Method for enhancing plant salt tolerance by using SlPSAN gene and application

Abstract

The invention discloses a method for enhancing plant salt tolerance by using an SlPSAN gene and application. The invention provides a new application of a tomato SlPSAN gene in response to salt stress, preliminary verification finds that the overexpressed SlPSAN gene can enhance the resistance to salt stress in saccharomycetes, and further research on tomato overexpressed and knockout mutant plants shows that under salt stress, the overexpressed SlPSAN can enhance the tolerance of tomatoes to salt stress, promote plant growth and improve the salt stress resistance. The chlorophyll content is increased; the determination of chlorophyll, antioxidant enzyme, ROS content and mineral content and transcriptome analysis prove that SlPSAN can activate a tomato defense system and improve the tolerance of tomatoes to salt stress. According to the invention, it is clear that the SlPSAN gene significantly improves the growth performance and salt tolerance of tomato plants in a salt stress environment, and new technical means and gene resources are provided for solving the problem that the growth of plants in salinized soil is limited.

Description

Technical Field

[0001] The present invention belongs to the technical field of plant genetic engineering, and more specifically, relates to a method and application of enhancing plant salt tolerance by using the SlPSAN gene. Background Art

[0002] Salt stress is one of the key environmental factors restricting plant growth and crop yields worldwide. + Ions enter the plant roots through non-selective cation channels, and excess Na + It will cause excessive production of ROS, ion toxicity and osmotic stress, which will further destroy the ion balance and redox homeostasis in plant cells, inhibit the absorption and transport of nutrients by plants, and lead to a series of problems such as stunted plant growth and development, decreased photosynthesis capacity, reduced chlorophyll and protein synthesis, hormone imbalance, etc., which will seriously reduce the yield and quality of crops.

[0003] At present, exploring the salt-tolerant genes of plants and analyzing their salt-tolerant mechanisms, and then improving the salt tolerance of plants through genetic engineering, has become an important research direction for dealing with salinization problems. At present, there are still few genetic resources for salt stress tolerance in tomatoes. For example, existing studies have found the SlWRKY42-SlMYC2 module, which can significantly enhance the salt-alkali tolerance of tomatoes by regulating jasmonic acid signal transduction and spermidine biosynthesis pathways; the negative regulator of salt stress in tomatoes, SlABIG1, plays a key role in the tolerance of tomatoes to salt stress. The knocked-out plants have higher chlorophyll content and photosynthetic capacity, as well as higher root dry weight and proline content, while the accumulation of reactive oxygen, malondialdehyde and sodium ions is significantly reduced; and the salt-tolerant gene SlHAK20, which encodes a sodium-potassium ion transporter. These genes may enhance the salt tolerance of tomatoes under salt stress by regulating different metabolic pathways and signal transduction networks.

[0004] Although some salt-tolerance-related genes have been reported, the understanding of the molecular mechanism of plant salt tolerance still needs to be deepened. With the continuous development of gene editing technology and a deeper understanding of the salt stress tolerance mechanism of tomatoes, more tomato varieties with excellent salt tolerance characteristics are expected to be bred in the future. Therefore, finding new key salt-tolerance genes and developing effective application methods have important theoretical and practical significance, which will help to make full use of saline-alkali land resources, improve agricultural production efficiency, and ensure food security. Summary of the invention

[0005] The technical problem to be solved by the present invention is to overcome the shortage of existing tomato salt stress tolerance gene resources and provide a method and application of enhancing plant salt tolerance by using SlPSAN.

[0006] The purpose of the present invention is to provide a method and application of enhancing plant salt tolerance by using the SlPSAN gene.

[0007] Another object of the present invention is to provide the application of the SlPSAN gene.

[0008] Another object of the present invention is to provide the application of the preparation for promoting the expression of the SlPSAN gene.

[0009] Another object of the present invention is to provide a method for promoting plant growth or cultivating salt-stress tolerant plants.

[0010] The above objects of the present invention are achieved by the following technical solutions:

[0011] The present invention provides a method for enhancing the salt tolerance of plants by using the SlPSAN gene, promoting the expression of the SlPSAN gene in plants, or transferring a recombinant vector or recombinant bacterium containing the overexpressed SlPSAN gene into plants; the sequence of the SlPSAN gene is as shown in SEQ ID NO:1.

