CN115927363A

CN115927363A - CgARF8 gene of cymbidium goeringii and application thereof

Info

Publication number: CN115927363A
Application number: CN202210786599.0A
Authority: CN
Inventors: 徐子涵; 尚旭岚; 胡凤荣; 田野
Original assignee: Nanjing Forestry University
Current assignee: Nanjing Forestry University
Priority date: 2022-07-06
Filing date: 2022-07-06
Publication date: 2023-04-07
Anticipated expiration: 2042-07-06
Also published as: CN115927363B

Abstract

The invention discloses a CgARF8 gene of cymbidium goeringii and application thereof, wherein the nucleotide sequence of the CgARF8 gene is shown as SEQ ID NO.1, and the amino acid sequence of an expression protein thereof is shown as SEQ ID NO. 2. The CgARF8 gene sequence is obtained by cloning from a cymbidium goeringii cultivar 'Song Mei', expression analysis is carried out in cymbidium goeringii, then the CgARF8 gene sequence is constructed to an overexpression vector to be introduced into a target plant to verify the function of the target plant, and the result shows that the Arabidopsis thaliana seedling overexpressing the CgARF8 gene is obviously shortened compared with the wild-type plant seedling, but the rooting rate of an isolated leaf on an MS culture medium containing IAA is obviously improved, the root length is increased, the contents of endogenous hormones IAA, GA and ABA in the leaf are reduced, and the contents of MeJA and BR are increased.

Description

CgARF8 gene of cymbidium goeringii and application thereof

Technical Field

The invention belongs to the technical field of plant genetic engineering, and particularly relates to a cymbidium CgARF8 gene and application thereof.

Background

The orchid family (Orchidaceae) is one of the largest of the flowering plants, with 25000 varieties worldwide, accounting for approximately 10% of all flowering plants. The Cymbidium goeringii belongs to the floret type of Cymbidium floribundum in the orchidaceae orchids, has peculiar flower type, elegant flower color and delicate flower fragrance, is She Zi beautiful, has extremely high ornamental value and economic value, and is a typical leaf art and flower art orchids. However, in recent years, excessive excavation of the species and deterioration of the ecological environment have presented major challenges to the maintenance of the cymbidium seed resources and living environment. The plant root system is one of the important organs of the plant and is the main part of the plant for absorbing nutrients, and good vegetative growth and root system development are vital to the growth state and the propagation success of the plant. Therefore, the research on the molecular mechanism of the gene acting on the growth and development of plants has important significance on the breeding, production and application of cymbidium goeringii. The ARF gene family plays an important role in plant growth and development and can provide an important basis for genetic improvement of plants.

Auxin Response Factors (ARFs) are a family of transcription factors found in 1997 that regulate the expression of auxin-responsive genes, and can be involved in the growth and development processes of various plants by interacting with auxin-responsive elements to regulate the expression of the relevant genes. In arabidopsis thaliana, atARF10 and AtARF16 have the effects of obviously promoting stem cell niche and root columella cell differentiation, and double mutants thereof show root crown deletion and have influence on root geotropism. The arf7 and arf19 double mutants show that the number of lateral roots is obviously reduced, and the fact that AtARF7 and AtARF19 jointly regulate the development of the lateral roots is proved, and the AtARF7 and AtARF19 are closely related to the appearance of lateral root primordia. In tomato, slARF2 regulates tomato lateral root formation probably by regulating auxin and ethylene response factors. Recent functional research shows that the ARF gene also participates in the development of adventitious roots and has great influence on the growth and development of the adventitious roots and primary roots of hypocotyls of plants such as rice, tobacco, mango and the like. The research proves that the ARF transcription factor can regulate the growth and development of root systems in other plant species. Therefore, the CgARF8 gene cloned from cymbidium goeringii is transferred into model plants by using a genetic engineering technology, has important significance for researching the functions of the plants, and has great application prospects.

Disclosure of Invention

Aiming at the defects in the prior breeding technology, the invention aims to provide a CgARF8 gene of cymbidium goeringii. Another object of the present invention is to provide the use of the CgARF8 gene of cymbidium goeringii in plant breeding.

In order to achieve the purpose of the invention, the technical scheme adopted by the invention is as follows:

a CgARF8 gene of cymbidium goeringii has a nucleotide sequence shown in SEQ ID NO. 1.

The amino acid sequence of the expression protein of the cymbidium CgARF8 gene is shown in SEQ ID NO. 2.

The cymbidium CARF8 gene is applied to plant growth and development.

Namely the application of CgARF8 in changing the root system growth of arabidopsis thaliana 'Columbia' seedlings, the application in promoting the rooting of arabidopsis thaliana 'Columbia' in-vitro leaves and the application in changing the endogenous hormone content of arabidopsis thaliana 'Columbia' leaves.

The CgARF8 gene of the cymbidium gomphrena is connected to a vector, is transformed to a wild arabidopsis thaliana 'Columbia' through agrobacterium-mediated transformation, is screened and cultured to obtain a transgenic plant.

