Application of TiO2 nanoparticles in relieving plant salt stress

Abstract

The invention discloses application of TiO2 nanoparticles in relieving plant salt stress, and belongs to the field of vegetable crop cultivation and planting. The application comprises the steps that TiO2 nanoparticles and water are evenly mixed to prepare a nano solution, then the nano solution is sprayed to the surfaces of leaves of plants in the flowering stage, and the result shows that the chlorophyll content can be remarkably increased, the photosynthetic efficiency of the plants can be improved, the antioxidant enzyme activity can be reduced, the physiological indexes of tomatoes can be adjusted from multiple aspects, and the adverse effect of salt stress can be effectively relieved.

Description

Technical Field

[0001] The invention belongs to the field of vegetable crop cultivation and planting, and particularly relates to an application of TiO2 nanoparticles in alleviating plant salt stress. Background Art

[0002] The formation of saline-alkali land is the result of a combination of natural factors and human activities. Natural factors include rainfall less than evaporation, high groundwater levels, and high salinity in the soil parent material; human factors include over-irrigation, irrational land use, and poor drainage. Saline-alkali land severely impacts agricultural production and the ecological environment, leading to reduced crop yields, disruption of the ecological balance, and impacts on biodiversity. Saline-alkali land poses numerous hazards to vegetable growth. High salt levels increase the osmotic pressure of the soil solution, making it difficult for vegetable roots to absorb water and even leading to dehydration. Excessive sodium and chloride ions are toxic, interfering with intracellular enzyme activity and affecting nutrient absorption and metabolism. High salinity also alters soil structure, causing compaction and reduced aeration and water permeability. These factors, combined, restrict vegetable growth and development, reducing yield and quality, and even causing their death, posing a significant challenge to agricultural production.

[0003] Tomatoes are a vegetable with both nutritional and medicinal value. Nutritionally, they are rich in antioxidants such as vitamin C, vitamin E, vitamin K, and lycopene, which can scavenge free radicals, boost immunity, prevent cardiovascular disease, and maintain eye health. They also contain minerals such as potassium, magnesium, and calcium to maintain normal physiological functions. Medicinally, they promote thirst and quench thirst, strengthen the stomach and aid digestion, and can alleviate symptoms such as loss of appetite and indigestion. Their bioactive ingredients also have anti-inflammatory properties and may reduce the risk of certain cancers. However, saline-alkali soils significantly impact tomato growth. High salt and alkaline levels increase the osmotic pressure of the soil solution, making it difficult for tomato roots to absorb water and nutrients. This leads to water and fertilizer shortages, slowed growth, and altered soil properties, inhibiting the absorption of trace elements by tomatoes, causing various physiological diseases and ultimately significantly reducing yields.

[0004] Nano-TiO2 is a nanomaterial with good photocatalytic and chemical stability. Its nanoscale structure gives it higher reactivity and specific surface area than traditional materials. When applied to plants, nano-TiO2 can alleviate the damage caused by salt stress through a variety of mechanisms. First, it can remove reactive oxygen species (ROS) produced by plants under salt stress, which can cause oxidative damage to cells. Studies have shown that nano-TiO2 can significantly increase the activity of antioxidant enzymes in plants, enhance the plant's self-defense mechanism, and thus reduce oxidative damage to cell membranes. Secondly, although titanium is not an essential element for plants, nano-TiO2 can promote some physiological metabolic processes in plants, improve the nutritional status of plants, promote root growth, and enhance the absorption capacity of water and nutrients. In addition, nano-TiO2 can also improve the osmotic regulation ability of plants, by enhancing the stability of cell membranes and reducing salt penetration damage, fundamentally improving the survival ability of plants in salt stress environments.

[0005] This article will examine the mechanisms by which nano-TiO2 alleviates salt stress in tomatoes from the perspectives of transcriptome and metabolomics. At the transcriptomic level, analysis of gene expression levels reveals which stress-resistance-related genes are upregulated or downregulated by nano-TiO2, thereby impacting key pathways such as growth, signal transduction, and ion transport, thereby enhancing salt tolerance in tomatoes. Metabolomics, however, allows for precise identification of metabolite changes in tomatoes under the influence of nano-TiO2, such as increases in osmotic regulators and antioxidants. These substances help maintain cellular osmotic pressure and scavenge excess free radicals, ultimately safeguarding the normal physiological functions of tomatoes under salt stress. Summary of the Invention

[0006] In view of this, the object of the present invention is to provide an application of TiO2 nanoparticles in alleviating plant salt stress.

