Preparation method of Baileucin and application of Baileucin in agriculture

Abstract

The invention relates to the field of agricultural biology, and particularly discloses a preparation method of white leucin and application of the white leucin in agriculture, the preparation method comprises the following steps: S1, carrying out liquid fermentation on Penicillium tomii with the preservation number of CGMCC NO.42204 to obtain mycelium; s2, performing ultrasonic-assisted extraction on the mycelium by adopting an ethanol solution to obtain a crude extract; s3, performing chemical synthesis modification on precursor substances in the crude extract, including Boc protected linear dipeptide synthesis, protecting group removal and cyclization reaction, so as to obtain the white bright peptide, a synergistic composition application system is constructed by scientifically compounding the leuleucin derived from the specific penicillium tomiorum strain, the alginic acid and the compound sodium nitrate, and broad-spectrum and efficient relief of adversity stress of various plants at ultralow concentration is successfully realized; the invention not only obviously enhances the stress resistance of plants, but also effectively overcomes the problems of single function, unstable effect, high application concentration, potential environmental risk and the like in the prior art.

Description

Technical Field

[0001] This invention belongs to the field of agricultural biology, specifically a method for preparing white bleach peptides and their application in agriculture. Background Technology

[0002] Plants often face various abiotic stresses throughout their growth cycle, among which soil salinization, low temperature, and drought are the main environmental factors restricting the improvement of crop yield and quality. These adverse conditions can trigger a series of physiological disorders in plants, such as osmotic imbalance, disruption of ion homeostasis, accumulation of reactive oxygen species, and damage to cell membrane structure, ultimately leading to inhibited plant growth, reduced biomass, and yield loss.

[0003] To address these issues, agricultural production often employs measures such as physical improvement, breeding of stress-resistant varieties, or application of exogenous plant growth regulators. Among these, the application of exogenous regulators has received widespread attention due to its ease of use and rapid effectiveness. Currently, various biological or chemical agents are used to enhance plant stress resistance, such as alginic acid and sodium nitrate, which possess certain biostimulatory or growth-regulating functions. However, most existing products still suffer from limitations such as single function, unstable effects, high effective application concentrations, or poor applicability across different crops and stress types, making it difficult to meet the comprehensive needs of modern agriculture for green, efficient, and multifunctional stress-resistant technologies. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention provides the application of compositions based on Penicillium thuringiensis extract in alleviating plant stress, thereby solving the problem in the prior art of lacking a plant stress resistance technology solution that combines broad-spectrum stress resistance, efficient synergistic effect, and environmental friendliness at ultra-low concentrations.

[0005] A method for preparing a brightening peptide includes the following steps:

[0006] S1. Penicillium thomii with accession number CGMCC NO.42204 was subjected to liquid fermentation to obtain mycelium;

[0007] S2. The mycelium is extracted with an ethanol solution using ultrasound-assisted extraction to obtain a crude extract;

[0008] S3. The precursor material in the crude extract is chemically modified, including the synthesis of Boc-protected linear dipeptides, removal of protecting groups and cyclization reaction, to obtain the white bright peptide.

[0009] Preferably, when the white peptide is used to prepare an anti-stress composition, it is mixed with an agriculturally acceptable adjuvant.

[0010] Preferably, alginate and sodium nitrate are also added when preparing the anti-stress composition; the effective concentration of the whitening peptide in the final composition is 5 ng / mL to 100 ng / mL, the effective concentration of the alginate is 10 mg / L to 100 mg / L, and the effective concentration of the sodium nitrate is 1 mg / L to 10 mg / L.

[0011] Preferably, the effective concentration of the whitening peptide in the final composition is 20 ng / mL, the effective concentration of the alginic acid is 40 mg / L, and the effective concentration of the sodium nitrate is 3 mg / L.

