Application of auxin glycosyltransferase mutant in improvement of plant stress resistance

Abstract

The invention discloses an application of an auxin glycosyltransferase mutant in improving stress resistance of plants. After the 100th glycine of the auxin glycosyl transferase UGT74E2 in arabidopsis thaliana is mutated into arginine (G100R), the ultraviolet stress resistance and drought stress resistance of a mutant plant are remarkably improved, and the enzyme activity of the auxin glycosyl transferase UGT74E2 is improved through G100R point mutation, which indicates that the UGT74E2 is a key factor necessary for improving the stress resistance of the plant. The invention provides a new method for improving the stress resistance of plants, and has important economic significance and application value.

Description

Technical Field

[0001] The present invention relates to the technical field of plant genetic engineering, and in particular, to the application of an auxin glycosyltransferase mutant in improving plant stress resistance. Background Art

[0002] Auxin is the earliest discovered and well-studied class of plant hormones, and the most important active form in plants is indole-3-acetic acid (IAA). Subsequent studies have discovered and extracted other substances with auxin activity in plants, such as indole-3-butyric acid (IBA), etc. These substances are collectively referred to as plant endogenous auxins. In plants, IAA and IBA can be converted into each other. Currently, most studies on auxin focus on the physiological effects and molecular mechanisms of IAA, and the research on IBA is very limited.

[0003] Studies have found that auxin not only regulates plant growth and development but also plays an important role in disease resistance and stress resistance. There is a phenomenon in plants of regulating auxin levels to coordinate growth and stress resistance. Physiological activities such as auxin signal transduction and metabolism affect the sensitivity of plants to stress signals and the resistance to pathogens. High concentrations of auxin often make plants susceptible to certain diseases, while low concentrations of auxin can improve the disease resistance of plants. For example, treating rice with IAA weakens the resistance of rice to Xanthomonas oryzae pv. oryzae. In addition, the maize disease resistance gene ZmAuxRP1 encodes an auxin regulatory protein, and when stressed by pathogens, the expression level of this gene rapidly decreases, resulting in the stagnation of root growth, but significantly enhancing the resistance of the plant to maize stalk rot and maize ear rot (PMID: 30853061). The above research results indicate that auxin plays an important role in plant defense, and plants can achieve a balance between growth and stress resistance by regulating auxin levels.

[0004] Many studies have also shown that key genes involved in auxin synthesis and its response are affected by environmental stress. For example, under salt stress, Arabidopsis thaliana regulates lateral root formation by increasing the synthesis of auxin at the shoot tip and then promoting its polar transport. Drought stress will lead to a decrease in auxin content, slowing down the growth rate of plants, thus alleviating the pressure on plants to complete normal physiological activities caused by insufficient water. Some studies have revealed the relationship between auxin and temperature stress. High temperature changes plant auxin response by altering auxin biosynthesis, and low temperature affects the polar and lateral transport of auxin. However, further in-depth research is still needed on the regulatory mechanism of auxin under stress conditions at the molecular level. In recent years, due to changes in the global climate, soil, and water environment, problems such as salt damage, drought, and high and low temperatures have become increasingly serious. Exploring the regulatory mechanism of auxin participating in plant response to stress has important significance for improving plant stress resistance.

[0005] The regulation of auxin levels in plants mainly focuses on four aspects: synthesis, transport, degradation, and modification. Different parts of plants have different sensitivities to auxin, and the action of auxin has a dual nature. Therefore, the auxin concentration in plants must be strictly regulated. The process in which auxin is coupled with certain molecules or groups to temporarily lose its activity is called auxin modification, which is an important way to regulate the level of endogenous active hormones in plants. The most common binding method is to couple through an ester bond with sugar or sugar alcohol, such as indoleacetic acid-glycoprotein, indoleacetic acid-inositol, etc. Auxin modification is an important way for plants to process excess auxin and temporarily store auxin.

[0006] When plants are stressed, they can rapidly down-regulate the auxin level in the body through the way of auxin modification. Different from degradation, auxin modification is reversible. When the crisis is lifted, these inactive auxin modifiers will reverse according to the needs of the plant to transform into auxin, enabling the plant to resume normal growth and development levels. In most plants, IAA exists in the form of inactive conjugates, which can be reversibly converted into IAA, and can rapidly regulate the auxin level without re-synthesis.