Has the advantages that: compared with the prior art, the CgARF8 gene of cymbidium goeringii is cloned and identified, the gene expression analysis and genetic transformation are carried out, the functions of the CgARF8 gene are verified, and the fact that the root length of an Arabidopsis seedling over-expressing the CgARF8 gene is shortened compared with that of a wild type Arabidopsis seedling, but the rooting rate of an in-vitro leaf is increased, the content of each endogenous hormone is changed is found, so that the gene has wide application in vegetative growth of cymbidium goeringii and other plant production and breeding.

Drawings

FIG. 1A is a bacterial examination electrophoretogram of CgARF8 gene clone of cymbidium goeringii, wherein M is DL2000 Marker, and the length of target band is 2427bp; b is a CgARF8 overexpression vector double enzyme digestion verification electrophoresis pattern;

FIG. 2A is a graph showing CgARF8 expression in various tissues of cymbidium goeringii, wherein R represents a root, S represents a pseudobulb, L represents a leaf, and F represents a flower; panel B shows the expression of CgARF8 gene in cymbidium under IAA treatment;

FIG. 3 is a schematic diagram of the construction of an overexpression vector for cloning and constructing the CgARF8 gene of cymbidium;

FIG. 4A is a diagram showing the PCR results of transgenic Arabidopsis plants, in which M represents DL2000 Marker,1 uses wild type DNA as a template for negative control, and 2-9 uses a DNA template of transgenic plants;

FIG. 5 is a comparison of plants overexpressing the CgARF8 gene with wild type Arabidopsis plants: a is a plant type comparison diagram; b is a comparison graph of the root length of seedlings. (ii) a

FIG. 6 is the rooting of the excised leaves of the plants overexpressing the CgARF8 gene and the wild type Arabidopsis plants on MS medium containing different concentrations of IAA;

FIG. 7 is a comparison of endogenous hormone content in leaves of plants overexpressing the CgARF8 gene with wild type Arabidopsis plants.

Detailed Description

The present invention will be further described with reference to the following specific examples.

Example 1

The material adopted in the embodiment is the tissues of cymbidium goeringii 'Song Mei', and the collected materials are quickly frozen in liquid nitrogen and stored in an ultralow temperature refrigerator (80 ℃ below zero).

1) Extraction of total RNA from cymbidium goeringii tissues

The method is carried out according to the instruction of a TaKaRa plant total RNA extraction kit, and comprises the following specific operations:

rapidly transferring the frozen cymbidium tissue into a mortar precooled by liquid nitrogen, grinding the tissue by a pestle, and continuously adding the liquid nitrogen until the tissue is respectively ground into powder; respectively adding the samples ground into powder into 1.5mL of sterilized tube containing 450 mul of Buffer PE, and repeatedly blowing and beating by using a pipette until no obvious precipitate exists in the lysate; the lysate was centrifuged at 12,000rpm for 5 minutes at 4 ℃; the supernatant was carefully pipetted into a fresh 1.5mL sterile tube. Adding Buffer NB with the volume of 1/10 of the supernatant, shaking and mixing uniformly, centrifuging at 12,000rpm and 4 ℃ for 5 minutes; carefully sucking the supernatant into a new 1.5mL sterile tube, adding 450. Mu.L Buffer RL, and uniformly mixing the solution by using a pipette; adding anhydrous ethanol with the volume of 1/2 of the mixed solution, and using a liquid-transferring gunAfter the solution is uniformly mixed, immediately transferring all the mixed solution into an RNA Spin Column; 12,000rpm, centrifuge for 1 minute, discard the filtrate, put RNA Spin Column back into 2ml Collection Tube; add 500. Mu.L of Buffer RWA to RNA Spin Column, centrifuge at 12,000rpm for 30 seconds, discard the filtrate; 600uL of Buffer RWB was added to the RNA Spin Column, centrifuged at 12,000rpm for 30 seconds, and the filtrate was discarded; adding 50 mu L of DNase I reaction solution into the center of an RNA Spin Column membrane, and standing for 15 minutes at room temperature; 350 μ L of Buffer RWB was added to the center of the RNA Spin Column membrane, centrifuged at 12,000rpm for 30 seconds, and the filtrate was discarded; the RNA Spin Column was re-mounted on a 2mL Collection Tube and centrifuged at 12,000rpm for 2 minutes; the RNA Spin Column was mounted on a 1.5mL RNase Free Collection Tube, and 30. Mu.L of RNase Free dH was added to the center of the RNA Spin Column membrane ₂ O was left standing at room temperature for 5 minutes, and centrifuged at 12,000rpm for 2 minutes to elute RNA. The obtained RNA is stored in a refrigerator at minus 80 ℃ for later use after concentration and purity detection.

The result of taking 2. Mu.L of RNA and detecting by 1% agarose gel electrophoresis shows that 28S and 18S bands are clearer, the brightness of the 28S band is about twice of that of the 18S band, and the RNA quality is better. Detection of RNA purity, OD by means of a micro-accounting protein assay ₂₆₀ /OD ₂₈₀ And OD ₂₆₀ /OD ₂₃₀ All of which are between 1.8 and 2.1, has better integrity and can be used for reverse transcription.

