Use of overexpression of populus tomentosa strigolactone receptor ptod14 gene in increasing wood yield

Abstract

The present invention relates to the use of the overexpression of a Populus tomentosa strigolactone receptor PtoD14 gene in increasing a wood yield. By means of cloning a Populus tomentosa strigolactone receptor PtoD14 gene from wild-type Populus tomentosa and introducing the PtoD14 gene into Populus tomentosa plants by means of a genetic engineering method, a Populus tomentosa line with enhanced secondary development is obtained. The number of secondary xylem cell layers in 3-month-old PtoD14 transgenic Populus tomentosa is 8 to 21 layers more than that in 3-month-old non-transgenic common Populus tomentosa, which is of important significance for providing a high wood yield for the large-scale production of Populus tomentosa.

Description

Application of overexpression of the strigolactone receptor PtoD14 gene in Populus tomentosa to improve wood yield Technical Field

[0001] The present invention relates to the field of biotechnology, and in particular to application of over-expressing a Populus tomentosa strigolactone receptor PtoD14 gene in improving wood yield. Background Art

[0002] Wood is one of the world's most abundant renewable resources and is a natural, environmentally friendly, and low-energy material. Wood formation is a complex developmental process consisting of two phases: primary growth and secondary growth. During the primary growth phase, stem cells in the apical meristem of woody plants continuously produce new cells, supporting upward growth and producing organs such as lateral branches and leaves (Aichinger et al., 2012; Miyashima et al., 2013; Ohashi-Ito and Fukuda, 2010; Weigel and Jurgens, 2002). During the secondary growth phase, plants undergo a process of growth perpendicular to the primary growth phase, driven by the continuous division of the secondary xylem and secondary phloem, which are generated inward and outward from the cambium. This growth promotes lateral growth and thickens the stem (Chao et al., 2018). Secondary growth is the biological basis for wood formation in perennial woody plants. The developmental mechanism of secondary xylem not only provides a theoretical foundation for increasing wood yield and improving wood quality, but also provides an ideal model for understanding the coordinated regulation of genetic and environmental factors. However, traditional forest tree breeding is faced with many difficulties, such as long breeding cycles and difficult selection. Therefore, the use of genetic engineering technology to create new forest tree germplasm with highly developed vascular tissue has broad development prospects.

[0003] Poplars (Populus spp.) are one of the world's most widely cultivated fast-growing timber species in mid-latitude plains. Characterized by rapid growth, high yield, and easy regeneration, they are widely used and cultivated for lumber, papermaking, and windbreaks and sand fixation. Furthermore, their deep roots and luxuriant branches provide windbreaks and sand fixation, reducing soil erosion and making them ideal for forest protection and urban and rural greening (Shi Gongming et al., 2009). In addition to their important ecological value, poplars also have a wide range of industrial and construction uses. They are used in pulp and papermaking, as a raw material for fiberboard and plywood, and as a building and furniture material. They are also a key raw material for the bioenergy industry (Wu Dingxin et al., 1997; Fu Feng et al., 1999; Huang Bei et al., 2013).

[0004] Populus tomentosa is a native tree species unique to my country. Due to its rapid growth, high-quality wood, and strong adaptability, it has become a widely planted timber species in northern China. In recent years, the development of genetic transformation systems and gene knockout technologies for Populus tomentosa has enabled in-depth research into the regulatory mechanisms of important traits such as wood formation and environmental adaptation (Fan et al. 2015; Xu et al. 2017). With the in-depth study and analysis of the regulatory mechanisms of secondary development in poplars, the creation of superior poplar species through genetic engineering to promote secondary development and thereby increase timber yield has important scientific and economic significance.

[0005] The plant hormones strigolactones (SLs) have been reported to positively regulate cambium activity (Agusti et al., 2011). As a key regulator of plant growth and development, DWARF14 (D14) functions downstream of strigolactone biosynthesis, acting as a component of hormone signaling or as an enzyme that converts strigolactones into their bioactive forms. In Arabidopsis, AtD14 regulates hypocotyl growth by mediating the hydrolysis of GR24 (Yao R et al., 2016). These studies suggest that D14 plays an important role in regulating secondary development in woody plants, but the underlying mechanisms remain unclear.

[0006] Summary of the Invention

[0007] In view of this, one of the objects of the present invention is to provide an application of overexpressing the Populus tomentosa strigolactone receptor PtoD14 gene in increasing wood yield; a second object of the present invention is to provide a method for increasing wood yield.

