Application of potato StGSTL21 gene in drought resistance

Abstract

The invention discloses a potato StGSTL21 gene and application thereof, a GST gene family is analyzed according to inbred tetraploid potato C88 genome data, and a core gene StGSTL21 responding to drought stress in potatoes is screened in combination with transcriptome data. Potato tissue culture seedlings are stably transformed by constructing a plant overexpression vector PC2300S-StGSTL21 of the StGSTL21 gene and an interference vector GATE8-StGSTL21, growth phenotypes and physiological and biochemical indexes of all transgenic materials under drought stress are observed and detected, results show that the StGSTL21 gene can respond to the drought stress, the drought resistance of plants can be improved through overexpression of the StGSTL21 gene, and the drought resistance of the plants can be improved. The StGSTL21 gene is interfered, so that the drought resistance of the plant is reduced.

Description

Technical Field

[0001] The invention relates to the technical field of gene engineering, and in particular to a StGSTL21 gene with drought resistance and application thereof. Background Art

[0002] Potato (Solanum tuberosum.L) is the fourth largest staple food crop after wheat, rice and corn. However, consuming the same amount of water, the food energy produced by potatoes is much higher than that of the first three food crops. The protein produced is twice that of corn and wheat, and the calcium produced is twice that of wheat and four times that of rice. As my country's food demand increases year by year, and the cultivated land area and water resources are limited, potatoes may become a guarantee of food security. At present, more than half of my country's potato producing areas are arid or semi-arid areas. And potatoes are shallow-rooted crops and are more sensitive to drought stress. Long-term or seasonal drought stress can seriously damage the growth and development of potatoes, thereby affecting the yield and commercial quality of tubers. Therefore, drought has always been a major problem in potato production. Revealing drought tolerance mechanisms and cultivating drought-resistant varieties have become important tasks in potato genetic breeding in arid areas of my country.

[0003] When plants are subjected to abiotic stresses such as drought, salinity, and temperature changes, a large amount of reactive oxygen will accumulate, causing oxidative damage to cell membranes and biomacromolecules, cell death, and other oxidative stress reactions. Plants use a variety of enzymatic and non-enzymatic systems to remove reactive oxygen damage to resist stress. Glutathione S-transferase (GST) is one of the important superfamily enzymes that can remove excess reactive oxygen produced by plants in adversity to protect the cell membrane structure and protein activity of plants. Studies in model plants and various crops have shown that GSTs respond to a variety of adverse stresses and play an important role in plant resistance, but the regulatory mechanism of its gene expression in response to stress signals is still not very clear. The present invention clones the relevant genes that respond to drought stress, constructs gene overexpression lines and RNA interference lines in potato cultivars to verify their functions, and provides technical support for opening up new germplasm innovation approaches for potatoes in arid areas. There is no report in the prior art that the potato StGSTL21 gene has the ability to improve drought resistance. Summary of the invention

[0004] The purpose of the present invention is to provide a StGSTL21 gene with drought resistance and its application to solve the problems existing in the above-mentioned prior art. The StGSTL21 gene can respond to drought stress, overexpression of the gene can improve the drought resistance of plants, and RNA interference gene reduces the drought resistance of plants. To achieve the above purpose, the present invention provides the following scheme:

[0005] 1. The present invention provides a StGSTL21 gene with drought resistance, the nucleotide sequence of the StGSTL21 gene is shown in SEQ ID NO.1.

[0006] 2. The present invention also provides two recombinant expression vectors, including the above-mentioned StGSTL21 gene, including: a plant overexpression vector PC2300S-StGSTL21 and an interference vector GATE8-StGSTL21.

[0007] 3. The present invention also provides two host cells, comprising the above-mentioned recombinant expression vector, wherein the host cell is a recombinant Agrobacterium.

[0008] 4. The present invention also provides the use of the above-mentioned StGSTL21 gene, recombinant expression vector or host cell in cultivating transgenic plants with drought resistance.

[0009] Furthermore, the plant is potato.

[0010] Furthermore, overexpression of the StGSTL21 gene can improve potato drought resistance.

[0011] Furthermore, overexpression of the StGSTL21 gene increased Pro content and GST activity, thereby improving drought resistance.