2) First strand cDNA was synthesized by reverse transcription using the obtained total RNA as a template using a Tiangen reverse transcription kit. The specific operation is as follows:

thawing template RNA on ice, 5 XFastking-RT SuperMix and RNase-Free ddH ₂ O was thawed at room temperature and placed on ice quickly after thawing. Preparing mixed solution in a centrifuge tube, wherein the Total amount is 10uL, the mixed solution contains 5 XFastking-RT SuperMix4uL and Total RNA 800ng, and the residual volume is RNase-Free ddH ₂ And O is complemented. Centrifuging the centrifugal tube to ensure that the mixed solution in the centrifugal tube is deposited at the bottom of the tube, slowly shaking up, removing genome and carrying out reverse transcription reaction on a PCR instrument at 42 ℃ for 15min, inactivating enzyme at 95 ℃ for 3min, and placing on ice to obtain a cDNA solution.

3) Design and cloning of target gene primer

According to the existing sequencing result of the cymbidium transcriptome, a cymbidium CgARF8 gene amplification primer is designed by using CE Design, and the primer sequence is as follows:

CgARF8-F:5’-GAGAACACGGGGGACTCTAGAATGAAGCTCTCGACTGTGGGAG-3’

CgARF8-R:5’-ATAAGGGACTGACCACCCGGGGCTGGAGTCGACACCCTGC-3’。

cloning of the CgARF8 gene from cymbidium was performed using the PrimerStar Max Hi enzyme from Takara using cDNA as template. The PCR amplification system (50. Mu.L) was: mu.l PrimerStar Max, 2. Mu.l Forward Primer, 2. Mu.L LReverse Primer, 2. Mu.L Template cDNA, 19. Mu.L ddH ₂ And O. The PCR procedure was: the reaction conditions are 94 ℃ pre-denaturation for 3min,98 ℃ denaturation for 10s,60 ℃ annealing for 15s,72 ℃ extension for 30s,32 cycles, 72 ℃ total extension for 5min and 16 ℃ heat preservation.

After the PCR reaction is completed, all PCR products are taken to be detected by 1.8% agarose gel electrophoresis (the PCR amplification result is shown in figure 3), target fragments are cut, and the target PCR amplification products are recovered and purified by gel. The DNA gel recovery kit of TransGen company is adopted to purify and recover the target fragment, and the specific operations are as follows: cutting a single target strip from the agarose gel, putting the cut single target strip into a clean centrifugal tube, and weighing; adding 3 times volume of GSB (300 μ L GSB solution if gel is 0.1g and volume is 100 μ L) into the gel block, standing in water bath at 55 deg.C while turning the centrifuge tube up and down continuously until the gel block is completely dissolved; cooling the melted gel solution to room temperature, adding 1 volume of isopropanol (if the gel is 0.1g, 100 μ L of isopropanol), and gently mixing; adding the mixture into a centrifugal column, standing at room temperature for 1min, centrifuging at 12000rpm for 1min, discarding eluate, and placing the centrifugal column back into the collection tube; adding 650 μ L of WB solution into the centrifugal column, centrifuging at 12000rpm for 1min, and discarding the effluent; centrifuging at 12000rpm for 2min to remove residual WB, opening the cover of the adsorption column at room temperature, standing for 5min, and completely drying; placing the centrifugal column into a clean centrifugal tube, suspending and dripping 30 mu L ddH into the middle position of the adsorption film ₂ O(ddH ₂ O needs to be placed in a water bath at 60-70 ℃ in advance for preheating), stands for 2min at room temperature, and is centrifuged at 12000rpm for 2min to collect DNA solution. Taking 2 microliter of the recovered and purified product, using 1.5% agarose for gel electrophoresis detection,the rest was placed in a-20 ℃ refrigerator and subsequently used for ligation with the pBI121 vector to construct an overexpression vector.

3) And (3) plasmid extraction:

extracting plasmids according to the specification of the small-extraction medium-volume kit of the Tiangen plasmids, and specifically comprising the following steps:

taking 10mL of overnight cultured bacterial liquid, centrifuging at 12000rpm for 1min, and removing supernatant; adding 500 mu L P1 solution (containing RNase A) into a centrifuge tube with a thallus precipitate, and completely suspending the thallus precipitate by using a vortex instrument; adding 500 mu L P2 solution into a centrifuge tube, fully cracking thalli when the centrifuge tube is turned up and down gently, adding 700 mu L P solution into the centrifuge tube, immediately turning the centrifuge tube up and down gently, fully mixing the solution uniformly, and centrifuging the centrifuge tube at 12000rpm for 10min when white flocculent precipitates appear; adding 500 μ L of equilibrium liquid BL into adsorption column CP4, centrifuging at 12000rpm for 1min, discarding waste liquid in the collection tube, returning the adsorption column to the collection tube, adding collected supernatant into filtration column CS in batches, centrifuging at 12000rpm for 2min, carefully adding solution collected in the collection tube into adsorption column CP4 in batches, centrifuging at 12000rpm for 1min, discarding waste liquid in the collection tube, and returning adsorption column CP4 to the collection tube; adding 500 μ L of deproteinized solution PD into adsorption column CP4, centrifuging at 12000rpm for 1min, discarding waste liquid in the collection tube, and replacing adsorption column CP4 into the collection tube; adding 600 μ l rinsing liquid PW (containing anhydrous ethanol) into adsorption column CP4, centrifuging at 12000rpm for 1min, discarding waste liquid in the collection tube, returning adsorption column CP4 to the collection tube, centrifuging at 12000rpm for 2min, and removing residual rinsing liquid in the adsorption column; the adsorption column CP4 was transferred to a new 1.5ml centrifuge tube, and 60. Mu.L ddH was added to the middle of the adsorption membrane ₂ O; standing at room temperature for 2min, centrifuging at 12000rpm for 1min, and collecting the solution in the centrifuge tube to obtain plasmid. Finally, the plasmid concentration was determined and prepared for the next experiment.

