A strain of Pseudomonas chlororaphis subsp. aurantiaca for controlling wheat basal stalk rot and its application

Abstract

The present invention relates to the technical field of agricultural biological control, and particularly to a strain of Pseudomonas chlororaphis subsp. aurantiaca for controlling wheat basal stalk rot and its application. The strain of Pseudomonas chlororaphis subsp. aurantiaca for controlling wheat basal stalk rot is P. chlororaphis subsp. aurantiaca , which has good antagonistic activity against both Fusarium pseudograminearum and Fusarium culmorum. The inhibition rate against the Fusarium pseudograminearum strain reaches 76.07%, and the inhibition rate against the Fusarium culmorum strain reaches 73.26%. P. chlororaphis subsp. aurantiaca It can induce wheat to produce resistance to Fusarium pseudograminearum and Fusarium culmorum. The control effect against the Fusarium pseudograminearum strain reaches 55.77%, and the control effect against the Fusarium culmorum strain reaches 51.19%. Therefore, Pseudomonas chlororaphis subsp. aurantiaca can significantly reduce the disease severity of wheat basal stalk rot, and at the same time can increase the plant height, fresh weight and root length of wheat, showing a significant growth-promoting effect on wheat plants.

Description

Technical Field

[0001] The present invention relates to the technical field of agricultural biological control, and in particular to a strain of Pseudomonas chlororaphis subsp. aurantiaca for controlling wheat basal stalk rot and its application. Background Art

[0002] The main pathogenic fungi of wheat basal stalk rot mainly include: Fusarium pseudograminearum ( F. pseudograminearum ), Fusarium culmorum ( F. culmorum ), Fusarium graminearum ( F. graminearum ), Fusarium asiaticum ( F. asiaticum ), Fusarium avenaceum ( F. avenaceum ), Fusarium oxysporum ( F. oxysporum ), Fusarium equiseti ( F. equisti ), Fusarium proliferatum ( F. proliferatum ), and Fusarium tricinctum ( F. tricinctum ) and more than 10 others.

[0003] Chemical control can lead to the development of pest resistance, environmental pollution, damage to beneficial microorganisms, and phytotoxicity and pesticide residues in plants when pesticides are used improperly.

[0004] Pseudomonas chlororaphis ( P. chlororaphis ) is a recognized environmentally friendly plant growth-promoting bacterium with a wide distribution range and strong adaptability to the ecological environment.

[0005] Currently, it is used to control tomato wilt, Phytophthora nicotianae, Phytophthora capsici, cypress canker, and bean anthracnose, etc., and at the same time has obvious inhibitory effects on several important agricultural pathogenic bacteria, such as Burkholderia capsici ( Burkholderia glumae ), Erwinia amylovora ( Erwinia amylovora ), Corynebacterium michiganense ( Clavibacter michiganesis ), Pectobacterium carotovorum ( Pectobacterium carotovora ), Pseudomonas syringae ( Pseudomonas syringae ), Xanthomonas campestris pv. campestris ( Xanthomonas campestris ), etc. After retrieval, the patent with the publication number CN112899205B provides a Pseudomonas chlororaphis MN225969 and its application. The content of this invention patent is that the control effect of Pseudomonas chlororaphis MN225969 on Fusarium graminearum can reach 39.60%. The sequence homology between the strain YL-21 of the present invention and the strain MN225969 is 95.54%. Therefore, the strain of the present invention has a relatively distant genetic relationship with the strain MN225969 and does not belong to the same type of strain. At present, there is no report on the use of the Pseudomonas chlororaphis subsp. aurantiaca of the present invention in controlling wheat basal stalk rot.

