Plant growth regulator for regulating plant stress resistance and application thereof

Abstract

The application discloses a plant growth regulator for regulating plant stress resistance and application, and belongs to the field of agricultural biotechnology. The plant growth regulator takes a surface positive electric property modified zinc oxide quantum dot solution as an active component, is prepared into a spraying solution, and is applied to plants in a leaf surface spraying treatment mode. The zinc oxide quantum dot is a kind of leaf surface interface signal regulation type nano preparation, the material has photocatalytic activity, can induce the spatiotemporal dynamic change of moderate active oxygen signal and calcium signal under the condition of leaf surface illumination, further activates jasmonic acid signal response, forms a cascade regulation process of "leaf surface interface stimulation-ROS / Ca 2+ signal transmission-jasmonic acid response activation". Through the mechanism, the plant leaf surface growth regulator can improve photosynthesis efficiency and biomass accumulation under normal growth conditions, regulates plant leaf epidermis structure development and secondary metabolite composition, and can also relieve plant growth inhibition under salt stress and drought stress conditions.

Description

Technical Field

[0001] This invention belongs to the field of agricultural biotechnology, specifically relating to a plant growth regulator that controls plant stress resistance and its application. Background Technology

[0002] The information disclosed in this background section is intended only to enhance understanding of the overall background of the invention and is not necessarily to be construed as an admission or in any way implying that such information constitutes prior art known to those skilled in the art.

[0003] Plant growth regulators are important agricultural inputs for regulating plant growth and development and improving crop productivity. Plant growth, development, and adaptation to stress are regulated by multiple endogenous signals. Among them, reactive oxygen species (ROS) signals, calcium signals, and plant hormone signals play crucial roles in plant perception of the external environment, regulation of photosynthesis, carbon metabolism, cell differentiation, and stress responses. Moderate accumulation of ROS does not simply cause oxidative damage but can act as a signaling molecule participating in plant growth regulation; calcium ions, as important second messengers, can mediate rapid plant responses to external stimuli; and plant hormone signals such as jasmonic acid, abscisic acid, and salicylic acid participate in the balance regulation between plant growth and stress resistance. Therefore, exogenous agents capable of precisely regulating the plant's endogenous signaling network hold promise for playing a significant role in promoting plant growth and enhancing stress adaptation.

[0004] Plant leaves are vital organs for photosynthesis, transpiration, and the sensing of external environmental stimuli. The leaf epidermis and its appendages, such as epidermal trichomes, serve as crucial interfaces for material exchange, signal sensing, and defense responses between plants and their environment. These structures not only influence leaf wetting, gas exchange, light response, and biological defense, but are also closely related to the synthesis, accumulation, and release of some plant secondary metabolites. Therefore, regulating plant signal responses, leaf epidermal structure development, and secondary metabolic processes through the leaf interface is an important direction for developing novel plant growth regulators.

[0005] Nanomaterials, with their small particle size, large specific surface area, high surface activity, and ease of functionalization, offer new technological avenues for plant growth regulation. Zinc oxide nanomaterials, containing the essential micronutrient zinc, show potential applications in plant nutrient supplementation, growth promotion, and stress resistance regulation. However, current agricultural applications of zinc oxide nanomaterials primarily emphasize zinc supply, biomass enhancement, or improved stress resistance phenotypes. A clear technical solution remains lacking regarding whether they can act as exogenous interfacial stimuli to trigger endogenous signal cascade responses in plant leaves and further drive photosynthetic carbon assimilation and stress adaptation processes. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the purpose of this invention is to provide a plant growth regulator for controlling plant stress resistance and its application. Specifically, it provides the preparation of a zinc oxide quantum dot plant leaf growth regulator based on leaf interface signal regulation and its application in promoting plant vegetative growth, regulating epidermal structure development, and alleviating environmental stress.

[0007] To achieve the above objectives, the technical solution of the present invention is as follows: In a first aspect, the present invention provides a plant growth regulator for regulating plant stress resistance. The plant growth regulator is prepared into a spray solution with a zinc oxide quantum dot (ZnO QDs) solution modified with positive surface charge as the active component and applied to plants by foliar spraying.