4) Double enzyme digestion reaction

The extracted pBI121 plasmid is digested with XbaI and SmaI at 37 ℃ for 30min, and the linear vector is recovered by electrophoresis and stored at-20 ℃ for later use. The double enzyme digestion reaction system is 50 mu L: pBI121 plasmid 20. Mu.L, 5 XBuffer 5. Mu.L, xbaI 1. Mu.L, smaI 1. Mu.L, ddH ₂ O 23μL。

5) Recombination reactions

Enzyme detection by agarose gel electrophoresisThe recovered target gene and the vector pBI121 are added with each reagent according to the detected purity and concentration. Wherein, the molecular number of the target fragment is as follows: the number of carrier molecules = 3:1-5:1, and the connection reaction system is as follows: linearized pBI121 vector 7. Mu.L, insert 3. Mu.L, 5 × CE II buffer 4. Mu.L, exnase II 2. Mu.L, ddH ₂ O Up to 20. Mu.L. The reaction was carried out at 37 ℃ for 30min, left at room temperature (without immediate cooling), and transformed to E.coli competent cells after 10 min.

6) Transfer of ligation product into E.coli

Competent cell Trans 5. Alpha. Strain was taken out from the ultra-low temperature refrigerator and thawed on ice. Pipetting 10. Mu.L of the recombinant product and adding to 100. Mu.L of competent cells; placing the centrifugal tube on ice for ice bath for 10min; heating in water bath at 42 deg.C for 90s without shaking; immediately placing on ice for ice bath for 2min; adding 500 μ L liquid culture medium without antibiotics into a super clean bench, and resuscitating at 37 deg.C and 200rpm for 25 min; centrifuging at 6000rpm for 1min, and sucking 350 μ L of supernatant; the precipitated cells were resuspended, plated on LB plates (Kana concentration: 50 mg/L), and cultured overnight at 37 ℃.

7) Identification of recombinants

Single colonies on the plates were picked and inoculated into LB liquid medium containing antibiotic (Kana), and shake-cultured overnight at 200rpm at 37 ℃. PCR was performed on the bacterial suspension using the full-length primers of the target gene to screen positive clones, and the results of the bacterial assay are shown in FIG. 1A. The positive clones after screening were sent to Nanjing Sipulin for sequencing. And (3) carrying out positive cloning with a correct sequencing result, after amplification culture, extracting plasmids by using a Tiangen plasmid extraction kit, carrying out double enzyme digestion verification, and judging whether the sizes of the fragments after enzyme digestion are consistent or not, wherein the enzyme digestion result is shown in figure 1B.

According to the analysis of the sequencing result, 1 CgARF coding gene of cymbidium goeringii is finally determined and cloned, named as CgARF8 gene, the nucleotide sequence of the CgARF8 coding gene is shown as SEQ ID NO.1, the coding length of the CgARF8 gene is 2427bp, the coding length of the CgARF8 coding gene contains ATG initiation codon and TAA termination codon, the total length of ORF is 2427bp, 808 amino acids are coded, and the amino acid sequence is shown as SEQ ID NO. 2.

Example 2

Designing a fluorescent quantitative primer by taking the cloned CgARF8 gene of the cymbidium goeringii as a reference, wherein the sequence of the primer is as follows:

qCgARF8-F：5’-CCAATAAGGAGGTTGAGGGC-3’

qCgARF8-R：5’-CGTGCATAGTCACATCGTGTAGTT-3’

meanwhile, 18S is taken as an internal reference gene, and the primer sequence is as follows:

18S-F：5’-GGTCCTATTGTGTTGGCT-3’

18S-R：5’-TCGCAGTGGTTCGTCTTT-3’

using a ChamQ ^TM The preparation of the reaction solution was carried out according to the instructions of the Universal SYBR Qpcr Master Mix kit (Vazyme) and the PCR program was run on an Applied Biosystems type real-time fluorescence quantitative analyzer: 5min at 95 ℃; circulating for 40 times at 95 deg.C 10s and 60 deg.C 30 s; 95 ℃ 15s,60 ℃ 1min,95 ℃ 15s. Obtaining an amplification curve after the reaction is finished, deriving data through StepOne Software v2.3, analyzing the data by using Excel, and using 2 according to the CT value ^-ΔΔCt The relative expression was calculated by the relative quantification method, and the data analysis results are shown in FIG. 2.

