Application of LOC7477828 gene in increasing the lignin content and S / G lignin ratio in poplar

Abstract

The present invention relates to the field of molecular biology technology, and discloses the application of LOC7477828 gene in increasing the lignin content and S / G lignin ratio of poplar. The present invention deeply studies the potential role of LOC7477828 gene in the synthesis and secondary growth of poplar lignin. The experimental results show that the expression of LOC7477828 gene in poplar is positively correlated with the lignin content and S / G lignin ratio. By regulating the expression level of LOC7477828 gene, the lignin content and S / G lignin ratio of poplar can be effectively increased, thereby enhancing the mechanical strength and durability of poplar.

Description

Technical Field

[0001] The invention relates to the technical field of molecular biology, and in particular to application of LOC7477828 gene in improving the lignin content and S / G lignin ratio of poplar. Background Art

[0002] Poplar is the most widely distributed and adaptable tree species in the world. Poplar wood has the advantages of light weight, high strength, good elasticity, long fiber, high content and easy processing. Therefore, poplar wood is widely used. Many countries list poplar as an important papermaking raw material and industrial raw material.

[0003] Plant growth includes primary growth and secondary growth. Primary growth is the height growth caused by the activity of the apical meristem (i.e., the stem tip and root tip), and secondary growth is the thickening growth caused by the activity of the vascular cambium. The vascular cambium is a lateral meristem that divides and differentiates outward to become secondary phloem and inward to become secondary xylem. Secondary xylem, also known as wood, is the most abundant biomass produced by terrestrial plants. It is mainly used in papermaking, textiles, and construction, and plays an important role in production and life.

[0004] Lignin contained in xylem is one of the components of plant cell walls. It has the function of connecting cells and can keep xylem extremely hard to bear the weight of the whole plant. Lignin is a phenolic polymer formed by phenylpropane monomers connected by CC and ether bonds. It is the second largest biomass resource in the plant kingdom after cellulose. Due to different monomers, lignin can be divided into three types: coniferyl alcohol, p-coumaryl alcohol and sinapyl alcohol, which respectively generate guaiacyl propane structural basic units (G type), p-hydroxyphenyl propane structural basic units (H type) and syringyl propane structural basic units (S type); gymnosperms are mainly guaiacyl lignin (G), dicotyledons mainly contain guaiacyl-syringyl lignin (GS), and monocotyledons are guaiacyl-syringyl-p-hydroxyphenyl lignin (GSH). The C-5 position of the benzene ring of the G-lignin monomer is in a free state and can cross-link with other groups to form a stable CC bond; while the C-5 position of the benzene ring of the S-lignin monomer is a methoxy group, which cannot form a CC bond and has a loose connection. Therefore, wood with a higher proportion of S-lignin is more suitable for papermaking / pulping and biofuel production.

[0005] However, current research on the mechanisms of tree secondary growth processes and lignin synthesis is still limited. Summary of the invention

[0006] The present invention proposes an application of LOC7477828 gene in improving the lignin content and S / G lignin ratio of poplar, aiming to fill the research gap of LOC7477828 gene in the field of secondary growth and lignin synthesis of poplar.

[0007] The present invention proposes an application of a coding gene or a protein encoded by the coding gene in any of the following:

[0008] A1) Application in promoting plant lignin synthesis;

[0009] A2) Application in increasing the ratio of S / G lignin in plants;

[0010] A3) Application in increasing the number of secondary xylem cell layers in plants;

[0011] A4) Application in increasing the number of plant conduits;

[0012] The coding gene is any of the following:

[0013] B1) The nucleotide sequence shown in SEQ ID NO:1.