[0008] Secondly, the present invention provides the application of the above-mentioned plant growth regulators that regulate plant stress resistance in promoting plant growth under normal or abiotic stress conditions.

[0009] Thirdly, the present invention provides a method for improving plant stress resistance or alleviating plant growth inhibition under abiotic stress, wherein the method is to apply the above-mentioned plant growth regulator that regulates plant stress resistance; The abiotic stresses include one or more of drought stress and salt stress.

[0010] One or more of the above technical solutions have the following advantages or beneficial effects: This invention discloses a zinc oxide quantum dot plant foliar growth regulator based on leaf interface signal modulation, which can be applied to promote plant vegetative growth and alleviate environmental stress. The zinc oxide quantum dots described in this invention do not only function through zinc nutrient supplementation, but also act as a leaf interface signal modulation nano-formulation. This material possesses photocatalytic activity, inducing moderate spatiotemporal dynamic changes in reactive oxygen species (ROS) and calcium signals under foliar illumination conditions, further activating the jasmonic acid signal response, forming a "leaf interface stimulation—ROS / Ca" response. 2+ The process involves a cascade regulation of "signal transduction—jasmonic acid response activation." Through this mechanism, the plant leaf growth regulator can improve photosynthetic efficiency and biomass accumulation under normal growth conditions, regulate the development of plant leaf epidermal structure and the composition of secondary metabolites, and alleviate plant growth inhibition under salt and drought stress. Attached Figure Description

[0011] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0012] Figure 1The results show the material characterization of zinc oxide quantum dots; (a) is the morphology captured by transmission electron microscopy, (b) is the Fourier transform infrared spectrum, and (c) is the photoluminescence spectrum. Figure 2 The electron paramagnetic resonance spectrum of zinc oxide quantum dots after illumination; Figure 3 Images of DAB staining on leaves at different times (6h, 12h, 36h) under light and dark conditions after zinc oxide treatment, with a scale bar of 100 μm; the yellow arrows indicate the accumulation of DAB in the glandular hairs. Figure 4 Spatiotemporal distribution changes of reactive oxygen species (ROS) signals induced by zinc oxide quantum dot foliar application in leaf glandular hairs, epidermal cells, and leaf veins, scale bar 50 μm; where BF indicates the field, DCF indicates the name of the fluorescent dye, and Overlay is the image after mixing the two fluorescence channels. Figure 5 Optical microscope images of leaves stained with calcium ions after different treatment groups; (a) is the CK group, (b) is the ZnO QDs group, scale bar is 100 μm; Figure 6 The effects of different treatment groups on hydrogen peroxide content, jasmonic acid content, and gene expression in tobacco leaves were investigated. (a) shows the effect of the ZnO QDs group and other treatment groups on hydrogen peroxide content in leaves after 14 days of treatment; (b) shows the effect of different treatment groups on jasmonic acid content; and (c) shows the effect of different treatment groups on tobacco leaf content. LOX6 and WRKY11 The impact of expression; Figure 7 The effects of the CK group and the ZnO QDs group on the growth indicators, photosynthetic parameters, and starch content of tobacco under normal conditions after 14 days of treatment were investigated. Among them, (a) shows the effect on fresh weight of tobacco, (b) shows the effect on dry weight of tobacco, (c) shows the effect on photosynthetic parameters of tobacco, and (d) shows the effect on starch content of tobacco. Figure 8 The effects of different treatment groups on the development of glandular trichomes in tobacco under normal conditions after 14 days of treatment are shown in the SEM images. (a) is the SEM image of the CK group, (b) is the SEM image of the ZnO QDs group, and (c) shows the effects of the CK group and the ZnO QDs group on the development of glandular trichomes in tobacco under normal conditions. The yellow and green pseudo-colors in (a) and (b) represent short-stalked and long-stalked glandular trichomes, respectively. Figure 9 The effects of treatment on the nicotine configuration of tobacco under normal conditions in the CK group and the ZnO QDs group after 14 days; Figure 10The effects of different treatment groups on the growth status of tobacco under drought and salt stress after 14 days of treatment were shown; (a) shows the effect of drought stress on tobacco dry weight, and (b) shows the effect of salt stress on tobacco dry weight. Figure 11 To compare the effects of different treatment groups on tobacco leaves under drought and salt stress conditions 14 days after treatment. LOX6 and WRKY11 The effects of expression; where (a) represents the effect of drought stress on tobacco leaves. LOX6 and WRKY11 The effect of expression, (b) on tobacco leaves under salt stress. LOX6 and WRKY11 The impact of expression. Detailed Implementation