[0012] An application of the white luminescent peptide prepared by the above method in agriculture, wherein the white luminescent peptide is applied to plants to alleviate the abiotic stress suffered by the plants; the abiotic stress is salt stress, low temperature stress or drought stress.

[0013] Preferably, the plant is corn, lettuce, or cucumber.

[0014] Preferably, the mitigation of plant abiotic stress manifests as one or more of the following effects:

[0015] Improve plant survival rate, fresh weight, dry weight, or root length;

[0016] Maintain a high chlorophyll content;

[0017] Increase the activity of superoxide dismutase (SOD), peroxidase (POD), or catalase (CAT);

[0018] Reduce the accumulation of malondialdehyde (MDA);

[0019] Maintain a high K+ / Na+ ratio within the cell.

[0020] The biomaterial preservation information of this invention is as follows:

[0021] The strain PFJ-4 used in this invention has been identified as *Penicillium thomii* and was deposited on September 16, 2025, at the China General Microbiological Culture Collection Center (CGMCC), located at Institute of Microbiology, Chinese Academy of Sciences, No. 3, No. 1 Beichen West Road, Chaoyang District, Beijing, 100101, China. The accession number is CGMCC No. 42204. The strain was confirmed to be viable by the collection center on September 16, 2025.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] By scientifically combining white bleach peptide derived from a specific Penicillium strain with alginate and sodium nitrate, a synergistic compound application system was constructed, which successfully achieved broad-spectrum and efficient relief of various plant abiotic stresses at ultra-low concentrations.

[0024] This invention not only significantly enhances the stress resistance of plants, but also effectively overcomes the problems of single function, unstable effect, high application concentration and potential environmental risks in existing technologies. It provides a new plant stress resistance strategy that is environmentally friendly, easy to operate and widely applicable, providing strong technical support for the sustainable development of modern agriculture. Attached Figure Description

[0025] Figure 1 This is a flowchart illustrating the preparation process of the whitening peptide of the present invention;

[0026] Figure 2 The effect of different concentrations of white bleaching peptide on the fresh weight of different plants under abiotic stress;

[0027] Figure 3 The effects of different treatments under salt stress on growth indicators of lettuce seedlings;

[0028] Figure 4 The effects of different treatments under salt stress on growth indicators of lettuce seedlings;

[0029] Figure 5 The effects of different treatments under salt stress on maize growth indicators;

[0030] Figure 6 The effects of different treatments under salt stress on cucumber growth indicators;

[0031] Figure 7 The chemical structural formula of the whitening peptide;

[0032] Figure 8 The phenotypes of lettuce under salt-alkali stress were shown in the figure after combining alginic acid and whitening peptide (treatment 1 was the water control under normal conditions, treatment 2 was the water control under salt stress, treatment 3 was a single treatment with 20 ng / mL whitening peptide; treatment 4 was a single treatment with 10 mg / L alginic acid, treatment 5 was a single treatment with 40 mg / L alginic acid, treatment 6 was a treatment with 100 mg / L alginic acid; treatment 7 was a combination treatment with 20 ng / mL whitening peptide and 10 mg / L alginic acid, treatment 8 was a combination treatment with 20 ng / mL whitening peptide and 40 mg / L alginic acid, and treatment 9 was a combination treatment with 20 ng / mL whitening peptide and 100 mg / L alginic acid).

[0033] Figure 9The phenotypic effects of maize under salt-alkali stress were shown in different combinations of white lecithin with alginic acid and sodium nitrophenolate (treatment 1 was the water control under normal conditions, treatment 2 was the water control under salt stress, treatment 3 was a single treatment with 20 ng / mL white lecithin; treatment 4 was a combination treatment with 20 ng / mL white lecithin and 40 mg / L alginic acid, treatment 5 was a combination treatment with 20 ng / mL white lecithin and 3 mg / L sodium nitrophenolate, and treatment 6 was a combination treatment with 20 ng / mL white lecithin, 40 mg / L alginic acid, and 3 mg / L sodium nitrophenolate).

