1. A method for promoting non-symbiotic spore production of arbuscular mycorrhizal fungi is characterized in that potassium myristate, strigolactone, methyl jasmonate and peptone are added into a culture medium of the arbuscular mycorrhizal fungi.

2. The method according to claim 1, wherein the concentration of potassium myristate added to the medium is 0.5mM, the concentration of strigolactone added to the medium is 100nM, the concentration of methyl jasmonate added to the medium is 1. mu.M, and the concentration of peptone added to the medium is 1 mg/L.

3. The method of claim 1, wherein the medium comprises, per liter: MgSO (MgSO)₄·7H₂O：739mg；KNO₃：76mg；KCl：65mg；Ca(NO₃)₂·4H₂O：359mg；KH₂PO₄：4.1mg；MnSO₄·4H₂O：2.45mg；ZnSO₄·7H₂O：0.28mg；H₃BO₃：1.85mg；CuSO₄·5H₂O：0.22mg；(NH₄)₆Mo₇O₂₄·4H₂O：0.034mg；NaMoO₄·2H₂O: 0.0024 mg; thiamine hydrochloride (VB)₁): 1 mg; pyridoxine hydrochloride (VB)₆): 0.9 mg; nicotinic acid: 1 mg; calcium pantothenate: 0.9 mg; vitamin B₁₂: 0.4 mg; biotin: 0.0009 mg; NaFeEDTA: 8 mg; sucrose: 1g of a compound; plant gel: 2.5 g; glucose: 1g of a compound; peptone: 1 mg; potassium myristate: 0.5 mmol; strigolactone: 100 nmol; methyl jasmonate: 1 mu mol, and the solvent is water.

4. A method according to claim 1, 2 or 3, wherein the arbuscular mycorrhizal fungus is rhizosporangium heteroclidum DAOM 197198.

5. A preparation for promoting non-symbiotic spore production of arbuscular mycorrhizal fungi is characterized in that potassium myristate, strigolactone, methyl jasmonate and peptone are added into a culture medium of the arbuscular mycorrhizal fungi.

6. The preparation according to claim 5, wherein the medium contains potassium myristate at a concentration of 0.5mM, strigolactone at a concentration of 100nM, methyl jasmonate at a concentration of 1. mu.M, and peptone at a concentration of 1 mg/L.

7. The application of potassium myristate, strigolactone, methyl jasmonate and peptone in promoting non-symbiotic spore production of arbuscular mycorrhizal fungi.

8. The use according to claim 7, wherein potassium myristate, strigolactone, methyl jasmonate and peptone are added to the culture medium of arbuscular mycorrhizal fungi.

9. The use according to claim 8, wherein potassium myristate is added at a concentration of 0.5mM, strigolactone is added at a concentration of 100nM, methyl jasmonate is added at a concentration of 1. mu.M, and peptone is added at a concentration of 1mg/L in the medium.

Background art:

the arbuscular mycorrhizal fungi is a living nutritional symbiotic fungus widely existing in soil, belongs to glomus sacculus subgenus, and can establish a symbiotic relationship with 80% of roots of land plants. After the arbuscular mycorrhizal fungi and the plants establish a symbiotic relationship, the root systems of the crops can be greatly promoted to absorb mineral nutrients such as phosphorus and nitrogen, the stress resistance of the crops is improved, for example, the tolerance of the crops to nutrient impoverishment, drought, heavy metal toxicity, pH value stress, plant diseases and insect pests and the like is improved, the growth vigor of the crops is improved, and further, the yield of the crops is improved, and the quality of the crops is improved. Therefore, the arbuscular mycorrhizal fungi have great application potential in agricultural production.

The existing method for propagating arbuscular mycorrhizal fungi spores needs to establish a symbiotic relationship with plants as a premise. At present, the expanding propagation of arbuscular mycorrhizal fungi spores is mainly carried out in two ways: firstly, sorghum and clover combination (or other plant combination) is used as a host plant, and is propagated in a certain proportion of soil, river sand, diatomite and other matrixes, so that the obtained microbial inoculum takes the soil as a carrier, and a larger plant cultivation space is needed in the cultivation process; secondly, establishing a dual culture system of arbuscular mycorrhizal fungi and hairy roots (such as carrots and tomatoes) under the aseptic conditions of a culture dish and the like, and propagating spores and the like under the aseptic conditions. Because spores obtained by the hairy root double culture system are sterile, the method is widely applied in the fields of scientific research, production and the like. In addition, the culture process only needs to be carried out in a constant temperature incubator, so that the occupied area is small, the space utilization rate is high, and the limitation of external environments (such as illumination, temperature and the like) is avoided.