[0006] Therefore, it is an urgent problem for those skilled in the art to provide a strain of Pseudomonas chlororaphis subsp. aurantiaca for controlling wheat basal stalk rot and its application. Summary of the Invention

[0007] The technical problem to be solved by the present invention is to provide a strain of Pseudomonas chlororaphis subsp. aurantiaca for preventing and controlling wheat basal stalk rot and its application in view of the deficiencies of the above-mentioned prior art. The biocontrol bacterium Pseudomonas chlororaphis subsp. aurantiaca provided by the present invention P. chlororaphis has good antagonistic activity against both Fusarium pseudograminearum and Fusarium culmorum. The inhibition rate against Fusarium pseudograminearum strains reached 76.07%, and the inhibition rate against Fusarium culmorum strains reached 73.26%. At the same time, it can also increase the plant height, fresh weight and root length of wheat, and has a significant growth-promoting effect on wheat plants.

[0008] The present invention provides a strain of Pseudomonas chlororaphis subsp. aurantiaca for preventing and controlling wheat basal stalk rot, and the strain of Pseudomonas chlororaphis subsp. aurantiaca for preventing and controlling wheat basal stalk rot is P. chlororaphis subsp. aurantiaca, with the preservation number of CGMCC No. 32270, the preservation unit is the General Microbiology Center of the China Committee for Culture Collection of Microorganisms, and the preservation date is October 21, 2024.

[0009] According to the strain of Pseudomonas chlororaphis subsp. aurantiaca for preventing and controlling wheat basal stalk rot provided by the present invention, the 16s nucleotide sequence of the genomic DNA of the strain of Pseudomonas chlororaphis subsp. aurantiaca is shown in SEQ ID NO: 1.

[0010] According to the strain of Pseudomonas chlororaphis subsp. aurantiaca for preventing and controlling wheat basal stalk rot provided by the present invention, the strain of Pseudomonas chlororaphis subsp. aurantiaca is inoculated in LB medium for fermentation culture to obtain a biocontrol agent of the strain of Pseudomonas chlororaphis subsp. aurantiaca.

[0011] According to the strain of Pseudomonas chlororaphis subsp. aurantiaca for preventing and controlling wheat basal stalk rot provided by the present invention, the LB medium is composed of the following raw materials by mass fraction: 1% tryptone, 0.5% yeast extract powder, 1% sodium chloride, and the rest is distilled water. The pH is adjusted to 7.0 ± 0.1, and then sterilized at 121 °C for 15 min.

[0012] According to the strain of Pseudomonas chlororaphis subsp. aurantiaca for preventing and controlling wheat basal stalk rot provided by the present invention, the fermentation time is 48 h.

[0013] According to the strain of Pseudomonas chlororaphis subsp. aurantiaca for preventing and controlling wheat basal stalk rot provided by the present invention, the concentration OD of the strain of Pseudomonas chlororaphis subsp. aurantiaca in the biocontrol agent 600 is 1.

[0014] The present invention also provides an application of the above-mentioned strain of Pseudomonas chlororaphis subsp. aurantiaca for controlling wheat basal stalk rot. The strain of Pseudomonas chlororaphis subsp. aurantiaca for controlling wheat basal stalk rot is applied to the rhizosphere of plants suffering from wheat basal stalk rot, and can treat wheat basal stalk rot caused by Fusarium fungi and promote the growth of wheat.

[0015] According to the application of a strain of Pseudomonas chlororaphis subsp. aurantiaca for controlling wheat basal stalk rot provided by the present invention, the pathogenic bacteria of the plants suffering from wheat basal stalk rot are Fusarium fungi, including Fusarium culmorum and Fusarium pseudograminearum.

[0016] According to the application of a strain of Pseudomonas chlororaphis subsp. aurantiaca for controlling wheat basal stalk rot provided by the present invention, the biocontrol agent of the strain of Pseudomonas chlororaphis subsp. aurantiaca can also treat wheat basal stalk rot caused by Fusarium fungi and promote the growth of wheat.

[0017] The present invention has the following advantages compared with the prior art:

[0018] ① The biocontrol bacterium Pseudomonas chlororaphis subsp. aurantiaca provided by the present invention P. chlororaphis subsp. aurantiaca has good antagonistic activity against both Fusarium pseudograminearum and Fusarium culmorum. The inhibition rate against the strain of Fusarium pseudograminearum reaches 76.07%, and the inhibition rate against the strain of Fusarium culmorum reaches 73.26%.

