Application of Bacillus sp. Cdb8-1 in improving salt and alkali tolerance of colorful-leaved poplar trees

Abstract

The present invention provides an application of Bacillus sp. Cdb8-1 in improving the salt and alkali tolerance of colored-leaf poplars. The present invention belongs to the technical field of microbial applications. By developing the existing strain Bacillus sp. Cdb8-1, the present invention discovers that this strain can improve the salt and alkali tolerance of colored-leaf poplars, which greatly expands the living space of colored-leaf poplars and provides new ideas for the improvement and utilization of saline-alkali land.

Description

Technical Field

[0001] The present invention relates to the technical field of microbial applications, and particularly to the application of Bacillus Cdb8-1 in improving the saline-alkali tolerance of colored-leaf poplars. Background Art

[0002] Soil salinization is an important factor restricting agricultural and forestry production and the ecological environment, and it is a worldwide problem. In arid and semi-arid regions, about 50% of the irrigated land is affected by salinization. Salinization also occurs in non-arid and semi-arid regions. Salinization seriously affects the growth and yield of crops, and greatly hinders the sustainable development of the agroforestry economy and the ecological environment. Developing and utilizing large areas of saline-alkali land, desertified land and rich saline water resources to develop agricultural and forestry production is an urgent problem to be solved.

[0003] Saline-alkali stress seriously hinders almost all important life processes during plant growth and development, including growth and development, photosynthesis, protein synthesis, lipid metabolism, etc., and further leads to the senescence and death of plants. Therefore, improving the saline-alkali tolerance of plants is of great significance for the development of agriculture and forestry.

[0004] The improvement of saline-alkali land is an important breakthrough for increasing the cultivated land area and restoring the cultivated land ecology, and the governance potential is huge. Chemical improvement aims to treat saline-alkali soil by adding new chemical substances to saline-alkali soil. This method has a quick effect but is easy to introduce a large amount of new chemical substances into the environment, causing secondary pollution. Physical improvement mainly focuses on building a large number of water conservancy facilities to take away a large amount of salt in the soil with water. However, this technical means has disadvantages such as large project volume, high investment cost, and non-sustainability. Compared with chemical improvement and physical improvement, bioremediation has the advantages of energy conservation, high efficiency, economy, strong persistence, and stable improvement effect, and is an important research direction for saline-alkali soil improvement.

[0005] With the strengthening of people's concept of environmental protection, plant growth-promoting rhizobacteria (PGPR) have been increasingly used in the research of saline-alkali soil improvement. PGPR can promote plant growth by secreting the plant growth hormone indole-3-acetic acid (IAA); it can produce extracellular polysaccharides, form soil aggregates with soil particles, increase soil air permeability, and improve soil structure; it can also dissolve phosphorus and potassium, and improve soil nutrient utilization rate. Among them, Bacillus grows fast, has simple nutritional requirements, and can produce extremely stress-resistant spores, which makes the batch production process of Bacillus preparations simple, the fermentation production cost low, the preparation easy to apply, and the product storage period long. It is an ideal microbial preparation for saline-alkali soil remediation. However, there are still deficiencies in this field, such as few strain species and poor adaptability of existing strains to special environments, especially saline-alkali soil environments. Therefore, the development of salt-tolerant and growth-promoting strains and their application in plant growth promotion and saline-alkali soil improvement are very important. Summary of the Invention

[0006] The purpose of the present invention is to develop salt-tolerant and growth-promoting strains, improve the salt tolerance of colorful poplars, and expand the living space of colorful poplars.

[0007] In order to achieve the above-mentioned invention purpose, the present invention provides the following technical solutions:

[0008] The present invention provides an application of Bacillus nitratirecucens Cdb8-1 in improving the salt tolerance of colorful poplars.

[0009] Preferably, the colorful poplars include Zhongshan Caiyun and Lianghong Poplar.