[0007] In Arabidopsis thaliana, auxin mainly forms glycosylated compounds that can be temporarily stored by binding with glucose. This process is mainly catalyzed by the auxin glycosyltransferase (UDP-glucuronosyltransferase, UGT) protein family. Jackson et al. first identified the auxin glycosyltransferase UGT84B1 in Arabidopsis thaliana. Its recombinant protein can glycosylate auxin to form the corresponding sugar esters in vitro and has high catalytic activities for IAA and IBA (PMID: 12445128). Secondly, three glycosyltransferases, UGT84B2, UGT75B1, and UGT75B2, have also been proven to have weak activities for IAA. Jackson et al. continued the research on UGT84B1 transgenic plants and proved that UGT84B1 has the same enzyme activity for endogenous active auxin in plants as in vitro, indicating that the glycosylation modification of auxin plays an important role in the growth and development of plants. There are also studies that have proven that UGT74E2 in Arabidopsis thaliana regulates plant morphogenesis by glycosylating IBA, disrupting the hormone homeostasis, and significantly improving the tolerance of overexpressing lines to drought and salt stresses (PMID: 33008047). This shows that glycosylation modification may regulate the plant's response to hormones and the plant's growth and development process by affecting the dynamic balance of hormones. However, most of the research on plant UGTs stays at the level of identifying the catalytic activity of glycosyltransferases and analyzing the biochemical characteristics of the enzymes. There is currently no research on how to apply it to cultivate crop varieties with high resistance. Summary of the Invention

[0008] The technical problem to be solved by the present invention is the above-mentioned defects and deficiencies in the prior art, and to provide an application of an auxin glycosyltransferase mutant in improving plant stress resistance.

[0009] The first object of the present invention is to provide an application of an auxin glycosyltransferase encoded by the plant UGT74E2 gene in regulating plant resistance to ultraviolet stress and / or drought stress.

[0010] The second object of the present invention is to provide an application of an auxin glycosyltransferase mutant in improving the ultraviolet stress resistance of plants.

[0011] The third object of the present invention is to provide an application of an auxin glycosyltransferase mutant in improving the drought stress resistance of plants.

[0012] The fourth object of the present invention is to provide a method for improving the ultraviolet stress resistance and / or drought stress resistance of plants.

[0013] The fifth object of the present invention is to provide an application of the encoding gene UGT74E2 of auxin glycosyltransferase UGT74E2 in evaluating the stress resistance of individual plants.

[0014] The sixth object of the present invention is to provide an application of an auxin glycosyltransferase encoded by the plant UGT74E2 gene in evaluating the stress resistance of individual plants.

[0015] In order to achieve the above objects, the present invention is realized by the following solutions:

[0016] In the present invention, the 100th glycine of auxin glycosyltransferase UGT74E2 in Arabidopsis thaliana is mutated to arginine (G100R) to obtain the Arabidopsis thaliana UGT74E2 G100R mutant (dor1). When the dor1 mutant plants are placed under ultraviolet UV-B stress and drought stress conditions, it is found that the dor1 mutant plants have good ultraviolet stress resistance and drought stress resistance. Further, the relative conversion rates of auxin glycosyltransferase UGT74E2 and UGT74E2 G100R to the IBA substrate are compared by in vitro enzymatic reaction kinetics, and it is found that the relative conversion rate of the GST-UGT74E2 G100R fusion protein is about twice that of the GST-UGT74E2 fusion protein within the same time, indicating that the G100R point mutation improves the enzymatic activity of auxin glycosyltransferase UGT74E2 towards IBA.

[0017] Therefore, the present invention claims to protect the following:

[0018] Use of auxin glycosyltransferase encoded by plant UGT74E2 gene in regulating plant resistance to ultraviolet stress and / or drought stress, wherein the amino acid sequence of the auxin glycosyltransferase is as shown in SEQ ID NO: 2.

[0019] Preferably, glycine at position 100 in the amino acid sequence of the auxin glycosyltransferase encoded by plant UGT74E2 gene is mutated to arginine, and the ability of the plant to resist ultraviolet stress and / or drought stress is improved.

