Application of nanometer Mn3O4 in relieving vegetable salt stress and / or increasing vegetable flavonoid compound content

Abstract

The invention relates to the technical field of vegetable planting, in particular to application of nano Mn3O4 in relieving vegetable salt stress and / or increasing the content of vegetable flavonoid compounds. The invention finds that nano Mn3O4 prepared by taking manganese acetate tetrahydrate as a manganese source not only can relieve salt stress of vegetables, but also can improve the content of flavonoid compounds in the vegetables, so that the nutritional value or medicinal value of the vegetables is improved. Furthermore, nano Mn3O4 is sprayed on vegetable leaves under salt stress, so that the salt stress of vegetables is relieved, and the content of flavonoid compounds in the vegetables is increased. According to the method provided by the invention, the physiological indexes of the vegetables are improved, the flavone content is increased, the influence of salt stress on the vegetables is relieved, and the method is a simple, effective and environment-friendly method for relieving the salt stress of the vegetables.

Description

Technical Field

[0001] The invention relates to the technical field of vegetable planting, and in particular to the application of nano Mn3O4 in alleviating salt stress of vegetables and / or increasing the content of flavonoid compounds in vegetables. Background Art

[0002] The formation of saline soil is usually due to the Na + and Cl - The high concentration of ions accumulates, resulting in high osmotic pressure and high ion conditions in the soil. This salinization phenomenon will have an adverse effect on the growth and development of vegetables. In a high-salt environment, the osmotic pressure of the soil increases, and the ability of vegetable roots to absorb water from the soil is severely hindered. At the same time, high concentrations of Na + and Cl - Ions can also interfere with the absorption of essential nutrients by vegetables, limiting the nutritional supply of vegetables. A large number of studies have shown that the impact of salt stress on vegetables is manifested in many aspects. First, the accumulation of salt can cause vegetables to be short and grow slowly. Secondly, salt stress can make vegetable leaves thicker and reduce the chlorophyll content of the leaves, leading to yellowing of the leaves, which may eventually cause the leaves to fall off. This change directly affects the photosynthetic capacity of vegetables. Salt stress can also lead to excessive accumulation of reactive oxygen species (ROS), which not only affects the normal function of cell membranes and organelles, but also inhibits the photosynthesis of vegetables and reduces the production of photosynthetic products. With the reduction of photosynthesis, the overall growth and development of plants will be severely inhibited, ultimately leading to poor growth performance of vegetables, and significantly reduced yield and quality. Therefore, the management and improvement of saline soils are of great significance for protecting vegetable growth and increasing agricultural output. However, there is currently a lack of vegetable protectants that can alleviate salt stress damage. Summary of the invention

[0003] In order to solve the above problems, the present invention provides the use of nano Mn3O4 in alleviating vegetable salt stress and / or increasing the content of vegetable flavonoids. The present invention finds that nano Mn3O4 prepared with manganese acetate tetrahydrate as a manganese source can not only alleviate vegetable salt stress, but also increase the content of vegetable flavonoids, thereby improving its nutritional value or medicinal value.

[0004] In order to achieve the above object, the present invention provides the following technical solutions:

[0005] The invention provides application of nano Mn3O4 in alleviating salt stress of vegetables and / or increasing the content of flavonoid compounds in vegetables. The manganese source for preparing the nano Mn3O4 is manganese acetate tetrahydrate.

[0006] Preferably, the vegetables include: iceberg lettuce, broccoli or tomato.

[0007] Preferably, the preparation method of nano Mn3O4 comprises:

[0008] dissolving manganese acetate tetrahydrate in anhydrous ethanol to obtain a mixed solution;

[0009] The mixed solution is subjected to a hydrothermal reaction to obtain the nano-Mn3O4.

[0010] Preferably, the temperature of the hydrothermal reaction is 120° C. and the time is 24 hours.

[0011] Preferably, the lining material of the hydrothermal reaction device is polytetrafluoroethylene.

[0012] Preferably, the effective concentration of the nano-Mn3O4 is 50-150 mg / L.