[0007] In order to achieve the above object, the present invention provides the following technical solutions:

[0008] The present invention provides an application of TiO2 nanoparticles in alleviating plant salt stress.

[0009] Preferably, the application comprises the following steps:

[0010] TiO2 nanoparticles are mixed evenly with water to prepare a nanosolution, which is then sprayed on the surface of plant leaves during flowering.

[0011] Preferably, the mass volume ratio of the TiO2 nanoparticles to water is 5-15:100 mg / L.

[0012] Preferably, the preparation method of the TiO2 nanoparticles is:

[0013] (1) TiCl4 was added dropwise to anhydrous ethanol under stirring and continued stirring until a gel was formed;

[0014] (2) heating the gel at 75-85°C until a white powder is formed;

[0015] (3) The white powder is dried, ground, and calcined in sequence to obtain TiO2 nanoparticles.

[0016] Preferably, the volume ratio of TiCl4 to anhydrous ethanol in step (1) is 1:4-6.

[0017] Preferably, in step (3), the drying temperature is 100-120° C., and the drying time is 40-50 min; the calcination temperature is 380-420° C., and the time is 1.5-2.5 h.

[0018] Preferably, the nano solution is sprayed 2 to 3 times per week.

[0019] Preferably, the alleviating plant salt stress comprises improving plant growth parameters, photosynthesis and antioxidant capacity.

[0020] Preferably, the plant is tomato.

[0021] The present invention has the following beneficial technical effects:

[0022] This study examined the role of physiological indicators in revealing the mechanism by which TiO2 nanoparticles alleviate salt stress in tomatoes, accurately measuring multiple indicators. The results showed increased chlorophyll content, enhanced photosynthetic efficiency, decreased antioxidant enzyme activity, and reduced malondialdehyde content, demonstrating that TiO2 nanoparticles can regulate tomato physiology in multiple ways, effectively alleviating the adverse effects of salt stress.

[0023] Furthermore, the present invention focuses on the mechanism by which TiO2 nanoparticles alleviate salt stress in tomatoes based on transcriptome and metabolome analysis. Under salt stress, tomatoes treated with TiO2 nanoparticles were studied at the transcriptome and metabolome levels, and it was found that significant changes occurred in gene expression and metabolite levels in tomatoes. Transcriptome analysis revealed a series of changes in gene expression patterns related to stress response, ion balance, and antioxidant defense, while metabolome analysis detected adjustments in the levels of multiple metabolites involved in osmotic regulation, energy metabolism, and secondary metabolism. This in-depth analysis based on transcriptomes and metabolomes provides detailed molecular and metabolic information for understanding the intrinsic mechanism by which TiO2 nanoparticles alleviate salt stress in tomatoes. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 Schematic diagram of the growth of tomato plants under different treatment conditions;

[0025] Figure 2The test results of tomato photosynthetic indicators under different treatment conditions, among which (A) is transpiration rate, (B) is net photosynthetic efficiency, (C) is intercellular CO2 concentration, and (D) is stomatal conductance;

[0026] Figure 3 The following are the physiological index test results of tomato plants under different treatment conditions; (A) is the chlorophyll content, (B) is the nitrogen content, (C) is the proline content, and (D) is the malondialdehyde content;

[0027] Figure 4 The following are the results of antioxidant enzyme activity tests on tomato plants under different treatment conditions; (A) is catalase, and (B) is superoxide dismutase;

[0028] Figure 5 is a graph showing the number of differentially expressed genes and the number of up-regulated and down-regulated genes in tomato fruits under different treatment conditions;

[0029] Figure 6 is the expression of differentially expressed genes in tomato fruits under different treatment conditions;

[0030] Figure 7 Figure 2 is the GO enrichment of differentially expressed genes in tomato fruits under different treatments; (A) is 100mM NaCl treatment group vs. 100mM NaCl + 100mg / L TiO2 NPs treatment group, (B) is 0mM NaCl treatment group vs. 100mM NaCl + 100mg / L TiO2 NPs treatment group, (C) is 100mM NaCl treatment group vs. 0mM NaCl treatment group;

[0031] Figure 8 Figure 2 is the KEGG enrichment of differentially expressed genes in tomato fruit under different treatments; (A) is the 100 mM NaCl treatment group vs. the 100 mM NaCl + 100 mg / L TiO2NPs treatment group, (B) is the 0 mM NaCl treatment group vs. the 100 mM NaCl + 100 mg / L TiO2NPs treatment group, and (C) is the 100 mM NaCl treatment group vs. the 0 mM NaCl treatment group.