[0012] The present invention firstly discovers a new application of the tomato photosystem I reaction center subunit (Solanum lycopersicum photosystem 1 reaction center subunit) SlPSAN gene in response to salt stress. The present invention uses wild-type tomatoes as materials, successfully isolates SlPSAN, then clones it into the yeast system, and finds that SlPSAN can induce salt tolerance in yeast under salt stress; subsequently, through the culture research of SlPSAN overexpression and knockout mutants under salt stress, it is found that overexpression of SlPSAN can enhance the salt stress tolerance of tomatoes, promote plant growth, increase chlorophyll content, and the overexpressed plants grow more robustly under salt stress. Further, by measuring the chlorophyll content, antioxidant enzyme activity, ROS content, and mineral content in tomato overexpression (OE7 and OE8) and knockout lines (psan1 and psan2), it is found that SlPSAN can activate the plant defense system and promote the steady-state absorption and transportation of nutrients to enhance salt stress tolerance and promote plant growth; through RNA sequencing and gene annotation, it is found that SlPSAN may help the immune system enhance the tolerance to salt stress and minimize harmful effects; finally, through GO and KEGG analysis, it is found that SlPSAN may activate the expression of stress environment adaptation response genes to induce salt stress tolerance. Based on this, the present invention determines that SlPSAN regulates the tolerance to salinity stress through the intermediary defense system, thereby reducing the negative impact of salt stress on plant growth, and finally achieving the goal of increasing crop yield, which has important significance for agricultural production in dealing with soil salinization problems, and also provides more methods for further enhancing the salt stress tolerance of plants.

[0013] Therefore, the present invention provides the following applications of SlPSAN:

[0014] Use in promoting plant growth or plant growth under salt stress.

[0015] Use in improving the tolerance of plants to salt stress.

[0016] Use in cultivating salt stress-tolerant plants.

[0017] Use in increasing the chlorophyll content of plants.

[0018] Preferably, SlPSAN is overexpressed in plants.

[0019] More preferably, the plant is a tomato.

[0020] The present invention also provides the use of a preparation for promoting the expression of SlPSAN in promoting plant growth or promoting plant growth under salt stress.

[0021] The present invention provides the use of a preparation for promoting the expression of SlPSAN in the preparation of a product for promoting plant growth or improving the salt stress tolerance of plants.

[0022] The present invention provides the use of a preparation for promoting the expression of SlPSAN in the chlorophyll content of plants or in the preparation of a product for increasing the chlorophyll content of plants.

[0023] The present invention provides the use of a preparation for promoting the expression of SlPSAN in cultivating salt stress-tolerant plants.

[0024] Preferably, the preparation is a plasmid, vector or recombinant bacterium overexpressing SlPSAN.

[0025] The present invention provides a method for promoting plant growth or cultivating salt stress-tolerant plants, which comprises treating the plants with a preparation for promoting the expression of SlPSAN.

[0026] The present invention has the following beneficial effects:

[0027] The present invention provides a new application of tomato SlPSAN in response to salt stress. Preliminary verification shows that overexpression of SlPSAN can enhance the resistance to salt stress in yeast. Further research on tomato overexpression and knockout mutant plants shows that under salt stress, overexpression of SlPSAN can enhance the salt stress tolerance of tomatoes and promote plant growth and increase the chlorophyll content; determination of chlorophyll, antioxidant enzymes, ROS content, mineral content and transcriptome analysis prove that SlPSAN can activate the tomato defense system and improve the salt stress tolerance of tomatoes. The present invention clarifies that SlPSAN significantly improves the growth performance and salt tolerance of tomato plants in a salt stress environment, providing new technical means and gene resources for solving the problem of limited plant growth in saline soil. Description of the Drawings

[0028] Figure 1 Response of SlPSAN to salt stress tolerance in yeast (A is under normal conditions; B is under 100 mM salt stress; C is the OD values measured for the bacterial solution under normal conditions and 100 mM NaCl conditions; the gradients in Figures A and B are different dilution concentrations of the yeast bacterial solution).

