Application of surfactin in promotion of rape root development

Abstract

The invention relates to the technical field of plants, in particular to application of surfactin in promotion of rape root development. According to the invention, a new function of the surfactin is found, and the surfactin can be used as a signal molecule to promote expression of related genes of auxin of the rape and promote development of lateral roots of the rape and formation of a branch prosite, so that development of a root system of the rape is remarkably promoted. Surfactin can be used for preparing products for promoting root development of rape, such as plant growth regulators, fertilizers or fertilizer additives and the like, and has a wide application prospect.

Description

Technical Field

[0001] The present invention relates to the field of plant technology, in particular to the application of surfactin in promoting the development of rapeseed root system. Background Art

[0002] Surfactin is a type of lipopeptide produced by Bacillus bacteria. A typical surfactin is composed of 7 α-amino acid residues and a C 13 -C 15 Surfactin is a cyclic compound composed of hydroxy fatty acids linked by lactone bonds. Variations in the length of the fatty acid chain and the position and type of amino acids on the peptide chain result in numerous homologues and isomers of surfactin.

[0003] Compared to traditional chemically synthesized surfactants, surfactants produced by bacterial strains have attracted considerable attention due to their sustainable availability, biodegradability, low toxicity, environmental compatibility, and structural stability in extreme environments such as high temperature and high salt levels. Surfactants can be used in the food industry as food additives and emulsifiers, and can also be developed into biopesticides to control pests and diseases and promote plant growth. They also have broad application prospects in daily chemicals and medicine.

[0004] Plant growth-promoting rhizobacteria (PGPRs) regulate the signaling pathways of plant root development by secreting abundant metabolites. These metabolites can be divided into two main categories: one is plant hormones, including auxins, gibberellins, cytokinins, abscisic acid, ethylene, and brassinosteroids, which directly regulate root development by activating downstream signaling pathways; the other is non-hormone signaling molecules, which regulate root development by influencing the homeostasis of endogenous plant hormones and the process of root development. Studies on the role of PGPRs in promoting root development are limited, but some literature reports suggest that the secreted volatile substances 2,3-butanediol and acetoin, as well as a microbial cyclic dipeptide diketopiperazine (DKP), may promote aboveground plant growth by affecting root development.

[0005] Most Bacillus species can produce surfactin, which means that biological surfactants such as surfactin may have a natural role in ecology. Previous studies on Bacillus subtilis mutants have confirmed the important role of surfactin in plant immune responses. As research gradually deepens, the role of surfactin in plant-microbe interactions deserves further study. Summary of the Invention

[0006] The present invention first discovered through experimental verification that surfactin can promote the development of rapeseed root system, and based on this, the following technical solution is proposed.

[0007] In a first aspect, the present invention provides the use of surfactin in promoting the development of rapeseed root system.

[0008] In a second aspect, the present invention provides the use of surfactin in preparing a product for promoting the development of rapeseed root system; preferably, the product is a plant growth regulator, a fertilizer or a fertilizer additive.

[0009] In some embodiments, promoting rapeseed root development is manifested as increasing rapeseed biomass.

[0010] In some embodiments, promoting rapeseed root development is manifested as increasing the number of lateral roots of the rapeseed root system.

[0011] In some embodiments, promoting rapeseed root development is manifested as increasing the number of pre-branching sites of the rapeseed root system.

[0012] In some embodiments, surfactin promotes rapeseed root development by promoting gene expression of the IAA gene family.

[0013] In some embodiments, the genes of the IAA gene family include IAA14 , IAA26 , GH3.12 , GH3.3 , YUC8 , YUC6 or YUC9 .

[0014] In some embodiments, surfactin is administered exogenously.

[0015] In some embodiments, the concentration of surfactin is 1 μM to 0.1 mM.

[0016] In a third aspect, the present invention provides a method for promoting the root development of rapeseed, comprising: soaking rapeseed seeds in a surfactin solution, and then culturing the rapeseed seeds in a light-culture room.

[0017] Preferably, the concentration of surfactin is 1µM~0.1mM.

[0018] Preferably, the rapeseed seeds are surface disinfected before being soaked in the surfactin solution.

[0019] Preferably, 75% anhydrous ethanol is used for disinfection.

[0020] Compared with the prior art, the present invention has the following beneficial effects: The present invention has discovered a new function of surfactin: it can act as a signaling molecule to promote the expression of rapeseed auxin-related genes, spurring the development of lateral roots and the formation of pre-branching sites, thereby significantly boosting rapeseed root development. Surfactin can be used to prepare products that promote rapeseed root development, such as plant growth regulators, fertilizers, or fertilizer additives, and has broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 The test results of surfactin promoting rapeseed root development in Example 1 are shown in Figure A. Figure A is a representative photo of rapeseed (Westar) cultured on a culture dish for 7 days. CK represents sterile water treatment and Surfactin treatment at a concentration of 0.1 mM. Figure B shows the biomass of rapeseed after 7 days. Data analysis was performed using one-way analysis of variance. Represents p < 0.0001; Figure C shows the total root length of rapeseed at 7 days. Data analysis was performed using one-way ANOVA. represents p<0.01, Represents p < 0.001.

