Disclosure of Invention
In view of this, the present invention aims at providing a newly mined functional gene fragment B that can be used for cultivating new plant materials.
The inventor continuously reforms and innovates through long-term exploration and trial and repeated experiments and efforts, and in order to solve the technical problems, the technical scheme provided by the invention is that the application of a gene segment B in cultivating new plant materials is provided, wherein the gene segment B comprises a nucleotide sequence selected from the following groups:
A. a nucleotide sequence shown in a sequence table Seq ID No. 1;
B. A nucleotide sequence complementary to the sequence of A, or a nucleotide sequence having a homology of 70% or more;
C. A nucleotide sequence encoding the amino acid sequence shown in Seq ID No.2 of the sequence listing.
Further, the gene segment B is used for improving the growth amount of new plant materials.
Further, the gene segment B is used for enhancing the adversity stress resistance of new plant materials.
Further, the adversity stress comprises one or more of drought, high temperature, salt stress and ABA.
Preferably, the plant is a gramineous plant.
Preferably, the plant is gramineous pasture.
Preferably, the plant is festuca arundinacea.
Further, the application steps are as follows:
s1, extracting RNA in plant materials,
S2, identifying whether a gene fragment B exists in the RNA;
s3, amplifying to obtain a full-length gene fragment B;
s4, constructing a plant expression vector;
S5, infection transformation, screening positive plants for culture;
s6, breeding the generation to a transgenic homozygous strain.
Further, in S2, the nucleotide sequences shown in Seq ID No.3 and Seq ID No.4 are used as specific primers for the gene fragment B, and the nucleotide sequences shown in Seq ID No.5 and Seq ID No.6 are used as reference genes.
Further, in S3, the nucleotide sequences shown in Seq ID No.7 and Seq ID No.8 are used as the full-length amplification primers of the gene fragment B.
Compared with the prior art, one of the technical schemes has the following advantages:
a) The experiment proves that the novel functional gene segment B mined by the applicant can be obviously induced to be expressed by drought, high temperature, salt stress and ABA treatment, and the transgenic plant biomass and stress resistance can be improved by the over-expression of the gene segment B through the transgenic and functional identification.
B) The results of the invention are helpful for improving stress resistance of plants, particularly festuca arundinacea, and shortening the breeding period through molecular assisted breeding.
Detailed Description
The following description is of one embodiment with reference to the accompanying drawings.
For the purpose of making the objects, technical solutions and advantages of the embodiments of the present invention more apparent, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention, and it is apparent that the described embodiments are some embodiments of the present invention, but not all embodiments. All other embodiments, based on the embodiments of the invention, which are apparent to those of ordinary skill in the art without inventive faculty, are intended to be within the scope of the invention. Thus, the following detailed description of the embodiments of the invention, as presented in the figures, is not intended to limit the scope of the invention, as claimed, but is merely representative of selected embodiments of the invention.
It should be noted that: like reference numerals and letters denote like items in the following figures, and thus, once an item is defined in one figure, it may not be further defined and explained in the following figures.
The gene fragment B described in this example comprises a nucleotide sequence selected from the group consisting of: A. a nucleotide sequence shown in a sequence table Seq ID No. 1; B. a nucleotide sequence complementary to the sequence of A, or a nucleotide sequence having a homology of 70% or more; C. a nucleotide sequence encoding the amino acid sequence shown in Seq ID No.2 of the sequence listing. Specifically, the gene fragment B is a festuca arundinacea DgMADS gene, the following description is made by the festuca arundinacea DgMADS gene or the DgMADS gene, the nucleotide sequence is shown as a sequence table Seq ID No.1, and the amino acid sequence coded by the nucleotide sequence is shown as a sequence table Seq ID No. 2.
Although duck Mao Quan genome is already published, genetic function resources based on the genome are not fully developed and utilized yet. The number of chromosomes of the festuca arundinacea is large, the genome is complex, the applicant firstly proposes a hypothesis of high-yield stress-resistance related genes in the festuca arundinacea genome according to the growth characteristics of the festuca arundinacea, and analyzes and identifies the genes to obtain the festuca arundinacea DgMADS and further verifies the expression result of the genes DgMADS114 in arabidopsis transgenic plants, so that the gene segment B can be used for cultivating new plant materials, and further screening new plant varieties suitable for agricultural production, wherein the plants are gramineae plants, particularly gramineae pastures, such as festuca arundinacea.
