Bnaap3l gene and application thereof in improving salt tolerance and / or drought tolerance of plants

Abstract

The present application relates to BnAAP3L gene and its application in improving plant salt tolerance and / or drought tolerance, and belongs to the field of biotechnology. The present application firstly clones the complete coding sequence of BnAAP3L gene, and on the basis, constructs a 35S strong promoter regulated overexpression vector system, effectively introduces the recombination vector into Brassica napus plants, realizes the stable overexpression of BnAAP3L gene in transgenic plants. And through the experiment, it is proved that the positive plants of overexpression gene BnAAP3L show significant salt resistance and drought resistance, thereby successfully obtaining stable genetic offspring with double stress resistance. The present application not only provides a key theoretical basis and practical tool for the stress resistance improvement and directional breeding of economic crops such as oilseed rape, but also has a profound influence on improving the growth adaptability and potential yield of oilseed rape under adverse environment.

Description

Technical Field

[0001] This invention relates to the BnAAP3L gene and its application in improving the salt and / or drought tolerance of plants, belonging to the field of biotechnology. Background Technology

[0002] In the context of global food security and sustainable agricultural development, improving the yield and quality of rapeseed (Brassica napus L.), one of the world's four major oilseed crops, is crucial. Although rapeseed oil production accounts for half of the total edible vegetable oil production in my country, domestic supply still faces significant pressure due to increasing consumer demand. Therefore, improving the resilience of rapeseed and increasing its yield to achieve a higher self-sufficiency rate has become an urgent issue to be addressed.

[0003] The efficient absorption of water and nutrients is a key factor determining crop productivity, which largely depends on the structure and function of the plant's root system. Especially when coping with abiotic stresses such as drought and high salinity, a robust root system, particularly a well-developed lateral root network, can significantly enhance a crop's ability to capture water and nutrients, thereby improving its survival and productivity. However, under drought and salt stress, root development is often severely affected, leading to restricted crop growth and reduced yield.

[0004] In recent years, although the scientific community has discovered and identified many genes involved in regulating root development, including the process of lateral root formation, research on the molecular mechanisms by which Brassica napus effectively resists drought and salt stress is still insufficient.

[0005] Therefore, this invention aims to explore genes in Brassica napus that regulate drought and salt tolerance and their potential in enhancing crop drought and salt tolerance. Through in-depth research and application of these genes, it is hoped that new strategies and valuable genetic resources can be provided to improve the growth performance and yield of rapeseed under adverse conditions, and further promote the development of rapeseed breeding. Summary of the Invention

[0006] In view of the shortcomings of the existing technology, the purpose of this invention is to provide the BnAAP3L gene and its application, especially the BnAAP3L gene of Brassica napus and its application in improving the drought and salt resistance of rapeseed, particularly in increasing the germination rate or improving root development under drought and salt stress.

[0007] To achieve the above-mentioned technical objectives, the present invention provides the following technical solution:

[0008] The present invention first provides a gene BnAAP3L to improve the salt tolerance and / or drought tolerance of plants, the nucleotide sequence of which is shown in SEQ ID No:1.

[0009] Furthermore, the improvement of salt and / or drought tolerance includes increasing the germination rate or improving root development under drought and / or salt stress; the plant includes rapeseed.

[0010] Furthermore, the improved salt and / or drought tolerance is achieved by overexpressing the gene BnAAP3L.

[0011] The present invention also provides a recombinant expression vector, wherein the recombinant expression vector contains the gene BnAAP3L.

[0012] Furthermore, the recombinant expression vector includes the vector pK7FWG2.0.

[0013] The present invention also provides a recombinant engineered bacterium, wherein the engineered bacterium contains the gene BnAAP3L or the recombinant expression vector.

[0014] Furthermore, the host bacterium of the engineered bacteria is Agrobacterium GV3101.