The results of this example show that the CgARF8 gene is expressed in all tissues of cymbidium (FIG. 2A), but the expression level of the gene is higher in the leaves and roots of cymbidium, which indicates that the gene is active in the functions of the two organs; expression analysis of leaves treated with cymbidium IAA hormone spray proved that the CgARF8 gene plays an important role in response to IAA treatment in cymbidium leaves (FIG. 2B).

Example 3

1) Preparation and transformation of Agrobacterium-infected competent cells

In the embodiment, agrobacterium GV3101 is used for preparing agrobacterium competence for carrying out an infection experiment of arabidopsis; the preparation process of the agrobacterium rhizogenes competence comprises the following steps: selecting an activated agrobacterium single colony, inoculating the agrobacterium single colony in 5mL of liquid LB culture medium, and performing shake culture at 28 ℃ and 250rpm for 20-24h; 2mL of the cell suspension was aspirated, inoculated into a flask containing 50mL of liquid LB medium, and shaken at 28 ℃ and 250rpm to OD ₆₀₀ The value is about 0.8; placing the expanded bacterial solution on ice for 30min, centrifuging at 4 deg.C and 5000rpm for 5min, and removing supernatant; 10mL of precooled 0.1mo1/L CaCl was added ₂ Solution, suspension of the precipitated bacteriaA body; centrifuging at 4 deg.C and 5000rpm for 5min, and discarding supernatant; 1mL of precooled 20mmo1/L CaCl was added ₂ The solution fully suspends the thalli to obtain the GV3101 competent cells to be prepared, the competent cells are subpackaged into 100 mu L/tube by a centrifuge tube, 20 percent of sterile glycerol is rapidly added, and the competent cells are placed and stored at the temperature of minus 80 ℃.

Agrobacterium transformation of recombinants: ice-bath to melt the agrobacterium-infected cells, adding 600ng of the recovered and purified plasmid into 100 mul of agrobacterium-infected cells, mixing the plasmid and the cells gently, and ice-bath for 5min; quickly freezing for 5min with liquid nitrogen, thermally exciting for 5min in metal bath at 37 deg.C, and rapidly placing on ice for 5min; adding 800 mul LB culture medium without any antibiotic, and resuscitating at 28 deg.C and 200rpm for 2h; centrifuging at 4000rpm for 3min, and sucking off part of liquid culture medium; using a liquid transfer gun to fully and uniformly mix the residual bacterial liquid, and then coating the liquid on a solid LB culture medium added with 50mg/L kanamycin and 200mg/L rifampicin; and (3) performing inverted culture at 28 ℃ for 30-48 h.

Identification of Agrobacterium recombinants: picking out single colony from the plate culture medium, and inoculating the single colony in a liquid culture medium containing corresponding antibiotics; carrying out PCR on the bacterial liquid after culturing overnight at 28 ℃ and 200rpm, detecting whether a PCR product contains a target fragment by 1.5% agarose gel electrophoresis, adding a proper amount of sterile 50% glycerol into the identified positive clone, and storing at-80 ℃ for later use.

2) Agrobacterium-mediated transformation of Arabidopsis thaliana

The method is characterized in that a target gene is transferred into arabidopsis thaliana by adopting an inflorescence infection method, and the specific operation method comprises the following steps: arabidopsis thaliana (columbia type) maintains healthy growth until flowering; activating the agrobacterium GV3101 strain carrying the target gene. Picking a single colony, inoculating the single colony in 5mL LB culture solution containing kanamycin and rifampicin, shaking the colony at the temperature of 28 ℃ and the rpm of 200 till the bacterial solution becomes turbid just, and keeping the bacterial solution for about 8-10 hours; 1mL of bacterial liquid is sucked and inoculated into a triangular flask (50 mL) for shaking bacteria for 24 hours until the OD value is about 0.8; centrifuging the bacterial liquid at 6000rpm at room temperature for 5min, removing supernatant, collecting thallus, and suspending with 3% sucrose solution with pH of 5.8; before soaking, silwetL-77 is added, the concentration is 0.03% (300 mul/L), and foam is shaken out; soaking the overground part of arabidopsis in agrobacterium suspension for 1min, and gently shaking the overground part of arabidopsis; the soaked arabidopsis thaliana is laid on a tray, covered by a preservative film, sealed by tinfoil paper and protected from light, and placed for 24 hours; the tinfoil paper is uncovered, cultured under normal conditions, and watering is stopped when the seeds are mature.

The 3% sucrose solution resuspension had the following composition: MS culture medium, adding sucrose 30g/L, silwet-77 u L/L. (Note: after preparation, pH was adjusted to 5.8, the bacterial solution was centrifuged and resuspended, and SilwetL-77 was added, and the conversion relationship between the suspension and the bacterial solution was that the amount of the resuspended solution was OD of the bacterial solution and the volume of the bacterial solution =0.8 of the resuspended solution).

3) Screening of transgenic plants

The collected T1 generation transgenic arabidopsis seeds are sterilized by alcohol and sodium hypochlorite, and the steps are as follows: placing appropriate amount of the obtained transgenic seeds in a 1.5mL centrifuge tube, soaking for 5min with 8% NaClO and ethanol mixed solution (prepared in situ, in a volume ratio of 1:1); sterilizing with 75% alcohol for 5-6 times, each time for 2min; washing with sterile water for 3-4 times; the suspension was suspended in 0.1% agarose solution.