[0010] By developing the existing strain Bacillus Cdb8-1, the present invention discovers that this strain can improve the salt tolerance of colorful poplars, which greatly expands the living space of colorful poplars and provides new ideas for the improvement and utilization of saline-alkali land. Description of the Drawings

[0011] Figure 1 Fresh weights of Zhongshan Caiyun and Lianghong Poplar seedlings after 4 weeks of treatment with 500 mL of 200 mM NaCl and 500 mL of 200 mM NaCl + 20 mL of suspended bacterial cells;

[0012] Figure 2 Plant heights of Zhongshan Caiyun and Lianghong Poplar seedlings after 4 weeks of treatment with 500 mL of 200 mM NaCl and 500 mL of 200 mM NaCl + 20 mL of suspended bacterial cells;

[0013] Figure 3Root weights of Zhongshancaiyun and Lianghongyang seedlings after 4 weeks of treatment with 500 mL of 200 mM NaCl and 500 mL of 200 mM NaCl + 20 mL of suspended bacterial cells;

[0014] Figure 4 Root lengths of Zhongshancaiyun and Lianghongyang seedlings after 4 weeks of treatment with 500 mL of 200 mM NaCl and 500 mL of 200 mM NaCl + 20 mL of suspended bacterial cells;

[0015] Figure 5 Chlorophyll contents of Zhongshancaiyun and Lianghongyang seedlings after 4 weeks of treatment with 500 mL of 200 mM NaCl and 500 mL of 200 mM NaCl + 20 mL of suspended bacterial cells;

[0016] Figure 6 Fv·Fm of Zhongshancaiyun and Lianghongyang seedlings after 4 weeks of treatment with 500 mL of 200 mM NaCl and 500 mL of 200 mM NaCl + 20 mL of suspended bacterial cells -1 value;

[0017] Figure 7 Malondialdehyde contents of Zhongshancaiyun and Lianghongyang seedlings after 4 weeks of treatment with 500 mL of 200 mM NaCl and 500 mL of 200 mM NaCl + 20 mL of suspended bacterial cells;

[0018] Figure 8 Proline concentrations of Zhongshancaiyun and Lianghongyang seedlings after 4 weeks of treatment with 500 mL of 200 mM NaCl and 500 mL of 200 mM NaCl + 20 mL of suspended bacterial cells;

[0019] Figure 9 SOD activities of Zhongshancaiyun and Lianghongyang seedlings after 4 weeks of treatment with 500 mL of 200 mM NaCl and 500 mL of 200 mM NaCl + 20 mL of suspended bacterial cells;

[0020] Figure 10 CAT activities of Zhongshancaiyun and Lianghongyang seedlings after 4 weeks of treatment with 500 mL of 200 mM NaCl and 500 mL of 200 mM NaCl + 20 mL of suspended bacterial cells;

[0021] Figure 11 POD activities of Zhongshancaiyun and Lianghongyang seedlings after 4 weeks of treatment with 500 mL of 200 mM NaCl and 500 mL of 200 mM NaCl + 20 mL of suspended bacterial cells;

[0022] Figure 12Hydrogen peroxide content of Zhongshancaiyun and Lianghongyang seedlings after 4 weeks of treatment with 500 mL of 200 mM NaCl and 500 mL of 200 mM NaCl + 20 mL of suspended bacteria

[0023] Figure 13 Superoxide anion content of Zhongshancaiyun and Lianghongyang seedlings after 4 weeks of treatment with 500 mL of 200 mM NaCl and 500 mL of 200 mM NaCl + 20 mL of suspended bacteria Detailed implementation method

[0024] The technical solutions provided by the present invention will be described in detail below in conjunction with the embodiments, but they cannot be construed as limiting the protection scope of the present invention.

[0025] The Bacillus (Bacillus nitratirecucens) Cdb8-1 used in the present invention and the following examples was a gift from Anhui Normal University, and the preservation number of this strain is CCTCC M 20231655.