[0015] This invention also provides the use of the gene BnAAP3L, or the recombinant expression vector, or the recombinant engineered bacteria in any of the following:

[0016] Improving plant salt and / or drought tolerance, increasing germination rate of plants under salt and / or drought stress, improving root development of plants under salt and / or drought stress, preparing products to improve plant salt and / or drought tolerance, preparing products to improve germination rate of plants under salt and / or drought stress, preparing products to improve root development of plants under salt and / or drought stress, and breeding or assisted breeding of salt- and / or drought-tolerant plants.

[0017] Furthermore, the application is achieved by overexpressing the BnAAP3L gene.

[0018] The present invention also provides a method for improving the salt tolerance and / or drought tolerance of plants, the method comprising the following steps:

[0019] The gene BnAAP3L was cloned, and a recombinant expression vector containing the gene BnAAP3L was constructed. The recombinant expression vector was transformed into rapeseed using Agrobacterium-mediated transformation, and transgenic plants were screened to obtain salt-tolerant and / or drought-tolerant rapeseed.

[0020] Furthermore, the Agrobacterium-mediated transformation of rapeseed includes transforming the recombinant expression vector into recipient bacteria to obtain recombinant engineered bacteria; expanding the culture of the obtained recombinant engineered bacteria; and using the obtained bacterial solution to infect the hypocotyl of rapeseed for transformation.

[0021] Furthermore, the cloned gene BnAAP3L was amplified by PCR using the sequences shown in SEQ ID No:2 and SEQ ID No:3 as primers and rapeseed cDNA as a template.

[0022] Furthermore, the recombinant expression vector is obtained by inserting the gene BnAAP3L sequence shown in SEQ ID No:1 into pENtry-D / TOPO, and then recombining the BnAAP3L CDS sequence with the pK7FWG2.0 plant expression vector using the Gateway method.

[0023] The present invention also provides a plant reagent for improving the salt tolerance and / or drought tolerance of plants, wherein the active ingredient of the plant reagent includes the gene BnAAP3L, or the recombinant expression vector, or the recombinant engineered bacteria, or a substance that promotes the expression of the gene BnAAP3L.

[0024] The beneficial effects of this invention are:

[0025] This invention successfully constructed a 35S promoter-driven overexpression vector pK7FWG2.0-BnAAP3L using the full-length coding sequence (CDS) of the cloned gene BnAAP3L. The vector was then genetically transformed into Brassica napus using Agrobacterium infection to obtain T2 generation positive transgenic plants. Compared with the control, the transgenic T2 generation plants exhibited improved salt and drought resistance. These agronomical results indicate that overexpression of the Brassica napus gene BnAAP3L can effectively improve the germination rate of plants under salt and drought conditions and promote root growth and development, which is of great significance for increasing the growth and yield of rapeseed. Attached Figure Description

[0026] Figure 1 To identify the expression site of BnAAP3L in Brassica napus for qRT-PCR detection.

[0027] Figure 2 This is a schematic diagram of the pK7FWG2.0-BnAAP3L vector; in the diagram: LB: left boundary sequence of T-DNA; RB: right boundary sequence of T-DNA.

[0028] Figure 3 A gel image for identifying positive seedlings that overexpress the gene BnAAP3L.

[0029] Figure 4The images show the germination results of positive seedlings overexpressing the BnAAP3L gene under different NaCl concentrations. The left image shows the germination of wild-type K407 and positive seedlings OE-BnAAP3L-8 and OE-BnAAP3L-9 under different NaCl concentrations. The upper right image compares the germination rate statistics of wild-type K407 and positive seedlings OE-BnAAP3L-8. The lower right image compares the germination rate statistics of wild-type K407 and positive seedlings OE-BnAAP3L-9.

[0030] Figure 5 The image shows the root development of positive seedlings OE-BnAAP3L-8 and wild-type K407 overexpressing the gene BnAAP3L under different NaCl concentrations. The top image shows the root growth of wild-type K407 and positive seedling OE-BnAAP3L-8 under different NaCl concentrations. The middle image shows a comparison of the taproot length of wild-type K407 and positive seedling OE-BnAAP3L-8. The bottom image shows a comparison of the number of lateral roots of wild-type K407 and positive seedling OE-BnAAP3L-8.