[0014] The present invention also provides an application of a biomaterial in any of the following:

[0015] C1) Application in promoting plant lignin synthesis;

[0016] C2) Application in increasing the ratio of S / G type lignin in plants;

[0017] C3) Application in increasing the number of secondary xylem cell layers in plants;

[0018] C4) Application in increasing the number of plant vessels;

[0019] The biological material is any of the following:

[0020] D1) an expression cassette containing the coding gene described in B1) or B2);

[0021] D2) a recombinant vector containing the coding gene described in B1) or B2), or a recombinant vector containing the expression cassette described in D1);

[0022] D3) a recombinant microorganism containing the coding gene described in B1) or B2), or a recombinant microorganism containing the expression cassette described in D1), or a recombinant microorganism containing the recombinant vector described in D2);

[0023] D4) a transgenic plant cell line containing the coding gene described in B1) or B2), or a transgenic plant cell line containing the expression cassette described in D1), or a transgenic plant cell line containing the recombinant vector described in D2);

[0024] D5) transgenic plant tissue containing the coding gene described in B1) or B2), or transgenic plant tissue containing the expression cassette described in D1), or transgenic plant tissue containing the recombinant vector described in D2);

[0025] D6) A transgenic plant organ containing the coding gene described in B1) or B2), or a transgenic plant organ containing the expression cassette described in D1), or a transgenic plant organ containing the recombinant vector described in D2).

[0026] Preferably, the amino acid sequence of the protein encoded by the coding gene is shown as SEQ ID NO:2.

[0027] Preferably, the plant is a tree.

[0028] More preferably, the plant is a Populus plant.

[0029] The present invention also proposes a method for promoting plant lignin synthesis, improving the plant S / G type lignin ratio, increasing the number of plant secondary xylem cell layers and / or increasing the number of plant vessels, which comprises overexpressing the above-mentioned encoding genes in the target plant.

[0030] The present invention also provides a method for cultivating plants with high wood content, plants with high S / G type lignin ratio, plants with high secondary xylem cell layers and / or plants with high vessel number, which comprises overexpressing the above-mentioned encoding genes in the target plant.

[0031] Preferably, the target plant is a tree.

[0032] More preferably, the target plant is a plant of the genus Populus.

[0033] Compared with the prior art, the present invention has the following beneficial effects:

[0034] The present invention has successfully proposed an innovative application and cultivation method by deeply studying the role of the LOC7477828 gene in the secondary growth and lignin synthesis of poplars. By overexpressing the LOC7477828 gene, the present invention not only significantly increases the lignin content of poplars, but also optimizes the ratio of S / G type lignin in lignin, further promoting the increase in the number of secondary xylem cell layers and the number of vessels. This innovative achievement not only fills the research gap in the field of secondary growth and lignin synthesis of poplars by the LOC7477828 gene, but also provides strong technical support for the cultivation of poplar varieties with excellent wood properties.

[0035] In addition, the present invention optimizes the application and cultivation methods, making the operation easier and the effect more significant. By selecting trees, especially poplar plants as target plants, the present invention further expands the scope of application, allowing more types of plants to benefit from the application of the LOC7477828 gene. Compared with the prior art, the beneficial effect of the present invention is that it not only improves the lignin content and quality, but also helps to enhance the growth potential and stress resistance of poplars, thereby showing higher economic value and social benefits in practical applications.

[0036] In summary, the present invention has made important contributions to the development of the field of poplar secondary growth and lignin synthesis through in-depth research and innovative application of the LOC7477828 gene, and has provided new ideas and methods for cultivating plant varieties with excellent wood properties. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Various other advantages and benefits will become apparent to those of ordinary skill in the art by reading the detailed description of the preferred embodiments below. The accompanying drawings are only for the purpose of illustrating the preferred embodiments and are not to be considered as limiting the present invention. Moreover, the same reference symbols are used throughout the accompanying drawings to represent the same components. In the accompanying drawings:

[0038] Figure 1 Transgenic expression results in OE plants:

[0039] Figure 2 This is the result of semi-thin section observation;

[0040] Figure 3 This is the statistical result of xylem cells at the base of wild-type 84K poplar and OE plants;