Spores are important propagules of arbuscular mycorrhizal fungi, and the number of the spores is an important index for quantifying the quality of the microbial inoculum. Therefore, how to increase the spore number of the arbuscular mycorrhizal fungi is an important factor in the propagation technology of the arbuscular mycorrhizal fungi, and is an important way for effectively improving the quality of the microbial inoculum.

The prior art (application number 201710058144.6) discloses an expanding propagation method of arbuscular mycorrhizal fungi, which uses corn, marigold and clover as host plants, applies water and fertilizer to expand the arbuscular mycorrhizal fungi in the growth process of the host plants, and adopts the measures of no fertilization, reduced watering, slight wilting or severe wilting of the plants and watering to make the plants suffer from drought stress in the later expanding propagation period, so that the infection rate, the spore yield and the expanding propagation efficiency of the arbuscular mycorrhizal fungi are all improved. However, the method is carried out under non-sterilization conditions, and the obtained arbuscular mycorrhizal fungi spores carry mixed bacteria, so that the requirements of many scientific research and multidisciplinary researches on aseptic spores cannot be met.

The prior art (application number 201911320670.0) discloses an application of abscisic acid in promoting arbuscular mycorrhizal fungi spore production, and the abscisic acid is added into spores of the arbuscular mycorrhizal fungi, so that the abscisic acid can directly act on the spores of the arbuscular mycorrhizal fungi, and the quantity of the spores of the arbuscular mycorrhizal fungi is obviously increased. The application of gibberellin-deficient mutants in promoting the sporulation of arbuscular mycorrhizal fungi (application No. CN202010718350.7) significantly improves the spore yield of the arbuscular mycorrhizal fungi by inoculating the arbuscular mycorrhizal fungi with the hairy roots of the gibberellin-deficient mutants of tomato, and significantly improves the spore number of the arbuscular mycorrhizal fungi under normal pH conditions (pH 6.5) and acidic conditions (pH 4.5) with the hairy roots of the gibberellin-deficient mutants. The spores propagated by the method are sterile, and are favorable for further research on arbuscular mycorrhizal fungi in scientific research. However, the above method needs to take root systems as host plants, and spores can be produced only after the arbuscular mycorrhizal fungi establish symbiotic relationship with the host plants, so the steps are complicated, and the production period of the spores is long.

Therefore, the research on the expanding propagation method of the arbuscular mycorrhizal fungi, which has the advantages of simple expanding operation, short period, high expanding propagation efficiency, small dependence on the external environment and capability of obviously increasing the spore yield under the non-symbiotic condition, is of great significance, and the method is a great step forward in the aspect of realizing pure culture of the arbuscular mycorrhizal fungi.

The invention content is as follows:

the technical problem to be solved by the invention is to overcome the defects and shortcomings of the existing arbuscular mycorrhizal fungi propagation technology and provide a method for promoting non-symbiotic spore production of arbuscular mycorrhizal fungi.

The method for promoting non-symbiotic spore production of the arbuscular mycorrhizal fungi comprises the step of adding potassium myristate, strigolactone, methyl jasmonate and peptone into a culture medium of the arbuscular mycorrhizal fungi.

The second purpose of the invention is to provide a preparation for promoting non-symbiotic spore production of arbuscular mycorrhizal fungi, which is prepared by adding potassium myristate, strigolactone, methyl jasmonate and peptone to a culture medium of the arbuscular mycorrhizal fungi.

Preferably, in the culture medium, the potassium myristate is added at a concentration of 0.5mM, the strigolactone is added at a concentration of 100nM, the methyl jasmonate is added at a concentration of 1. mu.M, and the peptone is added at a concentration of 1 mg/L.