[0034] Figure 10 The content of soluble glycoproteins, malondialdehyde, superoxide dismutase, and catalase in maize leaves under salt-alkali stress was determined by different compounding methods of white luminol peptide with alginic acid and sodium nitrophenolate.

[0035] Figure 11 The phenotypic effects of cucumbers under salt-alkali stress were observed under different combinations of white bleaching peptide with alginic acid and sodium nitrophenolate (treatment 1 was the water control under normal conditions, treatment 2 was the water control under salt stress, treatment 3 was a single treatment with 20 ng / mL white bleaching peptide; treatment 4 was a combination treatment with 20 ng / mL white bleaching peptide and 40 mg / L alginic acid, treatment 5 was a combination treatment with 20 ng / mL white bleaching peptide and 3 mg / L sodium nitrophenolate, and treatment 6 was a combination treatment with 20 ng / mL white bleaching peptide, 40 mg / L alginic acid, and 3 mg / L sodium nitrophenolate).

[0036] Figure 12 The content of abscisic acid, proline, malondialdehyde, and catalase in cucumber leaves under salt-alkali stress was determined by different compounding methods of white luminol peptide with alginic acid and sodium nitrophenolate.

[0037] Figure 13 This describes the chemical synthesis process of whitening peptide. Detailed Implementation

[0038] It should be noted that the following detailed descriptions are exemplary and intended to provide further illustration of the invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0039] Example 1: Preparation of Brightening Peptide

[0040] This embodiment provides a complete preparation process for whitening peptide. First, crude extract is obtained through fermentation with Penicillium thuringiensis, and then high-purity product is obtained through chemical synthesis and modification.

[0041] The specific steps are as follows:

[0042] (1) Fermentation of the strain and preparation of crude extract: Penicillium thuringiensis with accession number CGMCC NO.42204 was subjected to liquid fermentation. The mycelium was collected by centrifugation after fermentation, and the mycelium was dried, pulverized, and then extracted with ultrasonic-assisted extraction using 70% ethanol solution. The extract was concentrated under reduced pressure and freeze-dried to obtain a crude extract containing the precursor of white bleach peptide.

[0043] (2) Chemical synthesis, modification and purification: Starting with the precursor substances isolated from the crude extract, chemical modification was carried out through three steps: synthesis of Boc-protected linear dipeptides, removal of protecting groups and cyclization reaction. Finally, high-purity white bright peptide product with a well-defined structure was obtained through crystallization, filtration and drying.

[0044] Example 2: Verification of the anti-stress effect of whitening peptide

[0045] Experimental Design:

[0046] This experiment was conducted in indoor pots using lettuce, corn, and cucumber as materials. To systematically evaluate the stress resistance effects of white leucine peptide under salt (150 mM NaCl), low temperature (10℃ / 4℃), and drought stress, seven independent treatments were set up for each stress type: normal growth control (CK0), stress control (CK1), and white leucine peptide treatments at concentrations of 5, 10, 20, 50, 100, and 150 ng / mL. The alleviating effect of white leucine peptide under different crop and stress combinations was analyzed by measuring plant fresh weight.

[0047] Experimental results:

[0048] Under saline-alkali stress, the 5 ng / mL treatment significantly increased the biomass of the three crops compared to CK1, but the effect was optimal at 20 ng / mL. Compared to the stress control group (CK1), the 20 ng / mL treatment significantly increased the fresh weight of lettuce, corn, and cucumber by 71.5%, 101.8%, and 80.7%, respectively, restoring them to 91.4%, 90.4%, and 90.8% of normal levels. The promoting effect weakened significantly when the concentration increased to 150 ng / mL.