[0013] The present invention provides a method for alleviating salt stress of vegetables and / or increasing the content of flavonoid compounds in vegetables, comprising the following steps:

[0014] The nanometer Mn3O4 solution is sprayed on the vegetable leaves; the manganese source for preparing the nanometer Mn3O4 solution is manganese acetate tetrahydrate.

[0015] Preferably, the concentration of nano-Mn3O4 in the nano-Mn3O4 solution is 50-150 mg / L.

[0016] Preferably, the preparation method of nano Mn3O4 comprises:

[0017] dissolving manganese acetate tetrahydrate in anhydrous ethanol to obtain a mixed solution;

[0018] The mixed solution is subjected to a hydrothermal reaction to obtain the nano-Mn3O4.

[0019] Preferably, the vegetables include: iceberg lettuce, broccoli or tomato.

[0020] Beneficial effects:

[0021] The present invention provides an application of nano Mn3O4 in alleviating salt stress of vegetables and / or increasing the content of flavonoid compounds in vegetables, wherein the manganese source for preparing the nano Mn3O4 is tetrahydrated manganese acetate. The present invention finds that the nano Mn3O4 prepared with tetrahydrated manganese acetate as the manganese source can not only alleviate salt stress of vegetables, but also increase the content of flavonoid compounds in vegetables, thereby improving the nutritional value or medicinal value thereof.

[0022] Furthermore, the present invention achieves the alleviation of vegetable salt stress and the increase of flavonoid content in vegetables by spraying nano Mn3O4 on vegetable leaves under salt stress. The method provided by the present invention improves vegetable physiological indicators, increases the content of flavonoids, and helps alleviate the impact of salt stress on vegetables. It is a simple, effective, and environmentally friendly method for alleviating vegetable salt stress. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required to be used in the embodiments are briefly introduced below.

[0024] Figure 1 The growth diagram of ice plant, broccoli and tomato after salt stress and nano-Mn3O4 treatment;

[0025] Figure 2 The results of flavonoid gene expression in ice plant, broccoli and tomato; (a) relative expression of key genes of flavonoids in ice plant; (b) relative expression of key genes of flavonoids in broccoli; (c) relative expression of key genes of flavonoids in tomato; different lowercase letters represent significant differences among different groups (P < 0.05);

[0026] Figure 3 Schematic diagram of the nanoparticles synthesized to provide manganese source for manganese sulfate acting on three plants: ice plant, broccoli and tomato; the treatment conditions from left to right are: 0mM NaCl, 200mM NaCl, 200mM NaCl+100mg / LMn3O4 NPs;

[0027] Figure 4 Schematic diagram of the action of nano-ions synthesized using potassium permanganate as a manganese source on three plants: ice plant, broccoli and tomato; the treatment conditions from left to right are: 0mM NaCl, 200mM NaCl, 200mM NaCl+100mg / LMn3O4 NPs. DETAILED DESCRIPTION

[0028] The invention provides application of nano Mn3O4 in alleviating salt stress of vegetables and / or increasing the content of flavonoid compounds in vegetables. The manganese source for preparing the nano Mn3O4 is manganese acetate tetrahydrate.

[0029] The present invention finds that nano Mn3O4 synthesized with manganese acetate tetrahydrate as a manganese source can significantly improve the growth of vegetables under salt stress.

[0030] The present invention finds that under salt stress, the growth trend of vegetables sprayed with Mn3O4 nano solution is visibly different from that of vegetables not sprayed with Mn3O4 nano solution, and physiological indicators reveal that Mn3O4 nano solution can alleviate the damage of salt stress and increase the content of flavonoids in vegetables. The method of spraying Mn3O4 nano solution on vegetable leaves under salt stress is a simple, effective and environmentally friendly method for alleviating vegetable salt stress.

[0031] As an embodiment, the vegetables include: ice plant, broccoli or tomato.