[0012] The present invention discloses the following technical effects: The present invention analyzes the GST gene family according to potato genome data, and screens out the core gene StGSTL21 in potato that responds to drought stress in combination with transcriptome data. The present invention constructs a plant overexpression vector PC2300S-StGSTL21 and an interference vector GATE8-StGSTL21 of the StGSTL21 gene and stably transforms potato tissue culture seedlings, observes and detects the growth phenotype and physiological and biochemical indicators of each transgenic material under drought stress, to explore the function of the StGSTL21 gene in potato drought resistance. The results show that the StGSTL21 gene can respond to drought stress, overexpression of the StGSTL21 gene can improve the drought resistance of the plant, and RNA interference of the StGSTL21 gene can reduce the drought resistance of the plant. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some implementation cases of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0014] Figure 1This is the electrophoresis diagram of the PCR amplification product of StGSTL21 gene; wherein, M: Marker D2000; 1-2: PCR amplification product.

[0015] Figure 2 This is a gel image of double enzyme digestion detection of PC2300S-StGSTL21 plasmid; 1: plasmid after KPNI and BamHI digestion; 2: plasmid before digestion; M: KB Ladde Maker.

[0016] Figure 3 This is a gel image of double restriction enzyme digestion detection of GATE8-StGSTL21 plasmid; where 1: plasmid before restriction enzyme digestion; 2: plasmid after BamHI and NruI restriction enzyme digestion; M: KB Ladde Maker.

[0017] Figure 4 This is a statistical chart of the gene expression detection results of StGSTL21 in different potato tissues; different letters represent significant differences (P<0.05).

[0018] Figure 5 Positive identification of potato transgenic lines; the numbers on the left represent overexpression lines, and the numbers on the right represent RNA interference lines.

[0019] Figure 6 Relative expression levels of genes in potato transgenic lines; different lowercase letters indicate significant differences (P<0.05).

[0020] Figure 7 Phenotypic analysis of potato seedlings under drought stress (photo); E3: wild type; OE: overexpression line; RNAi: interference expression line; bar=2cm.

[0021] Figure 8 Phenotypic statistics of potato seedlings under drought stress; E3: wild type; OE: overexpression strain; RNAi: interference expression strain. * and ** indicate significant changes compared with the control group (*: P < 0.05; **: P < 0.01; T test). Different letters on the white columns of the bar graph indicate significant differences between normal treatments, and different letters on the black columns indicate significant differences between drought treatments (P < 0.05) (Duncan method).

[0022] Fig. 9 Analysis of physiological indicators of potato seedlings under drought stress; E3: wild type; OE: overexpression strain; RNAi: interference expression strain. * and ** indicate significant changes compared with the control group (*: P < 0.05; **: P < 0.01; T test). Different letters on the white columns of the bar graph indicate significant differences between normal treatments, and different letters on the black columns indicate significant differences between drought treatments (P < 0.05) (Duncan method).

[0023] Fig.10 It is the gene sequence of StGSTL21, and the one in the box is the interference fragment. DETAILED DESCRIPTION

[0024] The methods and devices used in the following embodiments of the present invention are conventional methods and devices unless otherwise specified; the equipment and reagents used are conventional equipment and reagents purchased by the reagent company. In order to make the purpose, technical scheme and advantages of the present invention clearer, the specific implementation methods of the present invention are described in detail in conjunction with specific embodiments. Examples of these preferred implementations are illustrated in the specific embodiments. It should also be noted that in order to avoid obscuring the technical scheme of the present invention due to unnecessary details, only the technical schemes and / or processing steps closely related to the scheme of the present invention are shown in the embodiments, and other details that are not very relevant are omitted.

[0025] Example 1

[0026] This example provides a potato StGSTL21 gene, wherein the CDS sequence of the StGSTL21 gene is shown in SEQ ID NO. 1 and Fig.10 By constructing the plant overexpression vector PC2300S-StGSTL21 and the interference vector GATE8-StGSTL21 of the StGSTL21 gene and stably transforming potato tissue culture seedlings, the growth phenotypes and physiological and biochemical indicators of each transgenic material under drought stress were observed and detected, and it was found that the StGSTL21 gene has the function of improving potato drought resistance.

[0027] Example 2

[0028] This embodiment provides a method for studying the function of potato StGSTL21 gene, comprising the following steps:

[0029] 1. Experimental Materials

[0030] Plant materials: Potato tissue culture seedlings Qingshu9, Atlantic, and E3 were provided by Gansu Agricultural University.