[0019] ② The biocontrol bacterium Pseudomonas chlororaphis subsp. aurantiaca provided by the present invention P. chlororaphis subsp. aurantiaca can increase the plant height, fresh weight and root length of wheat, and has a significant growth-promoting effect on wheat plants.

[0020] ③ The biocontrol bacterium Pseudomonas chlororaphis subsp. aurantiaca provided by the present invention P. chlororaphis subsp. aurantiaca can induce wheat to produce resistance to Fusarium pseudograminearum and Fusarium culmorum. The control effect against the strain of Fusarium pseudograminearum reaches 55.77%, and the control effect against the strain of Fusarium culmorum reaches 51.19%. Therefore, Pseudomonas chlororaphis subsp. aurantiaca can significantly reduce the disease severity of wheat basal stalk rot.

[0021] ④ The biocontrol bacterium Pseudomonas chlororaphis subsp. aurantiaca of the present invention P. chlororaphis subsp. aurantiaca can enhance the drought resistance and salt tolerance of wheat. Brief Description of the Drawings

[0022] To more clearly illustrate the technical solutions in the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0023] Figure 1 is the strain obtained by the present invention according to the 16S rDNA sequence P. chlororaphis subsp. aurantiaca phylogenetic tree diagram;

[0024] Figure 2 is Pseudomonas chlororaphis subsp. aurantiaca in Example 2 P. chlororaphis subsp. aurantiaca effect diagram of inhibiting the mycelial growth of Fusarium pseudograminearum (A - B) and Fusarium culmorum (C - D) on the plate;

[0025] Figure 3 is Pseudomonas chlororaphis subsp. aurantiaca in Example 3 P. chlororaphis subsp. aurantiaca effect on the growth of wheat plants;

[0026] Figure 4 is Pseudomonas chlororaphis subsp. aurantiaca in Example 4 P. chlororaphis subsp. aurantiaca result diagram of inhibiting the infection of wheat by Fusarium pseudograminearum;

[0027] Figure 5 is Pseudomonas chlororaphis subsp. aurantiaca in Example 4 P. chlororaphis subsp. aurantiaca result diagram of inhibiting the infection of wheat by Fusarium culmorum;

[0028] Figure 6 is Pseudomonas chlororaphis subsp. aurantiaca in Example 5 P. chlororaphis subsp. aurantiaca result diagram of enhancing the drought resistance coefficient of wheat;

[0029] Figure 7 is Pseudomonas chlororaphis subsp. aurantiaca in Example 6 P. chlororaphis subsp. aurantiaca effect on the root growth of wheat in the salt stress environment;

[0030] Figure 8 is Pseudomonas chlororaphis subsp. aurantiaca in Example 6 P. chlororaphis subsp. aurantiaca effect on the plant height of wheat in the salt stress environment;

[0031] Figure 9 is Pseudomonas chlororaphis subsp. aurantiaca in Example 6 P. chlororaphis subsp. aurantiaca Effect on fresh weight of wheat under salt stress environment.

[0032] The taxonomic naming of the strain of Pseudomonas chlororaphis subsp. aurantiaca for controlling wheat basal stalk rot is Pseudomonas chlororaphis subsp. aurantiaca Pseudomonas chlororaphis subsp. aurantiaca , with the preservation number of CGMCC No. 32270, the preservation unit is the China General Microbiological Culture Collection Center, and the preservation date is October 21, 2024. Specific implementation mode

[0033] Example 1

[0034] This example provides a method for isolating and screening Pseudomonas chlororaphis subsp. aurantiaca P. chlororaphis subsp. aurantiaca (denoted as YL-21), and the specific steps are as follows:

[0035] S1. Isolation of strain YL-21

[0036] The strain YL-21 of Pseudomonas chlororaphis subsp. aurantiaca was isolated from the soil of wheat fields in Yili by the Institute of Plant Protection, Xinjiang Academy of Agricultural Sciences.