[0020] More preferably, the base at position 298 of the coding frame of plant UGT74E2 gene is mutated from guanine to adenine, glycine at position 100 in the amino acid sequence of the auxin glycosyltransferase encoded by UGT74E2 gene is mutated to arginine, and the ability of the plant to resist ultraviolet stress and / or drought stress is improved; the nucleotide sequence of the UGT74E2 gene is as shown in SEQ ID NO: 1.

[0021] Preferably, the plant is Arabidopsis thaliana.

[0022] Use of auxin glycosyltransferase mutant in improving the ability of plants to resist ultraviolet stress, wherein the amino acid sequence of the auxin glycosyltransferase mutant is as shown in SEQ ID NO: 3.

[0023] Preferably, the plant is Arabidopsis thaliana.

[0024] Preferably, the ultraviolet stress is UV-B stress.

[0025] Use of auxin glycosyltransferase mutant in improving the ability of plants to resist drought stress, wherein the amino acid sequence of the auxin glycosyltransferase mutant is as shown in SEQ ID NO: 3.

[0026] Preferably, the plant is Arabidopsis thaliana.

[0027] A method for improving the ability of plants to resist ultraviolet stress and / or drought stress, which is to mutate glycine at position 100 in the amino acid sequence of the auxin glycosyltransferase encoded by plant UGT74E2 gene, and the amino acid sequence of the auxin glycosyltransferase is as shown in SEQ ID NO: 2.

[0028] More preferably, the base at position 298 of the coding frame of plant UGT74E2 gene is mutated from guanine to adenine, glycine at position 100 in the amino acid sequence of the auxin glycosyltransferase encoded by UGT74E2 gene is mutated to arginine, and the ability of the plant to resist ultraviolet stress and / or drought stress is improved; the nucleotide sequence of the UGT74E2 gene is as shown in SEQ ID NO: 1.

[0029] Preferably, the plant is Arabidopsis thaliana.

[0030] Use of the encoding gene UGT74E2 of auxin glycosyltransferase UGT74E2 in evaluating the stress resistance of individual plants, wherein the nucleotide sequence of the encoding gene UGT74E2 is as shown in SEQ ID NO: 1;

[0031] Align the amino acid sequence encoded and translated by the encoding gene UGT74E2 with the amino acid sequence shown in SEQ ID NO: 2. If the glycine at the 100th position of the amino acid sequence shown in SEQ ID NO: 2 is mutated to arginine, then the plant has stress resistance;

[0032] The stress resistance is resistance to ultraviolet stress and / or drought stress.

[0033] Preferably, the plant is Arabidopsis thaliana.

[0034] Use of the auxin glycosyltransferase encoded by the plant UGT74E2 gene in evaluating the stress resistance of individual plants, wherein the amino acid sequence of the auxin glycosyltransferase is as shown in SEQ ID NO: 2. If the glycine at the 100th position of its amino acid sequence is mutated to arginine, then the plant has stress resistance;

[0035] The stress resistance is resistance to ultraviolet stress and / or drought stress.

[0036] Preferably, the plant is Arabidopsis thaliana.

[0037] Compared with the prior art, the present invention has the following beneficial effects:

[0038] The present invention discloses the use of an auxin glycosyltransferase mutant in improving the stress resistance of plants. After mutating the glycine at the 100th position of auxin glycosyltransferase UGT74E2 in Arabidopsis thaliana to arginine (G100R), the present invention significantly improves the ultraviolet stress resistance and drought stress resistance of the mutant plants, and the G100R point mutation improves the enzyme activity of auxin glycosyltransferase UGT74E2, indicating that UGT74E2 is a key factor necessary for improving the stress resistance of plants. The present invention provides a new method for improving the ability of plants to resist adversity, and has important economic significance and application value. Description of the Drawings

[0039] Figure 1Schematic diagram of the mutation of glycine at position 100 to arginine (G100R) in the auxin glycosyltransferase UGT74E2 encoded by UGT74E2, where Gly100Arg represents the mutation of glycine (Gly) at position 100 to arginine (Arg) in the amino acid sequence of auxin glycosyltransferase UGT74E2, and G298A represents the mutation of the 298th base of the UGT74E2 gene coding frame from guanine (G) to adenine (A), resulting in the mutation of the corresponding 100th amino acid from glycine to arginine.

