CN116622760B - Application of LuAccD gene in regulating synthesis of plant fatty acid and salt tolerance and drought resistance - Google Patents

Abstract

The present invention provides an application of LuAccD gene for regulating plant fatty acid synthesis. After overexpressing LuAccD gene in plant, the amount of fatty acid synthesis in plant can be increased. The present invention also provides an application of LuAccD gene for regulating plant salt and drought resistance. After overexpressing LuAccD gene in plant, the salt and drought resistance of plant can be increased. By exploring the function of LuAccD gene in plant seed oil metabolism and response to abiotic stress, the present invention provides an application of LuAccD gene for regulating plant fatty acid synthesis and salt and drought resistance, filling the gap in the application of LuAccD gene in genetic engineering.

Description

Application of LuAccD gene in regulating plant fatty acid synthesis and salt and drought tolerance

Technical Field

The invention belongs to the technical field of plant molecular biology, relates to a LuAccD gene, and specifically relates to an application of the LuAccD gene in regulating plant fatty acid synthesis and salt and drought resistance.

Background technique

Acetyl-CoA carboxylase, as the rate-limiting enzyme for de novo fatty acid synthesis, is widely present in various organisms. It exists in two types, heterogeneous and homogeneous. Both types have biotin carboxyl carrier protein subunits, biotin carboxylase subunits, and α-CT and β-CT subunits of carboxyltransferase. During the fatty acid accumulation process in seeds, the activity of acetyl-CoA carboxylase is proportional to the fatty acid synthesis rate. Overexpression of the AccD gene encoding the β-CT subunit in tobacco plastids promoted the fatty acid synthesis in leaves and seeds. Specific expression of the AccD gene encoding the heterogeneous β-CT subunit of acetyl-CoA carboxylase in Escherichia coli can significantly increase the oil content of rapeseed seeds. In upland cotton, the four subunits of ACCase coordinate with each other to jointly regulate the oil content of seeds. Overexpression of GhBCCP1, GhBC1, Ghα-CT and Ghβ-CT genes can significantly increase the oil content of upland cotton seeds.

The gene encoding the acetyl-CoA carboxylase β-CT subunit of flax (i.e., the flax AccD gene) is highly expressed in developing seeds, but its function in plant oil metabolism and stress response is still unclear, thus limiting the genetic engineering application of the flax AccD gene.

Summary of the invention

In view of the shortcomings of the prior art, the purpose of the present invention is to provide the application of LuAccD gene for regulating plant fatty acid synthesis and salt and drought resistance, so as to solve the technical problem that the function of LuAccD gene in the prior art is unclear, resulting in the limitation of its genetic engineering application.

In order to solve the above technical problems, the present invention adopts the following technical solutions to achieve the above problems:

The LuAccD gene is used to regulate the synthesis of fatty acids in plants. After the LuAccD gene is overexpressed in plants, the amount of fatty acids synthesized in the plants can be increased.

The LuAccD gene is used to regulate the salt and drought resistance of plants. After the LuAccD gene is overexpressed in plants, the salt and drought resistance of plants can be improved.

The nucleotide sequence of the LuAccD gene is shown as sequence ID Numer 1 in the nucleotide or amino acid sequence table; the amino acid sequence encoded by the LuAccD gene is shown as sequence ID Numer 2 in the nucleotide or amino acid sequence table.

The present invention also has the following technical features:

Specifically, after the LuAccD gene is overexpressed in plants, the transcription level of plant oil accumulation-related genes can be increased; the oil accumulation-related genes include: AtBCCP1 gene, AtBCCP2 gene, AtMCAT gene, AtKAS1 gene, AtKAS2 gene, AtSSI2 gene, AtFAD2 gene, AtFAD3 gene and AtPDAT2 gene.

Specifically, after the LuAccD gene is overexpressed in a plant, the salt and drought resistance of the plant can be improved; the nucleotide sequence of the LuAccD gene is shown as sequence ID Number 1 in the nucleotide or amino acid sequence table.

