Pseudomonas veronii w6-1 and application thereof

Abstract

The application discloses a veronii pseudomonas W6-1 and application thereof, and relates to the technical field of microorganisms. The strain has a preservation number of CGMCC No.39669, and has multiple growth-promoting functions such as nitrogen fixation, phosphorus solubilization, iron carrier production, indole acetic acid production and ACC deaminase activity. The strain can increase the chlorophyll content and soluble protein content in the leaves of liriodendron tulipifera seedling, and can increase the catalase and superoxide dismutase activities, and can reduce the proline and malondialdehyde contents, so as to relieve the osmotic stress and oxidative damage caused by saline-alkali stress, and effectively increase the plant height and whole-plant biomass of liriodendron tulipifera. Meanwhile, the veronii pseudomonas W6-1 can colonize in the interior of the roots of liriodendron tulipifera seedlings, and can promote the colonization of other microbial groups in the interior of the roots of liriodendron tulipifera seedlings, and thus can help the liriodendron tulipifera seedlings to effectively relieve the saline-alkali stress and promote the growth of the host plants.

Description

Technical Field

[0001] This invention relates to the field of microbial technology, and in particular to a *Pseudomonas veronii* W6-1 and its applications. Background Technology

[0002] As a preferred tree species for modern forestry ecological construction and landscape greening, the tulip tree (Liriodendron tulipifera) possesses excellent characteristics such as rapid growth, beautiful tree shape, and strong resistance to diseases and pests, and is widely used in landscaping, ecological restoration, shelterbelt construction, and the cultivation of valuable timber. However, this tree species has limited resilience and adaptability, and is quite sensitive to saline-alkali environments, which greatly limits its large-scale promotion and planting in coastal and inland saline-alkali degraded lands. Low to medium concentrations of saline-alkali stress can significantly inhibit the growth of tulip tree seedlings, while high salinity environments damage chloroplast structure and disrupt metabolic pathways, seriously affecting seedling establishment and subsequent growth. This is a key bottleneck resulting in low survival rates and stunted growth of tulip tree in artificial afforestation in saline-alkali areas.

[0003] Soil salinization is one of the core abiotic stress factors restricting forestry ecological restoration and vegetation reconstruction in my country. Currently, the main technical means to improve the salt and alkali tolerance of trees include soil improvement, water and fertilizer regulation, and stress-resistant breeding. Among these, soil physical and chemical improvement suffers from drawbacks such as high cost, susceptibility to secondary pollution, and short-term effectiveness; stress-resistant breeding is time-consuming and has low selection efficiency. Plant growth-promoting microbial agents, as a form of soil biological improvement, have become a research hotspot in recent years due to their advantages of being green, safe, low-cost, and highly adaptable. However, among existing publicly available technologies, there is limited research on microbial improvement for salt and alkali stress in *Liriodendron tulipifera*, and resources of dedicated stress-resistant and growth-promoting bacterial strains adapted to the physiological characteristics of *Liriodendron tulipifera* are extremely scarce. Summary of the Invention

[0004] To address the shortcomings of the existing technology, this invention provides *Pseudomonas veronii* W6-1 and its applications. The technical solution of this invention is as follows: In a first aspect, the present invention provides a *Pseudomonas veronii* W6-1, which is deposited at the China General Microbiological Culture Collection Center (CGMCC) in Beijing, China, on July 10, 2026, with accession number CGMCC No. 39669, and classified as *Pseudomonas veronii*.

[0005] On the other hand, the present invention provides the application of the aforementioned Pseudomonas veronii W6-1 in improving the salt and alkali tolerance of plants and promoting plant growth.

[0006] Preferably, the plant is tulip tree.

[0007] Preferably, the *Pseudomonas veronii* W6-1 has at least one of the following functions: nitrogen fixation, phosphorus solubilization, antibacterial activity, siderophoresis production, and indoleacetic acid production.

[0008] Preferably, the *Pseudomonas veronii* W6-1 has ACC deaminase activity, which is used to reduce the ethylene level of *Liriodendron tulipifera* seedlings to alleviate salt stress.

[0009] Preferably, the *Pseudomonas veronii* W6-1 increases the chlorophyll content and soluble protein content in the leaves of *Liriodendron tulipifera* seedlings, and reduces the content of proline and malondialdehyde, thereby alleviating osmotic stress and oxidative damage caused by salt and alkali stress.