[0013] Based on existing technologies, there is an urgent need to develop a zinc oxide quantum dot plant growth regulator that can be applied foliarly to promote photosynthesis and vegetative growth in plants under normal growth conditions, regulate the developmental state of leaf epidermal trichomes and the stereoisomer composition of secondary metabolites, and alleviate plant growth inhibition under abiotic stress conditions.

[0014] The key technical mechanism of this invention lies in the fact that, after foliar spraying, positively charged zinc oxide quantum dots can form a nano-interface stimulation on the leaf surface, first inducing dynamic changes in reactive oxygen species signals in the leaf epidermis, glandular trichomes, and adjacent areas of leaf veins, accompanied by an enhancement of calcium signals; subsequently, ROS-Ca 2+ The signal is further correlated with and promotes the jasmonic acid signaling response, affecting physiological processes related to photosynthesis, carbon assimilation, and stress adaptation. Unlike traditional zinc fertilizers that mainly rely on zinc element supplementation, the plant leaf growth regulators described herein can improve photosynthetic efficiency and biomass accumulation under normal growth conditions, regulate the development of plant leaf epidermal structure and the stereoisomer composition of secondary metabolites, and alleviate plant growth inhibition under salt and drought stress conditions.

[0015] In one typical embodiment, the present invention provides a plant growth regulator for controlling plant stress resistance. The plant growth regulator is prepared into a spray solution with a zinc oxide quantum dot solution modified with positive surface charge as the active component and applied to plants by foliar spraying.

[0016] In some embodiments of this implementation, the positively charged zinc oxide quantum dots are prepared by an alcohol-phase base-catalyzed precipitation method combined with a silane surface modification method. The surface modifier for the zinc oxide quantum dots is 3-aminopropyltriethoxysilane.

[0017] The specific preparation method is as follows: potassium hydroxide solution and zinc acetate dihydrate are stirred and mixed at room temperature, then silane surface modifier and water are added, stirring is continued, and the mixture is centrifuged, washed and dried to obtain the final product.

[0018] Furthermore, the mass ratio of zinc acetate dihydrate to potassium hydroxide is (5~10):(1~5), preferably (5~6):(2~3). The volume ratio of silane surface modifier to water is (0.1~1):(1~2), preferably (0.5~1):(1.5~2). The mass-volume ratio of zinc acetate dihydrate to silane surface modifier is (5~10g):(400~800μL), preferably (5~6g):(400~600μL).

[0019] Furthermore, zinc acetate dihydrate is dissolved in an alcohol solvent by heating at 70-90°C to obtain an aqueous solution of zinc acetate dihydrate. The mass concentration of the zinc acetate dihydrate solution is 1-10 g / mL, preferably 5-10 g / mL. The heating time is 0.5-5 h, preferably 1-3 h.

[0020] Furthermore, potassium hydroxide is dispersed in anhydrous ethanol and ultrasonically treated to obtain a potassium hydroxide solution. The mass concentration of the potassium hydroxide solution is 1~10 g / mL, preferably 1~5 g / mL.

[0021] The transmission electron microscopy (TEM) particle size of positively charged zinc oxide quantum dots is 2–20 nm, preferably 5–10 nm; the hydrated particle size is 10–80 nm, preferably 20–40 nm.

[0022] The zeta potential of positively modified zinc oxide quantum dots is +10 to +50 mV, preferably +20 to +40 mV.

[0023] In some embodiments of this implementation, the plant includes tobacco.