[0026] Example 1

[0027] (1) Inoculate the fresh bacterial solution of Bacillus (Bacillus nitratirecucens) Cdb8-1 cultured overnight into LB medium at an inoculation amount of 2%, and culture it in a constant temperature shaker at 28 °C and 200 rpm / min for 16 hours. Centrifuge at 10000 rpm / min for 5 min to collect the bacteria, wash the bacteria three times with sterile water, and then resuspend the bacteria with sterile water to prepare a suspended bacteria with a final concentration of 6.4×10 7 CFU / mL for subsequent experimental treatment.

[0028] (2) Prepare 200 mM NaCl solution for subsequent experimental treatment.

[0029] (3) After 20 days of cutting, the seedlings of Zhongshan Caiyun and Lianghong Poplar were treated with 500 mL of 200 mM NaCl and 500 mL of 200 mM NaCl + 20 mL of suspended bacteria, respectively. During the treatment, the NaCl solution and the suspended bacteria were both applied with watering. When treating with 500 mL of 200 mM NaCl + 20 mL of suspended bacteria, the two solutions were fully mixed evenly and then applied to the seedlings. The size specifications of the experimental pots were a bottom diameter of 12.5 cm, a height of 16.5 cm, and a mouth diameter of 16 cm. There were holes and trays at the bottom of the pots, and the soil filling amount in each pot was 1600 g. Daily management such as watering and weeding was carried out every week. After 4 weeks, the external morphological indexes such as fresh weight, plant height, and root length of the two treatments of the two colored-leaf poplar varieties were respectively counted, the differences in chlorophyll content, the differences in physiological indexes such as the activities of malondialdehyde, proline, and redox enzymes (SOD, CAT, POD), and the differences in the contents of hydrogen peroxide, superoxide anion, etc. were counted.

[0030] The measurement of chlorophyll fluorescence and the measurement of chlorophyll fluorescence parameters were carried out using

[0031] the FMS-2 pulse-modulated fluorometer (UK). The measurement was carried out simultaneously with the light response curve. The marked leaves were measured, and the average value was taken as the measured value. First, the parameters under the light reaction were measured. After the measurement was completed, the light transmission hole was closed. After 30 min of dark treatment, the fluorescence parameters under the dark reaction were measured. The maximum photochemical efficiency of PSII: Fv / Fm = (Fm - Fo) / Fm;

[0032] Weigh the leaves of poplar seedlings under different treatments, cut them into pieces after removing the leaf veins and wash the leaves. The leaf fragments were collected and placed in 80% acetone and stored in the dark at 28 °C for 24 h until the leaves turned white to ensure complete extraction of chlorophyll. The chlorophyll extract was collected and quantified. 3 ml of the chlorophyll extract was taken to measure the absorbance value and calculate the total chlorophyll content at wavelengths of 663 nm, 645 nm, and 470 nm respectively, using 80% acetone as a blank control.

[0033] Determination of malondialdehyde (MDA) content

[0034] 1. Cut a leaf of the same part from each plant, take a mixed sample of 0.1 g, cut it into pieces, add 2 mL of 10% trichloroacetic acid and a small amount of quartz sand, grind it into a homogenate, and then add 8 mL of 10% trichloroacetic acid to further grind. The homogenate was transferred to a 10 mL centrifuge tube and centrifuged at 4000 rpm / min for 10 min. The supernatant was the malondialdehyde extract.

[0035] 2. Color reaction and determination: Take 4 clean test tubes, number them. 3 test tubes are for samples (with three replicates), each adding 2 mL of malondialdehyde extraction solution, and 1 test tube is for the control, adding 2 mL of ultrapure water. Then add 2 mL of 0.6% thiobarbituric acid solution to each tube and shake well. The mixed solution reacts in a boiling water bath for 10 min (starting from when small bubbles appear in the solution in the test tube), take out the test tubes and cool them quickly, centrifuge at 4000 rpm / min for 10 min, and measure the absorbance (A) values of the supernatant at wavelengths of 532 nm, 450 nm, and 600 nm respectively.