[0010] Preferably, the *Pseudomonas veronii* W6-1 enhances the activity of catalase and superoxide dismutase in the leaves of *Liriodendron tulipifera* seedlings.

[0011] Preferably, the *Pseudomonas veronii* W6-1 can colonize the roots of *Liriodendron tulipifera* seedlings and promote the colonization of other microbial communities within the roots of *Liriodendron tulipifera* seedlings.

[0012] The beneficial effects of this invention are: 1. Enhanced Salt and Alkali Tolerance and Growth Promotion: *Pseudomonas veronii* W6-1 significantly enhances the salt and alkali tolerance of *Liriodendron tulipifera* seedlings, effectively reducing leaf cell membrane damage caused by salt and alkali stress, decreasing malondialdehyde and proline accumulation, and simultaneously increasing superoxide dismutase and catalase activity, alleviating oxidative stress damage caused by salt and alkali stress. Furthermore, this strain effectively improves root vigor in *Liriodendron tulipifera* seedlings, significantly increases plant height and overall biomass, enhances chlorophyll and soluble protein content, and strengthens photosynthetic efficiency, thereby comprehensively improving the adaptability of *Liriodendron tulipifera* seedlings to saline-alkali environments.

[0013] 2. Improved Soil Microecological Environment and Colonization Advantages. *Pseudomonas veronii* W6-1 can survive long-term in saline-alkali soils, improving the composition of rhizosphere bacterial communities and enhancing the supply of available nutrients to the soil. Simultaneously, it can achieve stable colonization in a high number of *Liriodendron tulipifera* seedlings and recruit other beneficial bacteria to colonize the roots, synergistically promoting the host plant's absorption of soil nutrients and further enhancing its salt tolerance. This invention is the first to demonstrate the mitigation and growth-promoting functions of this strain on *Liriodendron tulipifera* seedlings under salt stress, providing a novel microbial resource and technical system for crop cultivation in saline-alkali lands. Furthermore, this strain is green and pollution-free, easy to operate, and low in cost, making it suitable for large-scale planting of *Liriodendron tulipifera* seedlings in saline-alkali lands, nursery seedling cultivation, and ecological restoration projects. Attached Figure Description

[0014] Figure 1 The colony morphology of *Pseudomonas veronii* W6-1 on LB solid medium in this invention; Figure 2The microscopic morphology of *Pseudomonas veronii* W6-1 in this invention is shown under a scanning electron microscope. Figure 3 This invention demonstrates the salt and alkali tolerance of *Pseudomonas veronii* W6-1 (where the left figure shows tolerance under salinity conditions and the right figure shows tolerance under alkaline conditions). Figure 4 The invention demonstrates the pot-growing effect of *Pseudomonas veronii* W6-1 in alleviating salt-alkali stress in *Liriodendron tulipifera* seedlings (the left image is the blank control group, and the right image is the treatment group). Figure 5 The study showed that *Pseudomonas veronii* W6-1 significantly affected the microbial community structure in the roots of *Liriodendron chinense* seedlings (the left figure represents the phylum level analysis, the middle figure represents the genus level analysis, and the right figure represents the species level analysis). Detailed Implementation

[0015] To enable those skilled in the art to better understand the present invention, the present invention will be specifically described below through embodiments. It should be noted that the following embodiments are only used to further illustrate the present invention and are not limited to the preferred embodiments described. They do not constitute a limitation on the content and scope of protection of the present invention. Any product that is the same as or similar to the present invention, derived by anyone under the guidance of the present invention or by combining the features of the present invention with other prior art, falls within the scope of protection of the present invention.

[0016] Example 1: Isolation, purification and identification of Pseudomonas veronii W6-1 1. Isolation and purification of bacterial strains The tested plant material was callus tissue from *Liriodendron tulipifera*, sourced from the State-owned Yellow River Forest Farm in Jinan City, Shandong Province. After culturing the callus tissue, *Liriodendron tulipifera* tissue culture seedlings were obtained. These seedlings were removed using sterile forceps and placed in sterile petri dishes. They were thoroughly rinsed with sterile water, then rinsed with 75% ethanol for 30 seconds, followed by rinsing three times with sterile water. The surface-sterilized seedlings were then cut into small pieces with sterile scissors and transferred to Erlenmeyer flasks containing 100 mL of sterile water. The flasks were incubated at 28℃ and 180 r / min on a shaker for 1 hour, followed by serial dilutions. 0.1 mL of each dilution was spread onto LB agar plates and incubated upside down at 30℃ for 3 days.