Specifically, after the LuAccD gene is overexpressed in the plant, the transcription level of genes related to stress response in the plant can be reduced; the genes related to stress response include: AtNCED3 gene, AtABI3 gene, AtAAO3 gene, AtEM1 gene and AtEM6 gene.

Specifically, after the LuAccD gene is overexpressed in plants, the plants can tolerate 150 mM sodium chloride and 300 mM mannitol.

Specifically, the method for overexpressing the LuAccD gene in a plant includes:

The LuAccD gene is connected to the overexpression vector pGreen-35S-6HA to obtain a 35S:LuAccD-6HA overexpression vector, and then the 35S:LuAccD-6HA overexpression vector is transferred into plants; the nucleotide sequence of the overexpression vector pGreen-35S-6HA is shown in sequence ID Number 3 in the nucleotide or amino acid sequence table.

Specifically, the plant is a wild-type plant.

The present invention also protects the method for overexpressing the LuAccD gene in plants as described above.

Compared with the prior art, the present invention has the following technical effects:

(I) The present invention explores the function of LuAccD gene in plant seed oil metabolism and response to abiotic stress, provides the application of LuAccD gene for regulating plant fatty acid synthesis and salt and drought resistance, and fills the gap in the application of LuAccD gene in genetic engineering.

(II) The present invention is of great significance for analyzing the regulatory mechanism of enzyme active molecules in the process of plant seed oil metabolism, improving the content and composition of flax fatty acids, and cultivating new high-resistant flax varieties.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is a schematic diagram of the insertion position of the LuAccD gene in the overexpression vector pGreen-35S-6HA. In Figure 1: RB represents the right border, LB represents the left border, NOS-pro represents the promoter; NOS-ter represents the terminator, Basta represents the glufosinate resistance screening gene, and 35S-pro represents the 35S strong promoter.

Figure 2 is a nucleic acid electrophoresis diagram of PCR identification of transgenic strain seeds. In Figure 2: Cas represents 35S: LuAccD-6HA overexpression vector.

FIG. 3 is a bar chart showing the expression level of the LuAccD gene in the seeds of the transgenic lines identified by qRT-PCR.

FIG. 4 is a macroscopic morphology of wild-type Arabidopsis seeds and transgenic line seeds.

FIG. 5 is a bar chart showing the thousand-grain weight of wild-type Arabidopsis seeds and transgenic strain seeds.

FIG. 6 is a bar chart showing the length and width of seeds of wild-type Arabidopsis thaliana and transgenic lines.

FIG. 7 is a bar chart showing the total fatty acid content in wild-type Arabidopsis seeds and transgenic line seeds.

FIG8 is a bar chart showing the contents of various fatty acid components in wild-type Arabidopsis seeds and transgenic strain seeds.

FIG. 9 is a bar chart showing the expression levels of genes related to oil accumulation in wild-type Arabidopsis seeds and transgenic strain seeds detected by qRT-PCR.

Figure 10 ^{is a diagram showing the germination status of wild-type Arabidopsis seeds and transgenic strain seeds under salt and mannitol stress. In Figure 10: 1/2 MS represents 1/2} _MS ^medium _, 150mM NaCl represents 150mM sodium chloride, and 300mM Mannitol represents 300mM mannitol.

Figure 11 is a bar chart ^{showing the germination rates of wild-type Arabidopsis seeds and transgenic lines under salt and mannitol stress. In Figure 11: 1/2 MS means 1/2 MS} _medium , 150 mM NaCl means 150 mM sodium chloride, _and 300 mM Mannitol means 300 mM mannitol.

FIG. 12 is a bar chart showing the expression levels of stress response-related genes in wild-type Arabidopsis seeds and transgenic line seeds under salt stress.

The specific contents of the present invention are further explained in detail below in conjunction with embodiments.

Detailed ways

It should be noted that all reagents, kits, enzymes and culture media used in the present invention, unless otherwise specified, are reagents, kits, enzymes and culture media known in the art, for example:

Plant RNA extraction kit was purchased from Hunan Aikerui Bioengineering Co., Ltd. with the catalog number of No.AG21019.