[0024] In some embodiments of this implementation, the concentration of positively charged modified zinc oxide quantum dots is 1~50 mg / L, specifically 1 mg / L, 5 mg / L, 6 mg / L, 7 mg / L, 8 mg / L, 9 mg / L, 10 mg / L, 11 mg / L, 12 mg / L, 15 mg / L, 16 mg / L, 18 mg / L, 20 mg / L, 30 mg / L, 40 mg / L, 50 mg / L, etc., preferably 5~20 mg / L, more preferably 10 mg / L.

[0025] In some embodiments of this implementation, the spray solution also includes a surfactant, which includes, but is not limited to, organosilicon surfactants (such as Silwet L-77), with a volume fraction of 0.01~0.1%, specifically 0.01%, 0.02%, 0.03%, 0.04%, 0.05%, 0.06%, 0.07%, 0.08%, 0.09%, 0.1%, etc., preferably 0.02~0.04%, and most preferably 0.02%.

[0026] Specifically, the zinc oxide quantum dot suspension can be ultrasonically dispersed to 10 mg / L, mixed with 0.02% surfactant, and then the mixed suspension can be evenly sprayed onto the leaf surface.

[0027] In some embodiments of this implementation, the foliar spraying treatment specifically includes the following steps: germinating plant seeds and cultivating them to the seedling stage, and spraying the spray solution evenly onto the leaf surface.

[0028] Furthermore, the plant culture conditions included 16 hours of light / 8 hours of darkness and a temperature of 20–22 °C. The seedlings used were 3–4 week old Nicotiana benthamiana.

[0029] Furthermore, based on the leaf area, spray until the leaf surface is evenly moistened, preferably using a zinc oxide quantum dot spray volume of 1-2 mL, and spraying frequency of once a week.

[0030] In some embodiments of this implementation, the plant growth regulator that regulates plant stress resistance includes at least one of the following (a1) to (a3): (a1) The plant growth regulator described above has photocatalytic activity, which can induce dynamic changes in reactive oxygen species (ROS) and calcium signals in plant leaves, activate the jasmonic acid (JA) signal response, and form a “leaf-interface stimulation-ROS / Ca” relationship. 2+ The cascade regulation of "signal transduction-jasmonic acid response activation" promotes photosynthetic carbon assimilation and vegetative growth in plants.

[0031] (a2) The plant growth regulator regulates the development of plant leaf epidermal structure and the composition of plant secondary metabolites; specifically: the plant growth regulator can increase the density of glandular hairs on tobacco stalks and reduce the proportion of L-nicotine in tobacco.

[0032] (a3) The plant growth regulators described herein differ from the zinc ion nutrient supplementation effect. They exert their effect in alleviating abiotic stresses through leaf interface signal regulation. The abiotic stresses include salt stress and drought stress.

[0033] It should be noted that the regulation in this invention is positive regulation. The plant leaf growth regulator can improve photosynthetic efficiency and biomass accumulation under normal growth conditions, regulate the development of plant leaf epidermal structure and the stereoisomer composition of secondary metabolites, and alleviate plant growth inhibition under salt stress and drought stress.

[0034] The drought stress conditions are a polyethylene glycol aqueous solution with a mass concentration of 5-20%, specifically 5%, 8%, 10%, 12%, 15%, 18%, 20%, etc., preferably a polyethylene glycol aqueous solution with a mass concentration of 10%.

[0035] The salt stress condition is a salt solution with a mass concentration of 0.1-0.9%, specifically 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, etc., preferably a salt solution with a mass concentration of 0.5-0.7%, and most preferably a salt solution with a mass concentration of 0.6%.

[0036] When the same concentration of zinc ions (zinc sulfate) is applied, it can also increase the dry weight of leaves under drought stress, but the effect is not as good as that of zinc oxide quantum dots. Under salt stress, however, the application of zinc ions has a further inhibitory effect.

[0037] In one typical embodiment, the present invention provides the application of the above-mentioned plant growth regulators for regulating plant stress resistance in promoting plant growth under normal conditions and under abiotic stress, thereby improving stress resistance.