[0032] As an embodiment, the preparation method of nano Mn3O4 includes:

[0033] dissolving manganese acetate tetrahydrate in anhydrous ethanol to obtain a mixed solution;

[0034] The mixed solution is subjected to a hydrothermal reaction to obtain the nano-Mn3O4.

[0035] As an embodiment, the mass volume ratio of the manganese acetate tetrahydrate and anhydrous ethanol is 1.225g:60mL.

[0036] As an embodiment, the temperature of the hydrothermal reaction is 120° C. and the time is 24 hours.

[0037] As an embodiment, the lining material of the hydrothermal reaction device is polytetrafluoroethylene.

[0038] As an embodiment, the effective concentration of the nano Mn3O4 is 50-150 mg / L. As another embodiment, the effective concentration of the nano Mn3O4 is 100 mg / L.

[0039] Based on the above advantages, the present invention provides a method for alleviating salt stress in vegetables and / or increasing the content of flavonoids in vegetables, comprising the following steps:

[0040] The nanometer Mn3O4 solution is sprayed on the vegetable leaves; the manganese source for preparing the nanometer Mn3O4 solution is manganese acetate tetrahydrate.

[0041] As an embodiment, the concentration of nano-Mn3O4 in the nano-Mn3O4 solution is 50-150 mg / L. As another embodiment, the concentration of nano-Mn3O4 in the nano-Mn3O4 solution is 100 mg / L.

[0042] As an embodiment, the preparation method of nano Mn3O4 includes:

[0043] dissolving manganese acetate tetrahydrate in anhydrous ethanol to obtain a mixed solution;

[0044] The mixed solution is subjected to a hydrothermal reaction to obtain the nano-Mn3O4.

[0045] As an embodiment, the temperature of the hydrothermal reaction is 120° C. and the time is 24 hours.

[0046] As an embodiment, the lining material of the hydrothermal reaction device is polytetrafluoroethylene.

[0047] As an embodiment, the vegetables include: ice plant, broccoli or tomato

[0048] To further illustrate the present invention, the application of nano Mn3O4 provided by the present invention in alleviating vegetable salt stress and / or increasing the content of vegetable flavonoids is described in detail below in conjunction with the accompanying drawings and examples, but they should not be construed as limiting the scope of protection of the present invention.

[0049] Example 1 Spraying Nano-Mn3O4 to Alleviate Salt Stress on Vegetables

[0050] Step 1: Preparation of nano-Mn3O4 (Mn3O4 NPs). Take 1.225g of manganese acetate tetrahydrate and dissolve it in 60mL of anhydrous ethanol, transfer it to a 100mL reactor, and perform hydrothermal reaction at 120°C for 24 hours. The reactor is lined with high-temperature and corrosion-resistant polytetrafluoroethylene; after cooling, centrifuge to remove impurities, rinse with water 3 times, and dry in a drying oven overnight. The brown powder obtained is nano-Mn3O4 (Mn3O4NPs).

[0051] Step 2: Preparation of nano-Mn3O4 solution: Weigh 50 mg, 100 mg, and 150 mg of Mn3O4 NPs respectively, disperse them in 1000 mL of distilled water under 180 W ultrasonic treatment for 30 min at room temperature, and prepare nano-solutions of different concentrations for later use.

[0052] Step 3: Planting of vegetable materials. Select iceberg lettuce, broccoli and tomato seeds that are in good condition and of the same size, and place them in their respective culture dishes. A layer of filter paper soaked in water is laid in the culture dish to provide a suitable germination environment for the seeds. After 72 hours of cultivation, the seeds are sown in 16cm×16cm flower pots filled with a mixture of nutrient soil and vermiculite in a volume ratio of 2:1. Six flower pots are placed on each tray, and 2.5L of water is poured at a time to ensure that the soil is fully moistened, providing the necessary conditions for the growth of vegetables;

[0053] Step 4: After the iceberg lettuce and broccoli have grown two pairs of leaves and the tomato has reached the flowering period, salt stress treatment is carried out. The iceberg lettuce, broccoli and tomato vegetable samples are divided into 5 groups for treatment, specifically:

[0054] 0mM NaCl treatment group: Pour 2.5L of clean water into the tray. After the soil in the flowerpot is fully hydrated, pour out the remaining water in the tray. The next day, spray the leaves with clean water to ensure that each leaf is evenly covered with clean water, twice a week.