The reverse transcription kit was purchased from Beijing Quanshijin Biotechnology Co., Ltd. with the catalog number No.AE311.

High-fidelity DNA polymerase was purchased from Bio-Rad Biotechnology (Beijing) Co., Ltd. with the catalog number of R045Q.

The DNA purification and recovery kit was purchased from Tiangen Biochemical Technology (Beijing) Co., Ltd. with the catalog number No. DP214.

Restriction enzymes EcoR I and Xma I were produced by New England Biolabs.

The one-step cloning kit was purchased from Nanjing Novogene Biotech Co., Ltd. with the trade name ClonExpressⅡOne Step Cloning Kit.

The plasmid extraction kit was produced by Omega Bio-Tek, USA.

The herbicide is produced by Bayer AG and its trade name is Basta herbicide. Its active ingredient is glufosinate-ammonium, and the content of glufosinate-ammonium is 20% [v/v].

1L of LB liquid culture medium includes the following components: 10g of tryptone, 5g of yeast extract, and 10g of NaCl; LB solid culture medium is based on the above formula and 15g of agar is added.

^1/2 MS culture medium was purchased from Beijing Solebow Technology Co., _Ltd. , with the catalog number No.M8527.

In the present invention:

The flax used is the flax (sesame) "Longya No. 10" known in the prior art, which is cultivated by the Crop Research Institute of Gansu Academy of Agricultural Sciences.

Specific embodiments of the present invention are given below. It should be noted that the present invention is not limited to the following specific embodiments, and all equivalent changes made on the basis of the technical solution of this application fall within the protection scope of the present invention.

Embodiment 1:

This example provides an application of the LuAccD gene for regulating plant fatty acid synthesis. After the LuAccD gene is overexpressed in the plant, the application can increase the amount of fatty acid synthesis in the plant.

As a specific solution of this embodiment, the method for overexpressing the LuAccD gene in a plant specifically includes the following steps:

Step 1, LuAccD gene cloning:

Step 1.1, LuAccD gene sequence acquisition and specific primer design:

The AtAccD protein sequence was obtained through the Arabidopsis database Tair website. The BLAST P program was run in the NCBI database based on the Arabidopsis AtAccD protein sequence to obtain a homologous sequence in flax, which was named LuAccD gene. The nucleotide sequence of the LuAccD gene is shown as sequence ID Number 1 in the nucleotide or amino acid sequence table, and the amino acid sequence encoded by the LuAccD gene is shown as sequence ID Number 2 in the nucleotide or amino acid sequence table.

The insertion position of the LuAccD gene on the vector was designed and determined, as shown in Figure 1; then the Primer BLAST program in NCBI was used to design specific primers (35S:LuAccD-6HA-EcoR I-F and 35S:LuAccD-6HA-Xma I-R), and the verification primer (35S-F) on the vector was designed at the same time. The primer sequences are shown in Table 1.

Table 1. Primer sequences

Primer name Primer sequence (5'→3') 35S:LuAccD-6HA-EcoR I-F GATAAGCTTGATATCGAATTCATGACTAGTTCAGATAGAAT 35S:LuAccD-6HA-Xma I-R GTATGGGTAACTAGAACTAGTATGAGTCAAAGCGTGGAGA 35S-F GACCCTTCCTCTATATAAGGAAGTTC

Step 1.2, RNA extraction and cDNA synthesis:

The total RNA of flax seeds at the germination stage was extracted using a plant RNA extraction kit, and the cDNA of flax seeds at the germination stage was synthesized using a reverse transcription kit using the total RNA of flax seeds at the germination stage as a template.

Step 1.3, LuAccD gene cloning:

Using the specific primers designed in step 1.1, the cDNA of flax germination seeds synthesized in step 1.2 as a template, and high-fidelity DNA polymerase, the target gene was amplified by PCR technology. The reaction system was: 10×PCR Buffer 2.5μL, Mg ²⁺ 1μL, dNTP 1μL, KOD-Plus 0.5μL, upstream and downstream primers 1μL each, cDNA template 1μL, and sterile water to 25μL; the PCR reaction conditions are shown in Table 2.