[0038] In one typical embodiment, the present invention provides a method for improving plant stress resistance or alleviating plant growth inhibition under abiotic stress, the method being the application of the above-mentioned plant growth regulators that regulate plant stress resistance; The abiotic stresses include one or more of drought stress and salt stress.

[0039] This invention provides a plant growth regulator based on positively charged zinc oxide quantum dots. Preferably, a zinc oxide quantum dot suspension is sprayed onto plant leaves so that the particles regulate plant leaf signals to promote plant growth and stress adaptation.

[0040] In this invention, unless otherwise specified, all other test materials and instruments are conventional test materials in the field and can be purchased through commercial channels.

[0041] The positively charged zinc oxide quantum dots used in the examples were prepared by an alcohol-phase base-catalyzed precipitation method combined with a silane surface modification method. The specific preparation method includes the following steps: 5.54 g of zinc acetate dihydrate was dissolved in 100 mL of anhydrous ethanol at 80 °C for 2 hours, and 2.06 g of potassium hydroxide was sonicated in 50 mL of anhydrous ethanol. The potassium hydroxide solution was then added dropwise to the zinc acetate dihydrate solution, and the mixture was stirred at room temperature for 30 min. Next, 500 μL of APTES (3-aminopropyltriethoxysilane) and 1.5 mL of ultrapure water were added dropwise to the solution, and the mixture was stirred at room temperature for 1 h. Finally, the product was centrifuged for 10 min, the precipitate was washed three times with ethanol, and dried at 60 °C for 2 h to obtain zinc oxide quantum dots.

[0042] Ag NPs were purchased from Shanghai Pantian Powder Materials Co., Ltd., with the product number PT-Ag-50nm; Se NPs were synthesized by chemical reduction; Fe3O4 NPs were synthesized by alkaline precipitation; BC represents gold core carbon black (which has a core-shell structure) and was synthesized by a two-step method of sodium citrate reduction-hydrothermal carbonization.

[0043] To enable those skilled in the art to better understand the technical solution of the present invention, the technical solution of the present invention will be described in detail below with reference to specific embodiments.

[0044] Example 1 1. Plant species and materials The plant species used in the experiment was Nicotiana benthamiana. This tobacco came from the Tobacco Research Institute of the Chinese Academy of Agricultural Sciences.

[0045] The positively charged zinc oxide quantum dots used in the experiment were prepared by an alcohol-phase alkaline catalytic precipitation method combined with a silane surface modification method, and the actual particle size was about 5-10 nm.

[0046] 2. Material spraying conditions The seedlings used are 3-4 week old Nicotiana benthamiana.

[0047] The spray concentration is 10 mg / L, which includes 0.02% surfactant. The spray volume is 1~2 mL, and the spray is applied once a week.

[0048] 3. Material spraying process Tobacco seedling cultivation: Sterilized seeds were sown in a culture medium consisting of a 1:1 volume ratio of potting soil and vermiculite. After 14 days, the seedlings were transplanted into individual pots. Cultivation was carried out under the following conditions: temperature 22±1℃, relative humidity 30%, photoperiod of 16 hours light / 8 hours dark, and light intensity of 80 μmol·m⁻¹. -2 ·s -1 Water every 5 days. Cultivate seedlings to 3-4 weeks of age for later use. Drought stress and salt stress were simulated using 10% polyethylene glycol and 0.6% sodium chloride solutions, respectively.

[0049] CK: No plant growth regulators applied.

[0050] ZnO QDs: Zinc oxide quantum dots with a concentration of 10 mg / L.

[0051] Zn ions: Apply 10 mg / L of zinc sulfate.

[0052] Figure 10 The "healthy CK" conditions refer to culture under normal conditions. Figure 10 The “CK” condition in the text refers to culture under the corresponding stress conditions.

[0053] The drought stress condition was 10% polyethylene glycol (PEG).

[0054] Salt stress conditions: 0.6% sodium chloride (NaCl).

[0055] Spraying treatment: Prepare a 10 mg / L nano-suspension by dispersing zinc oxide quantum dots in water and then ultrasonically disperse it. Transfer 1-2 mL of the suspension to a spray bottle and spray it onto the tobacco seedlings, ensuring that the leaves are completely covered by the suspension.