[0055] 200mM NaCl treatment group: Pour 2.5L 200mM NaCl into the tray. After the soil in the flowerpot is fully absorbed by the salt water, pour out the remaining salt water in the tray. The next day, spray clean water on the leaves to ensure that each leaf is evenly covered with clean water, twice a week.

[0056] 200mM NaCl+50mg / L Mn3O4 NPs treatment group: Pour 2.5L 200mM NaCl into the tray. After the soil in the flowerpot is saturated with the salt water, pour out the remaining salt water in the tray. The next day, spray 50mg / L Mn3O4NPs solution on the leaves to ensure that each leaf is evenly covered with Mn3O4NPs solution, twice a week.

[0057] 200mM NaCl+100mg / L Mn3O4 NPs treatment group: Pour 2.5L 200mM NaCl into the tray. After the soil in the flowerpot is saturated with the salt water, pour out the remaining salt water in the tray. The next day, spray 100mg / L Mn3O4 NPs solution on the leaves to ensure that each leaf is evenly covered with Mn3O4 NPs solution, twice a week.

[0058] 200mM NaCl+150mg / L Mn3O4 NPs treatment group: Pour 2.5L 200mM NaCl into the tray. After the soil in the flowerpot is saturated with the salt water, pour out the remaining salt water in the tray. The next day, spray 150mg / L Mn3O4 NPs solution on the leaves to ensure that each leaf is evenly covered with Mn3O4 NPs solution, twice a week.

[0059] There were 6 pots in each group, and irrigation and foliar spraying of the corresponding solution were carried out regularly every week.

[0060] Step 5: After 4 weeks of salt treatment and nanomaterial treatment, the photosynthetic and physiological indicators of the three vegetables were tested (the results are shown in Tables 2 to 9). The photosynthetic rate, transpiration rate, stomatal conductance and intercellular CO2 concentration of the three vegetables were measured using a photosynthetic meter; the chlorophyll content and nitrogen content in the leaves were measured using a vegetable nutrient analyzer. The malondialdehyde content was measured by the thiobarbituric acid method, the proline content was measured by the acid ninhydrin method, the superoxide dismutase (SOD) activity was measured by the nitroblue tetrazolium photoreduction method, the peroxidase (POD) activity was measured by the guaiacol method, and the CAT activity was measured by the catalase (CAT) catalyzing the decomposition of hydrogen peroxide into water and oxygen. The flavonoid content was measured by the vegetable flavonoid content kit, and the H2O2 content was measured by the hydrogen peroxide content detection kit.

[0061] Step 6: Download the gene sequences related to vegetable flavonoids from the National Center for Biotechnology Information (NCBI), and use the primer software to design qPCR primers. The primer sequences are shown in Table 1. Use the RNAprep Pure Vegetable Total RNA Extraction Kit to extract leaf RNA, and then use the FastKing cDNA First Chain Synthesis Kit to reverse transcribe the extracted RNA into cDNA. Finally, use the SuperReal Fluorescence Quantification Premix Enhanced Edition (SYBR Green) Kit for qPCR.

[0062] Table 1 Primer sequences required for qPCR

[0063]

[0064]

[0065] Results and analysis:

[0066] Figure 1 The following are schematic diagrams of the growth of ice vegetable, broccoli and tomato after treatment with 200mM NaCl solution and different concentrations of Mn3O4 nano solutions, respectively. The concentrations of Mn3O4 in the figure are 50mg / L, 100mg / L and 150mg / L, respectively. It can be seen from the figure that compared with the water treatment group, 200mM NaCl has a stress effect on the growth of vegetables that can be discerned by the naked eye. The ice vegetable, broccoli and tomato plants are weak, and the tomato fruits are small and the yield is low. After spraying the nano solution, the stress effect is significantly alleviated. When the concentration of Mn3O4 is 100mg / L, the vegetable crops grow best. Therefore, 100mg / L is the optimal Mn3O4 concentration for spraying on the vegetable leaves.

