Application of apparent modification protein OsMOF in improvement of salt tolerance character of rice

Abstract

The invention belongs to the technical field of gene breeding, and particularly relates to application of apparent modification protein OsMOF in improvement of salt tolerance of rice. An expression vector of the OsMOF gene is transferred into a rice receptor, an overexpressed rice transformation strain of the OsMOF gene is sown, and the fact that the functional protein OsMOF modified by histone acetylation in epigenetic modification not only can improve the germination character of rice seeds under salt stress, but also can improve the survival rate of rice seedlings under salt stress is found, so that the salt stress resistance of the rice is improved, and the salt stress resistance of the rice is improved. Therefore, the salt tolerance character of the rice is obviously improved. Therefore, the invention provides a new way for enhancing the salt tolerance of the rice, accelerating the stress-resistant molecular breeding process of the rice and the like.

Description

Technical Field

[0001] The present invention belongs to the technical field of genetic breeding, and specifically relates to the application of the epigenetic modification protein OsMOF in improving the salt tolerance trait of rice. Background Art

[0002] Rice (Oryza sativa L.), as one of the most important food crops globally, the improvement of its traits has always been a key area in crop genetic breeding. With the frequent occurrence of global climate change and extreme stress events, there is an urgent need for stress-resistant germplasm resources for crops. As a typical moderately salt-sensitive crop, the physiological metabolism of rice is affected by the salt concentration in the soil. Salt stress can cause restricted plant growth and hindered reproductive development, ultimately leading to a decline in salt tolerance. Currently, the creation of new salt-tolerant rice varieties mainly faces limiting factors such as a lack of gene resources. Identifying and storing new gene resources that promote the salt tolerance trait of rice is an important way to ensure food security.

[0003] Epigenetics is an important supplement to classical genetics, helping people deeply understand the mechanisms of biological adaptation to the environment and stress response, and is also a new way for the transformation and production application of life sciences. Epigenetic resources have become a new source of genetic diversity in future breeding and have the potential to revolutionize crop performance. Histone acetylation is one of the most concerned epigenetic modifications. The histone acetyltransferase MOF is a core member of the epigenetic modification complex in multiple species, but its stress-resistant function in rice is unknown, and there is no report on the application of the epigenetic modification protein OsMOF gene in improving the salt tolerance trait of rice. Summary of the Invention

[0004] In view of the above problems, the present invention provides the application of the epigenetic modification protein OsMOF in improving the salt tolerance trait of rice, and specifically adopts the following technical solutions.

[0005] On the one hand, the present invention provides the application of the OsMOF protein in improving the salt tolerance trait of rice, and the OsMOF protein is any one of the following (a)-(c): (a) A protein composed of the amino acids shown in SEQ ID NO.2; (b) A protein derived from (a) with the same function, which is obtained by substituting and / or deleting and / or adding one or several amino acid residues to the amino acids shown in SEQ ID NO.2; (c) A protein or its derivative having at least 85% sequence identity with the protein shown in (a) and having the same function, which is derived from other varieties of rice or other species.

[0006] The OsMOF protein in (a) above can be artificially synthesized, or its coding gene can be obtained first and then expressed biologically. The OsMOF protein in (b) above can be obtained by deleting the codons of one or several amino acid residues from the nucleotide sequence shown in SEQ ID NO.1 in the sequence listing, and / or performing missense mutations of one or several base pairs, and / or ligating the coding sequences of tags at its 5′ end and / or 3′ end.

[0007] The proteins or their derivatives with the same function generated from homologous sequences of other rice varieties or other species in the present invention are because there are a large number of rice varieties and it is impossible for the inventor to list them one by one. The rice varieties include but are not limited to Oryza sativa ssp. indica, Oryza sativa subsp. japonica, Oryza rufipogon, Oryza barthii, Oryza nivara, Oryza meridionalis, Oryza glaberrima, Oryza glumipatula, Oryza brachyantha. Other species include but are not limited to plants such as rice, wheat, sorghum, and corn. As shown above, those skilled in the art should be aware that the genes described in the present invention also include homologous genes that are highly homologous to the nucleotide sequence or protein sequence of the OsMOF gene and have the same function of improving the salt tolerance trait of rice.