[0017] Single colonies grown on the plate were picked and streaked onto LB agar plates for isolation. The purification process was repeated 2-3 times until a pure culture was obtained. The purified strain was then transferred to LB agar slants and stored at 4°C for later use. The strain was designated W6-1.

[0018] The LB solid medium consists of: 10 g / L peptone, 5 g / L yeast extract, 10 g / L NaCl, 18 g / L agar, and pH 6.8.

[0019] 2. Identification of strains 2.1 Morphological identification The purified strain W6-1 was streaked onto LB agar plates and incubated at 30°C for 24 h. Colony morphology was then observed. Figure 1 As shown, the colonies of strain W6-1 are round, milky white, opaque, with a smooth, moist, and raised surface. After Gram staining and observation under a light microscope, the bacteria appear red, indicating they are Gram-negative bacteria. The microscopic morphology of strain W6-1 under a scanning electron microscope is shown below. Figure 2 As shown, the bacterial cells are straight or curved rods and do not form spores.

[0020] 2.2 Molecular biological identification of 16S rDNA Genomic DNA was extracted from bacterial strain W6-1 using a bacterial genomic DNA extraction kit. Using this DNA as a template, PCR amplification was performed using universal primers 27F and 1492R for the bacterial 16S rRNA gene. The PCR reaction program was: 94℃ pre-denaturation for 4 min; 94℃ denaturation for 30 s, 55℃ annealing for 30 s, 72℃ extension for 2 min, 30 cycles; 72℃ extension for 10 min. The nucleotide sequence length of the PCR product was 1117 bp. Blast sequence alignment analysis showed that strain W6-1 had the highest 16S rRNA sequence similarity (99.72%) to *Pseudomonas veronii* LZH-G5 (OM850396.1).

[0021] Based on the combined results of colony morphology, microscopic morphology and 16S rDNA sequence analysis, strain W6-1 was identified as Pseudomonas veronii.

[0022] The 16S rRNA sequence of strain W6-1 was determined as follows:

[0023] Example 2: Salt and alkali tolerance and growth-promoting characteristics of Pseudomonas veronii W6-1 LB liquid medium was used as the basal medium, with sodium chloride added to achieve final salt concentrations of 1%, 2%, 3%, 4%, 5%, 6%, 7%, and 8% (m / v). The pH of the basal medium was adjusted to 7, 8, 9, and 10 using NaOH solution. Activated seed culture of *Pseudomonas veronica* W6-1 was inoculated sequentially at a 1% (v / v) inoculum and cultured in a rotary shaker at 180 r / min and 28℃ for 12 h. Cell concentration (OD600) was then measured to assess the salt and alkali tolerance of *Pseudomonas veronica* W6-1. Results are as follows: Figure 3 As shown, *Pseudomonas veronii* W6-1 can grow and reproduce well under saline-alkali conditions with salt concentrations of 1-8% (m / v) and pH values ​​of 7-9.

[0024] *Pseudomonas veronii* W6-1 was spot-inoculated onto Ashby nitrogen-free medium and then incubated in the dark at 28°C for 6 days. Its nitrogen-fixing potential was assessed based on colony growth. *Pseudomonas veronii* W6-1 was also inoculated onto phosphate-bound medium (NBRIP) and Alexandrov agar (AKP) solid media using a spot-inoculation method. After incubation at 28°C for 7 days, the ratio of hydrolysis zone to colony size reflected its phosphorus and potassium leaching capacity. To evaluate its inhibitory effect on plant pathogenic fungi, activated seed culture of *Pseudomonas veronii* W6-1 was evenly spread onto PDA solid media, and pathogenic fungal hyphae blocks with a diameter of 5 mm were placed on the surface of the medium. After 6 days of incubation, the inhibition rate was calculated based on the measured pathogenic fungal colony diameter. The indoleacetic acid content and ACC deaminase activity in the culture medium of *Pseudomonas veronii* W6-1 were quantitatively determined by the Salkowski colorimetric method and the DNPH colorimetric method, respectively; the soluble phosphorus content was determined by the molybdenum antimony colorimetric method; and the siderophore production was quantitatively detected by the CAS colorimetric method.