[0029] Figure 2 Characterization analysis of SlPSAN (A is the location of SlPSAN on chromosome 8; B is the three-dimensional structure of the PSAN protein; C-1 is promoter analysis; C-2 is the transcription factor motif of the PSAN promoter; D is the result of PSAN subcellular localization).

[0030] Figure 3 Expression level of SlPSAN in tomato seedlings under salt stress (A is the expression of SlPSAN among different tissues and organs of tomato; B is the expression of SlPSAN under salt stress).

[0031] Figure 4 Phenotypes (A) and biomass (B) of SlPSAN overexpression and knockout lines under salt stress.

[0032] Figure 5 SlPSAN regulates the contents of pigments (chlorophyll, carotenoids) in tomato leaves under salt stress.

[0033] Figure 6 Effect of SlPSAN on antioxidant enzyme activities and ROS content in tomato under salt stress.

[0034] Figure 7 Nutrient contents in tomato plants of SlPSAN under salt stress.

[0035] Figure 8 Transcriptome analysis of SlPSAN knockout lines and WT tomato seedlings under salt stress (A is the expression level of differentially expressed genes (DEGs); B is the tomato genome; C is the differentially expressed genes).

[0036] Figure 9 GO enrichment analysis (A) of SlPSAN and GO enrichment map (B) under salt stress.

[0037] Figure 10 KEGG analysis of SlPSAN (A) and KEGG pathways (B) under salt stress.

[0038] Figure 11 SlPSAN regulates the photosynthesis pathway (A) and gene expression of the photosynthesis pathway (B) in tomato seedlings under salt stress. Detailed implementation methods

[0039] The present invention will be further described below in conjunction with the accompanying drawings of the specification and specific embodiments. However, the embodiments do not impose any form of limitation on the present invention. Unless otherwise specified, the reagents, methods, and equipment used in the present invention are conventional reagents, methods, and equipment in the technical field.

[0040] Unless otherwise specified, the reagents and materials used in the following examples are all commercially available.

[0041] The primer sequences used in the following examples are specifically shown in Table 1.

[0042] Table 1 Primer Sequence Table

[0043]

[0044]

[0045] Example 1 Identification and Functional Verification of PSAN Gene in Yeast System

[0046] 1. Experimental Materials

[0047] Seeds of wild-type tomato (Micro Tom) and the pSR-416 vector are both stored in the laboratory of the inventor's research group. The Escherichia coli (E. coli) strain DH5α and the Agrobacterium strain GV3101 are both purchased from Shanghai Weidi Biotechnology Co., Ltd.

[0048] 2. Construction of Vector pSR-416

[0049] The wild-type tomato (Micro Tom) was cultured at 28 / 18 °C (light / dark) and a photosynthetically active radiation of 300 - 350 μmol·m -2 ·s -1 with the humidity maintained at 70 - 75%, and Hoagland nutrient solution was irrigated every two days. On the 15th day, the leaves of the tomato plants were taken as samples and immediately stored in liquid nitrogen at -80 °C. Total RNA of the samples was extracted according to the Aikerui Bio SteadyPure Universal RNA Extraction Kit, and the first-strand cDNA was synthesized using reverse transcription PrimeScript and RT reagents (including gDNA Eraser (TAKARA Bio)). After extracting DNA, it was cloned onto the vector using specific primers.

[0050] The CDS encoded by tomato SlPSAN (whose nucleotide sequence is shown in SEQ ID NO:1 and amino acid sequence is shown in SEQ ID NO:2) was ligated to the pSR-416 vector. The primers used for cloning are shown as SEQ ID NO:3 - 4 in Table 1, and yeast overexpressing SlPSAN was prepared.

[0051] 3. Salt Stress Tolerance in Yeast

[0052] Using the constructed pSR-416 vector overexpressing SlPSAN as the experimental group and the empty vector (pRS-416) as the control, they were exposed to 100 mM salt stress. The results are as Figure 1 shown. Under normal conditions (URA medium and culture solution), there was no significant difference in the growth of the SlPSAN-overexpressing yeast and wild-type yeast cell suspensions at different dilution concentrations ( Figure 1 A). However, under salt stress conditions (100 mM NaCl + URA medium and culture solution), the growth rate of the SlPSAN-overexpressing yeast was significantly faster than that of the wild-type yeast ( Figure 1 B, C). The results indicate that SlPSAN may be a candidate gene involved in salt tolerance in tomato and yeast.