[0008] The present invention provides representative sequences. For example, the OsMOF protein sequence shown as SEQ ID NO.2 in the present invention is derived from the indica rice (Oryza sativa ssp. indica) variety Minghui 63 (MH63); the sequence shown as SEQ ID NO.4 is derived from the japonica rice (Oryza sativa subsp. japonica) of cultivated rice in Asia, with 100% identity to SEQ ID NO.2; the sequence shown as SEQ ID NO.5 is derived from the common wild rice (Oryza rufipogon), with 100% identity to SEQ ID NO.2; the sequence shown as SEQ ID NO.6 is derived from the African wild rice (Oryza barthii), with 100% homologous consistency to SEQ ID NO.2; the sequence shown as SEQ ID NO.7 is derived from the nivara wild rice (Oryza nivara), with 99.8% identity to SEQ ID NO.2; the sequence shown as SEQ ID NO.8 is derived from the southern wild rice (Oryza meridionalis), with 99.8% identity to SEQ ID NO.2; the sequence shown as SEQ ID NO.9 is derived from the African cultivated rice (Oryza glaberrima), with 99.8% identity to SEQ ID NO.2; the sequence shown as SEQ ID NO.10 is derived from the glumipatula wild rice (Oryza glumipatula), with 99.3% identity to SEQ ID NO.2; the sequence shown as SEQ ID NO.11 is derived from the punctata wild rice (Oryza punctata), with 98.2% identity to SEQ ID NO.2; the sequence shown as SEQ ID NO.12 is derived from the brachyantha wild rice (Oryza brachyantha), with 94.7% identity to SEQ ID NO.2.

[0009] In some embodiments, the improved salt tolerance traits of rice include improving the germination traits of rice seeds under salt stress and improving the survival rate of rice seedlings under salt stress conditions.

[0010] On the other hand, the present invention also provides the application of the gene encoding the OsMOF protein in improving the salt tolerance traits of rice, and the gene sequence is any one of the following (d)-(f): (d) A DNA molecule whose coding region is the sequence shown as SEQ ID NO.1; (e) A DNA molecule that hybridizes with the DNA sequence defined in (d) under stringent conditions and encodes a protein with the same function; (f) A DNA molecule that has at least 90% sequence identity with the DNA sequence defined in (d) and encodes a protein with the same function.

[0011] The "stringent conditions" used in this article are well-known, including hybridization in a hybridization solution containing 400 mM NaCl, 40 mM PIPES (pH 6.4), and 1 mM EDTA. The temperature of the hybridization is preferably 53°C - 60°C, the hybridization time is preferably 12 - 16 hours, and then it is washed with a washing solution containing 0.5×SSC and 0.1% SDS. The washing temperature is preferably 62°C - 68°C, and the washing time is 15 - 60 minutes. Genes with 90% sequence identity also include DNA sequences that have at least 95%, 96%, 97%, 98%, or 99% sequence similarity to the sequence shown by the OsMOF gene disclosed in the present invention and have the function of improving the salt tolerance trait of rice. Among them, the sequence The percentage of similarity can be obtained by well-known bioinformatics algorithms, including the Myers and Miller algorithm, the Needleman-Wunsch global alignment method, the Smith-Waterman local alignment method, the Pearson and Lipman similarity search method, and the algorithm of Karlin and Altschul, which are well-known to those skilled in the art.

[0012] In some embodiments, the improvement of the salt tolerance trait of rice includes improving the germination trait of rice seeds under salt stress and the survival rate of rice seedlings under salt stress conditions.

[0013] On the other hand, the present invention also provides the application of a recombinant vector containing the above-mentioned OsMOF gene in improving the salt tolerance trait of rice.

[0014] In some embodiments, the recombinant vector is a vector in which the coding gene of the OsMOF protein is inserted downstream of the 35S constitutive promoter of the pCAMBIA1306 vector.

[0015] An existing plant expression recombinant vector can be used to construct a recombinant expression vector containing the above gene. In the embodiments of the present invention, the recombinant vector can be a vector in which the OsMOF protein gene is inserted downstream of the 35S constitutive promoter of the pCAMBIA1306 vector, named the OsMOF-pCAMBIA1306 expression vector. Other vectors such as the pCAMBIA1300 series vectors, the pCHF series vectors, etc., as long as they can achieve the overexpression of the OsMOF gene in rice, can also produce similar yield-increasing traits.

[0016] When constructing a recombinant plant expression vector using the said gene, any enhancer promoter or constitutive promoter can be added before the transcription start nucleotide; when constructing a plant expression vector using the gene of the present invention, an enhancer can also be used, including a translation enhancer or a transcription enhancer. These enhancer regions can be the ATG start codon or the start codon of the adjacent region, etc., but must be in the same reading frame as the coding sequence to ensure the correct translation of the entire sequence. The sources of the said translation control signal and the start codon are extensive and can be natural or synthetic. The translation start region can be from the transcription start region or the structural gene.

[0017] In addition, when constructing the OsMOF gene expression vector, codons can be optimized. For example, the bases at positions 1bp - 294bp are codon-optimized. This codon optimization only involves base substitution of codons, and the amino acid of the encoded product is the same as that encoded by the OsMOF gene with NCBI accession number XM_015789227.2. The optimized base sequence is as shown by the bases at positions 1 - 294bp in SEQ ID NO.3, and the amino acid sequence of the encoded product of the optimized sequence is as shown by the amino acids at positions 1 - 98aa in SEQ ID NO.2.