[0025] The results showed that *Pseudomonas veronii* W6-1 has certain abilities to fix nitrogen, solubilize phosphorus, and inhibit plant pathogenic fungi. Its phosphorus solubilization index (i.e., the ratio of the diameter of the halo to the diameter of the colony) was 4.33, and the colony diameter on nitrogen-free medium could reach 4.87 mm. The inhibition rate against *Alternaria alternata* was 51.35%, and the inhibition rate against *Russula simonii* was 27.43%.

[0026] The soluble phosphorus content of *Pseudomonas veronii* W6-1 culture medium in NBRIP medium was determined to be 228.17 μg / mL, demonstrating outstanding phosphorus solubility. Furthermore, *Pseudomonas veronii* W6-1 can produce a certain amount of a broad-spectrum auxin-like plant growth regulator, indoleacetic acid (1.90 mg / L), and possesses relatively high ACC deaminase activity (5.95 U / mg), which can reduce ethylene levels in plants and alleviate the inhibitory effects of abiotic stress on plant growth. *Pseudomonas veronii* W6-1 also produces a high yield of siderophores (0.89%), which helps to efficiently chelate ferric ions and promote iron absorption by crops.

[0027] Example 3: The effect of Pseudomonas veronii W6-1 on salt-alkali tolerance and growth promotion of Liriodendron tulipifera seedlings Uniformly grown Liriodendron tulipifera seedlings were selected and transplanted into potting soil (nutrient soil: native soil = 1:1), followed by a 10-day acclimatization period. Based on the volume of the potting soil, the soil pH was adjusted to 8.5 using NaHCO3 solution, and the final salt concentration of the potting soil was adjusted to 0.4% (m / v) using a salt stock solution (sodium chloride: sodium sulfate = 8:2). *Pseudomonas veronica* W6-1 was inoculated into 100 mL of LB liquid medium and cultured at 28℃ and 180 r / min for 24 hours. Then, it was centrifuged at 8000 rpm for 10 minutes at 4℃, and the supernatant was discarded. The precipitate was resuspended in sterile water and centrifuged again to remove residual culture medium, retaining the bacterial precipitate for later use. The bacterial precipitate was resuspended in sterile water and its concentration adjusted to OD0.05. 600 The value was 0.8, used for subsequent inoculation. A control group and a treatment group were set up, with three biological replicates in each group. Each seedling in the treatment group was irrigated with 10 mL of bacterial suspension, while the control group received an equal volume of sterile water. Inoculation was performed every 5 days, with the entire experimental period lasting 30 days; all seedlings were cultivated outdoors under natural light conditions.

[0028] Under saline-alkali stress, the control group of Liriodendron tulipifera seedlings that were not inoculated with Pseudomonas veronii W6-1 showed poor growth, exhibiting yellowing and wilting of leaves, even curling, loose root system, fewer fibrous roots, and even death of some seedlings. Figure 4 (Left image). In the treatment group inoculated with *Pseudomonas veronii* W6-1, the growth of *Liriodendron tulipifera* seedlings was significantly better than that of the uninoculated control group. The leaves were bright green, the root system had more branches and a denser structure, and the overall plant growth was good. Figure 4(See right figure). The results of the apparent index measurements are shown in Table 1. Compared with the control group, the *Liriodendron tulipifera* seedlings in the treatment group inoculated with *Pseudomonas veronii* W6-1 showed increases in plant height, root length, maximum leaf area, and fresh weight of 247.82%, 61.61%, 235.14%, and 403.33%, respectively. Therefore, the application of *Pseudomonas veronii* W6-1 suspension significantly enhanced the salt and alkali tolerance of *Liriodendron tulipifera* seedlings and demonstrated a significant growth-promoting effect.

[0029] Table 1. Measurement results of apparent indicators

[0030] Example 4: Salt-alkali tolerance-promoting response of *Pseudomonas veronii* W6-1 to *Liriodendron tulipifera* seedlings Leaves of *Liriodendron tulipifera* seedlings in the control and treatment groups under salt-alkali stress conditions in Example 3 were crushed and tested using a detection kit to determine the corresponding indicators, including total chlorophyll, chlorophyll a, chlorophyll b, soluble protein, proline and malondialdehyde content, as well as the activities of catalase, peroxidase and superoxide dismutase. The results are shown in Table 2. The test results effectively demonstrate the application potential of *Pseudomonas veronii* W6-1 as a multifunctional stress-resistant and growth-promoting bacterium in alleviating salt-alkali stress in host plants and promoting their growth.