[0008] In order to achieve the above object, the present invention provides the following technical solutions:

[0009] 1. Application of overexpression of the strigolactone receptor PtoD14 gene of Populus tomentosa in improving wood yield, wherein the sequence of the strigolactone receptor PtoD14 gene is shown in SEQ ID NO.1.

[0010] Preferably, the wood is Populus tomentosa.

[0011] Preferably, the timber yield is increased by increasing plant height and stem diameter.

[0012] Preferably, the method of increasing wood yield is by increasing the number of wood layers.

[0013] 2. A method for increasing timber yield, comprising introducing the Populus tomentosa strigolactone receptor PtoD14 gene into Populus tomentosa plants using genetic engineering methods to obtain plants that overexpress the Populus tomentosa strigolactone receptor PtoD14 gene, namely, Populus tomentosa with increased timber yield; the sequence of the Strigolactone receptor PtoD14 gene is shown in SEQ ID NO.1.

[0014] Preferably, in the present invention, the Populus tomentosa strigolactone receptor PtoD14 gene is driven to express by the xylem-specific promoter LMX5pro, and the nucleotide sequence of the xylem-specific promoter LMX5pro is shown in SEQ ID NO.3.

[0015] Preferably, the genetic engineering method of the present invention is to introduce a recombinant vector containing the PtoD14 gene into Populus tomentosa plants through Agrobacterium-mediated introduction.

[0016] Preferably, in the present invention, the recombinant vector containing the PtoD14 gene is obtained by ligating the nucleotide sequence shown in SEQ ID NO. 1 into the BamH I and Sac I restriction sites of the pCAMBIA1300 vector.

[0017] The beneficial effects of the present invention are as follows: the present invention discloses the application of over-expressing the PtoD14 gene, a strigolactone receptor of Populus tomentosa, in improving wood yield. By cloning the PtoD14 gene, a strigolactone receptor of Populus tomentosa, from wild-type Populus tomentosa, and introducing the PtoD14 gene into Populus tomentosa plants by genetic engineering methods, a Populus tomentosa strain with enhanced secondary development is obtained. The number of secondary xylem cell layers in the 3-month-old PtoD14 gene-transformed Populus tomentosa is 8-21 more than that in the 3-month-old non-transformed ordinary Populus tomentosa. The invention is of great significance for providing high wood yield for large-scale production of Populus tomentosa. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to make the purpose, technical solutions and beneficial effects of the present invention more clear, the present invention provides the following drawings for illustration:

[0019] Figure 1 shows the identification of LMX5-PtoD14-specific overexpression-positive plants in Populus tomentosa (A: PCR identification results of wild-type and LMX5-PtoD14-overexpression-positive lines; B: qPCR identification results of wild-type and LMX5-PtoD14-overexpression-positive lines);

[0020] Figure 2 shows the macroscopic phenotypes of the specifically overexpressing PtoD14 lines (A: macroscopic phenotypes of wild-type and LMX5-PtoD14 overexpressing plants; B: plant height and stem diameter statistics of wild-type and LMX5-PtoD14 overexpressing plants).

[0021] Figure 3 shows the section analysis of the specifically overexpressing PtoD14 lines (A: phenotypic analysis of sections of wild-type and LMX5-PtoD14 overexpressing plants; B: statistics of xylem layers of wild-type and LMX5-PtoD14 overexpressing plants). DETAILED DESCRIPTION

[0022] The present invention will be further described below with reference to the accompanying drawings and specific embodiments so that those skilled in the art can better understand the present invention and implement it. However, the embodiments are not intended to limit the present invention.

[0023] Example 1: Cloning of the Populus tomentosa PtoD14 gene promoter

[0024] (1) Extraction of total RNA from Populus tomentosa genome

[0025] Soak the spoon, mortar, and pestle needed for RNA extraction in DEPC water overnight, sterilize with high-temperature autoclave, and then dry until ready for use. Use the RNA extraction reagents according to the Axygen kit instructions, and store the resulting RNA in a -80°C freezer until ready for use. The specific steps are as follows:

[0026] 1) Wrap the fresh plant tissue in tin foil and freeze it in liquid nitrogen;

[0027] 2) Grind the sample thoroughly into powder using liquid nitrogen in an RNase-free mortar.