The inventors first downloaded MADS-box transcription factor conserved domain SRF-TF and K-box hidden Markov model (Hidden Markov Model, HMM) files (PF 00319 and PF 01486) from the Pfam database (http:// Pfam. Xfam. Org /), and then searched all proteins of the fescue for potential MADS-box proteins in the fescue with default parameters in the HMMER software (version 3.0) using the downloaded HMM files. And further confirming the searched MADS-box through a Pfam database, NCBI CDD and SMART. After further domain determination, 123 MADS-box transcription factors were identified in the Duck grass genome, one of which is DgMADS (DG7C03991.1) in the present application. The nucleotide sequence is shown as a sequence table Seq ID No. 1. The CDS sequence and the coded amino acid sequence of DgMADS (DG7C03991.1) genes are obtained from the festuca arundinacea genome annotation file through the gene ID of DgMADS, the CDS coding region is 531bp in total length and codes 176 amino acids, the gene is located on a festuca arundinacea No. 7 chromosome, the amino acid sequence is shown as a sequence table Seq ID No.2, the gene is located on a festuca arundinacea No. 7 chromosome, the position is 176042088-176042618, and the applicant names the gene as DgMADS114.
By physicochemical property analysis, the relative molecular mass of the protein is 19632.2Da, and the isoelectric point is 10.36. Analysis of the structure of the gene shows that, referring to FIG. 1A, the gene has only one exon and no intron; referring to FIG. 1B, the protein encoded by the gene contains a MADS domain, belonging to the MADS-box transcription factor family. The 2000bp sequence upstream DgMADS bp of the festuca arundinacea genome was extracted and its promoter was analyzed, see C in fig. 1, and DgMADS was found to contain 3 types of elements:
(1) Hormone response elements such as ABA, auxin, GA, meJA response elements;
(2) A light responsive element;
(3) Stress response elements, such as drought, stress defense elements.
Based on the above technical analysis, the inventors speculate that DgMADS114,114 may play an important role in festuca arundinacea growth and development, stress and photoperiod regulation.
Analysis of expression patterns of festuca arundinacea DgMADS114 under different stress treatments
1. Duck grass material culture and treatment
In order to verify the expression pattern of DgMADS gene under different treatments, the Duck grass variety "Dena tower" was selected as material. Dena tower seeds were placed in square small basins with quartz sand and watered with distilled water to ensure seed germination, germinated in day 14h (22 ℃) and 10h (20 ℃) dark conditions, and after seed germination, hoagland nutrient solution was watered for 60d, and then 20% polyethylene glycol (PEG-6000) treatment, 38℃heat stress treatment, 250mM NaCl treatment, 100. Mu.M ABA treatment, 100. Mu.M SA treatment, 100. Mu.M MeJA treatment were respectively carried out, plants were collected at 0h, 1.5h, 3h, 6h, 12h, 24h respectively, and rapidly frozen in liquid nitrogen, and then stored in a-80℃refrigerator for RNA extraction.
2. Duck grass RNA extraction
RNA from stress-treated ducks Mao Yangpin was extracted using the Direct-zol TM RNA MINIPREP kit (Zymo Research) according to the instructions attached hereto. The extracted RNA was checked for integrity by 1% agarose gel electrophoresis and for RNA concentration and purity by a NanoDrop ND-2000 spectrophotometer (Thermo Scientific).
3. Synthesis of first strand of cDNA:
The extracted RNA was synthesized into cDNA using MonScript TM RTIII All-in-One Mix WITH DSDNASE kit (Monad biotech).