[0040] Figure 2 Effect of deoxynivalenol (DON) stress on the phenotypes of Arabidopsis thaliana T-DNA insertion mutant plants ugt74e2-01 and ugt74e2-09. A: Root length phenotypes of wild-type WT plants, dor1 mutant plants, T-DNA insertion mutant plants ugt74e2-01, and T-DNA insertion mutant plants ugt74e2-09 grown vertically on MS solid medium containing 0 or 2.5 ppm DON for 10 days. Scale bar = 1 cm. B: Statistical chart of root length. C: Phenotypes of wild-type WT plants, dor1 mutant plants, T-DNA insertion mutant plants ugt74e2-01, and T-DNA insertion mutant plants ugt74e2-09 after growing on MS solid medium containing 0 or 2.5 ppm DON for 10 days. Scale bar = 1 cm. D: Quantitative statistics of plant biomass. Lowercase letters a, b, c, d indicate significant differences.

[0041] Figure 3 Effect of UV-B stress on the chlorophyll content of dor1 mutant plants. A: Phenotypes of wild-type WT plants, dor1 mutant plants, and T-DNA insertion mutant plants ugt74e2-01 after 7 days of recovery after UV-B light irradiation. B: Chlorophyll content of surviving wild-type WT plants, dor1 mutant plants, and T-DNA insertion mutant plants ugt74e2-01. Lowercase letters a, b, c indicate significant differences.

[0042] Figure 4 Effect of drought stress on the survival of dor1 mutant plants. A: Phenotypes of wild-type WT plants, dor1 mutant plants, and T-DNA insertion mutant plants ugt74e2-01 before stopping watering and 7 days after rewatering. B: Number of surviving wild-type WT plants, dor1 mutant plants, and T-DNA insertion mutant plants ugt74e2-01. Lowercase letters a, b indicate significant differences.

[0043] Figure 5 For auxin glycosyltransferase UGT74E2 and UGT74E2 G100REnzyme activity, A: HPLC detection chart of the reaction of purified GST-UGT74D1 protein, GST-UGT74E2 protein or GST-UGT74E2 G100R protein with IBA, B: Relative conversion rate of purified GST-UGT74D1 protein, GST-UGT74E2 protein or GST-UGT74E2 G100R protein to IBA; lowercase letters a, b, c indicate significant differences. Specific implementation mode

[0044] The present invention will be further described below in conjunction with specific embodiments, but the embodiments do not limit the present invention in any form. Unless otherwise specified, the reagents, methods and equipment used in the present invention are conventional reagents, methods and equipment in the technical field.

[0045] Unless otherwise specified, the reagents and materials used in the following examples are all commercially available.

[0046] Arabidopsis thaliana T-DNA insertion mutants ugt74e2-01 (SALK_016116) and ugt74e2-09 (SALK_091130) were purchased from the Nottingham Arabidopsis Stock Centre (NASC).

[0047] Ethyl methanesulfonate (EMS): Purchased from Sigma-Aldrich, product number: M0880-1G.

[0048] Example 1 Arabidopsis thaliana UGT74E2 G100R Screening of mutant (dor1) plants and mapping of mutant genes

[0049] I. Experimental methods

[0050] (1) First, vernalized Arabidopsis thaliana seeds were subjected to EMS mutagenesis. An EMS solution with a final concentration of 0.4% (v / v) was added to the seeds, and the mixture was shaken at 80 rpm at room temperature for 8-10 h. After incubation, the seeds were washed with 100 mM phosphate buffer to remove EMS, and M1 generation seeds were obtained;

[0051] (2) The M1 generation seeds were sown individually in the soil to ensure that the plants grown from the M1 generation seeds could receive M2 generation seeds. After the M2 generation seeds matured, the seeds were collected together to obtain a mutant library;