[0028] 3) Transfer the powder to AG buffer, shake thoroughly until a slurry forms, and let it stand at room temperature for 5-10 minutes;

[0029] 4) Refrigerated centrifugation at 4°C, 12,000 rpm, for 10 min;

[0030] 5) Transfer the supernatant to a new 1.5 mL EP tube, accurately estimate the volume of the supernatant, add 0.5 times the volume of anhydrous ethanol, and mix thoroughly.

[0031] 6) Transfer the mixture to a spin clum extraction column and centrifuge at 12000 rpm / min for 1 min;

[0032] 7) Discard the waste liquid in the collection tube, add 500 μL PG buffer to the column, and centrifuge at 12000 rpm / min for 1 min;

[0033] 8) Discard the waste liquid, add 600 μL of wash buffer to the column, and centrifuge at 12000 rpm for 30 seconds;

[0034] 9) Repeat step 8) once;

[0035] 10) Discard the waste liquid and centrifuge the empty tube at 12000 rpm / min for 1 min to remove all the liquid on the filter membrane;

[0036] 11) Add 30-50 μL of RElution buffer to the center of the membrane, let it stand at room temperature for 2 minutes, and centrifuge at 12,000 rpm / min for 1 minute to obtain total RNA;

[0037] 12) Take 1 μL of RNA sample and run agarose gel electrophoresis. Check the integrity of the RNA bands at 28s and 18s to check the extraction quality.

[0038] (2) Cloning of the Populus tomentosa PtoD14 gene

[0039] Total RNA from the Populus tomentosa genome was extracted and reverse transcribed using reverse transcriptase to obtain first-strand cDNA. Based on the DNA sequence shown in SEQ ID NO. 1, upstream and downstream primers for the complete coding frame were designed and synthesized as follows:

[0040] Upstream primer PtoD14-F: 5′-GGATCCATGAGTAGCCTCATCCTAG-3′ (SEQ ID NO. 4);

[0041] Downstream primer PtoD14-R: 5′-TCTAGATCACCGGGAAAGGGCTCGC-3′ (SEQ ID NO. 5);

[0042] The first-strand cDNA obtained by reverse transcription was used as a template, and the upstream primer shown in SEQ ID NO.4 and the downstream primer shown in SEQ ID NO.5 were used as a primer pair. After PCR amplification, sequencing verification was performed to verify that the sequence was correct and the encoded amino acids were as shown in SEQ ID NO.2.

[0043] Example 2: Cloning of the Populus tomentosa LMX5pro promoter

[0044] (1) Extraction of genomic DNA from Populus tomentosa genome

[0045] Poplar DNA was extracted using the modified CTAB method as follows:

[0046] 1) Take 1 g of fresh wild-type Populus tomentosa leaves in a mortar and grind into powder in liquid nitrogen;

[0047] 2) Add 3 ml of 1% CTAB and 90 μL of β-mercaptoethanol preheated at 65°C, incubate in a 65°C water bath for 30 min, and then cool to room temperature.

[0048] 3) Add equal volumes of chloroform and isoamyl alcohol (V / V 24:1) to the CTAB solution, shake vigorously, and then place flat to emulsify for 10 minutes.

[0049] 4) Centrifuge at 10,000 rpm for 10 min at room temperature;

[0050] 5) Take the supernatant and transfer it to another centrifuge tube, and repeat steps 3-4;

[0051] 6) Transfer 1 ml of the supernatant to a 2 ml centrifuge tube, add an equal volume of pre-chilled isopropanol, shake gently until a flocculent precipitate forms, and centrifuge at 4°C, 10,000 rpm, for 10 min.

[0052] 7) Rinse the pellet twice with 75% ethanol and once with 100% ethanol, and dry in a 37°C oven;

[0053] 8) Add 50 μL of ddH2O and 1 μL of RNase, and enzymatically digest at 37°C for 1 h; then store at -20°C.

[0054] (2) Cloning of the Populus tomentosa LMX5pro promoter

[0055] Total genomic DNA of Populus tomentosa was extracted, and upstream and downstream primers of the complete coding frame were designed and synthesized according to the DNA sequence shown in SEQ ID NO.3, as follows:

[0056] Upstream primer PtoLMX5-F: 5′-GGAATTCCAATGTGGGCCTGGTGTTATAAAG-3′ (SEQ ID NO. 6);

[0057] Downstream primer PtoLMX5-R: 5′-GGGTACCCGGTTGGTGGGGAAAGATGCATC-3′ (SEQ ID NO. 7);

[0058] The first-strand cDNA obtained by reverse transcription was used as a template, and the upstream primer shown in SEQ ID NO. 6 and the downstream primer shown in SEQ ID NO. 7 were used as a primer pair. After PCR amplification, sequencing verification was performed.