Preferably, the culture medium is: contains per liter: MgSO (MgSO)₄·7H₂O：739mg；KNO₃：76mg；KCl：65mg；Ca(NO₃)₂·4H₂O：359mg；KH₂PO₄：4.1mg；MnSO₄·4H₂O：2.45mg；ZnSO₄·7H₂O：0.28mg；H₃BO₃：1.85mg；CuSO₄·5H₂O：0.22mg；(NH₄)₆Mo₇O₂₄·4H₂O：0.034mg；NaMoO₄·2H₂O: 0.0024 mg; thiamine hydrochloride (VB)₁): 1 mg; pyridoxine hydrochloride (VB)₆): 0.9 mg; nicotinic acid: 1 mg; calcium pantothenate: 0.9 mg; vitamin B₁₂: 0.4 mg; biotin: 0.0009 mg; NaFeEDTA: 8 mg; sucrose: 1g of a compound; plant gel: 2.5 g; glucose: 1g of a compound; peptone: 1 mg; potassium myristate: 0.5 mmol; strigolactone: 100 nmol; methyl jasmonate: 1 mu mol, and the solvent is water.

Preferably, the arbuscular mycorrhizal fungus is heteroclite radiculospora DAOM 197198.

The third purpose of the invention is to provide the application of the potassium myristate, the strigolactone, the methyl jasmonate and the peptone in promoting the non-symbiotic spore production of the arbuscular mycorrhizal fungi.

Preferably, potassium myristate, strigolactone, methyl jasmonate and peptone are added to the culture medium of the arbuscular mycorrhizal fungi.

The invention has the following beneficial effects:

through creative exploration experiments, the invention obviously improves the production of the arbuscular mycorrhizal fungi spores by adding potassium myristate, strigolactone, methyl jasmonate and peptone into the spores of the arbuscular mycorrhizal fungi, and the spore quantity produced by single mother spores of the arbuscular mycorrhizal fungi in the addition treatment is 9 times that produced by single mother spores of the arbuscular mycorrhizal fungi without the addition treatment. The addition of potassium myristate, strigolactone, methyl jasmonate and peptone can significantly increase the production of arbuscular mycorrhizal fungal spores under non-symbiotic conditions.

Based on the above, the invention provides a preparation and a method for promoting non-symbiotic spore production of arbuscular mycorrhizal fungi, the method can expand propagation of the arbuscular mycorrhizal fungi in a non-symbiotic system, the expansion efficiency is high, the spore production of the arbuscular mycorrhizal fungi can be obviously increased, and the preparation and the method also have the advantages of simple and convenient operation, low cost, short period and the like; therefore, the method has wide application prospect in promoting the spore production of the arbuscular mycorrhizal fungi or preparing a preparation for promoting the spore production of the arbuscular mycorrhizal fungi.

Drawings

FIG. 1 shows the sporulation of the Pholiospora heteroclita DAOM197198 in a non-symbiotic culture system in example 1; wherein A is sporulation on modified MSR medium; b is sporulation on basal MSR medium. White arrows indicate the mother spores, and black (a) or gray (B) arrows indicate the sporozoites produced by the mother spores.

Detailed Description

The present invention is further illustrated by the following specific examples, which are not intended to limit the invention in any way. Reagents, methods and apparatus used in the present invention are conventional in the art unless otherwise indicated.

Unless otherwise indicated, reagents and materials used in the following examples are commercially available.

Example 1 Effect of different media on sporulation of arbuscular mycorrhizal fungi under non-symbiotic conditions

1. Experimental methods

In this embodiment, a model strain of arbuscular mycorrhizal fungi (heteroclite radiculospora DAOM197198) is selected to study the influence of an improved MSR culture medium on the spore production of arbuscular mycorrhizal fungi under non-symbiotic conditions, and specific experimental methods and experimental results are respectively as follows:

(1) strigolactone (0.3 mg) was weighed out and dissolved in 1mL of acetone to prepare a 1mM strigolactone solution.

(2) 11.4mg of methyl jasmonate was weighed and dissolved in 5ml of absolute ethanol to prepare a 10mM methyl jasmonate solution.

(3) 1.33g of potassium myristate was weighed and dissolved in 10ml of double distilled water to prepare a 0.5M potassium myristate solution.

(4) The strigolactone solution and the methyl jasmonate solution were filter sterilized with 0.22 μm organic phase of organic nylon (nylon) 66. The potassium myristate solution was filter-sterilized with a 0.22 μm inorganic Polyethersulfone (PES) filter.