4. Fluorescent quantitative PCR detection DgMADS of expression quantity of gene
(1) Specific primers of DgMADS114 genes (forward primers see Seq ID No.3 and reverse primers see Seq ID No. 4) were designed using Primer 6.0 software, and the cogongrass rhizome DgGAPDH gene was used as an internal reference gene (forward primers see Seq ID No.5 and reverse primers see Seq ID No. 6), the Primer sequences are shown in the following table:
DgMADS114-F:cggcaacggcaagaagacgaa,
DgMADS114-R:acggcaagctcggaggtctt,
DgGAPDH-F:tctgaccgttagacttgagaagg,
DgGAPDH-R:cttgagcttaccctcagactcct。
(2) Fluorescent quantitative PCR: using EvaGreen 2X qPCR Master Mix kit (ABM Inc.) and CXF Connect TM fluorescent quantitative PCR instrument (Bio-Rad). The specific process is as follows:
1) Diluting the cDNA stock solution synthesized by 20 times;
2) The reaction system (ice working) was prepared with a total reaction system of 20 μl:
mixing the prepared systems, centrifuging until no bubble exists, performing fluorescence quantitative PCR with CXF Connect TM fluorescence quantitative PCR instrument, and performing fluorescence quantitative PCR according to The manufacturer's recommendations for EvaGreen 2X qPCR Master Mix kit set the PRC program in a two-step process: pre-denaturation at 95℃for 3min; denaturation at 95℃for 15s, annealing at 60℃for 1min and extension for 40 cycles, and dissolution profile analysis was performed using CXF Connect TM fluorescent quantitative PCR instrument default procedure. After the completion of the above reaction, the data were derived, and the gene expression level was calculated according to the method of 2 -△△CT.
(3) Analysis of results:
as can be seen from fig. 2, the expression level of DgMADS114,114 was significantly changed in each treatment, and the expression level was different in each treatment condition and at different time points.
Under ABA treatment DgMADS114 was significantly induced to up-regulate expression at 12h, whereas both SA and MeJA significantly inhibited its expression.
Under PEG treatment, dgMADS114 expression was inhibited for the first 6 hours, while the expression levels were significantly increased at 12h and 24 h.
Under NaCl treatment, dgMADS114 had the highest expression level at 1.5h, and then began to decrease, and the expression level was higher after treatment for 3h and 12h compared with the control (0 h).
Under heat treatment, dgMADS114,114 was expressed in significantly higher amounts than the control.
These results indicate that DgMADS114,114 plays an important role in the adversity stress resistance of festuca arundinacea.
Identification of DgMADS Gene function by heterologous overexpression of Arabidopsis thaliana
1. DgMADS114 gene full-length amplification primer design
Primers were designed using Primer 6.0 software, and PCR was performed from Duck grass in the above step using cDNA as a sample for 0 h. In order to amplify the whole length of the coding region of the gene and add specific enzyme cutting sites, primers containing proper enzyme cutting sites are respectively designed at the start codon ATG and the stop codon according to CDS sequences. The enzyme cutting sites used are HIND and XBA1. Primer sequences are shown in the following tables (Seq ID No.7 and Seq ID No. 8):
F:ccagtctctctctcaagcttatggcgcagtcaccgctcgg,
R:gatacgaacgaaagctctagattaattaactgaagcgtgtgct。
2. DgMADS114-pHB plant expression vector construction
The vector used for genetic transformation is pHB, the promoter is CaMV35S, and the screening marker of the transformed plants is hygromycin (Hyg). The coding region of the gene of interest DgMADS114 was linked to vector pHB via two cleavage sites on vector HIND and XBA 1. The method specifically comprises the following steps: the cDNA of the Duck grass in Dena tower is used as a template to pass through the primerPCR amplification is carried out on Max Master Mix (Dye Plus) high-fidelity enzyme (Vazyme) to obtain a cogongrass rhizome DgMADS gene; detecting the PCR product by 1% agarose gel electrophoresis, and confirming whether the PCR product contains the fragment of the target gene; gel with target gene bandGel DNA Extraction Mini Kit (Vazyme) gel kit according to the instructions for recycling; the adaptor-carrying PCR product and the double digested pHB plasmid were then usedII One Step Cloning Kit the kit was ligated according to the instructions attached hereto. The ligation product is transformed into DH5 alpha competence of escherichia coli, LB culture dishes containing Kan antibiotics are used for screening, monoclonal colonies on the culture dishes are used for propagation, PCR detection is carried out at the same time, and the monoclonal colonies which are detected as positive are selected and sent to a sequencing company for sequencing. After sequencing and identification, the recombinant plasmid is transformed into EHA105 agrobacterium competent, positive clones are identified and screened through bacterial liquid PCR, and the monoclonal bacteria detected as positive are constructed plant expression vectors and stored at-80 ℃.