[0032] Figure 9 is a statistical diagram of the number of differential metabolites in tomato fruits under different treatments;

[0033] Figure 10 This is the result diagram of differential metabolite accumulation in tomato fruits under different treatments;

[0034] Figure 11The following are the enrichment results of differential metabolites in various pathways of tomato fruits under different treatments; (A) is the 100mM NaCl treatment group vs. 100mM NaCl+100mg / L TiO2NPs treatment group, (B) is the 0mM NaCl treatment group vs. 100mM NaCl+100mg / L TiO2NPs treatment group, and (C) is the 100mM NaCl treatment group vs. 0mM NaCl treatment group. DETAILED DESCRIPTION

[0035] The present invention provides TiO2 nanoparticles to alleviate the damage of salt stress to tomatoes and an analysis of the alleviation mechanism thereof. The titanium source for preparing the nano-TiO2 is titanium tetrachloride.

[0036] As an implementation method, tomato seeds need to be germinated in a constant temperature incubator at 28°C for 72 hours before being transferred into the soil.

[0037] As an implementation method, the soil is irrigated with water every four weeks to flush out excess salts to maintain a suitable salt concentration and prevent salt accumulation.

[0038] As an embodiment, the nano-TiO2 is dried to obtain white powder, and then calcined in air at 400°C for 2 hours to improve the thermal stability and chemical stability of the nano-TiO2.

[0039] As an embodiment, the nano-TiO2 solution is used at a concentration of 100 mg / L.

[0040] As an embodiment, the spraying treatment steps are as follows: spray the nano solution on tomatoes that have grown to the flowering stage twice a week to ensure that the leaves are evenly covered with the nano solution.

[0041] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0042] It should be understood that the terms described herein are intended only to describe particular embodiments and are not intended to limit the present invention. In addition, for numerical ranges herein, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Each smaller range between any intermediate value within a stated value or stated range and any other stated value or intermediate value within the stated range is also encompassed by the present invention. The upper and lower limits of these smaller ranges may be independently included or excluded within the scope.

[0043] Unless otherwise indicated, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art. Although only preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein may also be used in the practice or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of any conflict with any incorporated document, the contents of this specification shall prevail.

[0044] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments of the present invention without departing from the scope or spirit of the invention. Other embodiments will be apparent to those skilled in the art from the present invention. The present description and examples are intended to be illustrative only.

[0045] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0046] Unless otherwise specified, the "room temperature" and "normal temperature" mentioned in the present invention are all calculated as 25±2°C.

[0047] Unless otherwise specified, all raw materials and instruments used in the following examples of the present invention are commercially available.

[0048] Example 1

[0049] Spraying nano-TiO2 improves tomato's tolerance to salt stress

[0050] Step 1: Preparation of nano-TiO2 (TiO2 NPs). This experiment uses titanium tetrachloride as the starting material. The specific operation is as follows: 3mL of TiCl4 is added dropwise to 15mL of anhydrous ethanol while stirring. The resulting solution is then stirred continuously at room temperature until a gel forms. Next, the gel is heated on a hot plate at approximately 80°C to form a white powder. After that, the powder is placed in a furnace and dried at 110°C for 45 minutes. After drying, the powder is transferred to a mortar and ground. Finally, the ground powder is placed in a muffle furnace and calcined at 400°C for 2 hours in an air atmosphere.

[0051] Step 2: Preparation of Nano-TiO2 Solutions. For the solution preparation experiments, accurately weigh 50mg, 100mg, and 150mg of TiO2 NPs. Place the weighed TiO2 NPs in a container containing 1000mL of distilled water and fully disperse them in the distilled water at room temperature. Nano-solutions of varying concentrations were prepared for subsequent experiments.