[0052] (3)Perform phenotypic screening on the mutant library in batches: Sow the M2 generation seeds on MS solid medium containing 5 ppm DON and culture them in a plant growth chamber for 10 days. Observe the plants in the petri dishes and select the plants with slightly longer roots than other plants. Transplant them to MS solid medium without DON to recover growth for 7 days, then transplant them to soil to grow for 10 weeks, and harvest the M3 generation seeds;

[0053] (4)Evenly sow the M3 generation seeds on MS solid medium containing 1 ppm DON. After 7 days, observe the plants in the petri dishes and select the plants with longer roots than the wild-type plants. Transplant them to soil to grow for 10 weeks, and harvest the M4 generation seeds, which are Arabidopsis mutants with the DON-resistant phenotype. Name them dor1.

[0054] (5)Determine the localization of the mutant gene in the dor1 mutant plants by map-based cloning combined with MutMap method (PMID: 25798936).

[0055] II. Experimental Results

[0056] By map-based cloning combined with MutMap method, the mutation site of the dor1 mutant plants with the DON-resistant phenotype was mapped to AT1G05680 (UGT74E2 gene, the nucleotide sequence of which is shown in SEQ ID NO: 1). This gene encodes an auxin glycosyltransferase UGT74E2 (the amino acid sequence of which is shown in SEQ ID NO: 2). EMS mutagenesis caused the glycine at the 100th position of its amino acid sequence to be converted into arginine (G100R) (UGT74E2 G100R , the amino acid sequence of which is shown in SEQ ID NO: 3).

[0057] Example 2 Effects of DON Stress on the Phenotypes of Arabidopsis T-DNA Insertion Mutant Plants ugt74e2-01 and ugt74e2-09

[0058] I. Experimental Methods

[0059] Purchase two Arabidopsis T-DNA insertion mutant plants ugt74e2-01 and ugt74e2-09 from the Nottingham Arabidopsis Stock Centre (NASC). The T-DNA insertion site of ugt74e2-01 is located in the second exon of the UGT74E2 gene, while the T-DNA insertion site of the ugt74e2-09 gene is located in the promoter of the UGT74E2 gene.

[0060] The seeds of Arabidopsis wild-type Col-0 (WT) plants, dor1 mutant plants screened in Example 1, T-DNA insertion mutant plants ugt74e2-01, and T-DNA insertion mutant plants ugt74e2-09 were sown on MS solid medium containing 0 or 2.5 ppm DON. After growing vertically for 10 days under long-day conditions, the root length phenotypes were observed.

[0061] The seeds of Arabidopsis wild-type Col-0 (WT) plants, dor1 mutant plants screened in Example 1, T-DNA insertion mutant plants ugt74e2-01, and T-DNA insertion mutant plants ugt74e2-09 were sown on MS solid medium containing 0 or 2.5 ppm DON. After growing horizontally for 10 days under long-day conditions, the biomass was counted.

[0062] II. Experimental Results

[0063] The results are as Figure 2 shown. Under 2.5 ppm DON treatment, compared with the wild-type WT plants, the growth of T-DNA insertion mutant plants ugt74e2-01 and ugt74e2-09 was more severely inhibited. The results of the main root length measurement showed that the root lengths of T-DNA insertion mutant plants ugt74e2-01 and ugt74e2-09 were only 47% and 71% of that of the wild-type WT plants, respectively ( Figure 2 A and B in).

[0064] Under 2.5 ppm DON treatment, compared with the wild-type WT plants, the seedling growth of T-DNA insertion mutant plants ugt74e2-01 and ugt74e2-09 was also more severely inhibited. The results of the biomass count showed that the fresh weights of T-DNA insertion mutant plants ugt74e2-01 and ugt74e2-09 were 29.6% and 57.8% of that of the wild-type WT plants, respectively ( Figure 2 C and D in).

[0065] The above results indicate that the T-DNA insertion mutant plants ugt74e2-01 and ugt74e2-09 with impaired UGT74E2 gene function are extremely sensitive to DON, indicating that UGT74E2 is essential for Arabidopsis to resist DON, while the dor1 mutant plants have significant resistance to DON and may be a gain-of-function mutant of UGT74E2.