[0036] 3. Result calculation: The calculation formula for MDA concentration: C MDA = 6.45(A 532 - A 600 ) - A 450 (μmol / L), where A 450 , A 532 and A 600 are the absorbance values measured at wavelengths of 450 nm, 532 nm, and 600 nm. The content of MDA (μmol / L FW) = (C MDA * volume of extraction solution) / (fresh weight of leaves * 1000).

[0037] Determination of proline (Pro) content

[0038] 1. Extraction of proline: Select leaves at the same position from each plant, take a mixed sample of 0.1 g, cut them into pieces, place them in stoppered test tubes respectively, and then add 5 mL of 3% sulfosalicylic acid solution to each tube. Extract in a boiling water bath for 10 min (shake frequently during the extraction process), cool and filter into clean test tubes. The filtrate is the proline extraction solution.

[0039] 2. Determination of proline: Pipette 2 mL of proline extraction solution into a stoppered test tube, add 2 mL of glacial acetic acid and 2 mL of 2.5% acidic ninhydrin reagent, heat in a boiling water bath for 30 min, and the solution will turn red. After cooling, add 4 mL of toluene, shake for 30 s, let it stand for a while, take the upper layer solution into a 10 mL centrifuge tube, and centrifuge at 3000 rpm / min for 5 min. Gently pipette the upper layer of proline red toluene solution into a cuvette, use toluene solution as the blank control, and measure the absorbance value at a wavelength of 520 nm.

[0040] 3. Result calculation: Check the content X of proline in the sample determination solution from the standard curve, and calculate the proline content according to the following calculation formula.

[0041] Proline content (μg / g FW) = (X * total volume of extraction solution) / (fresh weight of sample * volume of extraction solution during determination).

[0042] Determination of superoxide dismutase (SOD) activity:

[0043] 1. Weigh the empty 1.5 mL centrifuge tube, then put about 100 mg of colorful poplar leaves into the 1.5 mL centrifuge tube for liquid nitrogen grinding. Add 1.5 mL of 1 / 15 mol / L phosphate buffer (pH 7.8), place it at 4 °C for 30 min, then centrifuge at 11,000 rpm for 20 min using a 4 °C centrifuge. Pipette the supernatant into a new pre-cooled 1.5 mL centrifuge tube as the crude enzyme solution.

[0044] 2. Dilute the crude enzyme solution 5-fold with 1 / 15 M phosphate buffer, then take 0.5 mL and put it into a new 2 mL centrifuge tube. Add 1.5 mL of SOD reaction solution, react in a 6-level light incubator at 30 °C for 10 min, then immediately terminate the reaction and immediately read the absorbance value at 560 nm, labeled as A2. Among them, 0.5 mL of double-distilled water (H2O) is mixed with 1.5 mL of SOD reaction solution as a control, labeled as A1, and 0.5 mL of diluted enzyme solution is mixed with 1.5 mL of H2O for zero adjustment.

[0045] 3. Calculation of enzyme activity: ΔA = (A1 - A2) / A1; SOD activity = (N × ΔA) / (W × T × 50%), where, A1: control reaction value; A2: reaction value after adding enzyme solution; N: dilution factor; W: material weight, g; T: reaction time, min.

[0046] Determination of Catalase (CAT) Activity

[0047] 1. The extraction of the crude enzyme solution is the same as above, so directly use the above crude enzyme solution for the determination of CAT activity.

[0048] 2. Determination of CAT enzyme activity: Add 3 mL of 20 mmol / L hydrogen peroxide solution to a 10 mL test tube, add 50 μL of the crude enzyme solution, quickly mix well and transfer it to a quartz cuvette, measure the absorbance value A at a wavelength of 240 nm, continuously measure for 1 - 3 min, and record the initial values (Ainitial and Aend).

[0049] 3. Calculation of CAT enzyme activity: Take a change in absorbance of 0.001 per minute per gram of fresh weight (FW) of the leaf sample as 1 unit of catalase activity.