[0067] Figure 2 The expression of flavonoid gene in ice vegetable, broccoli and tomato. According to the qPCR result, the expression level of flavonoid gene in the three vegetables under 200mM NaCl treatment is lower than that in the 0mM NaCl treatment group; the gene expression level in the group sprayed with 100mg / L Mn3O4 nano solution is higher than that in the 200mM NaCl treatment group. Therefore, salt stress will reduce the expression of flavonoid gene in vegetables, thereby reducing the content of flavonoid in vegetables. Flavonoid is a group of natural polyphenols with multiple biological activities such as antioxidant, antibacterial and anti-inflammatory. After spraying 100mg / LMn3O4 nano solution on vegetables under salt stress, the gene expression of flavonoid increases, indicating that the content of flavonoid in vegetables increases, which is consistent with the results of the content of flavonoid in vegetables in Table 3, Table 6 and Table 8, and at the same time confirms each other.

[0068] Net photosynthetic efficiency and stomatal conductance are both photosynthetic indicators of plant growth. Under salt stress, plant photosynthetic efficiency should decrease; nitrogen content reflects the plant's absorption of substances in the soil, and salt stress will hinder the plant's intake of nutrients; malondialdehyde is a marker of oxidative stress. When plants are subjected to salt stress, oxidative stress occurs and a large amount of reactive oxygen is produced, and the malondialdehyde content also increases accordingly; proline is an osmotic regulating substance in plants that helps cells maintain water balance.

[0069] When plants are subjected to salt stress, oxidative stress occurs and a large amount of reactive oxygen species are produced. Antioxidant enzymes eliminate excess reactive oxygen species by increasing their own activity, and return to normal levels when the stress is relieved. H2O2 content is one of the reactive oxygen species that accumulates excessively under salt stress. Its content increases significantly when plants are subjected to salt stress, and decreases when the salt stress is relieved.

[0070] Soluble proteins are involved in many functions such as cell metabolism, osmotic regulation, signal transduction and stress resistance. Salt-tolerant plants can cope with salt stress by increasing the content of soluble proteins. Intercellular CO2 concentration, stomatal conductance, transpiration rate and net photosynthetic efficiency are all photosynthetic indicators of plants. The photosynthetic efficiency of plants should be reduced under salt stress. The H2O2 content is one of the reactive oxygen species that accumulates excessively under salt stress. Its content increases significantly when the plant is under salt stress, and decreases after the salt stress is relieved.

[0071] As shown in Tables 2 to 9, physiological indicators such as leaf wet weight, leaf dry weight, root dry weight, leaf area, chlorophyll content, antioxidant enzymes, malondialdehyde content, proline content and flavonoid content all show the stress effect of salinity on plant growth. These data have a significant mitigating effect after spraying the Mn3O4 NPs solution, and there are significant differences between the treatment groups. It can be seen that spraying the Mn3O4 NPs solution prepared by the present invention can alleviate the effects of salt stress on physiological indicators such as malondialdehyde content, proline content and flavonoid content of vegetables.

[0072] Table 2 Physiological indicators of ice plant

[0073]

[0074] Note: 1 is the 0 mM NaCl treatment group, 2 is the 200 mM NaCl treatment group, 3 is the 200 mM NaCl and 100 mg / L mn3O4 NPs treatment group, different lowercase letters represent significant differences between different groups (P < 0.05), the same applies to the following table.