Table 2. High-fidelity PCR reaction conditions

After the PCR reaction is completed, agarose gel electrophoresis is performed to determine whether the size of the target gene is correct based on the DNA marker, and the band of the correct size is quickly cut out of the gel, and the target gene fragment is purified and recovered using a universal DNA purification and recovery kit.

Step 2: Construction of plant expression vector:

Step 2.1, connect the target gene fragment and the linear vector:

At 37°C, restriction endonucleases EcoR I and Xma I were used to digest the overexpression vector pGreen-35S-6HA and the target gene fragment obtained in step 1.3 overnight. The digestion product was purified and recovered using a DNA purification and recovery kit. Using a one-step cloning kit, the purified target fragment was mixed with the digestion vector in a 2:1 molar ratio, and the recombination reaction was carried out at 37°C for 30 minutes to complete the connection between the target gene fragment and the linear vector. The nucleotide sequence of the overexpression vector pGreen-35S-6HA is shown in sequence ID Number 3 in the nucleotide or amino acid sequence table.

Step 2.2, transformation of ligation product:

Add the ligation product obtained in step 2.1 to the competent E. coli DH5α cells, gently pipette to mix, place on ice for 20 minutes, incubate in a 42°C water bath for 90 seconds, quickly place on ice for 2 minutes, add 700 μL of LB liquid culture medium, place on a 37°C shaker for 30 minutes, spread the bacterial solution on an LB solid culture medium plate containing 50 μg mL ^-1 kanamycin, and invert at 37°C incubator overnight.

Step 2.3, single clone screening and identification:

Pick 10 monoclonal colonies from the plate cultured overnight in step 2.2, place them in 7 μL ddH ₂ O and mix them evenly, take 1 μL of bacterial solution as template, and use the primers 35S-F and 35S:LuAccD-6HA-XmaI-R designed in step 1.1 to perform colony PCR verification. After the PCR reaction is completed, the product is subjected to agarose gel electrophoresis, and the monoclonal colonies with correct 2 bands are selected and added to LB liquid culture medium containing 50 μg·mL ^-1 kanamycin, and cultured at 28°C and 220 rpm shaking for 20 hours.

The cultured bacterial solution was sequenced, and the sequencing result was consistent with the target gene sequence, indicating that the LuAccD gene had been successfully cloned into the overexpression vector pGreen-35S-6HA.

Step 2.4, obtain 35S:LuAccD-6HA overexpression vector:

The plasmid bacterial solution screened and identified correctly in step 2.3 was expanded and then the plasmid was extracted according to the instructions of the plasmid extraction kit to obtain the 35S:LuAccD-6HA overexpression vector.

Step 3: Arabidopsis genetic transformation, screening and identification:

Step 3.1, transformation and colony identification:

The 35S:LuAccD-6HA overexpression vector obtained in step 2.4 was transferred into Agrobacterium competent cells GV3101, single clone colonies were picked, and colony PCR verification was performed using primers 35S-F and 35S:LuAccD-6HA-Xma I-R designed in step 1.1.

Step 3.2, culture and collect positive colonies:

Add the positive colonies verified by PCR in step 3.1 to 200 mL of LB liquid culture medium containing 50 μg·mL ^-1 kanamycin and 50 μg·mL ^-1 rifamycin to expand the culture until the OD ₆₀₀ of the bacterial solution is 1.8-2.0, and centrifuge at 4000 rpm for 10 minutes at room temperature to collect the bacteria.

Step 3.3, transfect wild-type Arabidopsis thaliana using the Agrobacterium inflorescence infection method:

The cells collected in step 3.2 were resuspended to an OD ₆₀₀ value of 0.8 to 1.0 in Arabidopsis transformation solution containing 5% [w/v] sucrose and 0.02% [v/v] Silwet L-77 surfactant; the inflorescence of the whole plant was immersed in the Arabidopsis transformation solution for 30 to 40 seconds, the plant was taken out, placed on its side in a tray for dark culture for 2 days, and then cultured under normal light, and T ₀ generation seeds were harvested after maturity.