[0041] Figure 4 The results of lignin content determination of wild-type 84K poplar and OE plants are shown;

[0042] Figure 5 These are the results of nuclear magnetic resonance analysis of wild-type 84K poplar and OE plants. DETAILED DESCRIPTION

[0043] Exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments described herein. On the contrary, these embodiments are provided in order to enable a more thorough understanding of the present disclosure and to fully convey the scope of the present disclosure to those skilled in the art. It should be noted that, in the absence of conflict, the embodiments of the present invention and the features described in the embodiments can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0044] Example 1

[0045] 1.1 Material preparation

[0046] 1.1.1 Sequence

[0047] Through genetic engineering technology, the LOC7477828 gene was successfully integrated into the genome of 84K poplar, and three transgenic lines OE#5, OE#6, and OE#10 were obtained. The transgenic expression was as follows Figure 1 The nucleotide sequence of the LOC7477828 gene is shown in SEQ ID NO: 1; the amino acid sequence of the protein encoded by the LOC7477828 gene is shown in SEQ ID NO: 2.

[0048] SEQ ID NO: 1:

[0049]

[0050] SEQ ID NO: 2:

[0051] MEIHPNKNQNNNGEDKTVATIKNLRSRLESRIE TQHKTQLDLLASLQDLVPNIVSSLDLSLQIVSSFNNKPFTPTPPLPASTSRAHLEIGSNSRNPNDPRANIDSRPEILGESSKLERKDGNFDGDGAESGSPLAVVRVMVAECLLQRVPFNPIDSS TVLRKLENDQNATEAEKAAIREVGGESGAILAVEMALRSMAEENRGIELEEFVVSGKSRVMVLNIDRNRLVKELPESAQYTQNLELSGSSDFNQNQSSGIGNNVNSNGGVDVNGNGVYGIGGPVVMQRPLMGDMWMGGGGDMWPRGGMMGPRGMMMGPRGMMQRPPMPLPMQSQQQKQRSEEDEMKDLEALLNKKSFREMQKSKTGEELLDL IHRPTARETAVAAKFKTKGGSQLKEYCSALTKEDCRRQCGSFACEKVHFRRIIAPHTDVSQGDCSFLDTCRHMKTCKYVHYELDPTPDVSPMAMGAAALPPPKALKPQRAEYCSEVELGEPQWINCDIRNFKMEILGQFGVIMADPPWD IHMELPYGTMADDEMRNLNVPVLQTDGL IFLWVTGRAMELGRECLELWGYKRVEEIIWVKTNQLQRIIRTGRTGHWLNHSKEHCLVGIKGNPEVNRNIDTDVIVAEVRETSRKPDEMYPLLERI SPRTRKLELFARMHNTQAGWMSLGNQLEGVRLVDEGLRARFKAAYPDVVVQPSSPPRASAMEIDSTASQMRSPFSVTESKSMATQFADRAAPETVYTSEEKPMALDAVMAG*。

[0052] 1.1.2 Obtaining overexpressing plants

[0053] A whole wild-type Populus trichocarpa tissue culture seedling that had grown for one month was selected as the experimental object. High-quality RNA was successfully extracted in strict accordance with the operating procedures of the EASYspin Plus Complex Plant RNA Kit rapid extraction kit provided by Beijing Adelaide Company. Subsequently, the extracted RNA was effectively reverse transcribed into cDNA using a reverse transcription kit as a template for subsequent amplification of the target gene.

[0054] With the help of Primer Premier 5 software, cloning-specific primers were designed, and the target gene was amplified by PCR amplification technology. To verify the amplification results, 0.5% agarose gel was used for electrophoresis detection under the conditions of 160V and 90mA. The results showed that the target gene band was clear and about 2200bp in size, which preliminarily indicated that the LOC7477828 gene in Populus trichocarpa had been successfully cloned.