[0066] Example 3 Effect of UV-B Stress on Chlorophyll Content of dor1 Mutant Plants

[0067] I. Experimental Methods

[0068] The seeds of Arabidopsis wild-type Col-0 (WT) plants, the dor1 mutant plants screened in Example 1, and the T-DNA insertion mutant plants ugt74e2-01 were sown in MS medium and cultured for 4 days, and then the wild-type and mutant seedlings were irradiated with UV-B light at a intensity of 1000 lux in a 22 °C culture room for 10 days. The growth status of the plants was photographed and recorded, and the chlorophyll content of the surviving plants was detected after 7 days of recovery.

[0069] The steps for measuring the chlorophyll content are as follows: First, weigh the leaves and record the fresh weight (g), and then put the leaves into a 2 mL centrifuge tube. Add 1.5 mL of N-N dimethylformamide solution to the centrifuge tube respectively, and place it in a 4 °C refrigerator for dark treatment for 48 h. Take it out after the leaves turn white. Pipette 1 mL of the sample respectively, and measure the absorbance values at wavelengths of OD 664 and OD 647 with a spectrophotometer (Unico / UV2600A).

[0070] Calculate the chlorophyll content through the formula: Chlorophyll content (mg / g) = [1×(7.12×OD 664 × dilution factor + 17.67×OD 647 × dilution factor)] / (fresh weight × 1000).

[0071] II. Experimental results

[0072] The results are shown in A and B of Figure 3 . After UV-B light irradiation, the chlorophyll content of the dor1 mutant plants was significantly higher than that of the wild type. This result indicates that the ability of the dor1 mutant plants to resist UV-B is stronger than that of the wild-type WT plants.

[0073] Example 4 Effect of drought stress on the survival of dor1 mutant plants

[0074] I. Experimental method

[0075] The seeds of Arabidopsis wild-type Col-0 (WT) plants, the dor1 mutant plants screened in Example 1, and the T-DNA insertion mutant plants ugt74e2-01 were sown in MS medium and cultured for 10 days, and the seedlings with consistent growth (with 4 leaves) were transplanted into the soil. Each small pot of soil weighs about 100 g, and 4 seedlings are planted in each small pot. 15 small pots are planted with each of the two types of plants. The small pots are placed in a 22 °C culture room with 8 hours of light per day, and fertilized and watered uniformly. After 3 weeks, stop watering, and photograph and record the growth status of the plants. After stopping watering until 50% of the wild type died, re-water for 7 days, photograph and record the growth status of the plants, and count the number of surviving plants.

[0076] II. Experimental results

[0077] The results are asFigure 4 as shown by A and B in

[0078] Example 5 Comparison of the Enzyme Activities of Auxin Glycosyltransferase UGT74E2 and UGT74E2 in an in Vitro Enzymatic Reaction G100R of the enzyme

[0079] I. Experimental Method

[0080] In this experiment, the purified fusion protein was used for an enzymatic reaction with IBA. The product peak of IBA catalyzed by auxin glycosyltransferase UGT74D1 was used as a positive control. The conversion efficiency of IBA by auxin glycosyltransferases UGT74E2 and UGT74E2 G100R within 3 h was detected and compared by HPLC. The relative conversion rate was the amount of substrate reduction after the enzymatic reaction / the amount of remaining substrate × 100% under the specified same conditions.

[0081] This experiment referred to the method for measuring enzyme activity by Jin et al. (PMID: 23613909). The detailed experimental steps were as follows:

[0082] (1) In Vitro Enzymatic Reaction System and Conditions: 10 μL of 500 mM HEPES solution (pH = 7.0), 5 μL of 2.5 mM MgSO4 solution, 5 μL of 10 mM KCl solution, 5 μL of 5 mM UDP - glucose solution, 1 μL of 10% β - mercaptoethanol solution (w / v), 1 μL of 1 mM IBA solution, and 5 μg of purified GST protein (GST - UGT74D1 protein, GST - UGT74E2 protein, or GST - UGT74E2 G100R protein) were added in sequence, and then ddH2O was added to make up the reaction system to 100 μL. After reacting in a 30 °C constant temperature water bath for 3 h, 10 μL of 240 mg / ml trichloroacetic acid solution was added to terminate the reaction. After quick freezing in liquid nitrogen, the reaction samples were stored at -80 °C or directly analyzed by HPLC.