[0037] Collect the soil samples from wheat fields in Yili. After bringing them back to the laboratory, use the soil dilution method for isolation and purification, and use wheat basal stalk rot as the target. Screen the biocontrol bacteria through the plate confrontation method and the pot experiment method, and select a strain with obvious control effect on wheat basal stalk rot P. chlororaphis subsp. aurantiaca , named YL-21, with the preservation number of CGMCC No. 32270, the preservation unit is the China General Microbiological Culture Collection Center, and the preservation date is October 21, 2024. The 16s nucleotide sequence of the genomic DNA of the strain of Pseudomonas chlororaphis subsp. aurantiaca is shown in SEQ ID NO: 1;

[0038] S2. Taxonomic identification of strain YL-21

[0039] Using the genomic DNA of strain YL-21 as a template, perform PCR amplification with the bacterial universal primers 27F and 1492R to obtain a PCR amplification product;

[0040] Among them, the sequence of primer 27F is shown in SEQ ID NO.2, and the sequence of primer 1492R is shown in SEQ ID NO.3. In the sequence, M represents A / C; Y represents C / T;

[0041] The reaction system consisted of 25 μL of 2×Taq Master Mix, 1 μL each of 27F (10 ppm) and 1492R (10 ppm), 1 μL of DNA template, and 22 μL of ddH2O added to make up the volume;

[0042] The PCR amplification conditions were pre-denaturation at 94 °C for 5 min; denaturation at 94 °C for 30 s, annealing at 54 °C for 30 s, extension at 72 °C for 1.5 min, for 35 cycles; final extension at 72 °C for 10 min;

[0043] The obtained PCR product was sequenced by Hangzhou Youkang Biotechnology Co., Ltd., and the 16S rDNA gene sequence of strain YL-21 was as shown in SEQ ID NO.1;

[0044] The measured sequence was subjected to BLAST online homology comparison using NCBI, and a standard strain with relatively high homology was selected as the reference object. The results showed that the 16S rDNA homology between strain YL-21 and Pseudomonas chlororaphis subsp. aurantiaca reached 99%; a phylogenetic tree was constructed, and the results are shown in Figure 1 ; YL-21 and Pseudomonas chlororaphis subsp. aurantiaca clustered together, indicating that YL-21 belongs to Pseudomonas chlororaphis subsp. aurantiaca.

[0045] Example 2

[0046] 1. Inhibitory rate of Pseudomonas chlororaphis subsp. aurantiaca YL-21 against Fusarium pseudograminearum ( F. pseudograminearum )

[0047] Using the PDA plate confrontation method, the biocontrol bacteria described in Case 1 of the implementation were symmetrically inoculated at a distance of 2.5 cm from the edge of a 9-cm-diameter PDA medium plate containing 15 mL of PDA medium. A strain cake (5 mm in diameter) of the strain cultured for 2 - 3 d was inoculated at the center of the plate. A plate inoculated only with F. pseudograminearum the strain cake was used as a control. The plates were incubated at 25 °C in the dark. After 5 - 7 d, F. pseudograminearum the colony radius was measured, and the inhibition rate was calculated according to the following formula: F. pseudograminearum Inhibition rate (%) = (control growth - treatment growth) / control growth × 100

[0048] The above PDA medium was composed of the following raw materials by mass fraction: 0.6% potato infusion powder, 2% glucose, 2% agar, and the rest was distilled water. The pH was adjusted to 5.6 ± 0.2, and then sterilized at 115 °C for 20 min.

[0049] The test results are shown in Table 1 and

[0050] and Figure 2, it can be seen that the inhibition rate of Pseudomonas aeruginosa subsp. aurantiaca against F. pseudograminearum is more than 76%; it shows that Pseudomonas aeruginosa subsp. aurantiaca YL-21 has an obvious inhibitory effect on F. pseudograminearum .

