Plant growth-promoting and disease-resistant carbon quantum dot as well as preparation method and application thereof

Abstract

The invention discloses a carbon quantum dot for plant growth promotion and disease resistance and a preparation method and application thereof. The carbon quantum dot nanoparticles based on potassium ion modification are obtained by the preparation method disclosed by the invention. The method has the characteristics that the carbon quantum dots have good biocompatibility, are easily absorbed by plants, and have certain application values in the aspects of growth promotion and disease resistance of the plants.

Description

Technical Field

[0001] The present invention relates to the technical field of carbon nanomaterials, and relates to a carbon quantum dot for promoting plant growth and disease resistance, its preparation method and application, in particular to a preparation method of a carbon quantum dot nanomaterial with potassium ions on its surface and its application in promoting plant growth and disease resistance. Technical Background

[0002] Soybean is one of the most important food crops in China and also one of the oil crops with a large planting area at home and abroad. The industrial development of soybean has brought huge economic benefits to China's agricultural production and plays an extremely important role in promoting the process of agricultural development. With the continuous growth of the daily demand for plant protein and oil by humans, the planting area of soybean has also increased accordingly. However, the growth process of soybean is extremely vulnerable to various diseases, especially those caused by fungal seed-borne pathogens.

[0003] Soybean root rot has always been one of the serious diseases that have occurred since the development of soybean. It can occur in all growth stages of soybean and mainly harms the roots of soybean. At first, black spots will appear, and as time goes by, the spots will expand and irregular patches will appear. In the peak period of the disease, the whole root will rot, seriously affecting the growth and development of soybean. In recent years, the occurrence of soybean rust has also reached a level that cannot be ignored. Once the environmental temperature reaches the suitable survival range of rust fungi and the air moisture content is relatively high, soybean is extremely sensitive to rust pathogens. Rust will occur rapidly in a short time and will cycle multiple times, resulting in premature senescence, severe yellowing and empty pods of soybean. For these two diseases, the most common control strategies are usually the compound use of various chemical pesticides. According to the growth law and planting technology of soybean, agricultural control measures are adjusted, such as timely deep plowing and weeding, and removing diseased plants in the field. In addition, strengthening field management, scientific fertilization and proper field water management are also very common methods. However, simply relying on these methods to control the diseases suffered by soybean during the growth stage requires a long process and it is very difficult to achieve a radical cure. Therefore, there is an urgent need for a rapid, efficient and environmentally friendly scientific method to control the diseases on soybean plants.

[0004] Carbon quantum dots are a type of zero-dimensional carbon nanomaterial with remarkable fluorescence properties. They are composed of ultra-fine, dispersed, quasi-spherical carbon nanoparticles with a size below 10 nm. In addition to having excellent optical properties similar to those of traditional semiconductor quantum dots, carbon quantum dots also have incomparable advantages over traditional quantum dots, such as good photostability, low toxicity, good biocompatibility and environmental friendliness, mild preparation conditions, simple steps, and abundant and inexpensive raw materials. As a new type of nanomaterial in agriculture, carbon dots have great application potential. They can improve the disease resistance of plants and promote plant growth, thus contributing to the sustainability and efficiency of agricultural production. Carbon dots can enhance the resistance of plants to various abiotic stresses. Selenium and nitrogen co-doped carbon dots (Se,N-CDs) can improve the growth rate of rice seedlings and their resistance to salt stress. Selenium doping improves the antioxidant and free radical scavenging activities of carbon dots, while promoting the activities of antioxidant defense enzymes in rice plants and alleviating the inhibitory effect of oxidative stress on photosynthetic activity. Carbon dots can not only enhance the disease resistance of plants but also promote plant growth. Selenium and nitrogen co-doped carbon dots (Se,N-CDs) promote photosynthesis and plant growth by activating the Ca 2+ and jasmonic acid signaling pathways in rice seedlings, improving iron ion homeostasis and the activities of related enzymes. In addition, carbon dots can also improve the water use efficiency of plants. By upregulating the expression of aquaporin genes, they enhance the water absorption capacity of plants and further promote plant growth. Summary of the Invention

[0005] In view of this, the purpose of the present invention is to provide a preparation method of plant growth-promoting and disease-resistant carbon quantum dot nanoparticles that is environmentally friendly and has good effects. After research, the present invention adopts the following technical solutions:

[0006] A preparation method of carbon quantum dot nanoparticles for plant growth promotion and disease resistance, which includes the following steps: Using edible mushroom residue as a carbon source, reacting with potassium hydroxide in an aqueous solution by hydrothermal method to prepare carbon quantum dot nanoparticles.