[0049] Under low-temperature stress, lettuce achieved the best protective effect at an extremely low concentration of 5 ng / mL, with its fresh weight increasing by 43.9% compared to CK1 and recovering to 96.1% of the normal level, demonstrating extremely high sensitivity. Corn and cucumber, on the other hand, showed the best effect at 20 ng / mL, with their fresh weight increasing significantly by 57.5% and 43.6% compared to CK1, respectively. Furthermore, the response concentrations for all crops were concentrated in the range of 5-100 ng / mL.

[0050] Under drought stress, the fresh weight of lettuce and cucumber treated with a concentration of 20 ng / mL increased significantly by 74.3% and 81.2% respectively compared to CK1, showing the most outstanding recovery effect. Corn reached its optimal value at 50 ng / mL, with a fresh weight increase of 105.7% compared to CK1. Furthermore, within the effective range of 5-100 ng / mL, all treatments were significantly superior to CK1; however, the effect decreased beyond this range, and the promoting effect of the 150 ng / mL treatment was no significantly different from the lowest effective concentration.

[0051] In summary, bleaching peptides have significant alleviating effects on various abiotic stresses within a concentration range of 5-100 ng / mL, with 20 ng / mL being the most universally effective concentration.

[0052] like Figure 2 The figure shows the effect of different concentrations of white bleach peptide on the fresh weight of different plants under abiotic stress conditions.

[0053] Example 3: Synergistic effect of alginate and whitening peptide in alleviating plant salt stress

[0054] (1) Experimental design:

[0055] This study used lettuce as the experimental material. Seedlings were raised in plug trays. After two weeks of cultivation, the covering film was removed, and healthy, uniformly sized seedlings were transplanted into flowerpots (10×10×8cm). Five days after the seedlings recovered, they were treated with salt stress (150mM NaCl) by spraying the treatment solution onto the lettuce leaves. The following treatments were used: ① Normal growth control group (CK0); ② Salt stress control group (CK1); ③ 20 ng / mL white bleaching peptide; ④ 10 mg / L alginic acid (HA-10); ⑤ 40 mg / L alginic acid (HA-40); ⑥ 100 mg / L alginic acid (HA-100); ⑦ White bleaching peptide + HA-10; ⑧ White bleaching peptide + HA-40; ⑨ White bleaching peptide + HA-100. Samples were taken 14 days after treatment for analysis. The main indicators included: number of leaves, leaf area, leaf fresh weight, root fresh weight and chlorophyll content, to evaluate the salt resistance effect of the compound combination.

[0056] (2) Experimental results:

[0057] The experimental results showed that 150 mM NaCl salt stress had a significant inhibitory effect on lettuce growth. Compared with the normal control group (CK0), all indicators of the salt-stressed control group (CK1) decreased significantly. After exogenous application of the treatment solution, different treatment groups showed significant concentration effects and synergistic effects. Among them, the combined treatment of 20 ng / mL white bleaching peptide and 40 mg / L alginate (white bleaching peptide + HA-40) showed the best comprehensive effect.

[0058] Specifically, compared with CK1, the treatment with Bailiang peptide + HA-40 significantly restored all indicators: leaf area, leaf fresh weight, number of leaves, chlorophyll content, root length and root fresh weight increased significantly by 71.4%, 80.8%, 38.5%, 51.1%, 66.8% and 107.4%, respectively, showing a prominent effect on promoting biomass accumulation.

[0059] Meanwhile, the combined treatment with bleaching peptide and HA-40 showed significantly better results than the single treatment group, demonstrating a clear synergistic effect. Compared with the 20 ng / mL cyclic dipeptide treatment alone, the leaf fresh weight, chlorophyll content, and root fresh weight of the bleaching peptide + HA-40 treatment increased by 28.3%, 16.4%, and 34.7%, respectively; compared with the 40 mg / L alginic acid treatment alone (HA-40), the above indicators increased by 33.0%, 13.0%, and 29.0%, respectively.

[0060] like Figure 3 The figure shows the effects of different treatments under salt stress on the growth indicators of lettuce seedlings.