[0056] Material characterization: The morphology of zinc oxide quantum dots was photographed using transmission electron microscopy, and their Fourier transform infrared spectrum and photoluminescence spectrum were tested.

[0057] Tobacco leaf signal characterization: Leaves under different treatment conditions were stained with the DCFH-DA fluorescent probe and 3,3'-diaminobenzidine (DAB). The distribution of reactive oxygen species was observed using a conventional optical microscope and a laser confocal microscope. Alizarin staining was used to observe changes in calcium ion signals in the leaves. The total hydrogen peroxide content, jasmonic acid content, and jasmonic acid pathway-related genes in the leaves were measured after 14 days of treatment. LOX6 and WRKY11 The amount of expression.

[0058] Experiment under normal growth conditions: After 14 days of treatment, the tobacco was harvested, and the biomass of the aboveground parts, leaf photosynthetic parameters, starch content, glandular trichome density, and nicotine content of different configurations were measured.

[0059] Drought and salt stress experiments: tobacco was harvested 14 days after treatment, and growth indicators of tobacco under stress were measured.

[0060] 4. Experimental Results Figure 1 The transmission electron microscopy (TEM) results show that the zinc oxide quantum dots of this invention have a particle size of 6–10 nm. Fourier transform infrared spectroscopy confirms the presence of functional groups such as Si-O-Zn. Photoluminescence spectroscopy indicates that the maximum excitation wavelength and emission wavelength of the zinc oxide quantum dots are 346 nm and 562 nm, respectively. Figure 2 This indicates that zinc oxide quantum dots can generate superoxide radicals under light conditions. Figure 3 The results indicate that the use of zinc oxide quantum dots induced greater DAB accumulation under light compared to dark conditions. These results demonstrate that zinc oxide quantum dots possess photoluminescence properties and photocatalytic activity, and can induce more moderate reactive oxygen species signals on the leaf surface.

[0061] pass Figure 4 It is known that foliar application of zinc oxide quantum dots induces changes in reactive oxygen species (ROS) signals within tobacco leaves. ROS initially accumulate in glandular trichomes, are transmitted through epidermal and mesophyll cells, and then converge at the veins. Figure 5 Images of calcium ion staining show that zinc oxide quantum dot treatment significantly increased the concentration of calcium ions in the leaves. Through... Figure 6 It is known that, compared with other nanomaterials (Ag NPs, Se NPs, Fe3O4 NPs, BC) and traditional zinc fertilizers (Zn ions, specifically zinc sulfate), at the same application concentration, after 14 days of treatment with zinc oxide quantum dots, compared with the CK control group, the hydrogen peroxide content in leaves increased by 39.26%, and the jasmonic acid content increased by 18.31%, and genes related to the jasmonic acid pathway were also affected. LOX6 and WRKY11 The expression levels of these substances were significantly increased by 26.34% and 16.44%. These results indicate that foliar application of zinc oxide quantum dots can induce moderate reactive oxygen species and calcium ion signaling responses, activate the jasmonic acid signaling response, and achieve plant signal regulation, thereby promoting photosynthetic carbon assimilation, vegetative growth, and enhancing stress resistance.

[0062] pass Figure 7 Under normal conditions, the fresh weight and dry weight of tobacco increased by 14.88% and 31.52%, respectively. After applying zinc oxide quantum dots, the leaf transpiration rate, photosynthetic rate, and stomatal conductance increased by 15.78%, 25.25%, and 32.97%, respectively, and the starch content increased by 227%. These results indicate that under normal growth conditions, the application of zinc oxide quantum dots can effectively promote tobacco growth, increase the photosynthetic rate, and significantly improve carbon assimilation efficiency.

[0063] pass Figure 8 It can be seen that under normal conditions, the density of glandular trichomes in tobacco stalks significantly increases after the application of zinc oxide quantum dots. Through... Figure 9 The results show that the proportion of L-nicotine in tobacco was significantly reduced after the application of zinc oxide quantum dots. These results indicate that the application of zinc oxide quantum dots can regulate the development of tobacco epidermal structure and has applications in regulating tobacco metabolism.