[0031] Vector: The primer sequences of plant overexpression vector PC2300S-StGSTL21 and interference vector GATE8-StGSTL21 are shown in Table 1:

[0032] Table 1 Primer sequences

[0033]

[0034]

[0035] 2. Experimental Methods

[0036] 2.1 Experimental treatment of tissue culture seedlings

[0037] Gene cloning and tissue-specific expression pattern analysis: The roots, stems, leaves and tubers of potato potted plants treated with normal watering and drought for 45 days were quickly frozen with liquid nitrogen and stored in a -80°C refrigerator. Three biological replicates were taken for each tissue.

[0038] 2.2 Total RNA extraction and cDNA synthesis

[0039] The RNA of each sample was extracted using a plant total RNA extraction kit, detected by 0.1% agarose gel electrophoresis, and the purity and concentration of the RNA were detected using an ultra-micro spectrophotometer. The extracted RNA was then reverse transcribed into cDNA using a cDNA synthesis kit (TOYOBO), and the product was stored at -20°C for future use.

[0040] 2.3 Construction of StGSTL21 overexpression vector and RNA interference vector and transformation of Agrobacterium

[0041] 2.3.1 Target gene cloning

[0042] The full-length coding region sequence of potato StGSTL21 gene was used as an information probe, and primers were designed based on the obtained sequence using the potato database comparison, and cloned from potato cultivars. The cDNA of potato seedlings was used as a template, and KODFox high-fidelity enzyme was used for PCR amplification of potato CDS sequence. KOD FX high-fidelity enzyme reference instructions were used to amplify the target gene, and the amplification system and amplification program are shown in Tables 2 and 3 below.

[0043] Table 2 Target gene cloning PCR reaction system

[0044]

[0045] Table 3 PCR reaction procedure for target gene cloning

[0046]

[0047] 2.3.2 Construction and enzyme digestion identification of plant overexpression vectors and RNA interference vectors

[0048] The recombinant plasmid with the correct sequencing results was double-digested (the restriction sites were KpnI and BamHI respectively) and connected with the PC2300S vector after the same double-digestion to obtain the fusion recombinant plasmid PC2300S-StGSTL21. The recombinant plasmid was extracted in small amounts using the alkaline lysis method and digested with KpnI and BamHI for identification.

[0049] According to the interference sequence and the information of the vector GATE8, the forward fragment of RNA interference was inserted between XhoI (5') and XhoI (3') of the vector, and the reverse complementary fragment was inserted between XbaI (5') and XbaI (3'). The whole gene synthesis sample was digested and identified with BamHI and NruI.

[0050] 2.3.3 Transformation of Agrobacterium with overexpression vectors and RNA interference vectors

[0051] (1) Dissolve the above vector on ice and take out the competent Agrobacterium from the -80°C refrigerator and thaw it naturally on ice;

[0052] (2) After the fusion recombinant plasmids PC2300S-StGSTL21, GATE-StGSTL21 and Agrobacterium GV3101 were thawed at the same time, 2 μL of the fusion recombinant plasmids were placed in 100 mL of Agrobacterium GV3101 bacterial suspension, gently mixed, and placed on ice for 5 min, in liquid nitrogen for 5 min, in a 37°C water bath for 5 min, and in an ice bath for 5 min;

[0053] (3) After the ice bath, add 600 μL of LB liquid medium without resistance to the clean bench and place it in a constant temperature shaker at 28°C, 200 rpm, and shake for 3 h;

[0054] (4) Centrifuge at 6000 rpm for 1 min to collect the cells;

[0055] (5) Leave 100 μL of supernatant on the clean bench, discard the excess supernatant, resuspend and spread on a double antibody (50 mg / ml Kan, 50 mg / mL Rif) plate, and incubate upside down in a 28°C incubator;

[0056] (6) Two days later, colonies will grow and single clones will be picked for positive identification.