[0007] As a preferred embodiment of the present invention, the edible mushroom residue is dried and ground into a powdery residue powder. After mixing the residue powder, potassium hydroxide, and water in a ratio of 0.8 g - 1 g: 3 g: 10 mL, the reaction is carried out at 160 - 200 °C for 18 - 24 hours to obtain the carbon quantum dot nanoparticles.

[0008] As a further preferred embodiment of the present invention, the ratio of residue powder, potassium hydroxide, and water is 0.8 g - 1 g: 3 g: 10 mL.

[0009] As a preferred embodiment of the present invention, the conditions for the hydrothermal reaction are a reaction at 180 °C for 20 hours.

[0010] As a preference of the present invention, the preparation method further includes a step of dialyzing the product.

[0011] As a further preference of the present invention, after the hydrothermal reaction ends and the reaction solution cools down, centrifuge at 8000 rpm for 10 min, collect the supernatant, then dialyze with a dialysis bag having a molecular weight of 10000 Kda for 24 h, and dry at 65 °C to obtain the carbon quantum dot powder, which is the carbon quantum dot nanoparticles.

[0012] The carbon quantum dot nanoparticles obtained according to the preparation method of the present invention.

[0013] The application of the carbon quantum dot nanoparticles in promoting the growth of soybeans and / or promoting the germination of soybean seeds.

[0014] In the examples of the present invention, a carbon quantum dot nanoparticle dispersion of 1000 ng / μL or more can significantly promote the germination of soybean seeds, and the preferred concentration is 1000 - 3000 ng / μL.

[0015] In the examples of the present invention, a carbon quantum dot nanoparticle dispersion of 1 mg / mL can significantly increase the germination rate of soybeans and the weights of the above-ground and underground parts.

[0016] The application of the carbon quantum dot nanoparticles in improving the disease resistance of soybeans, preferably in improving the resistance of soybeans to Phytophthora sojae.

[0017] In the examples of the present invention, the carbon quantum dot nanoparticles can inhibit the growth of Phytophthora sojae hyphae and weaken the pathogenicity of Phytophthora sojae.

[0018] In the examples of the present invention, soaking the roots with the carbon quantum dot nanoparticles can enhance the resistance of soybeans to Phytophthora sojae.

[0019] A method for controlling soybean root rot, which inhibits the growth of Phytophthora sojae hyphae by applying the carbon quantum dot nanoparticles.

[0020] The beneficial effects of the present invention are as follows: The present invention provides a method for preparing carbon quantum dots from edible mushroom residues, which resourcefully utilizes the residues and prepares carbon quantum dots by a simple hydrothermal method, which is green and environmentally friendly. The obtained carbon dots have good water solubility, low toxicity, and are easily absorbed by plants. They have good application prospects in aspects such as plant disease resistance and growth promotion. Description of the Drawings

[0021] Figure 1 Schematic diagram of the method for preparing carbon quantum dots from edible mushroom residues

[0022] Figure 2 Transmission electron microscope image

[0023] Figure 3 Infrared spectrum

[0024] Figure 4 XPS spectrum

[0025] Figure 5 Picture of carbon quantum dot dispersion under ultraviolet lamp irradiation

[0026] Figure 6 Investigation on the effect of carbon quantum dots with different concentrations on soybean germination

[0027] Figure 7 Investigation on the effect of carbon quantum dots on plant growth promotion

[0028] Figure 8 Investigation on the hyphal morphology and pathogenicity of Phytophthora sojae by carbon quantum dots

[0029] Figure 9 Investigation on the effect of carbon quantum dots on plant disease resistance

[0030] Figure 10 Investigation on the effect of carbon quantum dot dispersions with different concentrations on plant resistance Specific implementation mode

[0031] In order to make the objectives, technical solutions and advantages of the present invention clearer, the preferred embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings.

[0032] The main reagents used in the preferred embodiments are as follows: edible mushroom residue (composition: cottonseed hulls, corn cobs, etc., commercially available edible mushroom residues are applicable to the present invention), potassium hydroxide, and the experimental water is deionized water;

[0033] The main instruments used in the preferred embodiments are as follows: electronic balance, 25 mL polytetrafluoroethylene hydrothermal reaction kettle, electrothermal constant temperature forced air drying oven, high-speed centrifuge, constant temperature incubator, light incubator, transmission electron microscope, Fourier transform infrared spectrometer.