[0031] Compared with the control group, inoculation with *Pseudomonas veronii* W6-1 increased the chlorophyll content in the leaves of *Liriodendron tulipifera* seedlings, with increases of 5.60%, 0.75%, and 4.77% in chlorophyll a, chlorophyll b, and total chlorophyll, respectively. Quantitative chlorophyll analysis showed that inoculation with *Pseudomonas veronii* W6-1 alleviated the inhibitory effect of salt-alkali stress on photosynthetic pigment biosynthesis and improved photosynthetic efficiency. Furthermore, the soluble protein content in the leaves of *Liriodendron tulipifera* seedlings in the treatment group increased by 435% compared with the control group, reaching 28.94 mg / g. This provides abundant substrates for the synthesis and metabolism of stress-response enzymes, thereby enhancing the adaptability of *Liriodendron tulipifera* seedlings to saline-alkali environments.

[0032] Salt-alkali stress led to a significant accumulation of malondialdehyde (MDA) in the leaves of *Liriodendron tulipifera* seedlings in the control group. However, the MDA content in the treatment group inoculated with *Pseudomonas veronii* W6-1 was reduced by 71.28% compared to the uninoculated control group. Simultaneously, the proline content in the treatment group was also reduced by 23.32% compared to the control group. The significant decrease in proline and MDA content in *Liriodendron tulipifera* leaves after inoculation with *Pseudomonas veronii* W6-1 indicates that inoculation with this strain can effectively alleviate osmotic stress and oxidative damage to *Liriodendron tulipifera* seedlings under salt-alkali conditions.

[0033] Regarding antioxidant enzyme activity, compared with the control group, the *Liriodendron tulipifera* seedlings inoculated with *Pseudomonas veronii* W6-1 showed significantly enhanced catalase and superoxide dismutase activities, increasing by 1400% and 64%, respectively, compared to the uninoculated control group. Simultaneously, peroxidase activity in the *Pseudomonas veronii* W6-1 inoculated group decreased slightly, with an activity value of 81.25% of the control group. Catalase and superoxide dismutase are core antioxidant enzymes for scavenging reactive oxygen species in plants. The significant increase in their activities indicates that inoculation with *Pseudomonas veronii* W6-1 effectively activates the antioxidant defense system of *Liriodendron tulipifera* seedlings, enhancing their ability to scavenge reactive oxygen species generated by salt and alkali stress. The moderate downregulation of peroxidase activity reflects a functional compensatory relationship in the plant's antioxidant system. *Pseudomonas veronii* W6-1 selectively regulates the antioxidant enzyme defense system, reconstructing the antioxidant response network of *Liriodendron tulipifera*, thereby enhancing the seedlings' tolerance to salt and alkali stress.

[0034] Table 2. Results of Physiological Indicators Measurement

[0035] Example 5: Effects of *Pseudomonas veronii* W6-1 on the structure of rhizosphere and endophytic bacterial communities in *Liriodendron chinense* seedlings The effects of inoculation with *Pseudomonas veronii* W6-1 on the diversity of rhizosphere and endophytic bacterial communities in *Liriodendron tulipifera* seedlings under salt-alkali stress were analyzed using high-throughput sequencing. Rhizosphere soil was collected from soil particles attached to the root surface. For endophytic bacterial analysis, lateral root tissue was selected. The surface soil was first washed away, then the tissue was disinfected by soaking in 75% ethanol for 30 seconds, followed by repeated rinsing with sterile distilled water. Under aseptic conditions, the surface layer of the lateral roots was cut open, and the internal tissue was collected for endophytic bacterial community structure analysis. Total genomic DNA was extracted from the samples. Using the extracted total DNA as a template, the V3–V4 hypervariable region of the 16S rRNA gene was amplified using universal primers 338F / 806R. The purified PCR products were used to construct an Illumina MiSeq sequencing library, followed by paired-end sequencing. Taxonomic annotation and bacterial diversity analysis were performed on the obtained sequences based on the Silva database.