[0083] (2) HPLC Analysis Conditions: The instrument used for HPLC analysis was ALLIANCE E2695 from Waters. The chromatographic column was a ZORBAX Eclipse Plus C18 (4.6 × 150 mm, 5 μm) reverse - phase column (Agilent, 959993 - 902), and the mobile phase was methanol and water (containing 0.01% phosphoric acid (w / v)).

[0084] Elution was carried out using a binary high-pressure concentration gradient method with 10 - 70% methanol (v / v) at a flow rate of 1 mL / min. The elution time was 32 minutes, and the detection wavelength for the substance peak was 280 nm.

[0085] II. Experimental Results

[0086] As Figure 5 shown, the reaction system containing only the GST-tagged protein had only one substrate peak of IBA, while the reaction system containing the purified GST-UGT74D1 fusion protein eluted an additional significant product peak at an elution time of 20.2 min. The elution time was consistent with that reported previously, so it was determined to be the glycosylated product IBA-Glc. The product peak of the reaction system of the GST-UGT74E2 fusion protein was lower than that of the reaction system containing the GST-UGT74E2 G100R fusion protein (A in Figure 5 ). Further, the results of calculating the relative conversion rate of IBA showed that the relative conversion rate of the GST-UGT74E2 G100R fusion protein was approximately twice that of the GST-UGT74E2 fusion protein (B in Figure 5 ). This result indicates that the G100R point mutation improved the enzyme activity of the auxin glycosyltransferase UGT74E2 towards IBA.

[0087] 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. Use of the auxin glycosyltransferase encoded by the plant UGT74E2 gene in regulating plant resistance to ultraviolet stress and / or drought stress, characterized in that, The amino acid sequence of the auxin glycosyltransferase is shown in SEQ ID NO:

2.

2. The use according to claim 1, characterized in that, Mutating the glycine at the 100th position in the amino acid sequence of the auxin glycosyltransferase encoded by the plant UGT74E2 gene to arginine enhances the ability of the plant to resist ultraviolet stress and / or drought stress.

3. Use of an auxin glycosyltransferase mutant in enhancing the ultraviolet stress resistance of plants, characterized in that, The amino acid sequence of the auxin glycosyltransferase mutant is shown in SEQ ID NO:

3.

4. The use according to claim 3, characterized in that, The plant is Arabidopsis thaliana.

5. Use of an auxin glycosyltransferase mutant in enhancing the drought stress resistance of plants, characterized in that, The amino acid sequence of the auxin glycosyltransferase mutant is shown in SEQ ID NO:

3.

6. The use according to claim 5, characterized in that, The plant is Arabidopsis thaliana.

7. A method for enhancing the ultraviolet stress resistance and / or drought stress resistance of plants, characterized in that, Mutating the glycine at the 100th position in the amino acid sequence of the auxin glycosyltransferase encoded by the plant UGT74E2 gene, and the amino acid sequence of the auxin glycosyltransferase is shown in SEQ ID NO:

2.

8. The method according to claim 7, characterized in that, The plant is Arabidopsis thaliana.

9. Use of the encoding gene UGT74E2 of the auxin glycosyltransferase UGT74E2 in evaluating the stress resistance of individual plants, characterized in that, The nucleotide sequence of the encoding gene UGT74E2 is shown in SEQ ID NO: 1; Comparing the amino acid sequence translated from the encoding gene UGT74E2 with the amino acid sequence shown in SEQ ID NO: 2, if the glycine at the 100th position in the amino acid sequence shown in SEQ ID NO: 2 is mutated to arginine, then the plant has stress resistance; The stress resistance is resistance to ultraviolet stress and / or drought stress.

10. Use of the auxin glycosyltransferase encoded by the plant UGT74E2 gene in evaluating the stress resistance of individual plants, characterized in that, If the glycine at the 100th position in the amino acid sequence of the auxin glycosyltransferase, whose amino acid sequence is shown in SEQ ID NO: 2, is mutated to arginine, then the plant has stress resistance; The stress resistance is resistance to ultraviolet stress and / or drought stress.

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