[0057] 2.4 Genetic transformation of potato

[0058] 2.4.1 Seeding

[0059] Potato tubers were sterilized, sown in 1 / 2MS medium and cultured in the dark until germination, and then transferred to light conditions for 6-8 days;

[0060] 2.4.2 Cotyledon pre-culture

[0061] Take the cotyledons of sterile seedlings and pre-culture for 2 days;

[0062] 2.4.3 Agrobacterium activation

[0063] Agrobacterium was activated on a medium containing 50 mg / L kanamycin;

[0064] 2.4.4 Agrobacterium infection and co-cultivation

[0065] Agrobacterium infection, followed by dark culture conditions, co-cultivation for 2 days;

[0066] 2.4.5 Screening, culture and differentiation

[0067] Transfer to screening medium and subculture once every 2 weeks until green buds appear;

[0068] 2.4.6 Rooting

[0069] The resistant buds were transferred to rooting medium and cultured under light, and roots formed in 2-3 weeks;

[0070] 2.5 PCR detection of transgenic plants

[0071] The DNA of potato test tube seedlings was extracted using Tiangen's high-efficiency DNA extraction kit, and the quality was tested by electrophoresis. PCR was performed using screening marker gene-specific primers (PCR system is shown in Table 4, PCR program is shown in Table 5). Real-time fluorescence quantitative PCR was used to analyze the gene expression of transgenic potatoes (real-time fluorescence quantitative PCR system is shown in Table 6, real-time fluorescence quantitative PCR program is shown in Table 7).

[0072] Table 4 Positive identification PCR reaction system

[0073]

[0074] Table 5 Positive identification PCR reaction procedure

[0075]

[0076] Table 6 Fluorescence quantitative PCR reaction system

[0077]

[0078] Table 7 Fluorescence quantitative PCR reaction program

[0079]

[0080] 2.6 Drought stress treatment and index determination of transgenic potatoes

[0081] First, the optimal drought stress concentration for the growth of transgenic potato tissue culture seedlings was screened, and transgenic and non-transgenic potato stem segments with the same growth were cut and inoculated on MS medium and MS medium containing 150mM mannitol. After 30 days of growth, their phenotypes were observed and physiological indicators were tested.

[0082] 2.6.1 Determination of phenotypic and physiological parameters of transgenic potatoes under drought stress

[0083] Transgenic potato stem segments and wild-type potato stem segments with the same growth were cut and inoculated on MS medium and MS medium containing 150 mM mannitol. After 30 days of growth, the plant height, leaf number, root length and fresh weight of the potato tissue culture seedlings were measured, and each indicator was repeated at least 3 times. Proline (Pro) content (determined by acid ninhydrin colorimetric method), peroxidase (POD) activity (determined by guaiacol colorimetric method), catalase (CAT) activity (determined by ultraviolet absorption method), and glutathione transferase (GST) activity (glutathione S-transferase kit, purchased from Suzhou Grace Biotechnology Co., Ltd.) were measured, and each indicator was repeated 3 times.

[0084] 2.6.2 Expression level of transgenic tobacco under drought stress

[0085] The stems and leaves of potato tissue culture seedlings grown for 30 days were used for RNA extraction, reverse transcription, qPCR and other experiments. The gene expression was measured using 2 -ΔΔCt Law.

[0086] 2.7 Data Analysis

[0087] Excel 2019 was used to perform basic statistical analysis on the original data, and SPSS24.0 software was used for significant difference analysis.

[0088] 3. Experimental results

[0089] 3.1 Cloning of potato StGSTL21 gene

[0090] The StGSTL21 gene was cloned using cDNA of potato cultivars as a template, and the PCR product was subjected to agarose gel electrophoresis. Figure 1 As shown, a band of about 700 bp was obtained. After recovery and purification, it was connected to the cloning vector, transformed into E. coli DH5α competent cells, cultured at 37°C overnight, and a single colony was picked for PCR detection and sequencing. The results showed that the full length of the StGSTL21 gene sequence was 708 bp.

[0091] 3.2 Construction of overexpression vector and RNA interference vector

[0092] The present invention uses enzyme ligation technology to construct the StGSTL21 plant expression vector PC2300S-StGSTL21, and uses KPNI and BamHI for enzyme digestion identification. Figure 2 The present invention constructs the GATE8-StGSTL21 interference vector, and uses BamHI and NruI for enzyme digestion identification, as shown in FIG. Figure 3 shown.