[0050] CAT enzyme activity calculation formula: CAT activity = (ΔA 240 *V) / (0.001*t*Vs*W), where, ΔA 240 : change in absorbance value of the reaction mixture (Ainitial - Aend); t: enzyme-catalyzed reaction time; V: total volume of the sample extraction solution; Vs: volume of the sample extraction solution taken during determination; W: sample mass.

[0051] Determination of Peroxidase (POD) Activity

[0052] 1. Crude enzyme solution extraction: Use the above-mentioned crude enzyme solution.

[0053] 2. POD enzyme reaction system and sample addition sequence: 3 mL of 25 mmol / L guaiacol solution, 0.2 mL of 250 mmol / L hydrogen peroxide solution, 0.1 mL of crude enzyme solution. Start recording the absorbance value of the reaction system at a wavelength of 470 nm every 30 s starting from 30 s after adding the crude enzyme solution, and continuously measure for 10 min.

[0054] 3. Calculation of POD enzyme activity: When the change in absorbance value per minute per gram of fresh weight (FW) leaf sample increases by 0.001, it is defined as 1 unit of peroxidase activity.

[0055] POD enzyme activity calculation formula: POD activity = (ΔA 470 *V) / (W*Vs*0.001*t), where, ΔA 470 : Change in absorbance value of the reaction mixture; V: Total volume of the sample extract; W: Sample mass; Vs: Volume of the sample extract taken during measurement; t: Enzyme-catalyzed reaction time.

[0056] Determination of H2O2 content

[0057] Determination was carried out according to the method of Christense et al. (1997). Take the leaves of poplar seedlings under different treatments, remove the leaf veins, weigh approximately 0.5 g, record the specific weight, grind them into a homogenate in a pre-cooled 0.1% trichloroacetic acid (TCA) ice bath, suck them into a centrifuge tube with a pipette, then rinse the mortar with trichloroacetic acid multiple times and suck them into the above centrifuge tube. Centrifuge at 1200 g for 10 min at 4 °C, discard the precipitate and retain the supernatant. Take 1 ml of the supernatant, add 0.1 ml of 95% hydrochloric acid containing titanium tetrachloride (TiCl4) (containing 20% w / v TiCL4) solution in sequence, add 0.2 ml of ammonia water (NH4OH) while mixing, let it stand for 2 min, then centrifuge at 1000 g for 10 min at 4 °C, discard the supernatant and retain the precipitate. Wash the above precipitate with pre-cooled acetone multiple times at least 3 times to ensure the precipitate is colorless. Finally, add 3 ml of 1 mol·L -1 sulfuric acid to dissolve the precipitate, and make the volume up to 5 ml. The resulting solution was colorimetric at a wavelength of 415 nm and the H2O2 content was calculated.

[0058] O2 - Determination of production rate

[0059] According to the method reported by Schneider et al., take the leaves of poplar seedlings under different treatments, remove the leaf veins, weigh approximately 0.5 g, record the specific weight, add the extraction solution phosphate buffer solution (65 mmol·L -1, 5 ml of it was thoroughly ground into a homogenate in an ice bath. The mixture was centrifuged at 4°C using a centrifuge, with the centrifugation conditions set at 5000 g / min for 15 min. The precipitate was discarded and the supernatant was retained, and it was re-quantified to 5 ml. Then, 0.5 ml of the supernatant was taken, and 0.5 ml of the reaction solution, phosphate buffer solution (65 mmol·L -1 , pH 7.8), and 1 ml of hydroxylamine hydrochloride (10 mmol·L -1 ) were added. After mixing, it was left to stand at room temperature for about 1 h. Then, 1 ml of sulfanilic acid (17 mmol·L -1 ) and 1 ml of α-naphthylamine (7 mmol·L -1 ) were successively added to the above mixture. The above mixture was reacted at room temperature for about 20 min. Finally, an equal volume of ether was added to the mixture, and it was shaken well. Then, it was centrifuged on a centrifuge at room temperature for 3 min, with the centrifugal force condition set at 3000 g. The supernatant (pink in color) after stratification was aspirated with a pipette and colorimetrically measured at a wavelength of 530 nm to obtain the A530 value, with the blank control set as the phosphate buffer solution. According to the established standard curve of NO2 - , the content of O2 - was calculated by conversion.