[0052] Step 3: Planting tomato materials. Select tomato seeds in good condition and uniform size, place them in a petri dish for germination, and the germination time is 72 hours. After 72 hours, the seeds have completed the cultivation stage and are now sown in 16cm×16cm pots. These pots are filled with soil made by mixing nutrient soil and vermiculite in a volume ratio of 2:1. Use one tray as a treatment group, and place 6 tomato seedlings neatly on each tray. Afterwards, water each tray with 2.5L of water at a time to ensure that the soil in the pot is fully soaked, creating good conditions for the subsequent growth of tomatoes.

[0053] Step 4: Salt solution and nano-solution treatment. Once the tomatoes reached their flowering stage, salt stress treatment was applied. Specifically, a 100mM NaCl solution was prepared and irrigated weekly. Every four weeks, the soil was irrigated to flush out excess salt, maintaining a constant salt concentration and preventing salt accumulation. Five treatment groups, each with six pots, were used. Irrigation and foliar spraying of the corresponding solution were performed regularly each week.

[0054] 0mM NaCl treatment group: Pour 2.5L of water into the tray. Wait for the soil in the pot to fully absorb the water until it stops absorbing water, then discard the remaining water in the tray. The next day, use a sprayer to evenly spray the water onto the tomato leaves, ensuring that every leaf is evenly covered with the water. Continue this foliar spraying twice a week.

[0055] 100mM NaCl treatment group: Pour 2.5L of 100mM NaCl into the tray. Wait for the soil in the pot to fully absorb the water until it stops absorbing water, then discard the remaining salt water in the tray. The next day, use a sprayer to evenly spray the tomato leaves with clean water, ensuring that every leaf is evenly covered with clean water. Continue this foliar spraying twice a week.

[0056] 100mM NaCl + 50mg / L TiO2 NPs treatment group: Pour 2.5L of 100mM NaCl into the potting tray. Wait for the soil in the pot to fully absorb the saline solution. Once the soil can no longer absorb it, discard the remaining saline solution in the tray. The next day, evenly spray the leaves with a 50mg / L TiO2 NPs solution using a sprayer, ensuring that every leaf is evenly covered with the TiO2 NPs solution. Repeat this foliar application of the TiO2 NPs solution twice a week.

[0057] 100mM NaCl + 100mg / L TiO2 NPs treatment group: Pour 2.5L of 100mM NaCl into the tray. Wait for the soil in the pot to fully absorb the saline solution. Once the soil can no longer absorb it, discard the remaining saline solution. The next day, evenly spray the leaves with a 100mg / L TiO2 NPs solution using a sprayer, ensuring that every leaf is evenly covered with the TiO2 NPs solution. Repeat this foliar application of the TiO2 NPs solution twice a week.

[0058] 100mM NaCl + 150mg / L TiO2 NPs treatment group: Pour 2.5L of 100mM NaCl into the potting tray. Wait for the soil in the pot to fully absorb the saline solution. Once the soil can no longer absorb it, discard the remaining saline solution in the tray. The next day, evenly spray the leaves with a 150mg / L TiO2 NPs solution using a sprayer, ensuring that every leaf is evenly covered with the TiO2 NPs solution. Repeat this foliar application of the TiO2 NPs solution twice a week.

[0059] Figure 1 The growth of tomatoes under five different treatment conditions is shown in Figure 2. Figure 1 It can be clearly observed that tomato plants subjected to salt stress exhibited significant growth phenotypes, manifested as short plants, yellowing leaves, and a small number of fruits, with fruits changing color prematurely. After spraying the nanomaterials, the growth of the tomato plants gradually approached that of the control group, with the most significant mitigation effect being achieved under the 100mg / L nano-TiO2 solution. As can be seen in the figure, tomatoes treated with 100mg / L TiO2 NPs exhibited an increased number of fruits and taller plants. Therefore, tomato plants treated with this concentration were selected for subsequent measurement indicators.

[0060] Step 5: Measurement of photosynthetic indexes. Use a plant photosynthesis meter to measure the photosynthetic efficiency, transpiration rate, stomatal conductance and intercellular CO2 concentration of plant leaves. The results are as follows: Figure 2 As shown, plants undergo specific physiological changes in response to stress. Transpiration and net photosynthetic rates decrease significantly. The former may be due to disruptions in water transport regulation mechanisms, while the latter may result from negative impacts on photosynthetic pigments and enzyme activities. Intercellular CO2 accumulates due to a decrease in CO2 assimilation capacity. Increased stomatal conductance, however, does not enhance photosynthesis. This may be because plants maintain gas exchange while impairing other physiological processes, leading to CO2 accumulation. Treatment with nano-TiO2 significantly alleviates these effects.