(5) The formula of the MSR basal medium is (the addition amount in 1L water): MgSO (MgSO)₄·7H₂O：739mg；KNO₃：76mg；KCl：65mg；Ca(NO₃)₂·4H₂O：359mg；KH₂PO₄：4.1mg；MnSO₄·4H₂O：2.45mg；ZnSO₄·7H₂O：0.28mg；H₃BO₃：1.85mg；CuSO₄·5H₂O：0.22mg；(NH₄)₆Mo₇O₂₄·4H₂O：0.034mg；NaMoO₄·2H₂O: 0.0024 mg; thiamine hydrochloride (VB)₁): 1 mg; pyridoxine hydrochloride (VB)₆): 0.9 mg; nicotinic acid: 1 mg; calcium pantothenate: 0.9 mg; vitamin B₁₂: 0.4 mg; biotin: 0.0009 mg; NaFeEDTA: 8 mg; sucrose: 10g of a mixture; plant gel: 2.5 g. According to the components and the content, the components are mixed evenly, and the pH value is adjusted: 5.5, sealing the mouth, and then sterilizing for 15min at the high temperature and the high pressure of 121 ℃. Thereby obtaining an MSR medium.

(6) Configuration of modified MSR medium: in 1L MSR culture medium, the sucrose addition amount is changed to 1g, and then 1g of glucose and 1mg of peptone are added, and other components are consistent with those of the basic MSR culture medium, the pH is adjusted to 5.5, and the MSR culture medium is sterilized at 121 ℃ for 15min under high pressure after sealing. Then, 100. mu.L of strigolactone solution of 1mM, 100. mu.L of methyl jasmonate solution of 10mM and 1mL of potassium myristate solution of 0.5M after filtration sterilization were added to the culture medium sterilized at high temperature and high pressure on a clean bench so that the final use concentrations of potassium myristate, strigolactone and methyl jasmonate were 0.5mM, 100nM and 1. mu.M, respectively, and the mixture was poured into a petri dish for use after being mixed uniformly.

(7) Adding solvent (acetone, anhydrous ethanol and double distilled water) with the same amount as the improved MSR culture medium into the MSR culture medium sterilized at high temperature and high pressure on a clean bench, mixing well, and pouring into a culture dish for later use.

(8) Half of the culture on the spore culture medium of the heteroclite radiculomycosis DAOM197198 propagated in the hairy root-arbuscular mycorrhizal fungi dual-culture system is completely transferred to a 50mL centrifuge tube, a 3-fold volume of 10mM sodium citrate solution with pH6.0 is added, the solution is filtered by a nylon membrane with the diameter of 25 mu m after being shaken on a shaking table (the shaking rotating speed is 120rpm and the temperature is 25 ℃) for 1h, and the spare spores are obtained.

(9) The spores were scattered by a dissecting needle under a stereomicroscope, inoculated into a medium, about 50 spores were inoculated into each dish, 5 times for each treatment, sealed with a sealing film, and placed in an incubator for dark culture (culture temperature 25 ℃).

(10) After dark culture in an incubator at 25 ℃ for 6 weeks, the dishes were taken out, placed upside down under a stereomicroscope for observation and counted for the number of newly formed spores in each dish.

2. Results of the experiment

The sporulation of the tomato hairy root-heteroclite root sporangium DAOM197198 nongenetic culture system in this example 1 is shown in FIG. 1, and it can be seen that the heteroclite root sporangium DAOM197198 produces a large amount of new spores in the non-symbiotic culture system of the modified MSR culture medium added with potassium myristate, strigolactone, methyl jasmonate and peptone.

The results of the effect of the modified MSR medium on the production of spores of arbuscular mycorrhizal fungi under non-symbiotic conditions are shown in table 1, and it can be seen that the number of sporozoites produced by a single mother spore of arbuscular mycorrhizal fungi under non-symbiotic conditions treated with the modified MSR medium supplemented with potassium myristate, strigolactone, methyl jasmonate, and peptone is 9 times greater than that treated with the base MSR medium compared with the base MSR medium, indicating that the modified MSR medium significantly increases the production of spores of arbuscular mycorrhizal fungi under non-symbiotic conditions.

TABLE 1 Effect of different treatments under non-symbiotic conditions on the production of arbuscular mycorrhizal fungal spores

Treatment group	Number of sporozoites produced by a single mother spore
		Basic MSR medium	0.65±0.08
Improved MSR culture medium	5.47±0.62***

Note: ". indicates that there was a significant difference in the independent sample T-test at the level of P.ltoreq.0.001.