[0059] Example 3: Construction of a recombinant plant expression vector and engineered bacteria containing the PtoD14 gene

[0060] The amplified LMX5pro gene was ligated to the linearized pCAMBIA1300 vector digested with EocR I and Kpn I using ligase. The vector was then transformed into Escherichia coli DH5α cells, and positive clones were screened. The plasmid was then extracted and verified by PCR and enzyme digestion. This resulted in a recombinant plant expression vector containing the LMX5pro promoter, named pCAMBIA1300-LMX5pro. Sequencing was performed by Beijing Qingke Biotechnology Co., Ltd. to confirm the correctness of the gene.

[0061] The amplified PtoD14 gene (DNA sequence shown in SEQ ID NO. 3) was ligated into the linearized pCAMBIA1300-LMX5pro vector digested with BamHI and XbaI using ligase. Escherichia coli DH5α was then transformed, and positive clones were screened. Plasmids were then extracted and verified by PCR and enzyme digestion. This resulted in a recombinant plant expression vector containing the LMX5pro promoter-driven PtoD14 gene, designated pCAMBIA1300-LMX5pro:PtoD14. Sequencing was performed by Beijing Qingke Biotechnology Co., Ltd. to confirm the correctness of the gene.

[0062] The pCAMBIA1300-LMX5pro:PtoD14 vector was transformed into Agrobacterium tumefaciens GV3101, and positive clones were screened to obtain an engineered bacterium containing the pCAMBIA1300-PtoD14 vector, which was named GV3101-pCAMBIA1300-LMX5pro:PtoD14.

[0063] Example 4: Agrobacterium tumefaciens-mediated transformation of PtoD14 gene into Populus tomentosa

[0064] (1) Two activation cultures of Agrobacterium

[0065] 1) Streak the GV3101-pCambia1300-LMX5pro:PtoD14 strain onto YEP solid medium containing 40 mg / L rifampicin and 50 mg / L kanamycin and incubate in a 28°C incubator for 36 h. Pick a single colony and inoculate it into 10 mL of YEP+Rifampicin+kanamycin liquid medium.

[0066] 2) Incubate at 28°C, 200 rpm / min, shaking for 36-48 hours until the bacterial solution reaches an OD600 of 0.8-1.0;

[0067] 3) At a ratio of 1:1000, pipette 50 μL of the first live bacterial solution into 50 mL of fresh YEP+Rif+kan dual-antibody liquid medium for second live liquid culture;

[0068] 4) Incubate the culture at 28°C, 200 rpm / min with shaking for 12-16 hours until the bacterial concentration reaches OD600 = 0.3-0.4 and set aside.

[0069] (2) Preparation of Agrobacterium infection solution

[0070] 1) Collect the two-viable bacterial solution in a 50 mL centrifuge tube and centrifuge at 4000 rpm / min for 8 min to collect the bacterial cells;

[0071] 2) Discard the culture supernatant and resuspend the Agrobacterium in 25 mL of WPM resuspension containing AS. Pour the resuspension into a sterile glass bottle.

[0072] 3) The resuspension was placed at 28°C and shaken at 200 rpm / min for 1-2 hours to enhance the infection activity of Agrobacterium.

[0073] (3) Leaf disk preparation

[0074] 1) In a clean bench, burn the sterilized scissors, tweezers, and scalpel handles with the outer flame of an alcohol burner for 15 seconds and let them cool.

[0075] 2) Use scissors to cut 5-6 leaves from healthy wild-type tissue culture seedlings and place them in a culture dish. Add 1 / 3 of the dish's volume of sterile water to keep the leaves moist.

[0076] 3) Place a sterile surgical blade into the handle, burn it with a flame, let it cool, and use the blade to cut the leaf into 0.5 cm pieces. 2 Square leaf disk.

[0077] (4) Infection

[0078] 1) Use tweezers to place the leaf disc into the Agrobacterium suspension. Gently shake the glass bottle to evenly coat the leaf disc with the suspension. Infect for 10 minutes.

[0079] 2) After infection, carefully remove the leaf disc with tweezers, place it on sterile paper, and absorb any excess infection fluid from the leaf disc.

[0080] 3) Place the leaf disc flat on the co-culture plate, place it in a dark box, and culture it in the dark at 25°C for 36-48 hours.