[0060] Results

[0061] (1) As Figure 1 shown, the fresh weights of the Zhongshan Caiyun and Lianghong Poplar seedlings after being treated with 200 mM NaCl for 4 weeks were 3.86 g and 3.47 g respectively. Compared with the fresh weights of the Zhongshan Caiyun and Lianghong Poplar seedlings after being treated with 200 mM NaCl for 4 weeks, the heights of the Zhongshan Caiyun and Lianghong Poplar seedlings treated with 200 mM NaCl + 20 mL of suspended bacteria significantly increased, being 5.23 g and 4.66 g respectively.

[0062] (2) As Figure 2 shown, the heights of the Zhongshan Caiyun and Lianghong Poplar seedlings after being treated with 200 mM NaCl for 4 weeks were 13.5 cm and 12.4 cm respectively. Compared with the heights of the Zhongshan Caiyun and Lianghong Poplar seedlings after being treated with 200 mM NaCl for 4 weeks, the heights of the Zhongshan Caiyun and Lianghong Poplar seedlings treated with 200 mM NaCl + 20 mL of suspended bacteria significantly increased, being 16.2 cm and 14.3 cm respectively.

[0063] (3) As Figure 3As shown, the root weights of Zhongshancaiyun and Lianghongyang seedlings after 4 weeks of treatment with 200 mM NaCl were 0.53 g and 0.47 g respectively. Compared with the root weights of Zhongshancaiyun and Lianghongyang seedlings after 4 weeks of treatment with 200 mM NaCl, the root lengths and root weights of Zhongshancaiyun and Lianghongyang seedlings treated with 200 mM NaCl + 20 mL of suspended bacterial cells were significantly increased, being 0.72 g and 0.58 g respectively.

[0064] (4) As Figure 4 shown, the root lengths of Zhongshancaiyun and Lianghongyang seedlings after 4 weeks of treatment with 200 mM NaCl were 6.2 cm and 5.6 cm respectively. Compared with the root lengths of Zhongshancaiyun and Lianghongyang seedlings after 4 weeks of treatment with 200 mM NaCl, the root lengths of Zhongshancaiyun and Lianghongyang seedlings treated with 200 mM NaCl + 20 mL of suspended bacterial cells were significantly increased, being 8.3 cm and 7.1 cm respectively.

[0065] (5) As Figure 5 、 6 shown, the chlorophyll contents of Zhongshancaiyun and Lianghongyang seedlings after 4 weeks of treatment with 200 mM NaCl were 3.23 mg·g -1 and 2.03 mg·g -1 respectively, and the Fv.Fm -1 values were 0.62 and 0.53 respectively. Compared with the chlorophyll contents and Fv.Fm -1 values of Zhongshancaiyun and Lianghongyang seedlings after 4 weeks of treatment with 200 mM NaCl, the chlorophyll contents (being 4.56 mg·g -1 and 2.69 mg·g -1 ) and Fv.Fm-1 values of Zhongshancaiyun and Lianghongyang seedlings treated with 200 mM NaCl + 20 mL of suspended bacterial cells were significantly increased (being 0.83 and 2.69 respectively).

[0066] (6) As Figure 7 shown, the MDA contents of Zhongshancaiyun and Lianghongyang seedlings after 4 weeks of treatment with 200 mM NaCl were 14.6 μmol·g -1 and 13.5 μmol·g -1 respectively. Compared with the MDA contents of Zhongshancaiyun and Lianghongyang seedlings after 4 weeks of treatment with 200 mM NaCl, the MDA contents of Zhongshancaiyun and Lianghongyang seedlings treated with 200 mM NaCl + 20 mL of suspended bacterial cells were significantly decreased, being 12.5 μmol·g -1 and 12.8 μmol·g -1 respectively.