Step 3.4, screening and identification of transgenic plants:

The _T0 seeds harvested in step 3.3 were evenly sown on the nutrient soil, cultured in the dark at 4°C for 2 to 3 days, and then transferred to the light culture room for further culture. After two true leaves grew, the seedlings were sprayed with herbicides continuously for about 1 week until resistant plants that could continue to grow were selected, and the working concentration of the herbicide was 0.06% [v/v]; the selected resistant plants were transferred to new nutrient soil for further growth, and DNA from young leaves of the plants was extracted at the rosette leaf stage, and PCR amplification was performed using the specific primers 35S-F and 35S:LuAccD-6HA-Xma IR designed in step 1.1. The results are shown in FIG2 , and the identified _T1 positive transgenic plants were further cultured to maturity and _T2 seeds were harvested; the _T2 seeds were sown on MS medium containing 10 μg·mL ^-1 glufosinate ammonium for further screening and culture, and finally _T3 homozygous seeds were obtained.

In this example, the specific primers 35S-F and 35S:LuAccD-6HA-Xma IR designed in step 1.1 were used to identify the expression level of the LuAccD gene in the _T3 generation homozygous seeds. The results are shown in FIG3 . As can be seen from FIG3 , the LuAccD gene in the _T3 generation homozygous seeds was expressed at the transcriptional level.

Effect verification of Example 1:

In order to examine the effect of LuAccD gene on plant oil accumulation-related genes, qRT-PCR primers were designed. The qRT-PCR primers are shown in Table 3:

Table 3. qRT-PCR primers for genes related to lipid accumulation

Primer name Primer sequence (5'→3') RT-qPCR-AtBCCP1-F TCACTCAAACCTCCTCGCAC RT-qPCR-AtBCCP1-R TTGTGCTTTCACCACAGGGT RT-qPCR-AtBCCP2-F AACCCAATGGGATCTCCTTTCCCT RT-qPCR-AtBCCP2-R ATAAATTCAGAGAGCTCGGCGGGT RT-qPCR-AtMCAT-F TCATGGAACCAGCAGTCTCG RT-qPCR-AtMCAT-R CTGGAGATGTCACCTGGCG RT-qPCR-AtKAS1-F TCGATTTCAACTGCTTGTGC RT-qPCR-AtKAS1-R CCTCCCAACCCAATAGGAAT RT-qPCR-AtKAS2-F TGCCTATCACATGACCGAGC RT-qPCR-AtKAS2-R CCAAAACAGTGAGCAAGGGC RT-qPCR-AtSSI2-F CGCTGTGCATAAGCATTCTC RT-qPCR-AtSSI2-R TTGGGGCCGGAGCTGAGAGC RT-qPCR-AtFAD2-F ATGGGTGCAGGTGGAAGAAT RT-qPCR-AtFAD2-R CCAGGAGAAGTAAGGGACGA RT-qPCR-AtFAD3-F CCACAGTACTCGGATGCTCAGA RT-qPCR-AtFAD3-R GCAATAAGCTTTCTCTCGCTTGGA RT-qPCR-AtPDAT2-F AGATGATGAGACGAGCCGAAGC RT-qPCR-AtPDAT2-R TCTCTGGTGCCTCCGGTAATTTG RT-qPCR-AtFAB2-F CGCTGTGCATAAGCATTCTC RT-qPCR-AtFAB2-R TTGGGGCCGGAGCTGAGAGC RT-qPCR-AtKCS17-F GTCGAGCCCTCGGTTAACAA RT-qPCR-AtKCS17-R GCCTTCTGGTACATGGAAACC

(A) The phenotypes of wild-type Arabidopsis seeds (denoted as Col-0) and transgenic line seeds (denoted as Col-0 35S:LuAccD-6HA) were analyzed, and the results are shown in Figures 4, 5, and 6. As shown in Figures 4, 5, and 6, heterologous expression of the LuAccD gene did not affect seed length, width, 1000-grain weight, and seed coat color.