[0036] Compared with the control group, the abundance of rhizosphere bacterial communities in the treatment groups inoculated with *Pseudomonas veronii* W6-1 showed a changing trend. In the control group, the relative abundance of the dominant phyla, namely *Pseudomonas* and *Acidobacteria*, was 56.72% and 9.54%, respectively; while in the treatment group, their relative abundance was 45.41% and 14.66%, respectively. At the genus level, inoculation with *Pseudomonas veronii* W6-1 also had a significant impact on the abundance of rhizosphere bacterial communities in *Liriodendron chinense* seedlings. In the control group, the relative abundance of the dominant genera, *Sphingosporium* and *Devrosella*, was 15.23% and 5.24%, respectively, while in the treatment group, they decreased to 6.30% and 2.84%, respectively.

[0037] Unlike the relatively dispersed distribution of rhizosphere bacterial communities in *Liriodendron tulipifera* seedlings, the distribution of endophytic bacterial genera in these seedlings showed a more concentrated trend. The relative abundance of *Pseudomonas* was only 4.81% in the control group, while it reached as high as 91.01% in the treatment group. Figure 5 (Left figure) Therefore, inoculation with *Pseudomonas veronii* W6-1 promoted the efficient enrichment of *Pseudomonas* phylum within the root. Endophytic bacterial diversity analysis at the genus level ( Figure 5 The middle figure also yielded similar conclusions: Klebsiella and Pseudomonas species accounted for 47% and 34.4% respectively in the treatment group, while in the control group they were only 0.04% and 0.02% respectively. Endophytic bacterial diversity analysis at the species level ( Figure 5 The right-hand panel shows that *Pseudomonas veronii* was detected at a relatively high abundance (5.39%) in the treatment group, while its detection rate was extremely low (0.004%) in the control group. This indicates that *Pseudomonas veronii* has established colonization within the roots of *Liriodendron tulipifera* seedlings. Furthermore, other *Pseudomonas* species (28.91%), *Klebsiella pneumoniae* (47.00%), and *Acinetobacter petitifer* (5.76%) also showed high relative abundance values ​​in the treatment group, while the population sizes of these bacteria in the control group were very small, at only 0.01%, 0.04%, and 0.01%, respectively.

[0038] Therefore, *Pseudomonas veronii* W6-1 not only enables itself to effectively colonize the roots of *Liriodendron tulipifera* seedlings, but also recruits other bacterial groups (such as *Pseudomonas*, *Klebsiella pneumoniae*, and *Acinetobacter pieti*) to colonize the roots, thereby helping *Liriodendron tulipifera* seedlings effectively alleviate salt and alkali stress and promote the growth of the host plant.

[0039] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A type of *Pseudomonas veronii* W6-1, characterized in that, The *Pseudomonas veronii* W6-1 strain is deposited at the China General Microbiological Culture Collection Center (CGMCC), Beijing, China, on July 10, 2026, with accession number CGMCC No. 39669, and is classified as *Pseudomonas veronii*.

2. The application of the *Pseudomonas veronii* W6-1 as described in claim 1 in improving the salt and alkali tolerance of plants and promoting plant growth.

3. The application according to claim 2, characterized in that, The plant in question is Liriodendron tulipifera.

4. The application according to claim 3, characterized in that, The *Pseudomonas veronii* W6-1 possesses at least one of the following functions: nitrogen fixation, phosphorus solubilization, antibacterial activity, siderophore production, and indoleacetic acid production.

5. The application according to claim 3, characterized in that, The *Pseudomonas veronii* W6-1 strain possesses ACC deaminase activity, which can be used to reduce the ethylene level in *Liriodendron tulipifera* seedlings to alleviate salt-alkali stress.

6. The application according to claim 3, characterized in that, The *Pseudomonas veronii* W6-1 strain increases the chlorophyll and soluble protein content in the leaves of *Liriodendron tulipifera* seedlings, while reducing the content of proline and malondialdehyde, thereby alleviating osmotic stress and oxidative damage caused by salt and alkali stress.

7. The application according to claim 3, characterized in that, The *Pseudomonas veronii* W6-1 strain enhances the activity of catalase and superoxide dismutase in the leaves of *Liriodendron chinense* seedlings.

8. The application according to claim 3, characterized in that, The *Pseudomonas veronii* W6-1 was able to colonize the roots of *Liriodendron tulipifera* seedlings and promote the colonization of other microbial communities within the roots of *Liriodendron tulipifera* seedlings.

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