[0051] Table 1 Inhibition rate of YL-21 against F. pseudograminearum

[0052] Strain name Control (mm) Treatment (mm) Inhibitory rate (%) YL-21 42.5±0.5 10.17±0.29 76.07±0.94

[0053] 2. Inhibition rate of Pseudomonas aeruginosa subsp. aurantiaca YL-21 against Fusarium culmorum ( F. culmorum )

[0054] Using the PDA plate confrontation method, the biocontrol bacteria described in Example 1 were symmetrically inoculated at a distance of 2.5 cm from the edge of a PDA medium plate with a diameter of 9 cm and containing 15 mL. A strain cake (diameter 5 mm) of the F. culmorum strain cultured for 2 - 3 d was inoculated at the center of the plate. A plate inoculated only with the F. culmorum strain cake was used as a control. The plates were cultured at 25 °C in the dark. After 5 - 7 d, the F. culmorum colony radius was measured, and the inhibition rate was calculated;

[0055] The test results are shown in Table 2 and Figure 2 , it can be seen that the inhibition rate of Pseudomonas aeruginosa subsp. aurantiaca against F. culmorum is more than 73%; it shows that Pseudomonas aeruginosa subsp. aurantiaca YL-21 has an obvious inhibitory effect on F. culmorum .

[0056] Table 2 Inhibition rate of YL-21 against F. culmorum

[0057] Strain name Control (mm) Treatment (mm) Inhibitory rate (%) YL-21 43±0.00 11.5±0.5 73.26±1.16

[0058] Example 3

[0059] This example detects the effect of Pseudomonas aeruginosa subsp. aurantiaca YL-21 on the growth of wheat itself. The detection method is as follows:

[0060] S1. Inoculate the Pseudomonas aeruginosa subsp. aurantiaca YL-21 strain into LB liquid medium. After overnight culture at 28 °C and 180 rpm / min, take part of the bacterial liquid and inoculate it into NB medium. Culture at 28 °C and 180 rpm / min for 48 h to obtain a bacterial suspension. Centrifuge the obtained bacterial suspension at 4000 rpm for 10 min, resuspend it with sterile water, and dilute it to OD 600 = 1 for standby;

[0061] The above LB liquid medium is composed of the following raw materials by mass fraction: 1% tryptone, 0.5% yeast extract powder, 1% sodium chloride, and the rest is distilled water. The pH is adjusted to 7.0 ± 0.1, and then it is sterilized at 121 °C for 15 min.

[0062] The above NB medium is composed of the following raw materials by mass fraction: 1% peptone, 0.3% beef extract powder, 0.5% sodium chloride, and the rest is distilled water. The pH is adjusted to 7.2 ± 0.2, and then it is sterilized at 121 °C for 15 min.

[0063] S2. Select flowerpots with a diameter of 7 cm, plant 12 wheat seeds with consistent germination and exposed radicles in each pot, and place them in a greenhouse at 25 °C for cultivation.

[0064] The experimental group (YL-21) is: the bacterial liquid resuspended with 10 ml of sterile water in each pot.

[0065] The control group (CK) is: 10 ml of sterile water is added to each pot.

[0066] Six replicates are set for each treatment in the experimental group and the control group.

[0067] S3. Water the wheat in each group with sterile water, and after 14 d, measure the plant height, root length, fresh weight, and root weight of the wheat.

[0068] The statistical results are as Figure 3 shown in Table 3:

[0069] Table 3 Statistical results of wheat root length, plant height, fresh weight, and root weight

[0070] Plant height / cm Root length / cm Fresh weight / g Root weight / g CK 29.37±0.19 14.84±0.30 4.36±0.05 1.43±0.04 YL-21 30.10±0.29* 14.40±0.25 4.64±0.08* 1.68±0.06**

[0071] In Table 3 above, the numerical expressions of root length, plant height, fresh weight, and root weight are: mean ± standard error, and * indicates significant difference ( P <0.05);

[0072] From the data in Table 3 above, it can be seen that the plant height and fresh weight of the experimental group are better than those of the control group, and the root weight increases significantly. The above results indicate that Pseudomonas chlororaphis subsp. aurantiaca has a growth-promoting effect on wheat plants.