[0093] 3.3 Relative expression of StGSTL21 in different potato tissues

[0094] The tissue-specific expression of StGSTL21 gene in tubers, roots, stems and leaves of potato varieties "Qingshu 9" and "Atlantic" was analyzed by qPCR. Figure 4 As shown in the figure, the StGSTL21 gene is expressed in both "Qingshu 9" and "Atlantic". The expression level in the leaves of "Qingshu 9" is about 172 times that of the tubers, 25 times that of the roots, and 5 times that of the stems. The expression level in the leaves of "Atlantic" is about 153 times that of the tubers, 7.6 times that of the roots, and 2 times that of the stems. The expression levels of both varieties in stems and leaves are relatively high, indicating that StGSTL21 plays an important role in potato growth and development and response to adverse stress. Among them, the expression level of StGSTL21 in leaves of "Qingshu 9" and "Atlantic" is the highest, and is significantly higher than that in tubers, roots and stems (P<0.05).

[0095] In order to explore the response of StGSTL21 to abiotic stress, qPCR was used to detect the relative expression level of StGSTL21 gene under drought stress. Figure 4 It can be seen that under drought treatment, the relative expression levels of the StGSTL21 gene in four different tissues, tubers, roots, stems and leaves, were significantly different (P<0.05). Under normal watering (control group) and drought conditions, the expression levels in leaves of "Qingshu 9" and "Atlantic" were the highest. After drought treatment, the expression levels in leaves increased by about one-fold, and the expression levels were roughly equal. Compared with "Qingshu 9", the expression level of the StGSTL21 gene in "Atlantic" fluctuated more widely and was more sensitive to drought.

[0096] 3.4 Obtaining and identifying potato transgenic lines

[0097] Potato tubers are sterilized, sown in 1 / 2MS medium and cultured in the dark until germination, and then transferred to light conditions for culture for 6-8 days; the cotyledons of sterile seedlings are taken and pre-cultured for 2 days; Agrobacterium is activated on a medium containing 50 mg / L kanamycin; Agrobacterium is infected, and then cultured in the dark for a total of 2 days; transferred to a screening medium, subcultured once every 2 weeks until green buds appear; the resistant buds are transferred to a rooting medium, cultured in the light, and roots are formed in 2-3 weeks.

[0098] The vector used in the present invention carries the KANA gene, so the use of specific primers for PCR amplification can directly reflect whether the KANA gene is expressed in the transgenic tobacco, that is, whether the strain is a positive strain. First, DNA was extracted by sampling, and PCR was performed using primers NPTIIF68 and NPTIIR356. The results are shown in Figure ( Figure 5 ), a total of 10 overexpression positive strains and 4 RNA interference positive strains were identified, and then these positive strains were tested by real-time fluorescence quantitative PCR to detect their expression levels at the transcriptional level. Figure 6 ): Compared with the wild type E3, the gene expression levels of G22: OE1, OE2, OE3, OE4, OE5, OE6, OE7, and OE8 were 8.9 times, 9.1 times, 8.3 times, 0.9 times, 7.2 times, 6.2 times, 2 times, and 5.1 times that of E3; the gene expression levels of G22: RNAi1, RNAi2, RNAi3, and RNAi4 were 0.010 times, 0.006 times, 0.012 times, and 0.011 times that of E3, indicating that transgenic potato lines have been successfully obtained, and two lines were selected for overexpression and RNA interference for subsequent experiments.

[0099] 3.5 Analysis of phenotypic indicators of potato transgenic lines under drought stress

[0100] In order to explore the overall phenotypic changes of transgenic potatoes before and after drought stress, the present invention photographed and observed transgenic plants under different treatments. Plant height is an important indicator for reflecting plant height growth and understanding the growth and development process of plants. The present invention used a ruler to measure the transgenic potatoes, such as Figure 7 As shown, after 30 days of normal culture, the plant heights of wild-type E3 and OE1, OE2, RNAi1, and RNAi2 were 11.29 cm, 11.79 cm, 13.49 cm, 12.46 cm, and 10.45 cm, respectively. After 30 days of mannitol treatment, the plant heights of wild-type E3 potato and OE1, OE2, RNAi1, and RNAi2 were 4.96 cm, 7.42 cm, 8.94 cm, 2.34 cm, and 2.73 cm, respectively. Under drought treatment, the plant height of wild-type E3 decreased by ( Figure 8 )56.1%, which was significantly higher than 37.3% of OE1 and 40.0% of OE2, and significantly lower than 81.2% of RNAi1 and 73.9% of RNAi2 (P<0.05).

