani ) and Trichoderma ( Trichoderma sp. The inhibition rate was between 22% and 25%, which is considered a moderate level of inhibition. The weakest inhibitory effect was against another Fusarium oxysporum, with an inhibition rate of 10.23%. Additionally, it showed relatively weak inhibition against Alternaria alternata (…). Alstroemeria AlternariaThe inhibition rate was 36.67%, indicating a strong effect. In summary, strain JY2025 exhibits broad-spectrum antibacterial activity, showing varying degrees of inhibition against common plant pathogenic fungi, including various Fusarium species, powdery mildew fungi, Rhizoctonia solani, and Alternaria alternata, with particularly outstanding inhibition against powdery mildew fungi. It also has some inhibitory effect on beneficial Trichoderma fungi; this should be noted in practical applications.

[0070] These biocontrol results provide experimental evidence for the subsequent development of biocontrol agents based on the fermentation broth or extracts of strain JY2025.

[0071] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A strain of *Pseudomonas urticae* ( Pseudomonas piscicola JY2025, characterized in that, It was deposited on January 5, 2026 at the China General Microbiological Culture Collection Center; accession number: CGMCC No. 37283.

2. Pseudomonas plecoglossicida according to claim 1, Pseudomonas piscicola ) JY2025, characterized in that, The Pseudomonas sp. Pseudomonas piscicola ) JY2025 has the abilities of indole-3-acetic acid production, inorganic phosphorus degradation, siderophore secretion and protease secretion.

3. The Pseudomonas plecoglossicida of claim 1, Pseudomonas piscicola ) JY2025 in inhibiting plant pathogenic bacteria, characterized in that, The plant pathogen is a fungus; the fungus is selected from *Cymbidium*. Bjerkandera adusta Powdery mildew Erysiphe cichoracearu Fusarium solani ( Fusarium solani ), Dinucleotidylcholine ( Ceratobasidium sp. Fusarium equisetifolium ( Fusarium equiseti Fusarium oxysporum ( Fusarium oxysporum ) and Alternaria Alternaria alstroemeriae One or more of them.

4. The Pseudomonas plecoglossicida of claim 1, Pseudomonas piscicola ) The use of JY2025 in the preparation of a composition for inhibiting plant pathogenic fungi, characterized in that, The composition comprises the Pseudomonas sp. ( Pseudomonas piscicola ) JY2025 or a derivative thereof, which is a lysate of the Pseudomonas sp. ( Pseudomonas piscicola ) JY2025. The plant pathogen is a fungus; the fungus is selected from *Cymbidium*. Bjerkandera adusta Powdery mildew Erysiphe cichoracearu Fusarium solani ( Fusarium solani ), Dinucleotidylcholine ( Ceratobasidium sp. Fusarium equisetifolium ( Fusarium equiseti Fusarium oxysporum ( Fusarium oxysporum ) and Alternaria Alternaria alstroemeriae One or more of them.

5. The Pseudomonas plecoglossicida of claim 1, Pseudomonas piscicola ) Application of JY2025 in crop growth promotion.

6. Pseudomonas plecoglossicida according to claim 1 for use in soil amelioration. Pseudomonas piscicola ) Use of JY2025 for soil amelioration.

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