[0067] (7) As Figure 8 shown, the proline concentrations of Zhongshancaiyun and Lianghongyang seedlings after 4 weeks of treatment with 200 mM NaCl were 28.4 μg·g-1 and 24.3 μg·g -1 Compared with the proline concentrations of Zhongshancaiyun and Lianghongyang seedlings treated with 200 mM NaCl for 4 weeks, the proline concentrations of Zhongshancaiyun and Lianghongyang seedlings treated with 200 mM NaCl + 20 mL suspended bacteria were significantly increased, being 32.7 μg·g -1 and 30.4 μg·g -1 respectively.

[0068] (8) As Figures 9 - 11 shown in and Tables 1 - 3, compared with the SOD, CAT, and POD enzyme activities of Zhongshancaiyun and Lianghongyang seedlings treated with 200 mM NaCl for 4 weeks, the SOD, POD, and CAT enzyme activities of Zhongshancaiyun and Lianghongyang seedlings treated with 200 mM NaCl + 20 mL suspended bacteria were significantly increased.

[0069] Table 1 SOD Activity

[0070] <![CDATA[SOD(U·g -1 FW)]]> Zhongshan Caiyun Lianghong Yang 200 mM NaCl 264.5 243.2 200 mM NaCl + Bacterial solution 305.8 265.7

[0071] Table 2 CAT Activity

[0072] <![CDATA[CAT(U·g -1 FW)]]> Zhongshan Caiyun Lianghong Yang 200 mM NaCl 87.4 74.5 200 mM NaCl + Bacterial solution 98.2 88.7

[0073] Table 3 POD Activity

[0074] <![CDATA[POD(U·g -1 FW)]]> Zhongshan Caiyun Lianghong Yang 200 mM NaCl 264.3 243.6 200 mM NaCl + Bacterial solution 305.4 265.2

[0075] (9) As Figures 12 - 13 shown in and Tables 4 - 5, compared with the hydrogen peroxide and superoxide anion contents of Zhongshancaiyun and Lianghongyang seedlings treated with 200 mM NaCl for 4 weeks, the hydrogen peroxide and superoxide anion contents of Zhongshancaiyun and Lianghongyang seedlings treated with 200 mM NaCl + 20 mL suspended bacteria were significantly decreased.

[0076] Table 4 H2O2 Content

[0077] <![CDATA[H2O2 content (μmol.g -1 FW)]]> Zhongshan Caiyun Lianghong Yang 200 mM NaCl 0.83 0.88 200 mM NaCl + Bacterial solution 0.57 0.72

[0078] Table 5 H2O2 Content

[0079] <![CDATA[O2 - content(umol.g -1 FW)]]> Zhongshan Caiyun Lianghong Yang 200 mM NaCl 42.5 46.8 200 mM NaCl + Bacterial solution 36.4 40.8

[0080] In summary, the treatment with 20 mL suspended bacteria can reduce the contents of hydrogen peroxide, superoxide anion, and MDA in the seedlings of Zhongshancaiyun and Lianghongyang after treatment with 200 mM NaCl by increasing the activities of SOD, POD, and CAT enzymes, and further increase the proline concentration, chlorophyll content, and Fv / Fm in the seedlings of Zhongshancaiyun and Lianghongyang -1, thereby causing changes in the external morphology such as plant height and root length of Zhongshan Caiyun and Lianghong Poplar seedlings, and enhancing the salt tolerance of Zhongshan Caiyun and Lianghong Poplar seedlings.

[0081] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A Bacillus ( Bacillus nitratireducens ) Application of Cdb8-1 in improving salt tolerance of colorful poplar, characterized in that: The Bacillus ( Bacillus nitratireducens ) The preservation number of Cdb8-1 is CCTCCM 20231655; the colorful poplars are Zhongshan Caiyun and Lianghong Poplar.

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