[0064] pass Figure 10 It is known that tobacco growth is significantly inhibited under drought stress, while the application of zinc oxide quantum dots can increase leaf dry weight by 48.02%. Similarly, under salt stress, tobacco dry weight increases by 11.68%. Figure 11 As shown in (a), under drought stress, LOX6 and WRKY11 The expression levels increased by 73.81% and 5.50%, respectively. Figure 11 As shown in (b) above, under salt stress, LOX6 and WRKY11The expression levels of these substances increased by 145.61% and 130.94%. However, under stress conditions, application of traditional zinc fertilizer could not achieve the same alleviating effect. These results indicate that under stress conditions, zinc oxide quantum dot-based plant growth regulators can improve the growth status of tobacco, alleviate growth inhibition to some extent, and are particularly evident in increased dry weight. LOX6 and WRKY11 The increased expression level indicates that jasmonic acid signaling response is also enhanced under stress conditions, thereby regulating tobacco to improve its stress adaptation ability.

[0065] In summary, the above results indicate that foliar application of positively charged zinc oxide quantum dots initially induces interface-induced reactive oxygen species (ROS) and calcium signaling responses in plant leaves. Subsequently, jasmonic acid (JA)-related indicators are activated, further manifesting as increased photosynthetic parameters, increased starch accumulation, enhanced biomass, increased glandular trichome density, altered nicotine conformation, and relief of growth inhibition under stress conditions. This process demonstrates that the effect of the zinc oxide quantum dots described in this invention is not simply dependent on zinc ion supplementation, but rather through a process involving "foliar interface stimulation—ROS / Ca..." 2+ The plant growth regulation function is achieved through a "signal transduction-jasmonic acid response activation" mechanism. Therefore, this invention provides a signal-regulated nano-plant growth regulator that differs from traditional zinc fertilizers and has broad application prospects.

[0066] 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. The application of a plant growth regulator that modulates plant stress resistance in promoting plant growth under abiotic stress conditions, characterized in that, The abiotic stresses include one or more of drought stress and salt stress; The plant growth regulator is prepared as a spray solution using a zinc oxide quantum dot solution with positively charged surface as the active component, and is applied to plants by foliar spraying. The plant in question is tobacco; the application is to increase the density of glandular hairs on the long stalk of tobacco and reduce the proportion of L-nicotine in tobacco. The positively charged zinc oxide quantum dots were prepared by an alcohol-phase alkaline catalytic precipitation method combined with a silane surface modification method. The surface modifier for the positively charged zinc oxide quantum dots is 3-aminopropyltriethoxysilane.

2. The application according to claim 1, characterized in that, The transmission electron microscopy (TEM) particle size of positively charged zinc oxide quantum dots is 2–20 nm; the hydrated particle size is 10–80 nm. The zeta potential of positively modified zinc oxide quantum dots is +10 to +50 mV.

3. The application according to claim 1, characterized in that, The concentration of positively charged zinc oxide quantum dots was 1~50 mg / L.

4. The application according to claim 1, characterized in that, The spray solution also includes surfactants; the surfactants include organosilicon surfactants, with a volume fraction of 0.01~0.1%.

5. The application according to claim 1, characterized in that, Foliar spraying treatment specifically includes: germinating plant seeds and cultivating them to the seedling stage, and then evenly spraying the spray solution onto the leaf surface; Plant culture conditions included 16 h light / 8 h darkness and a temperature of 20~22 ℃; The spray volume is 1-2 mL, and the spraying frequency is 1-2 times per week.

6. The application according to claim 1, characterized in that, The drought stress conditions are a polyethylene glycol aqueous solution with a mass concentration of 5-20%; the salt stress conditions are a salt solution with a mass concentration of 0.1-0.9%.

7. A method for increasing the density of glandular trichomes in tobacco stalks and reducing the proportion of L-nicotine in tobacco, characterized in that, The method involves applying a plant growth regulator that controls plant stress resistance as described in any one of claims 1 to 6 to tobacco.

Images