(B) The total fatty acid content and the content of each fatty acid component of wild-type Arabidopsis seeds and transgenic line seeds were analyzed, and the results are shown in Figures 7 and 8. As shown in Figures 7 and 8, the total fatty acid content and the content of each fatty acid component of transgenic line seeds are significantly higher than those of wild-type Arabidopsis seeds.

(C) Wild-type Arabidopsis seeds and transgenic line seeds were selected, and the transcription levels of genes related to oil accumulation were detected by qRT-PCR technology. The results are shown in Figure 9. As shown in Figure 9, the gene expression levels of AtBCCP1, AtBCCP2, AtMCAT, AtKAS1, AtKAS2, AtSSI2, AtFAD2, AtFAD3, and AtPDAT2 in Col-0 35S:LuAccD-6HA#4 were significantly higher than those in wild-type Arabidopsis seeds.

(D) Based on the analysis of (A), (B), and (C), it can be seen that the LuAccD gene can upregulate the expression of genes related to oil accumulation to promote the biosynthesis of fatty acids in Arabidopsis seeds; overexpression of the LuAccD gene in Arabidopsis can increase the amount of fatty acid synthesis without affecting other traits of Arabidopsis seed development.

Embodiment 2:

This example provides an application of LuAccD gene for regulating plant salt and drought resistance. After LuAccD gene is overexpressed in plants, the salt and drought resistance of plants can be improved. In this example, the method of overexpressing LuAccD gene in plants is exactly the same as that in Example 1.

Effect verification of Example 2:

In order to examine the effect of LuAccD gene on genes related to stress response, qRT-PCR primers were designed. The qRT-PCR primers are shown in Table 4:

Table 4. qRT-PCR primers for genes related to stress response

Primer name Primer sequence (5'→3') RT-qPCR-AtABI3-F TCCATTAGACAGCAGTCAAGGTTT RT-qPCR-AtABI3-R GGTGTCAAAGAACTCGTTGCTATC RT-qPCR-AtAAO3-F GGAGTCAGCGAGGTGGAAGT RT-qPCR-AtAAO3-R TGCTCCTTCGGTCTGTCCTAA RT-qPCR-AtNCED3-F AGGTCGTGTGAGTTCTTATG RT-qPCR-AtNCED3-R CACTGGTAAATCTCGCTCTC RT-qPCR-AtEM1-F TAGGGCACGAGGGTTATCAG RT-qPCR-AtEM1-R CGCTCTCCACCAGATTTTTC RT-qPCR-AtEM6-F GCAAACTCGAAAGGAGCAGT RT-qPCR-AtEM6-R TCTCGACTCCTTCCTCCTCA

(E) Seed germination test was conducted on wild-type Arabidopsis seeds and transgenic line seeds under 150 mM sodium chloride and 300 mM mannitol stress conditions, and the results are shown in Figures 10 and 11. As shown in Figures 10 and 11, under normal conditions, there was no significant difference in germination rate between wild-type Arabidopsis seeds and transgenic line seeds; however, under 150 mM sodium chloride and 300 mM mannitol stress conditions, the germination rate of transgenic line seeds was significantly higher than that of wild-type Arabidopsis seeds.

(F) The expression levels of stress response genes AtNCED3, AtABI3, AtAAO3, AtEM1 and AtEM6 in wild-type Arabidopsis seeds and transgenic line seeds during germination under sodium chloride stress were detected using qRT-PCR technology, and the results are shown in Figure 12. As shown in Figure 12, compared with wild-type Arabidopsis seeds, the expression levels of stress response-related genes AtNCED3, AtABI3, AtAAO3, AtEM1 and AtEM6 in transgenic line seeds were significantly reduced.