[0073] Example 4

[0074] This example is used to characterize the effect of Pseudomonas chlororaphis subsp. aurantiaca YL-21 on wheat basal rot.

[0075] The effect of Pseudomonas chlororaphis subsp. aurantiaca YL-21 on wheat basal rot caused by F. pseudograminearum wheat basal rot.

[0076] (1) Inoculate the strain Pseudomonas chlororaphis subsp. aurantiaca YL-21 into LB liquid medium. After overnight culture at 28 °C and 180 rpm / min, take a part of the bacterial liquid and inoculate it into NB medium. Culture it at 28 °C and 180 rpm / min for 48 h to obtain a bacterial suspension. Centrifuge the obtained bacterial suspension at 4000 rpm for 10 min, resuspend it with sterile water, and dilute it to OD 600 = 1 for standby;

[0077] (2) Inoculate the F. pseudograminearum strain cake into 2% mung bean powder medium. Culture it with shaking at 28 °C and 180 rpm / min for 7 d. After filtering to remove the mycelium, dilute the concentration of the spore suspension to 1×10 6 for standby;

[0078] (3) Select flowerpots with a diameter of 7 cm, and plant 12 wheat seeds with consistent white tips after germination in each pot. Place them in a greenhouse at 25 °C for cultivation;

[0079] Experimental group: Add 10 mL of the bacterial liquid resuspended with sterile water to each pot. After 24 h, pour 10 mL of F. pseudograminearum spore liquid into the wheat potted plants;

[0080] Control group: Inoculate 10 mL of F. pseudograminearum spore liquid;

[0081] Set 4 replicates for each treatment;

[0082] (4) Water the wheat plants in each group with sterile water. After 28 d, count the incidence of wheat plants, calculate the disease index and control effect. The results are as shown in Figure 4 and Table 4;

[0083] Table 4 Statistical results of the control effect of YL-21 on wheat basal rot caused by F. pseudograminearum

[0084] Disease index Control efficacy % CK 56.55±1.54a / YL-21 25.00±0.97b 55.77±1.76

[0085] In Table 4 above, the numerical expression of the colony diameter is: mean ± standard error, and a and b indicate significant differences at the 0.05 level.

[0086] The results in Table 4 show that when the disease index of the blank control wheat basal rot is 56.55, the disease index of the treatment with Pseudomonas chlororaphis subsp. aurantiaca YL-21 is 25.00, and its control effect on wheat basal rot can reach 55.77%.

[0087] It shows that Pseudomonas chlororaphis subsp. aurantiaca YL-21 has an effect on F. pseudograminearumIt has a good control effect on wheat basal stalk rot caused by

[0088] 2. Influence of Pseudomonas chlororaphis subsp. aurantiaca YL-21 on wheat basal stalk rot caused by F. culmorum

[0089] (1) Inoculate the strain of Pseudomonas chlororaphis subsp. aurantiaca YL-21 into LB liquid medium, culture overnight at 28 °C and 180 rpm / min, then take part of the bacterial liquid and inoculate it into NB medium, culture at 28 °C and 180 rpm / min for 48 h. Centrifuge the obtained bacterial suspension at 4000 rpm for 10 min, resuspend it with sterile water, and dilute it to OD 600 = 1 for standby.

[0090] (2) Inoculate the F. culmorum strain cake into 2% mung bean powder medium, culture it with shaking at 28 °C and 180 rpm / min for 7 d. After filtering out the mycelium, dilute the concentration of the spore suspension to 1×10 6 for standby.

[0091] (3) Select flowerpots with a diameter of 7 cm, plant 12 wheat seeds with consistent germination and exposed radicles in each pot, and place them in a 25 °C greenhouse for cultivation;

[0092] Experimental group: Add 10 mL of the bacterial liquid resuspended with sterile water to each pot. After 24 h, pour 10 mL of F. culmorum spore liquid into the wheat potted plants;

[0093] Control group: Inoculate 10 mL of F. culmorum spore liquid;

[0094] Set 4 replicates for each treatment.