[0031] Figure 6 The image shows the root development of positive seedlings OE-BnAAP3L-9 and wild-type K407 overexpressing the gene BnAAP3L under different NaCl concentrations. The top image shows the root growth of wild-type K407 and positive seedling OE-BnAAP3L-9 under different NaCl concentrations; the middle image shows a comparison of the taproot length of wild-type K407 and positive seedling OE-BnAAP3L-9; and the bottom image shows a comparison of the number of lateral roots of wild-type K407 and positive seedling OE-BnAAP3L-9.

[0032] Figure 7 The images show the germination results of positive seedlings overexpressing the BnAAP3L gene under different concentrations of PEG treatment. The left image shows the germination of wild-type K407 and positive seedlings OE-BnAAP3L-8 and OE-BnAAP3L-9 under different concentrations of PEG treatment, while the right image shows a comparison of the germination rate statistics of wild-type K407 and positive seedlings OE-BnAAP3L-8 and OE-BnAAP3L-9.

[0033] Figure 8The image shows the root development of wild-type K407 and positive seedlings OE-BnAAP3L-8 and OE-BnAAP3L-9 overexpressing the BnAAP3L gene under 20% PEG treatment. The left image shows the root growth of wild-type K407 and positive seedlings OE-BnAAP3L-8 and 9 under different NaCl concentrations. The upper right image compares the taproot length of wild-type K407 and positive seedlings OE-BnAAP3L-8 and 9. The lower right image compares the lateral root number of wild-type K407 and positive seedlings OE-BnAAP3L-9 and 9. Detailed Implementation

[0034] To enable those skilled in the art to better understand the technical solutions of the present invention, the preferred embodiments of the present invention will be described in detail below. However, the following embodiments do not limit the scope of protection of the present invention.

[0035] In the embodiments of the present invention, unless otherwise described, conventional experimental methods were used. The processes involved in the embodiments, unless otherwise described, can be understood and easily implemented by those skilled in the art based on the product manual or basic knowledge in the field, and therefore will not be described in detail.

[0036] In this embodiment of the invention, the Brassica napus K407 plant and seeds were provided by the Rapeseed Molecular Breeding Laboratory of the Shaanxi Hybrid Rapeseed Research Center and are publicly known materials. The Brassica napus genetic transformation method involved in this embodiment of the invention was provided by Professor Hong Dengfeng of Huazhong Agricultural University and is a publicly known method.

[0037] Example 1: Analysis of BnAAP3L Expression Pattern

[0038] The expression levels of the BnAAP3L gene in different tissues of rapeseed were demonstrated by RT-qPCR experiments, using Brassica napus K407 plants and seeds as examples.

[0039] Based on the nucleotide sequence of the gene BnAAP3L (NCBI gene ID: BnaC04g07210D), qPCR primers (SEQ ID Nos. 8 and 9 in Table 3) were designed. Using the rapeseed Actin gene as an internal control, the expression level of BnAAP3L in different rapeseed organs was identified. The RT-qPCR reaction system and procedure are shown in Tables 1 and 2. The expression level of BnAAP3L in rapeseed seeds (seed in the figure) was used as a control. Figure 1 ).

[0040] The results are as follows Figure 1As shown, the BnAAP3L gene is expressed at certain levels in the stem, flower, leaf, young silique, silique pericarp, and root of rapeseed.

[0041] Table 1. RT-qPCR reaction system

[0042]

[0043] Table 2. RT-qPCR reaction procedures

[0044]

[0045] Example 2: Cloning of the BnAAP3L gene and construction of an overexpression vector

[0046] Based on the whole genome DNA sequence (NCBI gene ID: BnaC04g07210D) and CDS sequence (SEQ ID No: 1) of *Brassica napus* published on NCBI (http: / / www.ncbi.nlm.nih.gov / ), overexpression primers, primers for amplifying the BnAAP3L CDS sequence, and universal primers for related vectors were designed using Primer 5 software. Primer sequences are shown in Table 3 below. All primers were synthesized by Sangon Biotech (Shanghai) Co., Ltd.