[0022] Figure 2 Figure 2 is a test result diagram of Surfactin activating the expression of IAA response genes, inducing lateral root increase and root elongation in Example 2; Figure A is the expression pattern of rapeseed DR5: GUS in the root system on the 7th day; Figure B is the relative expression level of auxin-related genes, the auxin-related genes are selected from B. mojavensis RNA-Seq data of rapeseed roots on the 7th day after HF4 (CGMCC No.33569) treatment. Data analysis was performed using t-test. represents p<0.05, represents p<0.01, represents p<0.001, Represents p < 0.0001; Figure C is the statistical diagram of the number of lateral roots when treated with 0.01 mM surfactin. Represents p < 0.001; Figure D is the statistical diagram of the number of front branch sites when treated with 0.01 mM surfactin. Represents p < 0.0001. DETAILED DESCRIPTION

[0023] In order to make the purpose, technical solutions and advantages of the present invention clearer, the technical solutions in the present invention will be clearly and completely described below. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. In the embodiments provided in this specification, if the specific technology or conditions are not specified, they shall be carried out in accordance with the technology or conditions described in the literature in this field, or in accordance with the product instructions. The reagents or instruments used without indicating the manufacturer are all conventional products that can be purchased through regular channels. The surfactin in the present invention was purchased from MedChemExpress with the item number HY-129555. B. mojavensis The HF4 strain was deposited on February 19, 2025, at the General Microbiology Center of the China Culture Collection Administration. The depository address is: Institute of Microbiology, Chinese Academy of Sciences, No. 3, Yard 1, Beichen West Road, Chaoyang District, Beijing; Postal Code: 100101. The classification name is Bacillus mohaiwei. Bacillus mojavensis , the deposit number is CGMCC No.33569.

[0024] Example 1: Lipopeptide Surfactin Promotes Rape Root Development (1) Take 100 mg of surfactin standard and dilute it in a gradient of 10 mM, 1 mM, 0.1 mM, 0.01 mM, and 1 µM. Place it on ice and set aside.

[0025] (2) Rapeseed (Westar) seeds were treated with 75% anhydrous ethanol for 5 minutes to inactivate surface microorganisms. Sterilized rapeseed seeds were soaked in different concentrations of surfactin standard for 1 hour. The seed surface was air-dried and the treated rapeseed seeds were placed in sterile culture dishes and cultured in a light-treated room for one week. Sterile water was used as the control (CK).

[0026] (3) One week later, the biomass and total root length of rapeseed were measured.

[0027] The test results are as follows Figure 1 The results showed that surfactin at a concentration of 0.1 mM had a significant growth-promoting effect on rapeseed for 7 days and could significantly increase the biomass of rapeseed ( Figure 1 A and Figure 1 B). Surfactin at different concentration gradients showed a significant promoting effect on rapeseed root growth at concentrations of 1 µM, 0.01 mM, and 0.1 mM. Surfactin at a concentration of 0.01 mM increased the total root length of rapeseed by 19.39% ( Figure 1 C).

[0028] Example 2 Surfactin activates the expression of IAA-responsive genes, inducing lateral root growth and root elongation (1) Take 100 mg of surfactin standard and dilute it in a gradient of 10 mM, 1 mM, 0.1 mM, 0.01 mM, and 1 µM. Place it on ice and set aside.

[0029] (2) Rapeseed (152) seeds labeled with the IAA signal reporter gene DR5:GUS were treated with 75% anhydrous ethanol for 5 min to inactivate surface microorganisms, and the seed surface was air-dried. Sterilized rapeseed seeds were soaked in surfactin standards of varying concentrations for 1 h, and the seed surface was air-dried. The treated rapeseed seeds were placed in sterile culture dishes and cultured in a light-treated room for one week. Sterile water was used as a control (CK).

[0030] (3) Use GUS dye to observe the expression of auxin in rapeseed roots.

[0031] (4) Count the number of lateral roots and pre-branching sites in the rapeseed root system.

[0032] The test results are as follows Figure 2 The results showed that at a concentration of 0.01 mM, surfactin could significantly enhance the IAA expression signal in rapeseed roots ( Figure 2 A) Exogenous addition of appropriate concentrations of surfactin significantly enhanced the expression of IAA-related genes. IAA14 , IAA26 , GH3.12 , GH3.3 , YUC8 , YUC6 , YUC9 Upregulated gene expression, PIN2 There was no significant difference in gene expression ( Figure 2 B). Plant auxin plays a key role in regulating the entire lateral root development stage. Lateral root formation begins with the oscillation of auxin concentration in the base of the meristem. The next stage is the formation of pre-branching sites (future sites of lateral root formation). The number of lateral roots and pre-branching sites in the lower half of the main root of rapeseed was counted. The results showed that exogenous application of surfactin stimulated a significant increase in the number of lateral roots and pre-branching sites in rapeseed roots ( Figure 2 C and Figure 2 D).

[0033] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. Application of surfactant in promoting rapeseed root development.

2. Use of surfactant in the preparation of a product for promoting the development of rapeseed root system; preferably, the product is a plant growth regulator, fertilizer or fertilizer additive.

3. The use according to claim 1 or 2, characterized in that Promoting the development of rapeseed root system is manifested in increasing the biomass of rapeseed.

4. The use according to claim 1 or 2, characterized in that Promoting the development of rapeseed root system is manifested in increasing the number of lateral roots of rapeseed root system.

5. The use according to claim 1 or 2, characterized in that: Promoting rapeseed root development is manifested in increasing the number of pre-branching sites in the rapeseed root system.

6. The use according to claim 1 or 2, characterized in that Surfactin promotes rapeseed root development by promoting the expression of genes in the IAA gene family.

7. The use according to claim 6, characterized in that The genes of the IAA gene family include IAA14 , IAA26 , GH3.12 , GH3.3 , YUC8 , YUC6 or YUC9 .

8. The use according to claim 1, characterized in that Surfactin is administered exogenously.

9. The use according to claim 1, characterized in that The concentration of surfactin is 1µM~0.1mM.

10. A method for promoting the root development of rapeseed, characterized in that: include: Rapeseed seeds were soaked in a surfactant solution and then cultured under light in a tissue culture room.

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