[0061] Step 6: To determine the concentration of the crude extract of plant leaves, select 0.1g of fresh leaves from the same leaf position of plants with different treatments and place them in a mortar. Add 1.5ml of 100mM pH 7.8 PBS buffer (prepared from Na2HPO4 and NaH2PO4 mother liquor, must be prepared and used immediately, and stored at room temperature) to the mortar, and complete the homogenization operation on ice. Then centrifuge at 4°C and 10000g for 20min; after the centrifugation is completed, transfer the supernatant to a new centrifuge tube and place it on ice for subsequent analysis. Finally, the formula protein concentration (mg / ml) = 1.55×A 280 -0.76×A 260 Determine the concentration of the crude extract.

[0062] Step 7: Detection of proline content and malondialdehyde (MDA) content. The acidic ninhydrin method reacts with proline to generate a colored compound, and the absorbance is measured at a wavelength of 520nm using a spectrophotometer to calculate the proline content; the thiobarbituric acid method is to react MDA with thiobarbituric acid under acidic conditions to generate a red product. The crude extract from step 6 is added with the above reagents and the absorbance is measured at a wavelength of 532nm using a spectrophotometer to quantitatively analyze the MDA content. The results are as follows: Figure 3 As shown in the study, when tomatoes are subjected to salt stress, their chlorophyll and nitrogen contents both show a downward trend, and oxidative stress occurs in the plant. Malondialdehyde, a key marker of oxidative stress, increases significantly. Proline, which plays a key role in maintaining cellular water balance during plant response to stress, also decreases significantly under salt stress. However, after treatment with nanomaterials, these adverse physiological changes caused by salt stress were alleviated to a certain extent, indicating that nanomaterials play a positive role in alleviating the damage caused by salt stress to tomatoes.

[0063] Step 8: Antioxidant enzyme activity. Under light conditions, nitroblue tetrazolium can be reduced by superoxide anion radicals to generate blue formazan, and SOD can inhibit this reaction. Its activity can be calculated by colorimetry. Catalase (CAT) can catalyze the decomposition of hydrogen peroxide into water and oxygen. Its activity can be measured by monitoring the reduction of hydrogen peroxide. The results are as follows: Figure 4As shown, under salt stress conditions, catalase and superoxide dismutase activities in plants increased significantly. This is a stress protection mechanism initiated by the plant itself. By increasing the activity of these two antioxidant enzymes, plants can promptly remove excess reactive oxygen species generated by stress, maintain intracellular redox balance, and thus mitigate the damage caused by stress to plant cells. However, after treatment with the nano-TiO2 solution, the activities of CAT and SOD showed a downward trend. This may be because the material effectively alleviates the negative effects of stress on plants, reducing the production of reactive oxygen species in the plant body. Plants no longer need to maintain high antioxidant enzyme activity to cope with stress, thus demonstrating its positive effect in alleviating plant stress damage.

[0064] Example 2

[0065] Mechanism of spraying nano-TiO2 alleviating salt stress in tomatoes based on transcriptome and metabolome analysis

[0066] Step 1: Collection of tomato samples. Samples were collected and preserved from the tomato fruits of the 0mM NaCl treatment group, 100mM NaCl treatment group, and 100mM NaCl + 100mg / L TiO2 NPs treatment group in Example 1. For each treatment group, three tomato fruits in the red fruit stage were carefully selected, and the fruits were required to be of uniform size and similar color. Subsequently, each fruit was evenly divided into eight lobes from the root to the tip, and one lobe from each fruit was selected and placed in a centrifuge tube, resulting in a total of eight centrifuge tubes, with three pulp samples placed in each centrifuge tube. Finally, the centrifuge tubes containing the samples were stored in a -80°C refrigerator in preparation for subsequent experiments.