[0047] SEQ ID No: 1(BnaC04g07210D):

[0048]

[0049] Table 3. Primers for overexpression primer amplification of the BnLBD29 CDS sequence and universal primers for related vectors.

[0050]

[0051] Using the sequences shown in SEQ ID No:2 and SEQ ID No:3 as primers, PCR amplification was performed using rapeseed cDNA as a template. The PCR system and procedure are shown in Tables 4 and 5.

[0052] Table 4. PCR System

[0053] reagents Dosage Template (50 ng / μL) 1μL KOD-Plus-Neo 10×PCR Buffer 5μL KOD-Plus-Neo 1μL <![CDATA[MgSO4(25mM)]]> 3μL dNTP Mixture (2mM) 5μL SEQ ID No:2 2μL SEQ ID No:3 2μL <![CDATA[ddH2O]]> To 50μL

[0054] Table 5. PCR Procedure

[0055]

[0056] The amplified product was recovered and ligated into the pENTR-D / TOPO entry vector (purchased routinely). After sequencing verification that the BnAAP3L CDS sequence was correct, the BnAAP3L CDS sequence was recombined with the pK7FWG2.0 (purchased routinely) plant expression vector using the Gateway method to obtain the recombinant expression vector pK7FWG2.0-BnAAP3L for overexpressing BnAAP3L. A schematic diagram of the vector is shown below. Figure 2 As shown. The recombinant vector was transformed into E. coli DH5α, and the plasmid was extracted, verified by PCR, and then used for later use. The specific steps are as follows:

[0057] First, the cloned BnAAP3L CDS sequence fragment is ligated into the entry vector pENTR / D-TOPO:

[0058] The connection system is as follows:

[0059] Table 6. System of connecting the entry carrier pENTR

[0060] Components Dosage (μL) pENTR / D-TOPO vector (20 ng / μL) 0.5 BnAAP3L fragment (20 ng / μL) 1.2 Salt solution 0.5 <![CDATA[ddH2O]]> 1.8

[0061] The vector pENTR-BnAAP3L was obtained by ligation at 22℃ for 3 hours. pENTR-BnAAP3L was then transformed into *E. coli* DH5α competent cells, and bacterial culture was identified by PCR using primers SEQ ID No:2 and SEQ ID No:3. The plasmid was extracted after identification and kept for later use.

[0062] Then, the introductory vector and the expression vector were subjected to an LR reaction:

[0063] Using the Gateway Reaction Kit, the BnAAP3L fragment from the entry vector pENTR-BnAAP3L was transferred to the expression vector pK7FWG2.0. The reaction system is as follows:

[0064] Table 7. System of LR reaction

[0065] reagents Dosage (μL) <![CDATA[LR Clonase TM II Enzyme]]> 1 pK7FWG2.0 plasmid (100 ng / μL) 0.7 pENTR-BnAAP3L plasmid (140 ng / μL) 0.5 TE buffer To 5μL

[0066] After reacting at 25℃ for 3 hours, 1 μL of protein kinase K was added, and the reaction was carried out at 37℃ for 10 minutes to obtain the recombinant vector pK7FWG2.0-BnAAP3L. This vector was then transformed into Escherichia coli DH5α competent cells and plated on a medium containing 50 mg / L spectinomycin. After culturing, single clones were picked and identified by PCR using SEQ ID No:4 and SEQ ID No:5 primers. Correctly identified clones were expanded and cultured, and the bacterial strain was stored at -80℃.

[0067] Example 3: Transformation of wild-type Brassica napus plants

[0068] S1. Transformation and identification of Agrobacterium:

[0069] The vector pK7FWG2.0-BnAAP3L obtained in Example 2 was transformed into Agrobacterium competent cells GV3101 using liquid nitrogen cold shock to obtain engineered bacteria GV3101-pK7FWG2.0-BnAAP3L containing the pK7FWG2.0-BnAAP3L vector. Then, the engineered bacteria were transformed into Brassica napus using the hypocotyl infection method, with the specific steps as follows:

[0070] (1) Take 30 μL of Agrobacterium competent cells GV3101 and thaw them on ice.