The sterilized transgenic Arabidopsis seeds are sown on MS solid culture medium containing antibiotics (kanamycin 50mg/L and cefamycin 100 mg/L), wrapped by tinfoil and placed in a refrigerator at 4 ℃ for vernalization. After 2 days, the medium was removed from the refrigerator and incubated at 22 ℃ under light. After about one week, arabidopsis thaliana which can grow normally on the medium is transplanted into soil and continues to grow.

4) DNA detection of transgenic plants

Taking a proper amount of T1 generation arabidopsis thaliana and young leaves of transgenic plants, and adopting a plant DNA direct amplification kit of the department of engine to detect, wherein the specific operation steps are as follows: shearing a proper amount of tender leaves, placing the cut tender leaves into a sterilized 2mL centrifuge tube, adding 50uL lysine Buffer A solution, heating and cracking at 95 ℃ for 10min, and continuously cracking at 4 ℃ overnight. The next day, centrifugation is carried out at 14000rpm for 3min, and the supernatant is taken and transferred to a new sterile centrifuge tube to be used as a PCR reaction template. PCR detection was performed using 2 XT 5 Direct PCR Mix and gene specific primers, and the results are shown in FIG. 4A.

5) Fluorescent quantitative PCR detection of transgenic plants

Total RNA was extracted from young cauline leaves of the 8 transgenic lines of Arabidopsis thaliana with CgARF8 gene over-expressed, the primers, methods and procedures for reverse transcription and fluorescence quantification were the same as those of example 2, and the final data analysis results are shown in FIG. 4B.

6) Obtaining transgenic homozygous lines

The harvested transgenic T1 generation seeds are sterilized, screened and cultured, and then transplanted into nutrient soil to be cultured at 22 ℃ for 16h under light/8 h in darkness; after detection, retaining the preliminarily confirmed transgenic plants, harvesting T1 generation seeds after the transgenic plants are mature, and numbering to obtain T2 generation; like the T1 generation, seeds of the T2 generation are sterilized and coated on a screening culture medium containing antibiotics, and the screening culture medium is placed at 22 ℃ for continuous illumination; performing survival rate statistics on T2 generation seeds with different numbers for about 10 days, selecting plants with survival rate of 75%, transplanting the plants into nutrient soil, culturing the plants in the nutrient soil at 22 ℃ for 16h under illumination/8 h in darkness, and taking leaves for positive detection; the positive T2 generation plants are numbered continuously, and seeds are collected to obtain T3 generation seeds; sterilizing the seeds, screening by using a screening culture medium, and placing under the light for continuous illumination culture; around 10 days, T3 plants of different numbers were observed, all survived and no segregating T3 homozygous plants appeared.

7) Phenotypic observations

A transgenic line with an obvious phenotype is selected for observation, and the result shows that compared with wild type Arabidopsis, the root of a transgenic Arabidopsis plant seedling is obviously shorter than that of the wild type, and the plant form is not obviously changed after the transgenic Arabidopsis enters a nutrition and reproduction stage.

The wild type and transgenic seeds are disinfected and then sown on an MS culture medium, seedlings with the same growth vigor are selected in an ultra-clean workbench after 4-6 true leaves are cultured, the true leaves are cut off and are respectively placed on MS, MS +0.2mg/L IAA and MS +0.5mg/LIAA culture media, 15 leaves are selected for each gene treatment, the process is repeated for 3 times, and the wild type arabidopsis thaliana is used as a reference for each treatment. After inoculation, the mixture is placed in an incubator under the conditions of 23 ℃ and 24h illumination, the illumination intensity is 6000lx and the relative humidity is 70%. Leaf growth changes were observed and recorded at inoculation 12d and transgenic leaves were found to have higher rooting rates and root lengths on each medium than wild type.

The endogenous hormone content of the arabidopsis leaves is determined by adopting an enzyme-linked immunosorbent assay (ELISA). The sample contained 1mM butyl hydroxyToluene (BHT) as an antioxidant in 10mL of 80% (v/v) methanol extraction medium. The extract was incubated at 4 ℃ for 4h and centrifuged at 4000rpm for 15min. The supernatant was passed through a C-18 column and washed successively with 80% (v/v) methanol, 100% (w/v) ether and 100% (w/v) methanol. The hormone fractions were then dried under N2 and dissolved in Phosphate Buffered Saline (PBS) containing 0.1% (v/v) Tween 20 and 0.1% (w/v) gelatin for analysis. Monoclonal antibodies and antibodies against IAA, ABA, GAs (GA 1+ GA 3), meJA and BR in the ELISA kit were produced by the phytohormone research institute of Chinese university of agriculture). Enzyme-linked immunosorbent assays were performed using 96-well microtiter plates. Each well was coated with 0.25. Mu.g/mL of an anti-hormone antigen-containing coating buffer (1.5 g/L Na) ₂ CO ₃ 、2.93g/L NaHCO ₃ 、0.02g/L NaN ₃ ) 100 μ L of the coating was incubated at 37 ℃ for 30min. After 4 washes with PBS containing 0.1% (v/v) Tween 20, each well was filled with 50. Mu.L of sample extract and 50. Mu.L of 20. Mu.g/mL antibody, incubated and washed as described above. 0-phenylenediamine at 1.5mg/mL and 0.008% (v/v) H per well ₂ O ₂ 100. Mu.L of the color developing solution (1). 12mol/L H per hole ₂ SO ₄ The reaction was stopped. Color was developed at 490nm using an ELISA instrument (model EL310, bio-TEK, winooski, VT). Hormone content was calculated according to Weiler et al (1981). Each hormone was assigned 3 biological replicates. The results show that the contents of endogenous hormones IAA, GA and ABA in the leaves of the transgenic plants are reduced compared with the wild type plants, and the contents of MeJA and BR are increased.