[0095] (4) Water each group of wheat plants with sterile water. After 28 d, count the disease incidence of wheat plants, and calculate the disease index and control effect. The results are as shown in Figure 5 and Table 5.

[0096] Table 5 Statistical results of the control effect of Pseudomonas chlororaphis subsp. aurantiaca YL-21 on wheat basal stalk rot caused by F. culmorum

[0097] Disease index Control efficacy % CK 49.41±1.54a / YL-21 24.11±1.50b 51.19±2.92

[0098] In Table 5 above, the numerical expression of the colony diameter is: mean ± standard error, and a and b indicate significant differences at the 0.05 level.

[0099] Table 5 results showed that when the disease index of the blank control for wheat basal rot was 49.41, the disease index of the treatment with Pseudomonas aeruginosa subsp. aurantiaca YL-21 was 24.11, and the control effect on wheat basal rot reached 51.19%.

[0100] It shows that Pseudomonas aeruginosa subsp. aurantiaca YL-21 of the present invention F. culmorum has a good control effect on wheat basal rot caused by

[0101] Example 5

[0102] In this example, the drought resistance enhancement ability of Pseudomonas aeruginosa subsp. aurantiaca YL-21 on wheat was detected. The specific method was as follows:

[0103] S1. Inoculate the strain of Pseudomonas aeruginosa subsp. aurantiaca YL-21 into NB medium and shake culture at 28 °C until OD 600 = 1 for standby;

[0104] S2. Select clean seeds with plump grains and consistent sizes, soak them in 75% ethanol for 1 min and disinfect them with 5% sodium hypochlorite for 1 min, rinse them with distilled water 5 - 6 times, sow the wheat seeds in pots, and place them in a greenhouse (about 25 °C) for normal growth;

[0105] S3. Conduct experimental treatment when the wheat grows to the three - leaf and one - heart stage;

[0106] Use clear water as the control: Pour 10 mL of clear water into each pot;

[0107] Treatment group: Pour 10 mL of resuspended bacterial solution into each pot;

[0108] After the treatment, start the water - cut (simulating drought) treatment, and do not water for 15 consecutive days;

[0109] Each treatment is repeated 5 times;

[0110] S4. Evaluate the drought resistance coefficient every day for 15 consecutive days;

[0111] The drought resistance coefficient refers to observing the growth status of wheat every day starting from the water - cut, continuously observing for 15 days, and according to the wilting degree shown by the wheat plants, investigating and counting each repeated tiller according to the following grading standard: Grade 0: The plant grows normally without wilting; Grade 1: The plant grows basically normally, and only 1 leaf shows slight wilting; Grade 2: The wilting of the plant is aggravated, and 2 leaves show wilting; Grade 3: The plant is significantly wilted, and more than 3 leaves are wilted; The leaves are wilted and drooping, and it is difficult to recover;

[0112] Calculate the drought resistance coefficient according to the following formula based on the statistical results:

[0113] Drought resistance coefficient = [1 - ∑(number of plants at each level × corresponding level) / (total number of plants × 3)] × 100%;

[0114] The results are as Figure 6 shown in

[0115] Table 6 Statistical results of wheat drought resistance coefficient

[0116] 3 d 4 d 5 d 6 d 7 d 8 d 9 d 10 d 11 d 12 d CK 74.08±9.44 58.52±4.83 22.96±6.08 20.00±6.20 16.29±6.20 14.81±4.55 8.15±4.83 5.93±4.22 5.18±4.22 5.18±4.22 YL-21 91.52±7.13* 65.93±1.66* 57.78±10.34* 34.07±1.66* 28.15±4.22* 20.00±3.31 15.55±3.10* 14.07±1.65* 13.33±2.03* 11.85±3.10*

[0117] The numerical expression of the drought resistance coefficient in Table 6 above is: mean ± standard error, * indicates significant difference ( P <0.05).