[0055] Next, the cloned gene was purified and recovered, and the target gene was successfully connected to the pCAMBIA2300 vector using homologous recombination.

[0056] To further verify the gene function, the direct differentiation technique established in our laboratory was used to successfully obtain positive plants. The specific process is as follows: First, the leaves were pretreated and cultured; then, the leaves of 84K poplar were directly infected by Agrobacterium-mediated method; then, differentiation culture was carried out under dark culture conditions; finally, the adventitious buds obtained by preliminary differentiation were transferred to the resistance rooting screening medium containing 30mg / L Kan for culture. After 5-10 days of culture, the positive adventitious buds were able to take root and grow normally, while the false positive adventitious buds showed growth inhibition, inability to take root, yellowing or bleaching.

[0057] After the overexpression resistant plants were grown in the culture medium for about 1 month, the gene expression was analyzed. To this end, a sequence of about 150-200bp with strong specificity was selected, and qRT-PCR primers were designed online through the NCBI website (see Table 1). Subsequently, the expression of the LOC7477828 gene was accurately detected using a fluorescent quantitative PCR experiment. The results showed that there were significant differences in the expression levels of the transgenic lines, among which the lines marked as OE#5, OE#6 and OE#10 performed particularly well.

[0058] Table 1

[0059] Primer name Primer sequences Clone-F 5'ATGGAGATTCATCCAAACAAG 3' Clone-R 5'TCAGCCAGCCATAACAGCA 3' OE-F 5'AATTGAGACTTTTCAACAAAG 3' OE-R 5'ATGGACTCCCACTCTCAGC 3' 18S-F 5'CGAAGACGATCAGATACCGTCCTA 3' 18S-R 5'TTTCTCATAAGGTGCTGGCGGAGT 3'

[0060] 1.1.3 Cultivation of experimental samples

[0061] The experimental samples included wild-type (WT) and transgenic (OE#5, OE#6 and OE#10) 84K poplar samples, which were cut into 2 cm long stem segments and cultured on rooting medium for 40 days (16 hours of light, 8 hours of darkness, and a temperature of 23°C). At this time, the root system of the poplar seedlings had developed more abundantly. Next, the poplar seedlings were removed from the rooting medium, the excess medium was removed, transplanted into pots, and continued to be cultured in the greenhouse (16 hours of light, 8 hours of darkness, and a temperature of 21°C). Table 2 shows the rooting medium formula for 84K poplar (pH 5.8-6.0).

[0062] Table 2

[0063]

[0064] 1.2 Observation of the secondary xylem sections of transgenic plants

[0065] 1.2.1 Preparation of Spurr resin embedding material

[0066] A two-month greenhouse growth experiment was conducted on three independent strains of wild-type 84K poplar and overexpressing LOC7477828 plants, OE#5, OE#6 and OE#10. The experimental process is as follows:

[0067] (1) The base of the plant was cut into pieces of appropriate size and then placed in a 2% paraformaldehyde-2.5% glutaraldehyde fixative;

[0068] (2) Use a vacuum pump to evacuate the material for 5 minutes and maintain for 30 minutes to ensure that the fixative fully penetrates into the material, and fix it for more than 48 hours;

[0069] (3) Remove the fixed material and wash it with PBS four times, each time for 15-20 minutes;

[0070] (4) Dehydration with ethanol gradient, 30%, 50%, 60%, 70%, 80%, 90%, 100%, 100%, 100%, 20 minutes each time;

[0071] (5) gradient replacement using a mixture of acetone and ethanol (ratios of 1 / 3 acetone + 2 / 3 alcohol, 1 / 2 acetone + 1 / 2 alcohol, 2 / 3 acetone + 1 / 3 alcohol, and 100% acetone twice, each for 20 minutes);

[0072] (6) gradient replacement was performed using a mixture of Spurr resin and acetone (the ratios were 1 / 3 Spurr resin + 2 / 3 acetone, 1 / 2 Spurr resin + 1 / 2 acetone, and 2 / 3 Spurr resin + 1 / 3 acetone, each for 3 hours), and finally four Spurr resin replacements were performed, with replacement every 12 hours;

[0073] (7) Carefully place the processed material into the sample well of the embedding plate, add 2 / 3 volume of Spurr resin, and adjust the position and section of the material to make it straight for subsequent trimming and slicing;

[0074] (8) Gently place the embedded plate into an oven and dry it at 40°C for 2 hours. If the material moves during the process, use tweezers to adjust it in time.