This example transfers the recombinant plasmid of the overexpressed cymbidium CgARF8 gene into the model plant Arabidopsis thaliana, and performs phenotypic observation and analysis. The results show that the length of roots of Arabidopsis plants over-expressing CgARF8 genes is shortened compared with wild plant seedlings, the rooting rate of in vitro leaves on an MS culture medium containing IAA is improved, the root length is increased, the contents of endogenous hormones IAA, GA and ABA in the leaves are reduced, the contents of MeJA and BR are increased, and the genes have influence on the growth and development of the roots of the plants and the hormone content thereof.

SEQ ID NO.1：

ATGAAGCTCTCGACTGTGGGAGTCGTGGTCCAGCAGGAGGAGCAAGGCGGGGACAAG

AGATGCTTGAACTCCGAGCTTTGGCATGCTTGTGCTGGTCCTTTGGTGTGTCTACCCAA

TGTCGGCACTCGTGTTGTCTACTTTCCGCAGGGCCACAGCGAACAGGTTGTGGCTTCCA

CCAATAAGGAGGTTGAGGGCCATATTCCTAATTATCCGAATTTGCCGCCTCAATTGATC

TGTCAACTACACGATGTGACTATGCACGCTGATGCCGAGACAGATGAAGTCTACACGC

AGATGACGTTACAGCCGTTAAATCCGCAGGAGCTGAAAGATACTTACCTTCCAGCTGA

GATGGGGCTACCAAGCAAGCAGCCCATGAATTATTTTTGTAAGACTTTGACTGCAAGC

GATACAAGCACCCATGGAGGGTTTTCTGTCCCTCGTCGTGCAGCAGAAAAAGTGTTTCC

CCCACTGGATTTCTCTCAACAGCCACCAGCACAAGAGCTAATTGCACGGGATATTCAT

GATGTTGAGTGGAAGTTCAGGCATATATTTAGAGGACAACCCAAGAGGCATCTTCTTA

CTACAGGCTGGAGTGTTTTTGTCAGTGCTAAGAGACTTGTTGCTGGTGATTCTGTTTTAT

TTATATGGAATGAAAAAAATCAGCTTCTGTTGGGAATCCGACGGGCTAATCGAACACA

AAATTCTGTACCTTCTTCTGTTATATCAAGTGATAGCATGCATATTGGACTGCTTGCTGC

AGCAGCACATGCTGCTGCAACAAATAGTCGTTTCACTATTTTTTACCACCCAAGGGCTT

GTCCTTCAGAGTTTGTGATACCACTATCAAAATATGTTAAGGCTGTGTTTCATACTCGT

GTCTCAGTCGGTATGCGTTTTAGGATGCTTTTTGAGACAGAAGAGTCAAGTGTTCGTCG

GTATATGGGTACAATAACAGGAGTAAGTGACTTGGATCCTATACGATGGCCAAATTCC

CATTGGAGATCCGTGAAGGTTAATTGGGACGAATCAACTGCGGGTGATAGACAACCAA

GAGCATCTTTATGGGAAATTGAGCCTTTGACAACATTTCCCATGTATCCATCACTGTTC

CCTCTCAGACTTAAACCACCTTGGTACACTGGAGTTTCCTCTCTAAATGACTACAAGTT

AGATGATGGGAACGCATACATGTGGCTCAGGGGGAGCTCAGGGGGAGGTATTAGGTCT

TTGAATTTTCAATCTCCTGGACTTGGTCCCTGGGTTCAGCAGCAGGTGCAACCACAGTT

GGGTAACAATCACAGTCCTTACCAACCAATAGATGCTGCAACTTTTGATATTGGGGGC

GTGGATTCACTGAGGCAGCCATTTTTAAACTTCCAGCAGCCATTTCAGTTCCCTCAGCA

GTTCTGCTTGAACCCATTATTGCAGCAGCAAATTATTCAGCAAGCTCACCATGAACAAA

TCATGAATTCTCACTCTCAGTGTATGTTGGATAGCCAACCAAACATTACTTCAAATCAG

TTGCTGCAACAGCCATACGGTGATCAGCAGAAGCAAAAAGTTCAACAGCAACCAACTT

ATCCCGAACTCTTTCATGTTCAGAACAATAATATAGAACAGCAGCAGATGCCACTATC

CTCCCCATCATCTCAAAAGTCCGTATTTCCTGATTCAAATGTGAACTTTTCATCAGTTGC

AACACCCAGCTGCATGCAGAATTTGTCAGCAGCTACTTATCCTGAATCAAATGCTAATA

ACTTGCAGTTTGCTAGACCTGGTCAGACAATACTGGCTGAGCAGCATCAGCAAAAATG

GGATCCACAGTTCGCAGTACCGAAGGATTCTTCTTTTGGTAATACAGTTTTACTTCAAC

CATTTCATGGCAAAGATGGTACAAGAGAATCTGATGTCTCTGCCGCTGATACACAAAA