[0071] (2) Add 300 ng pK7FWG2.0-BnAAP3L vector plasmid to Agrobacterium, place on ice for 5 min, freeze in liquid nitrogen for 5 min, immediately in a 37°C water bath for 5 min, and then in an ice bath for 5 min.

[0072] (3) Add 700 μL of LB medium (manufacturer: Oxoid, catalog number: CM0996B) and incubate at 28℃ with shaking for 2-3 hours.

[0073] (4) Then centrifuge to collect the bacterial cells, discard the supernatant, and use a spreader to spread the bacterial solution on the culture medium containing 50 mg / L rifampicin, gentamicin and kanamycin respectively, and incubate at 28°C for 36-48 h.

[0074] (5) Select single clones for expansion culture and perform bacterial culture PCR identification. The correctly identified strains are preserved for later use. The Agrobacterium that is correctly transformed with plasmids is screened.

[0075] Brassica napus seeds (K407 type) provided by the Rapeseed Molecular Breeding Laboratory of the Shaanxi Hybrid Rapeseed Research Center were used. After sowing and germination, the hypocotyls of the rapeseed were selected for genetic transformation. Aseptic operation was strictly maintained throughout the experiment, and all materials were prepared and the pH of all culture media was correct before the experiment.

[0076] S2. Sowing:

[0077] Preparations before the experiment: M0 culture medium, sterile Erlenmeyer flasks or centrifuge tubes, and sterile water.

[0078] (1) Place the seeds in a centrifuge tube and disinfect them by soaking them in 75% alcohol for 1 minute.

[0079] (2) Discard the alcohol, then add hypochlorous acid-bleach disinfectant and soak the seeds for 4 minutes to disinfect them.

[0080] (3) Remove the disinfectant and rinse the seeds 3-5 times with sterilized RO water.

[0081] (4) Use tweezers to sow the sterilized seeds onto M0 medium, 20-25 seeds per dish. Incubate at 24℃ in the dark for 6 days.

[0082] S3. Activation and preparation of Agrobacterium:

[0083] (1) Take out Agrobacterium strain containing vector pK7FWG2.0-BnAAP3L, streak to activate, and screen using LB medium containing 50 mg / L rifampicin, gentamicin and spectinomycin respectively. Pick single bacteria and culture them in medium containing the corresponding antibiotics at 28℃ and 220 rpm for 12-24 h.

[0084] (2) After bacterial culture was identified by PCR, the culture was expanded to the OD value of the bacterial culture. 600 It is around 0.4-0.6.

[0085] (3) Take 2 mL of bacterial culture, centrifuge at 5,000 rpm for 10 min to collect the bacterial cells, resuspend them twice with 2 mL of DM medium, and store them in a refrigerator at 4℃ for later use.

[0086] S4. Preparation and staining of explants:

[0087] (1) Add 18 mL of DM (AS+) to a sterile glass petri dish, and use a sterile scalpel to cut the rapeseed hypocotyl into DM. The explant length is about 0.8-1 cm.

[0088] (2) Pour 2 mL of the prepared bacterial solution into the cut explant and soak for 10-15 min, shaking 4-5 times during the process.

[0089] (3) After 10-15 minutes, remove the DM bacterial solution, use sterile tweezers to pick up the explant and place it on sterile filter paper, and remove the excess bacterial solution from the explant.

[0090] (4) Transfer the explants to M1 medium and culture them in the dark at 24°C for 36-48 hours. Then transfer the explants to M2 selection medium and culture them under light for 15 days (16 hours during the day and 8 hours at night at 24°C). After 15 days of culture under light, transfer the explants to M3 medium and subculture them every 2-3 weeks until green shoots appear. Transfer the green shoots with intact growth points to rooting medium, and transplant them into soil after they have grown and rooted.