[0053] Example 2 Prediction, Functional Annotation and Subcellular Localization of SlPSAN

[0054] 1. Functional Annotation of Tomato PSAN

[0055] The characteristics of tomato SlPSAN were analyzed to gain an in-depth understanding of the functional annotation of PSAN in tomato. In the tomato genome, SlPSAN is located on chromosome 8, and its gene contains two intron phases ( Figure 2 A). The three-dimensional structure of the PSAN protein was constructed using SWISS-MODEL, showing a complex structure ( Figure 2 B). In addition, the analysis of the promoter showed that the PSAN promoter contains various cis-elements related to development, phytohormones and stress ( Figure 2 C-1). During development and abiotic stress, it may interact with many signaling pathways, phytohormones and transcription factors. The PSAN promoter has multiple transcription factor motifs, including MYB, Nin-like, 2 TCPs, 2 BBRBPCs, HSF, CCP, AP2, 2 C2Hs, TALE and CAMTA, as Figure 2 shown in C-2. These results indicate that the SlPSAN promoter is rich in cis-acting elements and transcription factor binding sites and may play a key role in plant growth and development, including enhancing tolerance to abiotic stress by activating the melatonin signaling pathway.

[0056] 2. Subcellular Localization

[0057] To detect the subcellular localization of the SlPSAN protein, its coding sequence was cloned into the pBI-121-GFP vector, and the primers used for cloning are shown as SEQ ID NO:5-6 in Table 1; and it was co-expressed in tobacco leaves, and then the fluorescence signal was observed using a laser scanning confocal microscope.

[0058] The results are as Figure 2 shown in D. The subcellular localization results show that SlPSAN is localized in the nucleus. The above findings indicate that SlPSAN may play a key role in plant growth and stress response by mediating or interacting with plant signaling pathways.

[0059] Example 3 Expression profiles of SlPSAN in different tissues of tomato and under salt stress

[0060] Tomato seedlings of the same size were selected at the first true leaf stage for 200 mM salt treatment. Hoagland solution was used as a nutritional supplement and also for adjusting the salt stress concentration. The Hoagland solution was replaced regularly every two days for 10 days. Samples of different tissue organs were collected at 30 days, 45 days, and 85 days after sowing, and the expression levels were measured. The primers used for qPCR detection are shown as SEQ ID NO:7-8 in Table 1, and the reference gene SlUBI and its primers are shown as SEQ ID NO:9-10.

[0061] The results are as Figure 3 shown. The expression pattern of SlPSAN is the same among different tissue organs of tomato at different times (30 days, 45 days, and 85 days after sowing), being the highest in leaves and lower in roots, flowers, stems, and fruits ( Figure 3 A). To study the role of SlPSAN in salt stress, wild-type tomato seedlings were collected at 0, 2, 4, 8, 12, and 24 hours after treatment, and the expression levels under salt stress were analyzed. The results show that the expression level of SlPSAN reached the highest at 1 hour after salt treatment, then showed a downward trend until 8 hours, and increased again at 12 hours ( Figure 3 B).

[0062] Example 4 Tolerance to salt stress induced by SlPSAN

[0063] Using the target gene established by the plant CRISPR / Cas9 gene editing system (Reference: Nekrasov V, Staskawicz B, Weigel D, et al. Targeted mutagenesis in the model plant nicotianabenthamiana using cas9 rna-guided endonuclease[J]. 2013, 31(8): 691-693), knockout lines (psan1 and psan2) were obtained through Baoguang Biotechnology Company and identified and confirmed for later use. The primers used for identification are shown as SEQ ID NO:11-12 in Table 1; Tomato overexpression lines (OE7 and OE8) were purchased from Baoguang Company and identified and confirmed for later use. The primers used for identification are shown as SEQ ID NO:13-14.