[0101] The root system affects the plant's absorption of water and nutrients, thereby affecting the growth and development of the plant. The root sends signals to the aboveground organs, affecting the function of the aboveground organs. The present invention has found that after 30 days of normal cultivation, if Figure 7As shown, the root lengths of wild type E3 and OE1, OE2, RNAi1, and RNAi2 were 10.35 cm, 9.52 cm, 6.68 cm, and 8.15 cm, respectively. After 30 days of mannitol treatment, the root lengths of wild type E3 and OE1, OE2, RNAi1, and RNAi2 were 5.89 cm, 7.94 cm, 6.33 cm, 5.57 cm, and 4.54 cm, respectively. The root length of wild type decreased under drought treatment ( Figure 8 )42.0%, which was significantly higher than 16.4% of OE1 and 5.6% of OE2, and significantly lower than 0.4% of RNAi1 and 44.3% of RNAi2 (P<0.05).

[0102] The number of plant leaves reflects the growth status and adaptability of the plant, and can also reflect the plant's ability to adapt to environmental conditions. The present invention found that after 30 days of normal cultivation, if Figure 7 As shown, the leaf numbers of wild type E3 and OE1, OE2, RNAi1, and RNAi2 were 12, 10.63, 11, 9.65, and 13.63, respectively. After 30 days of mannitol treatment, the leaf numbers of wild type E3 and OE1, OE2, RNAi1, and RNAi2 were 8.76, 9, 9.33, 6.33, and 8.33, respectively. Under drought treatment, the leaf number of wild type decreased ( Figure 8 )27.8%, which was significantly higher than 15.7% and 15.1% of OE1, and significantly lower than 34.5% of RNAi1 and 39.0% of RNAi2 (P<0.05).

[0103] Fresh weight reflects the moisture content of plants. By comparing the fresh weight of plants, we can understand the moisture status of plants, which is of great significance for studying plant drought resistance, disease resistance, etc. The results of the present invention found that after 30 days of normal cultivation, if Figure 6 As shown, the fresh weights of wild-type E3 and OE1, OE2, RNAi1, and RNAi2 were 0.46 g, 0.68 g, 0.87 g, 0.45 g, and 0.40 g, respectively. After 30 days of mannitol treatment, the fresh weights of wild-type E3 and OE1, OE2, RNAi1, and RNAi2 were 0.16 g, 0.37 g, 0.44 g, 0.16 g, and 0.09 g, respectively. Under drought treatment, the fresh weight of the wild-type decreased by ( Figure 8 )65.7%, which was significantly higher than 46.0% and 48.8% of OE1, and significantly lower than 63.3% of RNAi1 and 75.0% of RNAi2 (P<0.05).

[0104] The results showed that under drought treatment, the phenotypic indexes of the overexpression strains decreased significantly less than those of the wild type, and the interference strains decreased significantly more than those of the wild type. Compared with the wild type, the overexpression strains of potatoes were more resistant to drought stress, while the interference strains of potatoes were less resistant to drought stress.

[0105] 3.6 Analysis of physiological indicators and expression levels of potato transgenic lines under different drought stresses

[0106] Proline (Pro) has strong hydrophilicity and can stabilize protoplasmic colloids and tissue metabolic processes, playing an important role in preventing cell dehydration. Therefore, measuring proline content can be used as one of the physiological indicators of drought resistance. The results of the present invention show that ( Fig. 9 ), after 30 days of mannitol treatment, the Pro contents of wild-type E3, OE1, OE2, RNAi1 and RNAi2 were 3.59 times, 2.47 times, 3.12 times, 2.58 times and 3.24 times that of normal treatment, respectively. The increase in Pro accumulation in overexpressed potato and RNAi potato was significantly lower than that in wild type, and the Pro content in overexpressed potato was significantly higher than that in RNAi potato (P<0.05).

[0107] Superoxide dismutase (SOD) is the first antioxidant enzyme to play a role in the active oxygen scavenging system. SOD can dismutate superoxide anion free radicals to generate hydrogen peroxide and molecular oxygen, which is of great significance in protecting plants from oxidative damage. The results of the present invention show that ( Fig. 9 ), after 30 days of mannitol treatment, the SOD activities of wild-type E3, OE1, OE2, RNAi1 and RNAi2 were 1.47, 1.13, 1.34, 1.13 and 1.11 times that of normal treatment, respectively. The increase in SOD activity of overexpressed potato and RNA interference potato was significantly lower than that of wild type, and the SOD activity of RNA interference potato was significantly higher than that of overexpressed potato (P<0.05).