[0091] Total DNA was extracted from the leaves of transgenic rapeseed plants using the CTAB method. Positive plants were identified by PCR using specific primers (SEQ ID No:4 and SEQ ID No:5). Plants amplified with the expected length band (SEQ ID No:4 and SEQ ID No:5 were used as F and R primers in this example; primer F was 131 bp upstream of BnAAP3L, primer R was 251 bp downstream of BnAAP3L, the BnAAP3L gene fragment is 1482 bp, therefore the target band was 1864 bp). Results are as follows: Figure 3 As shown in the figure, M is the marker, lanes 1-13 are the obtained transformants, and + is the positive control. Two positive transformants, 8 and 9, were obtained after identification and are denoted as OE-BnAAP3L-8 and OE-BnAAP3L-9.

[0092] The preparation of the culture medium involved in this embodiment:

[0093] MS medium and MS medium (containing organic matter) were purchased through regular commercial channels (manufacturer: Duchefa Biochemie, model: M0222.0100).

[0094] (1) DM medium

[0095] The formula is shown in Table 8 below. After dissolving and bringing the volume to a final volume, adjust the pH to 5.8. Autoclave at 121℃ for 15 minutes, cool, and then add 1 mL of 100 mM AS (acetylsuccinone) for later use.

[0096] Table 8. Formulation of DM medium

[0097]

[0098] (2) Seed germination medium (M0)

[0099] The formula is shown in Table 9 below. Agar powder is dispensed into culture flasks in advance, the pH is adjusted to 5.8 and then the volume is brought to a final volume. The flasks are dispensed into 40 mL each and autoclaved at 121°C for 15 min.

[0100] Table 9. Formulation of M0 medium

[0101] reagents Dosage D-sucrose 20g MS medium (containing organic matter) 4.42g Agar powder 8g <![CDATA[ddH2O]]> To 1L

[0102] (3) Co-culture medium (M1)

[0103] Table 10. Formulation of M1 medium

[0104] reagents Dosage D-sucrose 30g MS medium (containing organic matter) 4.42g Agar powder 8g Mannitol 18g <![CDATA[ddH2O]]> To 1L

[0105] The formula is shown in the table above. Weigh and dissolve the reagents, adjust the pH to 5.8, and autoclave at 121℃ for 15 minutes. After cooling, add the reagents from the table below in a clean bench, and dispense into petri dishes for later use.

[0106] Table 11. Hormone formulation for M1 culture medium

[0107] reagents Dosage (mL) 1 mg / mL 2,4-D 1 0.3 mg / mL KT 0.3 100mM AS 1

[0108] (4) Screening medium (M2)

[0109] The formula is shown in the table below. After weighing and dissolving, adjust the pH to 5.8 and autoclave at 121℃ for 15 minutes. After cooling, add the hormone in a laminar flow hood and dispense into petri dishes for later use.

[0110] Table 12. Formulation of M2 medium

[0111] reagents Dosage MS medium (containing organic matter) 2.21g D-sucrose 15g Mannitol 9g agarose 4g <![CDATA[ddH2O]]> To 500mL 1 mg / mL 2,4-D 0.5mL 1mg / mL KT 0.15mL 300mg / mL Timentin 0.5mL STS 0.75mL 30mg / mL Kan 0.4mL

[0112] (5) Subculture medium (M3)

[0113] The formula is shown in the table below. After weighing and dissolving, adjust the pH to 5.8 and autoclave at 121℃ for 15 minutes.

[0114] Table 13. Formulation of M3 medium

[0115] reagents Dosage MS medium (containing organic matter) 2.21g Glucose 5g D-xylose 0.125g MES 0.3g Agarose 4g <![CDATA[ddH2O]]> To 500mL

[0116] After cooling, add the hormones listed below in the clean bench and dispense them into petri dishes for later use.

[0117] Table 14. Hormone formulation for M3 culture medium

[0118] Hormone Name volume 2mg / mL ZT 0.25mL 300mg / mL TMT 1mL 1 mg / mL IAA 0.5mL 30mg / mL Kan 0.8mL

[0119] (6) Rooting medium (M4)

[0120] The formula is shown in the table below. After weighing and dissolving, adjust the pH to 5.8 and autoclave at 121℃ for 15 minutes. After cooling, add 1 mL of 300 mg / mL TMT in a clean bench and dispense into petri dishes for later use.