[0064] To clarify the function of SlPSAN under salt stress, tomato overexpression lines (OE7 and OE8) and knockout lines (psan1 and psan2) were treated with 100 mM salt stress. Samples were taken on the 10th day after treatment to measure and count the physiological indices (upper fresh weight, root fresh weight, shoot dry weight, root dry weight) of the plants in each treatment group.

[0065] The results are as Figure 4 shown, indicating that overexpression of SlPSAN induced tomato tolerance to salt stress. In contrast, the knockout lines (psan1 and psan2) were sensitive to salt stress, and compared with the wild type (WT), tomato seedlings were significantly damaged ( Figure 4 A). Under salt stress, compared with the wild type, the upper fresh weights of overexpression lines OE7 and OE8 increased by 17.45% and 10.54% respectively, and the root fresh weights increased by 15.50% and 16.67% respectively. While the upper fresh weights of psan1 and psan2 seedlings decreased by 34.68% and 38.36% respectively compared with the wild type, and the root fresh weights decreased by 33.34% and 28.47% respectively. In addition, under salt stress, there were significant differences in the upper and root fresh weights of overexpression lines OE7 and OE8 compared with the wild type. Similarly, the shoot dry weight of OE7 line increased by 17.35%, and the root dry weight increased by 20.91%; the shoot dry weight of OE8 line increased by 15.10%, and the root dry weight increased by 20.95% ( Figure 4 B). It shows that overexpression of SlPSAN can improve the tolerance of plants to salt stress and promote plant growth.

[0066] Example 5 Regulation of tomato leaf pigment content by SlPSAN under salt stress

[0067] To further study the role of SlPSAN in regulating pigment content under salt stress, the chlorophyll and carotenoid contents of tomato overexpression lines (OE7 and OE8) and knockout lines (psan1 and psan2) were measured. The results are as Figure 5 shown. The results show that salt stress had an adverse effect on chlorophyll content. At the same time, SlPSAN alleviated this damage and increased chlorophyll content.

[0068] Under salt stress, compared with the wild type, the chlorophyll a content in the overexpression lines OE7 and OE8 increased by 18.87% and 8.16%, respectively, the chlorophyll b content increased by 15.95% and 23.66%, respectively, the carotenoid (Car) content increased by 38.16% and 49.15%, respectively, and the total chlorophyll (Chl A+B) content increased by 10.47% and 3.23%, respectively. In the knockout lines psan1 and psan2, compared with the wild type, the chlorophyll a content decreased by 37.61% and 44.19%, respectively, the chlorophyll b content decreased by 33.63% and 43.48%, respectively, the carotenoid content decreased by 29.23% and 21.02%, respectively, and the total chlorophyll content decreased by 29.02% and 34.91%, respectively. In summary, the differences between the SlPSAN overexpression lines and the knockout lines were also significant. These results indicate that overexpression of SlPSAN can increase the chlorophyll content in tomatoes and mitigate the adverse effects of salt stress.

[0069] Example 6 SlPSAN Regulates Antioxidant Enzyme Activity

[0070] To explore the role of SlPSAN under salt stress, the antioxidant enzyme activities and reactive oxygen species (ROS) contents of tomato overexpression lines (OE7 and OE8) and knockout lines (psan1 and psan2) were measured.

[0071] The results are as Figure 6 shown. Compared with the wild type and overexpression lines, a decrease in the activities of antioxidant enzymes (superoxide dismutase SOD, peroxidase POD, ascorbate peroxidase APX, and catalase CAT) was observed in the knockout lines psan1 and psan2. In contrast, compared with the wild type and knockout lines, overexpression of SlPSAN significantly increased the antioxidant enzyme activities and decreased the levels of MDA, hydrogen peroxide (H2O2), and oxygen (O2). These findings indicate that SlPSAN can activate the defense system against salt stress, reduce the levels of ROS and malondialdehyde (MDA), and protect plant tissues from damage caused by excessive production of ROS.

[0072] Example 7 SlPSAN Regulates Mineral Contents in Tomatoes

[0073] Plants have specific ion channels for mineral absorption and transport. These channels are sensitive to abiotic stresses, which can lead to a significant reduction in nutrient absorption and transport, thereby causing nutrient deficiency. To explore the role of SlPSAN in nutrient absorption and accumulation, the contents of micronutrients and macronutrients in tomato leaves of overexpression lines (OE7 and OE8) and knockout lines (psan1 and psan2) under salt stress were measured.