[0081] (5) Leaf disc selection and cultivation

[0082] 1) After dark culture, select appropriate plant resistance according to the carrier and prepare a selective medium containing antibiotics;

[0083] 2) In a laminar flow hood, transfer the leaf disc to a selective medium to induce callus. Every seven days, transfer the leaf disc to fresh medium for 3-4 weeks, until white or light yellow callus grows around the edge of the disc. Incubate in a dark box at 25°C throughout the entire process.

[0084] (6) Callus induction

[0085] Transfer the leaf discs with callus to a budding medium containing the appropriate antibiotic and incubate at 8000 Lux, 25°C for 5-6 weeks, changing the medium weekly. During this period, the callus will fully expand. Around the fifth week, buds will form on the callus, producing clusters of shoots.

[0086] (7) Root induction of clustered shoots

[0087] When the clustered shoots grow to approximately 3-5 cm, cut them off with sharp scissors and insert them into rooting medium with tweezers. Incubate them at 8000 Lux and 25°C for 7-10 days to obtain rooted seedlings. These are candidate transgenic plants and can be transplanted to soil after subsequent positive identification. Transgenic seedlings are designated LMX5-PtoD14 plants.

[0088] Example 5: PCR molecular identification of pCAMBIA1300-LMX5pro:PtoD14 transgenic plants

[0089] (1) DNA extraction from wild-type and pCAMBIA1300-LMX5pro:PtoD14 transgenic Populus tomentosa

[0090] Select 10 to 15 transgenic resistant regenerated plants and extract genomic DNA from Populus tomentosa. The method is as follows:

[0091] 1) Prepare CTAB buffer and preheat in a 65°C water bath.

[0092] 2) Grind approximately 0.5 g of wild-type and pCAMBIA1300-LMX5pro:PtoD14 transgenic Populus tomentosa leaves into powder in liquid nitrogen, add to 500 μL of the preheated CTAB extract, and mix thoroughly.

[0093] 3) Incubate in a 65°C water bath for 45 min, shaking gently three times to mix thoroughly.

[0094] 4) After the water bath, cool to room temperature, add an equal volume of chloroform:isoamyl alcohol (24:1), gently invert to mix, and then place flat to emulsify for 10 minutes. Centrifuge at 4°C, 12,000 rpm / min, and centrifuge for 10 minutes.

[0095] 5) Pipette the supernatant into a new sterile centrifuge tube, add an equal volume of -20°C pre-cooled isopropanol, and mix thoroughly by inversion until a white flocculent precipitate is visible;

[0096] 6) Centrifuge at 4°C, 12,000 rpm / min for 10 min, remove the supernatant, rinse the pellet twice with 500 ml of 75% (v / v) ethanol, rinse once with 500 ml of anhydrous ethanol, and remove the liquid; dry the pellet on a rotary evaporator at 37°C until translucent;

[0097] 7) Dissolve the precipitate with 25 μL of sterile water to obtain crude DNA extracts from wild-type and pCAMBIA1300-LMX5pro:PtoD14 transgenic white poplar leaves;

[0098] 8) Add approximately 1 μl of RNase to the crude DNA extract and digest the RNA at 37°C for 1 hour.

[0099] 9) Store the DNA sample in a -20°C refrigerator for later use.

[0100] (2) PCR amplification of positive plants

[0101] Since wild-type plants do not contain exogenously introduced pCAMBIA1300 vector sequences, positive plants were screened for amplification using primers derived from the vectors pCAMBIA1300-F and pCAMBIA1300-R. Using wild-type DNA as a negative control and the correctly sequenced vector plasmid corresponding to the transgenic plants as a positive control, DNA from the transgenic plants was amplified by PCR and imaged by gel electrophoresis to identify transgenic lines (Figure 1A). A 750-bp target band was amplified only from the pCAMBIA1300-LMX5pro:PtoD14 plasmid DNA and DNA from L1, L3, and L5-L9 lines. This confirmed that pCAMBIA1300-PtoD14 had been successfully introduced into the PtoD14-OE L1, L3, and L5-L9 lines.

[0102] The screening was performed by amplification using the vector pCAMBIA1300-F and the gene primer pCAMBIA1300-R. The sequences of the designed specific primers are as follows:

[0103] pCAMBIA1300-F: 5′-ATGGTGAGCAAGGGCGAGGAGC-3′ (SEQ ID NO. 8);

[0104] pCAMBIA1300-R: 5'-ACTTTATTGCCAAATGTTTGAACG-3' (SEQ ID NO. 9).