[0075] Table 3 Physiological indicators of ice plant

[0076]

[0077] Table 4 Physiological indicators of ice plant

[0078]

[0079] Table 5 Physiological indicators of broccoli

[0080]

[0081] Table 6 Physiological indicators of broccoli

[0082]

[0083] Table 7 Physiological indicators of broccoli

[0084]

[0085] Table 8 Physiological indexes of tomato

[0086]

[0087] Table 9 Physiological indexes of tomato

[0088]

[0089] Comparative Example 1

[0090] Manganese sulfate was used as a manganese source to react with sodium bicarbonate to form a precipitate, which was then calcined to synthesize Mn3O4NPs as follows:

[0091] Prepare 0.1M manganese nitrate in distilled water, stir until it reaches 90°C, add 0.05M sodium bicarbonate to make the pH reach 9, then stop adding sodium bicarbonate, continue heating and stirring for 3 hours, cool to room temperature and stir overnight. Wash the reactant by centrifugation, dry at 70°C overnight, and then calcine the obtained reactant at 600°C for 12 hours to obtain nano Mn3O4.

[0092] Comparative Example 2

[0093] Mn3O4NPs were synthesized by hydrothermal reaction of potassium permanganate and glucose in a reactor as follows:

[0094] Weigh 0.2376g potassium permanganate and 0.585g glucose, dissolve them in 80mL deionized water, transfer them to a polytetrafluoroethylene autoclave, adjust the solution to alkalinity with sodium hydroxide, and react at 120℃ for 24 hours. Wash the reaction product by centrifugation, and place it in a drying oven at 80℃ for vacuum drying. The obtained reactant is nano-Mn3O4.

[0095] Using a similar method to Example 1, three treatment groups were set up: 0mM NaCl, 200mM NaCl, 200mM NaCl + 100mg / L Mn3O4 NPs, and the nano Mn3O4 prepared in Comparative Examples 1 and 2 was sprayed on ice plant, broccoli and tomato, respectively. The results are shown in Figure 3 and Figure 4 .

[0096] Depend on Figure 3 and Figure 4 It can be seen that when nano Mn3O4 prepared using manganese sulfate or potassium permanganate as a manganese source is sprayed on the leaves of plants under salt stress, there is no obvious effect of alleviating salt stress. However, the nanoparticles synthesized using manganese acetate as a manganese source in Example 1 of the present invention can alleviate the effect of salt stress on plants.

[0097] Although the above embodiment describes the present invention in detail, it is only a part of the embodiments of the present invention, not all of the embodiments. People can also obtain other embodiments based on this embodiment without creativity, and these embodiments all fall within the protection scope of the present invention.

Claims

1. Application of nano-Mn3O4 in alleviating salt stress of vegetables and / or increasing the content of flavonoids in vegetables, wherein the manganese source for preparing the nano-Mn3O4 is manganese acetate tetrahydrate.

2. The use according to claim 1, characterized in that: The vegetables include: ice plant, broccoli or tomato.

3. The use according to claim 1, characterized in that: The preparation method of nano Mn3O4 comprises: dissolving manganese acetate tetrahydrate in anhydrous ethanol to obtain a mixed solution; The mixed solution is subjected to a hydrothermal reaction to obtain the nano-Mn3O4.

4. The use according to claim 3, characterized in that: The temperature of the hydrothermal reaction is 120° C. and the time is 24 hours.

5. The use according to claim 3 or 4, characterized in that: The lining material of the hydrothermal reaction device is polytetrafluoroethylene.

6. The use according to claim 1, characterized in that: The effective concentration of the nano-Mn3O4 is 50-150 mg / L.

7. A method for alleviating salt stress in vegetables and / or increasing the content of flavonoids in vegetables, characterized in that: The following steps are involved: The nanometer Mn3O4 solution is sprayed on the vegetable leaves; the manganese source for preparing the nanometer Mn3O4 solution is manganese acetate tetrahydrate.

8. The method according to claim 7, characterized in that The concentration of nano Mn3O4 in the nano Mn3O4 solution is 50-150 mg / L.

9. The method according to claim 7 or 8, characterized in that: The preparation method of nano Mn3O4 comprises: dissolving manganese acetate tetrahydrate in anhydrous ethanol to obtain a mixed solution; The mixed solution is subjected to a hydrothermal reaction to obtain the nano-Mn3O4.

10. The method according to claim 7, characterized in that The vegetables include: ice plant, broccoli or tomato.

Images