(G) Based on the analysis of (E) and (F) above, it can be seen that the LuAccD gene improves the salt tolerance of Arabidopsis seeds during the germination period by regulating the expression of genes related to stress response; overexpression of the LuAccD gene in Arabidopsis can improve the tolerance of Arabidopsis seeds during the germination period to salt and mannitol.

Based on the effects of Example 1 and Example 2, it can be seen that the LuAccD gene has great potential in increasing the fatty acid content of seeds. By using transgenic technology, the gene is overexpressed in oil crops to obtain transgenic strains with high oil content and salt and drought resistance.

Claims (10)

1. Application of LuAccD gene for regulating plant fatty acid synthesis. After LuAccD gene is overexpressed in plants, the amount of fatty acid synthesis in plants can be increased. The nucleotide sequence of the LuAccD gene is shown in SEQ ID NO.1. The plant is Arabidopsis thaliana. 2. The use of the LuAccD gene as claimed in claim 1 for regulating plant fatty acid synthesis, characterized in that after the LuAccD gene is overexpressed in the plant, the transcription level of plant oil accumulation-related genes can be increased; the oil accumulation-related genes include: AtBCCP1 gene, AtBCCP2 gene, AtMCAT gene, AtKAS1 gene, AtKAS2 gene, AtSSI2 gene, AtFAD2 gene, AtFAD3 gene and AtPDAT2 gene. 3. The use of the LuAccD gene for regulating plant fatty acid synthesis according to claim 1, wherein the method for overexpressing the LuAccD gene in a plant comprises: The LuAccD gene is connected to the overexpression vector pGreen-35S-6HA to obtain a 35S:LuAccD - 6HA overexpression vector, and then the 35S:LuAccD - 6HA overexpression vector is transferred into plants; the nucleotide sequence of the overexpression vector pGreen-35S-6HA is shown in sequence ID Number 3 in the nucleotide or amino acid sequence table. 4. Use of the LuAccD gene according to any one of claims 1 to 3 for regulating plant fatty acid synthesis, characterized in that the plant is a wild-type plant. 5. Application of LuAccD gene for regulating salt and drought resistance of plants. After overexpression of LuAccD gene in plants, the salt and drought resistance of plants can be improved. The nucleotide sequence of the LuAccD gene is shown in SEQ ID NO.1. The plant is Arabidopsis thaliana. 6. The use of the LuAccD gene for regulating plant salt and drought resistance as claimed in claim 5, characterized in that after the LuAccD gene is overexpressed in the plant, the transcription level of genes related to stress response in the plant can be reduced; the genes related to stress response include: AtNCED3 gene, AtABI3 gene, AtAAO3 gene, AtEM1 gene and AtEM6 gene. 7. Use of the LuAccD gene for regulating plant salt and drought resistance as claimed in claim 5, characterized in that after the LuAccD gene is overexpressed in the plant, the plant can tolerate 150 mM sodium chloride and 300 mM mannitol. 8. The use of the LuAccD gene for regulating plant salt and drought resistance as claimed in claim 5, characterized in that the method for overexpressing the LuAccD gene in a plant comprises: The LuAccD gene is connected to the overexpression vector pGreen-35S-6HA to obtain a 35S:LuAccD - 6HA overexpression vector, and then the 35S:LuAccD - 6HA overexpression vector is transferred into plants; the nucleotide sequence of the overexpression vector pGreen-35S-6HA is shown in sequence ID Number 3 in the nucleotide or amino acid sequence table. 9. Use of the LuAccD gene according to any one of claims 5 to 8 for regulating salt and drought tolerance of plants, characterized in that the plants are wild-type plants. 10. A method for overexpressing the LuAccD gene in a plant, characterized in that the method comprises: connecting the LuAccD gene to the overexpression vector pGreen-35S-6HA to obtain a 35S:LuAccD - 6HA overexpression vector, and then transferring the 35S: LuAccD - 6HA overexpression vector into the plant; the nucleotide sequence of the overexpression vector pGreen-35S-6HA is shown in sequence ID Number 3 in the nucleotide or amino acid sequence table; the nucleotide sequence of the LuAccD gene is shown in SEQ ID NO.1.