[0061] Example 4: Synergistic effect of sodium nitrophenolate and whitening peptide in alleviating plant salt stress

[0062] (1) Experimental design:

[0063] This study used lettuce as the experimental material. Seedlings were raised in plug trays. After two weeks of cultivation, the covering film was removed, and robust, uniformly sized seedlings were transplanted into flowerpots (10×10×8cm). Five days after the seedlings recovered, they were subjected to salt stress (150mM NaCl) treatment by spraying the solution onto the lettuce leaves. The following treatments were used: ① Normal growth control group (CK0); ② Salt stress control group (CK1); ③ 20 ng / mL White Bright Peptide; ④ 1 mg / L Sodium Nitrophenolate (SN-1); ⑤ 3 mg / L Sodium Nitrophenolate (SN-3); ⑥ 10 mg / L Sodium Nitrophenolate (SN-10); ⑦ White Bright Peptide + SN-1; ⑧ White Bright Peptide + SN-3; ⑨ White Bright Peptide + SN-10. Samples were taken 14 days after treatment for analysis of key indicators including leaf number, leaf area, leaf fresh weight, root fresh weight, and chlorophyll content, to evaluate the salt tolerance effect of the compound treatments.

[0064] (2) Experimental results:

[0065] The results showed that 150 mM NaCl stress (CK1) significantly inhibited various growth indicators of lettuce. Exogenous application of 3 mg / L sodium nitrophenolate (SN-3) or 20 ng / mL cyclic dipeptide alone could effectively alleviate salt stress, and the effects of the two were comparable. However, the combination of 20 ng / mL bleaching peptide and 3 mg / L SN-3 (bleaching peptide + SN-3) showed the best synergistic effect.

[0066] The treatment with Brilliant Peptide + SN-3 showed a remarkably significant effect in alleviating salt stress. Compared with CK1, this treatment increased leaf area, leaf fresh weight, leaf number, chlorophyll content, root length, and root fresh weight by 72.4%, 93.1%, 41.4%, 61.5%, 73.3%, and 106.7%, respectively, with a particularly prominent effect on promoting biomass accumulation (leaf fresh weight and root fresh weight).

[0067] The synergistic effect of the combined treatment was significantly better than that of the single treatment. The effect of the Bailiang peptide + SN-3 treatment significantly surpassed that of the Bailiang peptide or SN-3 single treatment. Compared with the Bailiang peptide single treatment, the leaf area, leaf fresh weight, and root fresh weight of the combined treatment increased by 32.6%, 41.4%, and 55.4%, respectively; compared with the SN-3 single treatment, the increases were 29.7%, 38.4%, and 48.1%, respectively.

[0068] like Figure 4 The figure shows the effects of different treatments under salt stress on the growth indicators of lettuce seedlings.

[0069] Example 5: Verification and optimization of the universality of the optimal composition for salt tolerance in different crops

[0070] Experiment 1: Effects of different compounding methods on salt tolerance of maize

[0071] (1) Experimental design:

[0072] Select uniform and plump corn seeds, place them in a petri dish with a layer of moist nutrient soil, ensuring no overlap between seeds, then cover the surface with another layer of moist nutrient soil, place in an artificial climate chamber to germinate in the dark, and after 48 hours when the seeds show white sprouts, select seeds with uniform growth for sowing.

[0073] Fill small flowerpots 4 / 5 full with a suitable amount of moistened potting soil. Sow 4 seeds per pot, spreading them evenly on the surface of the soil without overlapping. After sowing, fill the pots completely with potting soil. After salt stress treatment, place the pots in an artificial climate chamber with a temperature of 23℃, humidity of 50%-60%, and light intensity of 6000-7000 lux. Water regularly to keep the soil moist. The experimental treatments are as follows: ① Normal growth control group (CK0); ② Salt stress control group (CK1); ③ 20 ng / mL white bleaching peptide; ④ White bleaching peptide combined with 40 mg / L alginic acid (white bleaching peptide + HA-40); ⑤ White bleaching peptide combined with 3 mg / L sodium nitrophenolate (white bleaching peptide + SN-3); ⑥ White bleaching peptide combined with 40 mg / L alginic acid and 3 mg / L sodium nitrophenolate (white bleaching peptide + HA-40 + SN-3).