[0118] From the data in Table 6, it can be seen that starting from the 3rd day after water cut-off, there are differences in the performance of the two groups of treated wheat. As the number of days of water cut-off increases, the drought resistance coefficients of each treatment show a downward trend, and there are significant differences among different treatments. From the 3rd day to the 7th day after water cut-off, the drought resistance coefficient of the wheat treated with YL-21 is significantly higher than that of the control, and the wheat leaves in the control group wilt and droop first. After measuring the fresh weight of each group of wheat 15 days after water cut-off, the average fresh weight of the treated group increases by 25.83% compared with the control, which is significantly higher than that of the control group, indicating that the Pseudomonas chlororaphis subsp. aurantiaca YL-21 of the present invention has a growth-promoting effect on wheat plants.

[0119] Example 6

[0120] In this example, the ability of Pseudomonas chlororaphis subsp. aurantiaca YL-21 to enhance the salt and alkali tolerance of wheat was detected. The specific detection method is as follows:

[0121] S1. Inoculate the Pseudomonas chlororaphis subsp. aurantiaca YL-21 strain into LB medium and culture it overnight at 28 °C and 180 rpm / min to obtain a seed solution;

[0122] S2. Inoculate the seed solution into NB medium and culture it at 28 °C and 180 rpm / min for 48 h. Centrifuge the obtained bacterial suspension at 4000 rpm for 10 min, resuspend it with an equal volume of sterile water, and dilute it to OD 600 = 1 for standby;

[0123] S3. Select clean seeds with plump grains and uniform size, soak them in 75% ethanol for 1 min, disinfect them with 5% sodium hypochlorite for 1 min, rinse them with distilled water 5 - 6 times, germinate for 2 d, then select wheat seedlings with consistent growth vigor, soak them in the bacterial suspension for 10 min, and then place them in Hoagland nutrient solution (PH = 8.5) with NaCl concentrations of 50 mmol / L, 100 mmol / L, and 200 mmol / L respectively. Use the treatment without salt stress and without inoculation as the blank control, and the treatment without inoculation under salt stress as the salt treatment control. Repeat 5 times;

[0124] S4. After 7 d, measure the plant height, root length, and fresh weight of the wheat. The results are as Figures 7 - 9 shown in Table 7.

[0125] Table 7 Statistical results of wheat plant height, root length, and fresh weight

[0126]

[0127] In Table 7 above, the numerical expression of the colony diameter is the mean ± standard error;

[0128] As can be seen from the data in Table 7, when wheat seedlings are cultured in salt solution for 7 d, after treatment with the YL - 21 bacterial suspension, the plant height of the wheat seedlings increases significantly under the conditions of 50 mmol / L NaCl and 100 mmol / L NaCl respectively; under the condition of 100 mmol / L NaCl, the fresh weight of the wheat seedlings treated with the YL - 21 bacterial suspension increases significantly.

[0129] The above are only the preferred embodiments of the present invention and do not impose any limitations on the present invention. Any simple modifications, changes, and equivalent variations made to the above embodiments based on the technical essence of the invention still fall within the protection scope of the technical solution of the present invention.

Claims

1. A strain of Pseudomonas chlororaphis subspecies orange for preventing and treating wheat stem rot, characterized in that: The Pseudomonas chlororaphis subspecies orange strain for preventing and controlling wheat stem rot is P. chlororaphis subsp. aurantiaca, the deposit number is CGMCC No. 32270, the depositor is the General Microbiology Center of China Microorganism Culture Collection Administration, and the deposit date is October 21, 2024.

2. The Pseudomonas chlororaphis subsp. orange strain for preventing and treating wheat stem rot according to claim 1, characterized in that: The 16s nucleotide sequence of the genomic DNA of the Pseudomonas chlororaphis subsp. aurantiacus strain is shown in SEQ ID NO:

1.

3. A use of the Pseudomonas chlororaphis subsp. orange strain for preventing and treating wheat stem rot according to any one of claims 1 to 2, characterized in that: The Pseudomonas chlororaphis orange subspecies strain for controlling wheat stem base rot is applied to the rhizosphere of plants suffering from wheat stem base rot, thereby treating the wheat stem base rot caused by Pseudomonas graminearum or Fusarium erythrorhizium and promoting wheat growth.

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