[0121] Table 15. Formulation of M4 medium

[0122] Reagent Name Dosage MS medium (purchased from Duchefa Biochemie) 2.21g D-sucrose 10g Agar 3g <![CDATA[ddH2O]]> To 500mL

[0123] Example 4: Investigation of drought and salt resistance in transgenic Brassica napus plants overexpressing BnAAP3L

[0124] In Example 3, two positive seedlings were identified. Figure 3 ).

[0125] Different levels of salt stress were simulated using aqueous solutions containing different concentrations of NaCl (0 mM, 150 mM, and 200 mM). Seeds of wild-type K407 and rapeseed transformant seedlings were treated in petri dishes containing different salt concentrations for 10 days (treatment solution was added every 3 days, with the filter paper being moistened as the standard). The number of germinating seeds was then counted. The results are as follows: Figure 4 As shown in the figure, rapeseed seeds overexpressing the BnAAP3L gene (positive seedlings) exhibited a higher germination rate under salt stress compared to the wild type. Phenotypic observation of the seedlings was conducted on day 20, and the results are as follows... Figure 5 and Figure 6 As shown in the figure, compared with the wild type, rapeseed seeds overexpressing the BnAAP3L gene (positive seedlings OE-BnAAP3L-8 and OE-BnAAP3L-9) showed improved root development under salt stress, and the positive seedlings had more developed root systems.

[0126] Similarly, different levels of drought stress were simulated using aqueous solutions containing different concentrations of PEG (0%, 5%, 10%, and 20%). Seeds of wild-type K407 and rapeseed transformants were treated for 7 days in petri dishes containing different concentrations of PEG solution (treatment solution was added daily, with the filter paper being moistened as the standard). The number of germinating seeds was then counted. Figure 7 Phenotypic observations were conducted on seedlings treated with 20% PEG at day 20. Figure 8 Compared with the wild type, rapeseed seeds overexpressing the BnAAP3L gene had a higher germination rate under drought stress and improved the root development of rapeseed seedlings.

[0127] The above results demonstrate that the BnAAP3L gene has the ability to enhance plant tolerance to salt and drought environments.

Claims

1. The use of a gene BnAAP3L, or a recombinant expression vector containing the gene BnAAP3L, or a recombinant engineering bacteria containing the gene BnAAP3L in any of the following: improving the salt and / or drought tolerance of plants, improving the germination rate of plants under salt and / or drought stress conditions, improving the root development of plants under salt and / or drought stress conditions, preparing a product for improving the salt and / or drought tolerance of plants, preparing a product for improving the germination rate of plants under salt and / or drought stress conditions, preparing a product for improving the root development of plants under salt and / or drought stress conditions, breeding or assisting breeding of salt and / or drought tolerant plants; the plants are Brassica napus; the use is achieved by overexpressing the BnAAP3L gene; the CDS sequence of the gene BnAAP3L is shown as SEQ ID No:

1. The method comprises the following steps:

2. A method for improving the salt and / or drought tolerance of a plant, characterized in that, cloning the gene BnAAP3L as described in claim 1, constructing a recombinant expression vector containing the gene BnAAP3L, transforming Brassica napus by Agrobacterium mediation with the recombinant expression vector, screening transgenic plants, and obtaining salt and / or drought tolerant Brassica napus. The cloning of the gene BnAAP3L uses the sequences shown as SEQ ID No: 2 and SEQ ID No: 3 as primers, and Brassica napus cDNA as a template for PCR amplification.

3. The method of claim 2, wherein, 4. The use of the gene BnAAP3L as described in claim 1, or a recombinant expression vector containing the gene BnAAP3L, or a recombinant engineering bacteria containing the gene BnAAP3L, or a substance promoting the expression of the gene BnAAP3L in the preparation of a kit for improving the salt and / or drought tolerance of Brassica napus. ​

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