[0075] (9) Allow to solidify at 70°C for 8-16 hours until the embedded block is completely solidified, then sectioning can be performed.

[0076] 1.2.2 Semi-thin sectioning, staining and observation of Spurr resin embedded materials

[0077] (1) Use a blade to trim the sample so that the sample surface is appropriately exposed and the part to be cut is trapezoidal. Finally, use a blade to cut the grinding surface of the sample block flat;

[0078] (2) First, use a glass cutter to cut the glass strip into a square block with a side length of 25 mm;

[0079] (3) Fix the sample block and the glass knife on the semi-thin slicer, and adjust the front and rear position of the glass knife so that it is close to the sample block;

[0080] (4) Start the slicer, adjust the cutting distance and speed, and let the glass knife slowly cut the sample block until the cut surface of the sample block is flat and smooth; when formally slicing, the slice thickness is 2 μm;

[0081] (5) Use a toothpick to pick up the slice, place it on a glass slide with water droplets, and put the glass slide into a baking machine and bake it at 60°C;

[0082] (6) Add 0.05% methylamine blue dye solution to the slice and stain for 1 minute;

[0083] (7) Use ddH 2 O Wash off the excess dye solution and then put the slices into the slice baking machine for baking;

[0084] (8) Add 1 drop of xylene clearing agent and a mixture of equal volumes of neutral gum, cover with a coverslip, and seal the slide;

[0085] (9) Observe and take photos under an optical microscope.

[0086] Figure 2 The semi-thin section observation results shown (the changes in the secondary xylem at the base of wild-type 84K poplar and OE plants) show that the radius of the base of the OE plant is significantly larger than that of the WT (wild-type 84K poplar). Further studies have found that the width of the secondary xylem of the OE plant has increased, which may be due to the fact that overexpression of the LOC7477828 gene promotes the differentiation of the vascular cambium into the xylem, thereby increasing the diameter of the plant.

[0087] 1.3 Statistics of secondary xylem cells in transgenic plants

[0088] (1) Open ImageJ software, drag the slice to be counted into the software interface, click set scale according to the scale size, set the scale to 4.2812 μm, and the unit to μm;

[0089] (2) Then change the image's color mode to 8-bit grayscale in Image\Type\8-bit;

[0090] (3) Adjust the image contrast appropriately, manually adjust it through Image\Adujust\Brightness / Contrast or click Auto;

[0091] (4) Click Edit\Invert to invert the image;

[0092] (5) Click Analyze\AnalyzePart ica l es and set the minimum size of "particles" to 250μm 2 , select Outlines in Show, select Summarize, click OK to complete the counting.

[0093] The WT plants and three OE lines were analyzed as above, with three replicates for each line. The statistical results are shown in Figure 3 (Statistics of xylem cells at the base of wild-type 84K poplar and OE plants) showed that the number of cell layers and vessels in the secondary xylem of OE plants increased significantly, and the total area of ​​all vessel cells and the average area of ​​xylem cells also increased significantly.