[0105] The PCR reaction system was the same as that in Table 2. The reaction procedure was as follows: 1 cycle of pre-denaturation at 94°C for 3 min, 31 cycles of denaturation at 94°C for 30 s, annealing for 30 s, and extension at 72°C for 1 min, and 10 min of extension at 72°C. The amplified products were detected by 1% agarose gel electrophoresis.

[0106] The PCR reaction system is shown in Table 1.

[0107] Table 1. PCR reaction system

[0108] (3) RT-qPCR identification of positive plants

[0109] Stems of WT and LMX5-PtoD14 overexpressing plants were harvested for RNA extraction and reverse transcribed into cDNA. Fluorescence quantitative PCR was performed using Takara's quantitative enzyme. The reaction system is shown in Table 2, and the amplification primers are as follows:

[0110] qPCR-PtoD14-F: 5′-GATTCTCATCGGAGCATCA-3′ (SEQ ID NO.10)

[0111] qPCR-PtoD14-R: 5′-TACATCCTTAGATGTCTGG-3′ (SEQ ID NO. 11).

[0112] As shown in Figure 1B, the results showed that the expression of the PtoD14 gene was significantly increased in strains L6-L9. The L6 and L8 strains were used for further phenotypic analysis.

[0113] Table 2. qPCR system

[0114] Amplification was performed using a German Jena fluorescent quantitative gene amplification instrument, and the qPCR program was as follows: pre-denaturation at 95°C for 3 min; 95°C for 30 sec, 60°C for 1 min, 60°C for 30 sec; 95°C for 15 sec, and 40 cycles.

[0115] Example 6: Phenotypic Analysis of Populus tomentosa PtoD14 Overexpressing Plants

[0116] One-month-old tissue culture seedlings were transplanted into pots and grown in a greenhouse at 25°C under long-day conditions (16 hours light / 8 hours dark, light intensity 10,000 lux) for three months. The plant height and stem diameter of WT and LMX5-PtoD14 transgenic poplars were measured and counted.

[0117] The results are shown in FIG2 . The plant height and stem diameter of LMX5-PtoD14 L6 and L8 plants were significantly increased compared with those of WT plants ( FIG2 ).

[0118] Example 7: Analysis of secondary development of LMX5-PtoD14 transgenic plants

[0119] Sections of 3-month-old WT and PtoD14-OE transgenic poplars were observed. As shown in Figure 3, overexpression of the PtoD14 gene in the xylem significantly increased the number of secondary xylem layers in Populus tomentosa.

[0120] The above embodiments are merely preferred embodiments for the purpose of fully illustrating the present invention, and the scope of protection of the present invention is not limited thereto. Equivalent substitutions or modifications made by those skilled in the art based on the present invention are within the scope of protection of the present invention. The scope of protection of the present invention shall be subject to the claims.

Claims

1. Application of overexpression of Populus tomentosa strigolactone receptor PtoD14 gene in increasing wood yield, characterized in that: The sequence of the strigolactone receptor PtoD14 gene is shown in SEQ ID NO.

1.

2. The use according to claim 1, characterized in that: The wood is Populus tomentosa.

3. The use according to claim 1, characterized in that: The improved wood yield is achieved by increasing plant height and stem diameter.

4. The use according to claim 1, characterized in that: The improved wood yield is achieved by increasing the number of xylem layers.

5. A method for increasing wood production, characterized in that: The Populus tomentosa strigolactone receptor PtoD14 gene is introduced into Populus tomentosa plants using genetic engineering methods to obtain plants that overexpress the Populus tomentosa strigolactone receptor PtoD14 gene, namely, Populus tomentosa with improved wood yield; the sequence of the Populus tomentosa strigolactone receptor PtoD14 gene is shown in SEQ ID NO.

1.

6. The method according to claim 5, characterized in that: The Populus tomentosa strigolactone receptor PtoD14 gene is driven to express by the xylem-specific promoter LMX5pro, and the nucleotide sequence of the xylem-specific promoter LMX5pro is shown in SEQ ID NO.

3.

7. The method according to claim 5, characterized in that: The genetic engineering method is to introduce the recombinant vector containing the PtoD14 gene into the Populus tomentosa plant through Agrobacterium-mediated introduction.

8. The method according to claim 5, characterized in that: The recombinant vector containing the PtoD14 gene is obtained by connecting the nucleotide sequence shown in SEQ ID NO.1 into the BamH I and Sac I restriction sites of the pCAMBIA1300 vector.

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