[0034] Example 1: Preparation of carbon quantum dots using edible mushroom residue as carbon source

[0035] 1. Preparation of carbon quantum dots

[0036] After drying the fresh mushroom residue at 65 °C for 30 min, it is ground into powder with a mortar; take 1 g of mushroom residue powder, add 3 g of potassium hydroxide to 10 mL of deionized water, place it in a 30 mL polytetrafluoroethylene stainless steel reaction kettle, and react at 180 °C for 20 h; the obtained reaction solution is cooled to room temperature, centrifuged at 8000 rpm for 10 min, the supernatant is taken, dialyzed with a 10000 kDa dialysis bag for 24 h, and then dried at 65 °C to obtain carbon quantum dot powder; the carbon quantum dot powder is dissolved with deionized water to obtain a carbon quantum dot dispersion with the required concentration, and stored at 4 °C.

[0037] 2. Characterization of Carbon Dots

[0038] Refer to the synthesis schematic diagram Figure 1 , refer to the transmission electron microscope image Figure 2 , refer to the infrared spectrum Figure 3 , refer to the XPS spectrum Figure 4 (Full-scan XPS spectrum of CDs ((A) and high-resolution spectra of C1s (B), O1s (C), K2p (D))

[0039] Example 2: Preparation of carbon quantum dots using edible mushroom residue as the carbon source. The conditions and ratios are different from those in Example 1. Place the fresh mushroom residue in an oven at 65 °C and dry it for 45 min, then grind it into powder with a juicer for quantitative weighing. Take 0.8 g of mushroom residue powder, add 3 g of potassium hydroxide to 10 mL of deionized water, place it in a 30 mL polytetrafluoroethylene stainless steel autoclave, and react at 200 °C for 24 h; after the obtained reaction solution cools to room temperature, centrifuge it using an ultrafiltration tube. Each tube can be added with 500 μL, and centrifuge at 12000 rpm for 10 min. Discard the waste liquid, then add 500 μL of deionized water to the tube and centrifuge again for 10 min. Repeat this step 5 times until the waste liquid turns light yellow. Finally, invert the adsorption column in the tube, centrifuge at 1000 rpm for 1 min, recover the product, and dry it at 65 °C to obtain carbon quantum dot powder; dissolve the carbon quantum dot powder with deionized water, load it into a quartz cuvette, irradiate the sample with an ultraviolet lamp, and set the water treatment as a control group to observe the fluorescence characteristics of the carbon quantum dots prepared using edible mushroom residue as the carbon source( Figure 5 )

[0040] Example 3: Application of carbon quantum dots prepared from edible mushroom residue in seed germination

[0041] Dissolve the carbon quantum dot powder with deionized water, and prepare carbon quantum dot dispersions with concentrations of 0, 10, 50, 100, 500, 1000, 2000, and 3000 ng / μL respectively. Inoculate soybean seeds into 90 mm petri dishes, and add 30 mL of carbon quantum dot dispersions with different concentrations to the petri dishes respectively. Incubate in a 25 °C light incubator for 3 days, and then observe the germination of the seeds. By measuring the bud length, it can be seen that the higher the concentration of the carbon quantum dot dispersion, the better the germination effect of the seeds, indicating that the carbon quantum dots prepared from edible mushroom residue can promote seed germination( Figure 6 ).

[0042] Example 4: Application of carbon quantum dots prepared from edible mushroom residue in plant growth promotion

[0043] Prepare a 1 mg / mL carbon quantum dot dispersion solution. When the soybean seedlings germinate and grow to 7 cm, irrigate the roots of the seedlings with 10 mL of the solution per plant. After 4 days, observe the germination rate of each pot, the above-ground and underground weights of each seedling, and the Rubisco activity. Use H2O as a control in the same experimental method. Compared with water treatment, the 1 mg / mL carbon quantum dot dispersion solution promotes photosynthesis by increasing the Rubisco activity of plants ( Figure 7 E). Compared with water treatment, the carbon quantum dots prepared from edible mushroom residues can increase the germination rate of soybeans ( Figure 7 D), and the above-ground part ( Figure 7 B) and the underground weight ( Figure 7 C) of each plant both increase. This indicates that the carbon quantum dots prepared from edible mushroom residues have broad application prospects in promoting plant growth.