Comparative example 1 Effect of Potassium myristate on spore production of arbuscular mycorrhizal fungi under non-symbiotic conditions

1. Experimental methods

In this example, a model strain of arbuscular mycorrhizal fungi (heteroclite radiculospora DAOM197198) is selected to study the influence of potassium myristate on the spore production of arbuscular mycorrhizal fungi under non-symbiotic conditions, and specific experimental methods and experimental results are as follows:

(1) 1.33g of potassium myristate was weighed, dissolved in 10ml of double distilled water to prepare a 0.5M potassium myristate solution, and the potassium myristate solution was subjected to filtration sterilization with a 0.22 μ M inorganic phase Polyethersulfone (PES) filter.

(2) The MSR basic culture medium has the formula of (1LAddition amount): MgSO (MgSO)₄·7H₂O：739mg；KNO₃：76mg；KCl：65mg；Ca(NO₃)₂·4H₂O：359mg；KH₂PO₄：4.1mg；MnSO₄·4H₂O：2.45mg；ZnSO₄·7H₂O：0.28mg；H₃BO₃：1.85mg；CuSO₄·5H₂O：0.22mg；(NH₄)₆Mo₇O₂₄·4H₂O：0.034mg；NaMoO₄·2H₂O: 0.0024 mg; thiamine hydrochloride (VB)₁): 1 mg; pyridoxine hydrochloride (VB)₆): 0.9 mg; nicotinic acid: 1 mg; calcium pantothenate: 0.9 mg; vitamin B₁₂: 0.4 mg; biotin: 0.0009 mg; NaFeEDTA: 8 mg; sucrose: 10g, 2.5g of plant gel and water as a solvent. According to the components and the content, the components are mixed evenly, and the pH value is adjusted to 5.5. Sealing, and sterilizing at 121 deg.C under high pressure for 15 min.

(3) And pouring the MSR culture medium on a clean bench into a culture dish, cooling and solidifying for later use as a control.

(4) When the MSR culture medium is cooled to about 40 ℃, 0.5M potassium myristate (myr) solution which is sterilized by filtration is added to ensure that the final use concentration of the potassium myristate is 0.5mM respectively, and the mixture is poured into a culture dish for later use after being mixed uniformly.

(5) Half of the culture on the spore culture medium of the heteroclite radiculomycosis DAOM197198 propagated in the hairy root-arbuscular mycorrhizal fungi dual-culture system is completely transferred to a 50mL centrifuge tube, a 3-fold volume of 10mM sodium citrate solution with pH6.0 is added, the solution is filtered by a nylon membrane with the diameter of 25 mu m after being shaken on a shaking table (the shaking rotating speed is 120rpm and the temperature is 25 ℃) for 1h, and the spare spores are obtained.

(6) The spores were scattered by a dissecting needle under a stereomicroscope, inoculated into MSR medium, about 50 spores were inoculated into each dish, 5 replicates of each treatment were sealed with a sealing film, and placed in a constant temperature incubator for dark culture (culture temperature 25 ℃).

(7) After dark culture in an incubator at 25 ℃ for 6 weeks, the dishes were taken out, placed upside down under a stereomicroscope for observation and counted for the number of newly formed spores in each dish.

2. Results of the experiment

From table 2 it can be seen that the addition of potassium myristate to MSR medium significantly promoted the formation of non-symbiotic spores, each mother spore producing 1.6 sporozoites, whereas on MSR medium without potassium myristate only 0.7 sporozoites were produced per mother spore, with spore yields 2.4 times higher per mother spore after potassium myristate treatment (myr) than without (MSR). But was inferior to the modified MSR medium of example 1, which was 9 times the treatment of the basal MSR medium.

TABLE 2 Effect of Potassium myristate on arbuscular mycorrhizal fungal spore production under non-symbiotic conditions

Treatment group	Number of sporozoites produced by a single mother spore
		MSR	0.67±0.14
Myr-added MSR	1.58±0.32*

Note: "+" indicates that there was a significant difference in the independent sample T-test at the level P.ltoreq.0.05.

The above embodiments are preferred embodiments of the present invention, but the present invention is not limited to the above embodiments, and any other changes, modifications, substitutions, combinations, and simplifications which do not depart from the spirit and principle of the present invention should be construed as equivalents thereof, and all such changes, modifications, substitutions, combinations, and simplifications are intended to be included in the scope of the present invention.