[0074] (2) Experimental results:

[0075] The experimental results showed that under salt stress, all treatments could effectively alleviate the inhibition of maize growth by salt stress, and the combined treatment was significantly better than the single treatment, showing a significant synergistic effect.

[0076] From the perspective of growth indicators, all treatments effectively reversed the inhibitory effect of salt stress, with the ternary compound (Bright Peptide + HA-40 + SN-3) showing the most outstanding effect, significantly increasing the aboveground fresh weight, underground fresh weight, and leaf area of ​​maize by 141.8%, 135.9%, and 61.4%, respectively, compared to the stress control group (CK1). The activities of superoxide dismutase (SOD) and catalase (CAT) in this treatment recovered to 92.0% and 92.9% of normal levels, respectively, enhancing the plant's antioxidant defense capabilities. The content of malondialdehyde (MDA), representing membrane damage, was significantly reduced by 58.6% compared to CK1, effectively protecting the integrity of the cell membrane. At the same time, the treatment also optimized the plant's osmotic regulation strategy, reducing the content of soluble sugars that abnormally accumulated under salt stress to maintain osmotic balance from 1.60 mg / g (CK1) to nearly normal 1.30 mg / g, indicating that its physiological state shifted from stress defense to normal metabolism.

[0077] In summary, the ternary combination of Brightening Peptide, Sodium Nitrophenolate, and Alginic Acid (Brightening Peptide + HA-40 + SN-3) is the best solution for alleviating corn salt stress by enhancing antioxidant capacity, reducing membrane damage, and optimizing osmotic regulation.

[0078] like Figure 5 The figure shows the effects of different treatments on maize growth indicators under salt stress.

[0079] Experiment 2: Effects of different compounding methods on the salt tolerance of cucumber

[0080] (1) Experimental design:

[0081] Cucumber seedlings of uniform size were selected and transplanted into pots containing nutrient soil. After 7 days of acclimatization, salt stress treatment (150 mM NaCl) was applied, and foliar sprays of different treatment solutions were applied simultaneously. The experiment included the following treatments: ① Normal growth control group (CK0); ② Salt stress control group (CK1); ③ 20 ng / mL whitening peptide; ④ Whitening peptide combined with 40 mg / L alginic acid (whitening peptide + HA-40); ⑤ Whitening peptide combined with 3 mg / L sodium nitrophenolate (whitening peptide + SN-3); ⑥ Whitening peptide combined with 40 mg / L alginic acid and 3 mg / L sodium nitrophenolate (whitening peptide + HA-40 + SN-3).

[0082] (2) Experimental results:

[0083] The experimental results showed that white radiance peptide and its compound combination effectively alleviated salt stress damage in cucumbers through a differentiated synergistic mechanism, significantly promoted plant growth and improved physiological status.

[0084] In terms of growth indicators, the ternary compound (Bright Peptide + HA-40 + SN-3) showed the best overall effect, with key indicators such as root length and leaf fresh weight being closest to normal levels, demonstrating its comprehensive synergistic advantages. Meanwhile, the two binary compound systems exhibited distinct functional focuses: the combination of Bright Peptide and sodium nitrophenolate (Bright Peptide + SN-3) was most effective in expanding leaf area, reflecting the role of sodium nitrophenolate in promoting cell expansion; while the combination of Bright Peptide and alginate (Bright Peptide + HA-40) showed significant advantages in root fresh weight, plant height, and stem diameter.