[0074] The results are as Figure 7As shown, it was found that salt stress significantly reduced the contents of micronutrients and macronutrients in tomatoes. Overexpression of SlPSAN significantly enhanced the contents of micronutrients and macronutrients; conversely, the loss-of-function lines significantly reduced the contents of micronutrients and macronutrients in tomatoes. In addition, there were significant differences between the wild type and the overexpression lines (OE7 and OE8). These results indicate that SlPSAN activates the absorption and transport of nutrient homeostasis, thereby enhancing the tolerance to salt stress and promoting plant growth.

[0075] Example 8 RNA Sequence Analysis and Gene Annotation

[0076] To better understand the molecular mechanism of SlPSAN in the salt stress response, RNA-Seq analysis was performed on the knockout lines psan1 and psan2 and compared with wild-type plants after 10 days of salt stress treatment.

[0077] The results are as Figure 8 shown, indicating that salt stress significantly affected psan1 and psan2, reducing the expression levels of differentially expressed genes (DEGs) ( Figure 8 A). Compared with the differentially expressed genes of the wild type, the up-regulation ratio was more obvious than the down-regulation ratio; during salt stress, the mutation of SlPSAN led to significant changes in the tomato genome ( Figure 8 B). In addition, among the wild type and the psan1 group, 982 differentially expressed genes were down-regulated and 445 were up-regulated; while in the wild type and the psan2 group, 729 differentially expressed genes were up-regulated and 478 were down-regulated ( Figure 8 C). These results are consistent with the conclusion in Example 6 above that SlPSAN may promote the immune system to enhance the tolerance to salt stress and reduce harmful effects.

[0078] Example 9 GO and KEGG Enrichment Analysis

[0079] Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses were used to deeply explore the molecular mechanism of the enhanced response of SlPSAN under salt stress. GO enrichment analysis was divided into three groups: biological process (BP), cellular component (CC), and molecular function (MF). The differentially expressed genes in each group played specific functions during salt stress. As Figure 9 shown, the most abundant GO terms in biological processes included response to stimulus, immune system process, and detoxification, which may be related to the response of tomatoes to salt stress tolerance. However, in the molecular function and cellular component groups, catalytic activity and antioxidant activity were prominent, which may be related to the immune role during the salt stress tolerance process. These findings indicate that SlPSAN modifies the expression of stress response genes, thereby inducing tolerance to salt stress.

[0080] However, KEGG pathway analysis showed that, asFigure 10 As shown in A, the related genes are involved in metabolism (carbohydrate, energy, amino acid metabolism, etc.), genetic information (translation, folding, sorting and degradation, transcription and replication repair), environmental information processing (signal transduction and membrane transport), organismal systems (environmental adaptation), and cellular processes (transport and catabolism). It is worth noting that genes related to environmental adaptation are crucial for plants to cope with abiotic stress tolerance. On the other hand, among the top 20 pathways, important pathways such as photosynthesis, plant-pathogen interaction, glutathione metabolism, mitogen-activated protein kinase (MAPK) signaling pathway, etc. were identified ( Figure 10 B), indicating that SlPSAN improved the metabolic processes of plants during salt stress. In addition, we noticed that genes in the environmental adaptation pathway were enriched, suggesting that SlPSAN might activate the expression of stress environmental adaptation response genes, thereby inducing tolerance to salt stress.

[0081] Example 10 Regulation of Photosynthesis-Related Genes by SlPSAN under Salt Stress

[0082] To study the regulatory role of SlPSAN on photosynthesis-related genes in tomato under salt stress, the photosynthesis pathway and its gene expression of tomato seedlings regulated by SlPSAN under salt stress were analyzed. Plants under salt stress can lead to the overproduction of reactive oxygen species (ROS). ROS is highly toxic and reactive to plants and can affect plant metabolism, hormone signaling pathways, chlorophyll synthesis, and photosynthesis-related genes, thereby causing a significant slowdown in plant growth.