[0094] 1.4 Determination of lignin content in stems of transgenic plants

[0095] (1) Three WT and three transgenic poplar seedlings grown in a greenhouse for 6 months were peeled and cut into small pieces, dried in an oven at 80°C to constant weight, crushed and passed through a 40-mesh sieve;

[0096] (2) Take 20 mg of the sieved powder from each plant, put it into a 10 mL centrifuge tube, add 5 mL of acetyl bromide, close the lid and seal it, mix it thoroughly, and heat it in a 50°C water bath for 4 hours for acetylation;

[0097] (3) Mix gently every 10 minutes. After the reaction is completed, cool naturally to room temperature, centrifuge at 3500 rpm for 15 minutes, and transfer the supernatant to a 5 mL centrifuge tube;

[0098] (4) Add 500 μL of 2M NaOH solution and 600 μL of glacial acetic acid to a 2 mL centrifuge tube and mix well. Then add 200 μL of the supernatant in step 3 and shake well. Then add 50 μL of hydroxylamine (0.5 M) and mix well.

[0099] (5) Pipette 200 μL and add it to a 96-well UV plate, with 3 technical replicates for each sample;

[0100] (6) Turn on the microplate reader, adjust the wavelength to 280 nm, adjust to zero with glacial acetic acid, and measure the absorbance at 280 nm;

[0101] (7) Lignin content = absorbance reading / 17.12 (mg / g / CWR).

[0102] The results of lignin content determination were as follows Figure 4 As shown, the total lignin content of OE plants was significantly increased compared with that of WT plants.

[0103] 1.5 NMR analysis of changes in stem lignin structure and composition in transgenic plants

[0104] (1) After growing in the greenhouse for 6 months, WT and OE plants were peeled and cut into small pieces, and then dried in an oven at 60°C to constant weight;

[0105] (2) The dried stem segments were ground into powder using a tissue grinder, and extracted with benzene and ethanol in a volume ratio of 2:1 for 6 h. The dewaxed samples were ball milled in a planetary ball mill (Fr itsch GMBH) for 5 h.

[0106] (3) adding 96% of dioxane to the ball-milled powder, extracting at room temperature for 24 hours (twice), combining the extracts, and concentrating the respective rotary evaporation solutions to 30 mL;

[0107] (4) dropping the above liquid into 10 times the volume of acidic water, slowly adding hydrochloric acid solution until the solution pH = 2.0, stirring to obtain a precipitate, centrifuging and freeze-drying to obtain coarse ground lignin;

[0108] (5) Dissolving the coarsely ground lignin at a ratio of 1 g lignin / 20 mL 90% acetic acid, then dropping it into 10 times the volume of acidic water (pH = 2.0), and centrifugally freeze-drying to obtain purified lignin;

[0109] (6) Then, the purified lignin was dissolved in a solution of dichloromethane: ethanol ratio of 2:1 (v / v) at a ratio of 1 g / 20 mL, and added dropwise to 5 volumes of anhydrous ether to obtain a precipitate, which was washed with petroleum ether after centrifugation and air-dried under a fume hood to obtain a second purified lignin;

[0110] (7) 60 mg of the purified lignin was dissolved in 0.5 mL of DMSO-d6 and the composition was determined using a nuclear magnetic resonance spectrometer (Bruker AVIII 400-MHz, Karlsruhe, Germany).

[0111] Nuclear magnetic resonance analysis ( Figure 5 ) revealed the structure and bonding mode of lignin monomers. The results showed that in the wild type (WT) and overexpression LOC7477828 plants (OE), the content of S lignin monomers and G lignin monomers was high, while the content of H lignin monomers was extremely low. Specifically, the content of lignin monomer S in WT plants was 63, the content of G monomers was 36, and the content of H monomers was 1; the content of S in OE plants was 67, the content of G monomers was 32, and the content of H monomers was 1. These data indicate that the content of S monomers increased and the content of G monomers decreased in OE plants, resulting in an increase in the S / G / H ratio.

[0112] In addition, the analysis of the bonding mode showed that the side chain bonding mode of lignin in OE plants was different from that in 84K plants. Compared with 84K plants, the β-O-4 bonding mode increased in OE plants, accounting for 25.34 / 100Ar, while the β-β and β-5 bonding modes decreased to 1.30 / 100Ar and 5.09 / 100Ar, respectively. The summary of the stem wood monomers and bonding modes of WT and OE plants (results expressed per 100Ar) is shown in Table 3.