[0085] At the physiological level, the combination of white leucine peptide and SN-3 most effectively inhibits the accumulation of the stress signaling molecule ABA, alleviating stress perception in plants from upstream. The combination of white leucine peptide and HA-40 shows better performance in directly protecting cell membrane structure (significantly reducing MDA) and finely regulating osmotic balance (effectively regulating proline). The ternary compound integrates the above advantages and achieves the optimal level of activating the key antioxidant enzyme CAT, thereby constructing a more comprehensive and stable homeostasis in the plant.

[0086] In summary, the three-component combination of Bailiang peptide (Bailiang peptide + HA-40 + SN-3) is the optimal strategy for comprehensive relief of salt stress, and the relative advantages of the two binary combinations in specific physiological directions have been clarified.

[0087] like Figure 6 The figure shows the effects of different treatments on cucumber growth indicators under salt stress.

[0088] Example 6:

[0089] like Figure 13 The synthesis process of the cyclic (L-isoleucine-L-leucine) dipeptide (white leucine peptide) is as follows:

[0090] L-leucine methyl ester, dichloromethane, EDCI, HOBT, triethylamine, and Boc-L-leucine were added to a 250 ml single-necked flask and reacted at room temperature for 5 h. After the reaction was completed, the flask was washed once with 1 N hydrochloric acid solution and once with saturated sodium bicarbonate solution.

[0091] The aqueous layer was discarded, and 6 equivalents of trifluoroacetic acid were added to dichloromethane. The mixture was stirred at room temperature for 1 hour to remove the Boc protecting group. After the reaction was complete, the pH was adjusted to 7-8 with 10% sodium hydroxide solution. The mixture was separated, the aqueous layer was discarded, and the dichloromethane layer was concentrated to dryness to obtain a yellow oily substance.

[0092] The yellow oily substance was dissolved in methanol, and an equal volume of concentrated ammonia was added. The mixture was reacted overnight at room temperature, resulting in the formation of a large amount of white solid. The solid was filtered and dried to obtain the white bright peptide.

[0093] 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 method for preparing a brightening peptide, characterized in that, Includes the following steps: S1. The Penicillium thuringiensis with accession number CGMCC NO.42204 was subjected to liquid fermentation to obtain mycelium; S2. The mycelium is extracted with an ethanol solution using ultrasound-assisted extraction to obtain a crude extract; S3. The precursor material in the crude extract is chemically modified, including the synthesis of Boc-protected linear dipeptides, removal of protecting groups and cyclization reaction, to obtain the white bright peptide.

2. The method for preparing whitening peptide according to claim 1, characterized in that, When the white peptide is used to prepare an anti-stress composition, it is mixed with agriculturally acceptable excipients.

3. The method for preparing whitening peptide according to claim 2, characterized in that, In preparing the anti-stress composition, alginate and sodium nitrate are also added; the effective concentration of the whitening peptide in the final composition is 5 ng / mL to 100 ng / mL, the effective concentration of the alginate is 10 mg / L to 100 mg / L, and the effective concentration of the sodium nitrate is 1 mg / L to 10 mg / L.

4. The method for preparing whitening peptide according to claim 3, characterized in that, The effective concentration of the whitening peptide in the final composition is 20 ng / mL, the effective concentration of the alginic acid is 40 mg / L, and the effective concentration of the sodium nitrate is 3 mg / L.

5. The application of a brightening peptide prepared by the method described in claim 1 in agriculture, characterized in that, The white peptide is applied to plants to alleviate the abiotic stresses suffered by the plants, namely salt stress, low temperature stress, or drought stress.

6. The application according to claim 5, characterized in that, The plant in question is corn, lettuce, or cucumber.

7. The application according to claim 5 or 6, characterized in that, The mitigation of plant abiotic stress manifests itself through one or more of the following effects: Improve plant survival rate, fresh weight, dry weight, or root length; Maintain a high chlorophyll content; Increase the activity of superoxide dismutase, peroxidase, or catalase; Reduce malondialdehyde accumulation; Maintaining high intracellular K + / Na + ratio.

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