3. Agrobacterium-mediated selection of transgenic and positive transgenic lines of Arabidopsis thaliana
(1) Culturing Arabidopsis thaliana: charging proper amount of Col ecological type Arabidopsis thaliana seeds (wild type, WT) into an EP pipe with volume of 1.5ml, then adding 1ml of 10% NaClO solution for sterilization for 10min, then washing 5 times with sterile water, sucking the seeds with a gun head, sowing on an MS solid culture medium prepared in advance, sealing with a sealing film, placing in a dark condition at 4 ℃ for vernalization for 3d, placing in a climatic chamber for germination growth, and keeping the temperature at 22 ℃;16h light/8 h dark, and the illumination intensity is 80-200 mu mol/M 2/S. After the seeds germinate on an MS culture medium for 7 days, selecting strong and consistent-growth seedlings, transplanting the seedlings into a culture medium soaked in water in advance, wherein the culture medium consists of 2:1:1 peat soil, vermiculite and perlite, covering a preservative film after the arabidopsis seedlings are transplanted, and removing the seedlings after the seedlings grow normally. During the growth of arabidopsis, the water and the application of the flower multiple compound fertilizer (N: P: K=20:20:20) are paid attention to maintain the humidity and nutrition required by the growth of the arabidopsis.
(2) Transformation of arabidopsis inflorescence infection: an appropriate amount of Agrobacterium solution containing plant expression vector at-80℃was inoculated into LB liquid medium (50 ml blue cap centrifuge tube) containing 1.5ml of antibiotics (Kan, rif), and the culture was performed at 30℃with shaking at 200rpm for 24 hours to activate the Agrobacterium solution. Adding 1ml of activated bacterial liquid into 100ml of LB liquid medium containing antibiotics (Kan, rif), and culturing at 30deg.C under shaking at 200rpm until OD600 = 1.0; the cells were collected by centrifugation at 4000rpm for 15min and the supernatant was discarded. Resuspending the collected cells with a 5% sucrose solution to an OD600 = 1.0 or so; then 0.05% (v/v) silwet L-77 was added and shaken well as a conversion solution. When the arabidopsis to be transplanted starts to bloom, selecting a plant which grows robustly as a plant to be transformed, and continuously removing inflorescences at the top before transformation so as to enable the plant to generate more flower buds, wherein the plant to be transformed needs to be fully watered one day before transformation. The arabidopsis inflorescence is placed in a transformation medium for 30-50s, and after dip dyeing, the arabidopsis is placed flatly for 24h under the light-proof condition. Placing the infected arabidopsis thaliana under normal conditions for culture; to increase the transformation efficiency, repeated infestations can be performed after about one week. After the infected plant seeds are mature, the arabidopsis seeds are harvested to be transgenic T0 generation seeds. The harvested Arabidopsis seeds were placed in centrifuge tubes, sterilized with 1ml of 10% NaClO solution for 10min, then rinsed 5 times with sterile water, the seeds were sucked up with a gun head and plated onto MS solid medium containing 50ug/ml hygromycin. Vernalizing at 4deg.C in darkness for 3d, transferring to artificial climate chamber, and heating to 22deg.C; the light period is 16h light/8 h dark, and the illumination intensity is 80-200umol/M 2/S. After 8-15d of culture, selecting positive plants with green leaves and normal root development, transplanting the positive plants into a culture medium for continuous culture, and enabling negative plants to yellow and even die. The culture medium fully absorbs water before transplanting, the preservative film is covered after transplanting, the seedling is uncovered after the seedling grows normally, and the management is the same as the above. After the plant grows for one month, a proper amount of leaf extract DNA is taken, and whether the target gene is inserted into the Arabidopsis genome is detected by PCR. The positive strain detection is carried out on plants of each generation until the plants are propagated to the generation T3, and homozygous transgenic arabidopsis strains are obtained for experiments.