[0044] Example 5: Application of carbon quantum dots prepared from edible mushroom residues in the growth and pathogenicity of pathogenic bacteria

[0045] Prepare a V8 medium containing 1 mg / mL carbon quantum dots, and then make it into a plate. After the medium solidifies, use a sterilized punch to punch out multiple Phytophthora sojae cakes and inoculate them in the center of the medium. Place them in a constant temperature incubator at 28 °C and culture continuously for 3 days. Observe the colony morphology, and use a microscope to observe the hyphal morphology and sporulation situation. It is found that the growth of Phytophthora sojae hyphae is inhibited ( Figure 8 A), and the sporulation ability is reduced ( Figure 8 B). Then use a sterilized punch to punch out multiple cakes and inoculate them onto the soybean hypocotyls. Observe the disease incidence at the inoculation site after 3 days ( Figure 8 C). The lesion area of the treatment group is relatively reduced compared with water treatment ( Figure 8 D), indicating that the carbon quantum dots prepared from edible mushroom residues will affect the pathogenicity of Phytophthora sojae.

[0046] Example 6: Application of carbon quantum dots prepared from edible mushroom residues in plant disease resistance

[0047] When the soybean seedlings grow the first true leaf, pull them out intact from the soil and transfer them to a 50 mL centrifuge tube for hydroponics for 1 day. Then soak the roots with 10 mL of 1 mg / mL carbon quantum dot dispersion solution for 2 days, and inoculate Phytophthora sojae cakes on the hypocotyls. Observe the disease incidence at the inoculation site after 3 days ( Figure 9 ). Compared with the control group, the resistance of soybeans treated with carbon quantum dots to Phytophthora sojae is enhanced, and the diseased parts are alleviated. This indicates that the carbon quantum dots prepared from edible mushroom residues have good application prospects in plant disease resistance. Select soybean seedlings with uniform growth, soak the roots with carbon quantum dot dispersion solutions of different concentrations for 2 days, inoculate Phytophthora sojae cakes on the hypocotyls, and observe the disease incidence after 3 days ( Figure 10) It was found that after treatment with carbon quantum dot dispersions at different concentrations, there was no significant effect on the resistance of soybeans to Phytophthora sojae.

[0048] Finally, it is stated that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Without departing from the design spirit of the present invention, various deformations and improvements made by those of ordinary skill in the art to the technical solutions of the present invention should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A preparation method of carbon quantum dot nanoparticles for promoting plant growth and disease resistance, characterized in that, It includes the following steps: Using edible mushroom residue as a carbon source, a hydrothermal reaction occurs with potassium hydroxide in an aqueous solution to prepare carbon quantum dot nanoparticles.

2. The preparation method according to claim 1, wherein, After drying the edible mushroom residue, it is ground into a powdery residue powder. After mixing the residue powder, potassium hydroxide, and water in a ratio of 0.8 g - 1 g: 3 g: 10 mL, the reaction is carried out at 160 - 200 °C for 18 - 24 hours to obtain the carbon quantum dot nanoparticles.

3. The preparation method according to claim 2, characterized in that, The ratio of the residue powder, potassium hydroxide, and water is 1 g: 3 g: 10 mL.

4. The preparation method according to claim 2, wherein The conditions for the hydrothermal reaction are a reaction at 180 °C for 20 hours.

5. The preparation method according to claim 1, wherein The preparation method further includes a step of dialyzing the product.

6. The preparation method according to claim 5, characterized in that, After the hydrothermal reaction ends and the reaction solution cools, it is centrifuged at 8000 rpm for 10 min, the supernatant is collected, and then dialyzed with a dialysis bag with a molecular weight of 10000 Kda for 24 h, and then dried at 65 °C to obtain carbon quantum dot powder, which is the carbon quantum dot nanoparticles.

7. Carbon quantum dot nanoparticles obtained by the preparation method according to any one of claims 1 - 6.

8. Use of the carbon quantum dot nanoparticles according to claim 7 in promoting the growth of soybeans and / or promoting the germination of soybean seeds.

9. Use of the carbon quantum dot nanoparticles according to claim 7 in improving the disease resistance of soybeans, preferably in improving the resistance of soybeans to Phytophthora sojae.

10. A method for preventing and controlling soybean root rot, characterized in that, Inhibiting the growth of Phytophthora sojae hyphae by applying the carbon quantum dot nanoparticles according to claim 7.

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