CCACAGCCTATTTGGTATCAATGTAGGTTCTTCCTCTCTCCTCGGCAATGTTGTGCCTAA

TCTAATTAGTGCAAACAATAGTGACAATGGGGTATCCAGCGTGCCATTTACCAGTTCCT

ATCTTCAAAATTCTCTTTATCACAGCCTTGATGAATCATCAGGTATGCTGCAACATGCA

TATGAGATTGATCCATCAATCAAAACTTTTGTAAAGGTTTACAAGTCAGGATCAGTTGG

GAGGTCCCTAGACATCACCCGGTTCAGCAACTATACTGAATTACGTAAGGCACTGGGT

CAGATGTTTGGTATTGAGGGTCAACTTGAAAACCCTCGTAGATCAGGCTGGCAGCTTGT

ATTTGTTGACAGGGAGAATGATGTGCTTCTTCTTGGAGACGATCCTTGGGAATCATTTG

TGAACAATGTGTGGTACATCAAGATACTTTCACCAGAGGATGTTCAGCAAATGGGGCA

GCAGGGTGTCGACTCCAGCTAA

SEQ ID NO.2：

MKLSTVGVVVQQEEQGGDKRCLNSELWHACAGPLVCLPNVGTRVVYFPQGHSEQVVAST

NKEVEGHIPNYPNLPPQLICQLHDVTMHADAETDEVYTQMTLQPLNPQELKDTYLPAEMG

LPSKQPMNYFCKTLTASDTSTHGGFSVPRRAAEKVFPPLDFSQQPPAQELIARDIHDVEWKF

RHIFRGQPKRHLLTTGWSVFVSAKRLVAGDSVLFIWNEKNQLLLGIRRANRTQNSVPSSVIS

SDSMHIGLLAAAAHAAATNSRFTIFYHPRACPSEFVIPLSKYVKAVFHTRVSVGMRFRMLF

ETEESSVRRYMGTITGVSDLDPIRWPNSHWRSVKVNWDESTAGDRQPRASLWEIEPLTTFP

MYPSLFPLRLKPPWYTGVSSLNDYKLDDGNAYMWLRGSSGGGIRSLNFQSPGLGPWVQQ

QVQPQLGNNHSPYQPIDAATFDIGGVDSLRQPFLNFQQPFQFPQQFCLNPLLQQQIIQQAHH

EQIMNSHSQCMLDSQPNITSNQLLQQPYGDQQKQKVQQQPTYPELFHVQNNNIEQQQMPL

SSPSSQKSVFPDSNVNFSSVATPSCMQNLSAATYPESNANNLQFARPGQTILAEQHQQKWD

PQFAVPKDSSFGNTVLLQPFHGKDGTRESDVSAADTQNHSLFGINVGSSSLLGNVVPNLISA

NNSDNGVSSVPFTSSYLQNSLYHSLDESSGMLQHAYEIDPSIKTFVKVYKSGSVGRSLDITR

FSNYTELRKALGQMFGIEGQLENPRRSGWQLVFVDRENDVLLLGDDPWESFVNNVWYIKILSPEDVQQMGQQGVDSS-

Claims

1. The application of CgARF8 of cymbidium in changing the root growth of seedlings of arabidopsis thaliana 'Columbia' is disclosed, and the nucleotide sequence of the CgARF8 is shown as SEQ ID NO. 1; the method comprises the following steps: the CgARF8 gene of the cymbidium gomphrena is connected to a vector, is transformed to a wild arabidopsis thaliana 'Columbia' through agrobacterium-mediated transformation, is screened and cultured to obtain a transgenic plant.

2. The application of CgARF8 in promoting the rooting of the arabidopsis thaliana 'Columbia' in-vitro leaves is disclosed, and the nucleotide sequence of the CgARF8 is shown in SEQ ID NO. 1; the method comprises the following steps: the CgARF8 gene of the cymbidium gomphrena is connected to a vector, is transformed to a wild arabidopsis thaliana 'Columbia' through agrobacterium-mediated transformation, is screened and cultured to obtain a transgenic plant.

3. The application of CgARF8 in changing the endogenous hormone content of the leaf of arabidopsis thaliana is shown in SEQ ID NO. 1; the method comprises the following steps: the CgARF8 gene of the cymbidium gomphrenatum is connected to a vector, is transformed to wild arabidopsis thaliana 'Columbia' through agrobacterium-mediated transformation, and is screened and cultured to obtain a transgenic plant.