4. Phenotype identification and analysis of transgenic Arabidopsis plant culture and treatment
To investigate the effect of over-expression DgMADS114 on arabidopsis biomass, wild-type (WT) and over-expressed plant (OE) seeds were sown on 0.5ml EP tubes. The specific operation is as follows: a round hole with the diameter of 2mm is drilled in the middle of a cover of a 0.5ml centrifuge tube, the bottom is sheared off, the round hole is sealed by a transparent adhesive tape, 150 μl of 0.7% agarose is added from the sheared bottom, and then 1/2 Hoagland nutrient solution is filled. The prepared 0.5ml EP tube was placed in a 2ml EP tube box filled with 1/2 Hoagland solution, and then seeds were sown on demand in the round holes of the 0.5ml EP tube cover, which was covered with the EP tube box. Placing the EP tube box into a climatic chamber at a temperature of 22 ℃; the light period is 16h light/8 h dark, and the illumination intensity is 80-200 mu mol/M 2/S. After 2 weeks, WT and OE plants of consistent vigor were transferred together with 0.5ml EP tubes and inserted into round holes in EU boxes prepared in advance, and the boxes were covered with EU boxes filled with 1/2 holland solution for continued cultivation of the plants, and after 20d photographing and fresh weight measurement of the plants were performed. Note that 1/2 of the holland nutrient solution was supplemented during the culture.
Drought, salt stress, ABA stress treatment: transgenic T3 generation plants (OE) and Wild Type (WT) arabidopsis seeds were sterilized with 10% naclo for 10min, then rinsed 5 times with sterile water, the seeds were aspirated with a gun head, and sown on MS solid medium. Vernalizing at 4deg.C in darkness for 3d, transferring to artificial climate chamber, and heating to 22deg.C; the light period is 16h light/8 h dark, and the illumination intensity is 80-200 mu mol/M 2/S. After 3d germination of the seeds, seedlings were transferred to MS medium containing 100mM NaCl, 8% PEG-6000 and 30. Mu.M ABA, cultured for 10d and root length of WT and OE plants was measured with a root scanner.
And (3) heat treatment: after the sterilization of the WT and OE sterilized seeds, the seeds are sown on an MS solid culture medium, vernalized for 3d under the dark condition of 4 ℃, then transferred into a climatic chamber for culture, after the seeds germinate for 13d, the flat plate is transferred into an incubator, cultured for 5d at 35 ℃, and returned to 22 ℃ for 10d, the phenotype is observed, and the survival rate of the WT and the OE is counted.
5. Phenotypic identification and analysis of transgenic Arabidopsis plants
As shown in FIG. 3, after 34d of 1/2 Hoagland nutrient solution water culture, the wild type Arabidopsis plants were significantly smaller than the transgenic Arabidopsis plants (see FIG. 3, panel A), and fresh weights of the plants were measured and found to be significantly higher than the wild type Arabidopsis plants (see FIG. 3, panel B).
As shown in fig. 4, root growth of wild-type arabidopsis was limited under ABA, PEG and NaCl treatments, whereas transgenic arabidopsis was significantly better than wild-type, whereas root growth development of transgenic arabidopsis and wild-type arabidopsis was more consistent under control conditions (MS), without significant differences (see panel a in fig. 4). By measuring the root length of transgenic and wild-type arabidopsis, it was found that under control conditions (MS), the root length of transgenic and wild-type arabidopsis was not significantly different, whereas under ABA, PEG and NaCl treatments, the root length of transgenic arabidopsis was significantly longer than that of wild-type (see panel B in fig. 4).
Under ABA treatment, the root length of transgenic line OE12 was significantly longer than that of the wild type.
Under PEG treatment, the root length of transgenic lines OE6 and OE12 was significantly longer than that of the wild type.
Under NaCl treatment, the root length of each of the three transgenic lines (OE 6, OE12 and OE 16) was significantly longer than that of the wild-type.
It is shown that over-expression DgMADS of the gene can enhance the adversity stress resistance of plants.
Referring to fig. 5, the transgenic arabidopsis plants grew significantly better than the wild type after high temperature treatment (see panel a in fig. 5). By counting the survival rates of transgenic and wild-type arabidopsis thaliana after high temperature treatment, it was found that the survival rate of the transgenic lines was significantly higher than that of the wild-type, in particular that of the transgenic lines OE12 and OE16 reached a significant level compared to the wild-type (see panel B in fig. 5).
It is shown that over-expression of DgMADS114,114 gene can reduce the damage of high temperature to plants.
The foregoing is merely a preferred embodiment of the present invention, and it should be noted that the above-mentioned preferred embodiment should not be construed as limiting the invention, and the scope of the invention should be defined by the appended claims. It will be apparent to those skilled in the art that various modifications and adaptations can be made without departing from the spirit and scope of the invention, and such modifications and adaptations are intended to be comprehended within the scope of the invention.