[0067] Step 2: Transcriptome Sequencing. To ensure the use of qualified samples for transcriptome sequencing, the extracted total RNA quality is rigorously tested using advanced molecular biology equipment. Purity and concentration are measured spectrophotometrically, and integrity is precisely monitored using the Agient2100 / LabChip GX. Once qualified, the sample enters the library construction process. First, eukaryotic mRNA is enriched using Oligo(dT)-tagged magnetic beads. Fragmentation Buffer is added to randomly shear the mRNA. First- and second-strand cDNAs are synthesized and purified using these templates. The double-stranded cDNA is then end-repaired, A-tailed, and ligated with sequencing adapters. Fragment size is selected using AMPure XP beads, and finally, the cDNA library is enriched by PCR. After library construction, quality control is performed. Initial quantification is performed using the Qubit 3.0 Fluorometer, followed by insert detection using the Qsep400 High-Throughput Analysis System. Once the inserts meet expectations, the effective concentration is accurately quantified using Q-PCR. Libraries that pass quality control are sequenced in PE150 mode using a high-throughput sequencing platform.

[0068] Step 3: Metabolome sequencing. The metabolome detection process mainly includes metabolite extraction, on-machine detection, and metabolite qualitative and quantitative analysis. When extracting metabolites, add an appropriate volume of extraction solution and magnetic beads for grinding and ultrasonic treatment, then centrifuge and take the supernatant for subsequent on-machine detection. The sample is analyzed according to the corresponding parameters. Metabolite qualitative and quantitative analysis is based on the self-built database GB-PLANT. The sample metabolites are subjected to mass spectrometry qualitative and quantitative analysis, and the characteristic ions are screened by triple quadrupole to obtain their signal intensity. After obtaining the metabolite mass spectrometry analysis data of different samples, the peak area of ​​all substance mass spectrometry peaks is integrated, and the mass spectrometry peaks of the same metabolite in different samples are integrated and corrected.

[0069] The results are as follows Figure 5 The figure shows a statistical analysis of the number of differentially expressed genes (DEGs) in tomato fruit under different treatments. The results showed that there were 3819 differentially expressed genes in the 0mM NaCl treatment group compared with the 100mM NaCl treatment group, of which 1898 genes were upregulated and 1921 genes were downregulated. Compared with the 100mM NaCl treatment and the 100mM NaCl + 100mg / LTiO2 NPs treatment, there were 1738 differentially expressed genes, of which 828 genes were upregulated and 910 genes were downregulated.

[0070] The results are as follows Figure 6 As shown, Figure 6 The expression of differentially expressed genes under different treatments in tomato fruit was demonstrated. A total of 45 core differentially expressed genes were screened in the three treatments of 0mM NaCl, 100mM NaCl, and 100mM NaCl + 100mg / LTiO2NPs. The results showed that compared with the 100mM NaCl treatment, the expression levels of 8 genes, including VIF, TIL, LYK8, XET2, CCD1A, FBA3, and SQ01, were significantly upregulated in the 0mM NaCl treatment, while the expression levels of genes such as CLV1, PIN7, MKK4, and ACS2 were significantly downregulated. This may be one of the reasons why tomato plants under salt stress exhibit significant growth phenotypes. Compared with the 100mM NaCl treatment and the 100mg / LTiO2 NPs treatment, the expression levels of 10 genes including ZF2, Hcr90, MKK4, THOM1, TDR8 were significantly upregulated. This may be because spraying nano-TiO2 solution alleviated the damage of salt stress to tomatoes.

[0071] The results are as follows Figure 7 As shown, Figure 7GO enrichment analysis of differentially expressed genes revealed their distribution patterns under the three different treatment conditions. In biological processes, these genes were primarily concentrated in metabolic processes and cellular processes, which respectively support key cellular activities such as material transformation and growth and division. In terms of cellular components, these genes were significantly enriched in anatomical structures and intracellular components, providing the space and material basis for cellular physiological activities. In terms of molecular function, these genes were primarily concentrated in binding functions and catalytic activities, ensuring efficient signal transduction, material transport, and biochemical reactions.