[0108] Peroxidase (POD) can directly oxidize phenolic or amine compounds, and has the dual function of eliminating the toxicity of hydrogen peroxide and phenolic amines. It works synergistically with SOD and CAT to remove excess free radicals in the body, thereby improving the stress resistance of plants. The results of the present invention show that ( Fig. 9 ), after 30 days of mannitol treatment, the POD activities of wild-type E3, OE1, OE2, RNAi1 and RNAi2 were 1.28, 1.29, 1.15, 1.54 and 1.60 times that of normal treatment, respectively. The increase in POD activity of overexpressed potato was significantly lower than that of wild type, the increase in SOD activity of RNA interference potato was significantly higher than that of wild type, and the POD activity of RNA interference potato was significantly higher than that of overexpressed potato (P<0.05).

[0109] When plants age or suffer from adversity, the metabolism of active oxygen in the body is enhanced, resulting in the accumulation of H2O2, which in turn causes cell damage. Catalase (CAT) is ubiquitous in all tissues of plants and can remove H2O2. It is one of the important enzymatic defense systems in plants. The results of the present invention show that ( Fig. 9), after 30 days of mannitol treatment, the CAT activities of wild-type E3, OE1, OE2, RNAi1 and RNAi2 were 1.11, 1.17, 1.21, 1.10 and 1.15 times that of normal treatment, respectively. The increase in CAT activity of overexpressed potato was significantly higher than that of wild-type, and there was no significant difference in the increase in CAT activity of RNA interference potato compared with wild-type. The CAT activity of RNA interference potato was significantly higher than that of overexpressed potato (P<0.05).

[0110] Glutathione transferase (GST) can remove the excessive reactive oxygen produced by plants in adverse conditions to protect the cell membrane structure and protein activity of plants. Fig. 9 ), after 30 days of mannitol treatment, the GST activities of wild-type E3, OE1, OE2, RNAi1 and RNAi2 were 1.16 times, 1.21 times, 1.18 times, 0.95 times and 0.88 times of those in normal treatment, respectively. The increase in GST activity of overexpressed potato was significantly higher than that of wild-type, and the increase in GST activity of RNA interference potato was significantly lower than that of wild-type. The GST activity of overexpressed potato was significantly higher than that of RNA interference potato (P<0.05).

[0111] The results showed that under drought treatment, the Pro content of the overexpression strain was significantly higher than that of the wild type, and that of the RNA interference strain was significantly lower than that of the wild type; the GST activity was increased and significantly higher than that of the wild type, and the GST activity of the RNA interference strain was decreased and significantly lower than that of the wild type (P<0.05); but the SOD, POD and CAT activities of the RNA interference strain were higher than those of the wild type, which may be because the antioxidant pathway involved in GST in the RNA interference strain was affected, stimulating other antioxidant pathways and forcing the SOD, POD and CAT enzyme activities to increase.

[0112] In general, compared with the wild type, the overexpression potato line has stronger resistance to drought stress, while the interference potato line has worse resistance to drought stress.

[0113] The embodiments described above are only descriptions of the preferred modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. Application of overexpressing StGSTL21 gene to improve drought resistance of potato, characterized in that The CDS sequence of the StGSTL21 gene is shown in the sequence listing SEQ ID NO.

1.

2. Application of overexpressing StGSTL21 gene to increase proline content and GST activity in potato, characterized in that The CDS sequence of the StGSTL21 gene is shown in the sequence listing SEQ ID NO.

1.

3. Potato StGSTL21 gene, characterized in that The CDS sequence of the StGSTL21 gene is shown in the sequence listing SEQ ID NO.

1.

4. A recombinant plant expression vector, characterized in that The vector comprises the StGSTL21 gene described in any one of claims 1 to 3, specifically a plant overexpression vector PC2300S-StGSTL21 and an interference vector GATE8-StGSTL21.

5. Agrobacterium host cell, characterized in that The Agrobacterium cell comprises the recombinant expression vector of claim 4.

6. A method for cultivating transgenic plants with drought resistance, characterized in that The method comprises: genetically transforming the StGSTL21 gene of claim 2 into a plant body, causing it to be overexpressed or expressed by RNA interference in the plant body, and cultivating the transgenic plants with drought resistance and reduced drought resistance.

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