[0083] The results are as Figure 11 shown in A. Under salt stress, the mutation of PSAN can cause changes in genes involved in the photosynthesis mechanism. In addition, in the photosynthesis mechanism, the expression of genes such as PsbA, PsbC, PcbE in photosystem II, PsaA and PsaB in photosystem I, PetB in cytochrome b6 / f, and PetF in photosynthetic electron transport was up-regulated, while the expression of the PSAN gene in photosystem I was down-regulated due to mutation, as Figure 11 shown in B. Thus, overexpression of SlPSAN can regulate the pigment content in tomato leaves under salt stress.

[0084] In summary, the study discovered a new application of tomato SlPSAN in response to salt stress. In this invention, SlPSAN was cloned into the yeast system, and it was found through research under salt stress that SlPSAN could induce salt tolerance in yeast. Then, through the cultivation and research of SlPSAN overexpression and knockout mutant seeds, it was found that the overexpressing plants grew more robustly under salt stress, could improve the plant's tolerance to salt stress, and promote plant growth. Further, by measuring the chlorophyll content, antioxidant enzyme activity, ROS content, and mineral content in tomato overexpressing (OE7 and OE8) and knockout lines (psan1 and psan2), it was found that overexpressing SlPSAN could increase the chlorophyll content of tomatoes, alleviate the adverse effects of salt stress, activate the immune system at the same time, protect plant tissues from damage caused by excessive ROS production, and also activate the absorption and transport of nutrient homeostasis, thereby enhancing the tolerance to salt stress and promoting plant growth.

[0085] Furthermore, through RNA sequencing and gene annotation, it was found that SlPSAN might help the immune system enhance the tolerance to salt stress and minimize the harmful effects. Through GO and KEGG analysis, it was found that SlPSAN might activate the expression of stress environment adaptation response genes to induce salt stress tolerance. Based on this, the present invention determined that SlPSAN regulates salinity stress tolerance through the intermediary defense system. Overexpressing SlPSAN can improve the salt stress tolerance of tomatoes and promote plant growth and increase the chlorophyll content. These findings will open up a new research direction, hopefully further enhancing the plant's ability to cope with salt stress, thereby reducing the negative impact of salt stress on plant growth and ultimately achieving the goal of increasing crop yields, which is of great significance for agricultural production in dealing with soil salinization problems.

[0086] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited by the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications made without departing from the spirit and principle of the present invention shall be equivalent replacement methods and are all included in the protection scope of the present invention.

Claims

1. A method for enhancing the salt tolerance of plants by using the SlPSAN gene, characterized in that, Promote the expression of the SlPSAN gene in plants, or transfer a recombinant vector or recombinant bacterium containing the overexpressed SlPSAN gene into plants; the sequence of the SlPSAN gene is as shown in SEQ ID NO:

1.

2. Use of the SlPSAN gene as shown in SEQ ID NO:1 in promoting plant growth or plant growth under salt stress.

3. Use of the SlPSAN gene as shown in SEQ ID NO:1 in improving the salt stress tolerance of plants.

4. Use of the SlPSAN gene as shown in SEQ ID NO:1 in cultivating salt stress-tolerant plants.

5. Use of the SlPSAN gene as shown in SEQ ID NO:1 in increasing the chlorophyll content of plants.

6. Use of a preparation for promoting the expression of the SlPSAN gene as shown in SEQ ID NO:1 in promoting plant growth or promoting plant growth under salt stress.

7. Use of a preparation for promoting the expression of the SlPSAN gene as shown in SEQ ID NO:1 in preparing a product for promoting plant growth or improving the salt stress tolerance of plants.

8. Use of a preparation for promoting the expression of the SlPSAN gene as shown in SEQ ID NO:1 in the chlorophyll content of plants or in preparing a product for increasing the chlorophyll content of plants.

9. Use of a preparation for promoting the expression of the SlPSAN gene as shown in SEQ ID NO:1 in cultivating salt stress-tolerant plants.

10. A method for promoting plant growth or cultivating salt stress-tolerant plants, characterized in that, Treat the plants with a preparation for promoting the expression of the SlPSAN gene as shown in SEQID NO:1.

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