[0072] The results are as follows Figure 8 As shown, Figure 8 Through in-depth exploration of the KEGG analysis results, we can understand the enrichment of differentially expressed genes in various pathways under different treatment conditions. Comparing the treatments of 0mM NaCl and 100mM NaCl, the differentially expressed genes are concentrated in CO2 metabolism, amino acid biosynthesis and endoplasmic reticulum protein processing pathways, indicating that salt stress significantly affects plant basal metabolism, interferes with photosynthesis, protein synthesis and processing, and may be an adjustment for plant adaptation to stress, but it will also inhibit growth. Compared with the treatments of 100mM NaCl and 100mM NaCl+100mg / LTiO2NPs, the differentially expressed genes are concentrated in plant-pathogen interaction, plant hormone signal transduction, CO2 metabolism and mitogen-activated protein kinase (MAPK) signaling pathways, indicating that the addition of nano-TiO2 changes the defense mechanism and signal transduction network of plants under salt stress, which may enhance disease resistance, regulate hormone signals, further affect photosynthesis, and help plants adapt to salt stress through the MAPK pathway.

[0073] The results are as follows Figure 9 As shown, Figure 9 This is a statistical analysis of the number of differential metabolites in tomato fruits under different treatments. The results showed that there were 49 common metabolites under the three treatments.

[0074] The results are as follows Figure 10 As shown, Figure 10The results show the accumulation of differential metabolites in tomato fruit under different treatment conditions. A total of 38 core differential metabolites were screened out in the three treatments of 0mM NaCl, 100mM NaCl and 100mg / L TiO2NPs. Among them, the levels of 9 metabolites were significantly downregulated in the comparison between 0mM NaCl treatment and 100mM NaCl treatment, among which the representative ones were the natural flavonoid compound pinobanksin and the natural alkaloid compound tomatine (also known as tomato). In the comparison between 100mM NaCl treatment and 100mM NaCl + 100mg / L TiO2 treatment, the levels of 5 metabolites were significantly upregulated, involving substances such as xanthohumol B, 15-demethylplumieride, auramycinone, and pulchinenoside E2.

[0075] The results are as follows Figure 11 As shown, Figure 11 In-depth analysis of the KEGG analysis revealed the enrichment of differential metabolites in various pathways across tomato fruit treated under different conditions. When comparing 0 mM NaCl with 100 mM NaCl, differential metabolites were significantly concentrated in D-amino acid metabolism, aminoacyl-tRNA synthesis, and the glyoxylate and dicarboxylic acid cycles. This suggests that the two treatments differentially impacted the metabolic utilization of amino acids within the cell, key steps in protein synthesis, and the glyoxylate cycle, which is associated with energy metabolism. When comparing 100 mM NaCl with 100 mM NaCl plus 100 mg / L TiO2 NPs, differential metabolites were concentrated in cysteine ​​and methionine metabolism, aminoacyl-tRNA synthesis, and D-amino acid metabolism, suggesting that TiO2 NPs significantly altered cellular metabolic patterns. Cysteine ​​and methionine metabolism are involved in antioxidant defense and methylation reactions, and these changes suggest that cells may be enhancing their stress tolerance. Differences in aminoacyl-tRNA synthesis suggest that protein synthesis is affected, potentially interfering with cell growth and repair. D-amino acid metabolism is associated with cell structure and signal transduction, which overall reflects the adaptive response of plant cells to TiO2 NPs.

[0076] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. Application of TiO2 nanoparticles in alleviating plant salt stress.

2. The use according to claim 1, characterized in that The application comprises the following steps: TiO2 nanoparticles are mixed evenly with water to prepare a nanosolution, which is then sprayed on the surface of plant leaves during flowering.

3. The use according to claim 2, characterized in that The mass volume ratio of the TiO2 nanoparticles to water is 5-15:100 mg / L.

4. The use according to claim 3, characterized in that The preparation method of the TiO2 nanoparticles is: (1) TiCl4 was added dropwise to anhydrous ethanol under stirring and continued stirring until a gel was formed; (2) heating the gel at 75-85°C until a white powder is formed; (3) The white powder is dried, ground, and calcined in sequence to obtain TiO2 nanoparticles.

5. The use according to claim 4, characterized in that In the step (1), the volume ratio of TiCl4 to anhydrous ethanol is 1:4-6.

6. The use according to claim 4, characterized in that In the step (3), the drying temperature is 100-120° C., and the drying time is 40-50 min; the calcination temperature is 380-420° C., and the time is 1.5-2.5 h.

7. The use according to claim 2, characterized in that The nano solution is sprayed 2 to 3 times per week.

8. The use according to claim 1, characterized in that The alleviating of plant salt stress includes improving plant growth parameters, photosynthesis and antioxidant capacity.

9. The use according to claim 8, characterized in that The plant is tomato.

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