[0113] Table 3

[0114] sample β-O-4 β-β β-5 PB S / G / H WT 24.75 1.47 6.06 10.30 63 / 36 / 1 OE 25.34 1.30 5.09 10.02 67 / 32 / 1

[0115] In summary, the present invention reveals the significant effect of LOC7477828 gene overexpression on poplar secondary xylem development and lignin characteristics by in-depth analysis of the stem lignin content and structure of transgenic poplar OE. Compared with wild-type plants (WT), OE plants showed a significant increase in the number of secondary xylem cell layers and vessels, and the total lignin content also increased significantly. These changes are due to the key role of LOC7477828 gene in regulating cell division and lignin synthesis pathways.

[0116] In terms of lignin monomer composition, the S monomer content of OE plants increased and the G monomer content decreased, resulting in an increase in the S / G ratio. This change affected the physical and chemical properties of lignin, such as hardness, toughness, and corrosion resistance. In addition, nuclear magnetic resonance analysis results showed that the side chain connection mode of lignin in OE plants also changed, with an increase in β-O-4 connection mode and a decrease in β-β and β-5 connection modes. These changes further affected the degree of polymerization and stability of lignin.

[0117] In summary, overexpression of the LOC7477828 gene significantly changed the content and structure of lignin in poplar stems, providing valuable clues for a deeper understanding of the regulatory mechanism of lignin synthesis and improving wood quality through genetic engineering.

[0118] The technology of this invention is Science and Technology Innovation 2030 - Major Project (2023ZD04069). The English label is "ST I2030 - Major Project (2023ZD04069)".

[0119] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the relevant field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. Use of a coding gene or a protein encoded by the gene in any of the following: A1) Application in promoting plant lignin synthesis; A2) Application in increasing the ratio of S / G lignin in plants; A3) Application in increasing the number of secondary xylem cell layers in plants; A4) Application in increasing the number of plant vessels; The coding gene is: B1) the nucleotide sequence shown in SEQ ID NO: 1; The plant is poplar.

2. Use of a biomaterial in any of the following: C1) Application in promoting plant lignin synthesis; C2) Application in increasing the ratio of S / G lignin in plants; C3) Application in increasing the number of secondary xylem cell layers in plants; C4) Application in increasing the number of plant vessels; The biological material is any of the following: D1) an expression cassette containing the coding gene described in B1) of claim 1; D2) a recombinant vector containing the coding gene described in B1) of claim 1, or a recombinant vector containing the expression cassette described in D1); D3) a recombinant microorganism containing the coding gene described in B1) of claim 1, or a recombinant microorganism containing the expression cassette described in D1), or a recombinant microorganism containing the recombinant vector described in D2); D4) a transgenic plant cell line containing the coding gene described in B1) of claim 1, or a transgenic plant cell line containing the expression cassette described in D1), or a transgenic plant cell line containing the recombinant vector described in D2); D5) transgenic plant tissue containing the coding gene described in B1) of claim 1, or transgenic plant tissue containing the expression cassette described in D1), or transgenic plant tissue containing the recombinant vector described in D2); D6) a transgenic plant organ containing the coding gene described in B1) of claim 1, or a transgenic plant organ containing the expression cassette described in D1), or a transgenic plant organ containing the recombinant vector described in D2); The plant is poplar.

3. The use according to claim 1, characterized in that: The amino acid sequence of the protein encoded by the coding gene is shown in SEQ ID NO:

2.

4. A method for cultivating plants with high wood content, plants with high S / G lignin ratio, plants with high number of secondary xylem cell layers and / or plants with high number of vessels, characterized in that: The method comprises overexpressing the coding gene described in claim 1 in the target plant; The plant is poplar.

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