[0018] To facilitate the identification and screening of transgenic plant cells or plants, the used plant expression vector can be processed or other components can be added, which mainly depends on the purpose and use of the vector construction. For example, genes encoding enzymes or luminescent compounds that can produce color changes and are expressed in plants (such as the GUS gene, luciferase gene, etc.) are added, or the coding sequence of the fusion Flag-tag protein is added.

[0019] In certain embodiments, the improved salt tolerance traits of rice include improving the germination traits of rice seeds under salt stress and improving the survival rate of rice seedlings under salt stress conditions.

[0020] On the other hand, the present invention also provides the use of an expression cassette, a transgenic cell line or a recombinant bacterium containing the coding gene of the said OsMOF protein in improving the salt tolerance traits of rice.

[0021] The recombinant vector, expression cassette, transgenic cell line or recombinant bacterium provided by the present invention can be inserted into a plasmid, cosmid, yeast artificial chromosome, bacterial artificial chromosome or any other vector suitable for transformation into a host cell. When the host cell is a plant cell, the expression cassette or recombinant vector can be inserted into or transformed into the genome of the plant cell.

[0022] In certain embodiments, the improved salt tolerance traits of rice include improving the germination traits of rice seeds under salt stress and improving the survival rate of rice seedlings under salt stress conditions.

[0023] On the other hand, the present invention also provides a method for improving the salt tolerance trait of rice, constructing the recombinant vector as described above, transforming the recombinant vector into a rice receptor, and obtaining a rice transformed line with overexpression of the OsMOF gene.

[0024] In some embodiments, the rice receptor is a cell, a leaf or a callus.

[0025] The transfer of a nucleotide sequence, an expression vector or an expression cassette into a plant, the introduction of a nucleotide sequence, an expression vector or an expression cassette into a plant or the transformation of a plant in the present invention all refer to the transfer of a nucleotide sequence, an expression vector or an expression cassette into a recipient cell or a recipient plant by a conventional transgenic method. Any transgenic method known to those skilled in the field of plant biotechnology can be used to transform a recombinant expression vector into a plant cell to produce the transgenic plant of the present invention. The transformation methods include Agrobacterium-mediated plant transformation methods, polyethylene glycol-induced DNA uptake, liposome-mediated transformation, gene gun introduction, electroporation, and microinjection, etc.

[0026] In the examples of the present invention, the Agrobacterium transformation method was used to obtain the transformed rice lines.

[0027] Specifically, the construction of the expression vector of the OsMOF gene in the examples of the present invention includes optimizing some codons of the endogenous OsMOF coding sequence of rice, which is more suitable for the efficient expression of this gene in rice; it also includes an expression vector of an OsMOF protein gene, which inserts the OsMOF protein gene downstream of the 35S constitutive promoter of the pCAMBIA1306 vector, and this expression vector is applied to improve the salt tolerance trait of rice.

[0028] In the examples of the present invention, the Agrobacterium transformation method was used to transform the rice receptor with the OsMOF gene expression vector OsMOF-pCAMBIA1306.

[0029] In the examples of the present invention, the rice transformed lines with overexpression of the OsMOF gene were sown, and the histone acetylation modification functional protein OsMOF in epigenetic modification was used to improve the salt tolerance trait of rice, and the obtained rice transformed lines with overexpression of the OsMOF gene were used for the production application of increasing rice yield.

[0030] The amino acid sequences shown in SEQ ID NO.4 - SEQ ID NO.12 of the present invention are only homologous sequences with the same function listed in the present invention. Proteins composed of amino acids shown in any one of SEQ ID NO.4 - SEQ ID NO.12, and proteins with the same function obtained by substitution and / or deletion and / or addition of one or several amino acid residues to the amino acids shown in any one of SEQ ID NO.4 - SEQ ID NO.12; the functional domains of proteins composed of amino acids shown in any one of SEQ ID NO.4 - SEQ ID NO.12; genes encoding proteins shown in any one of SEQ ID NO.4 - SEQ ID NO.12; recombinant vectors containing proteins shown in any one of SEQ ID NO.4 - SEQ ID NO.12; and the applications of expression cassettes, transgenic cell lines or recombinant bacteria containing proteins shown in any one of SEQ ID NO.4 - SEQ ID NO.12 in improving the salt tolerance traits of rice should all be regarded as the protection scope of the present invention.

[0031] Compared with the prior art, the present invention transfers the expression vector of the OsMOF gene into a rice receptor and sows the overexpressed rice transformant lines of the OsMOF gene. It is found that using the histone acetylation modification functional protein OsMOF in epigenetic modification can not only improve the germination traits of rice seeds under salt stress, but also improve the survival rate of rice seedlings under salt stress, thereby significantly improving the salt tolerance traits of rice. Therefore, the present invention provides a new way for enhancing the salt tolerance of rice and accelerating the process of molecular breeding for rice stress resistance, etc. Brief Description of the Drawings

[0032] Figure 1 It is the genomic transcriptional structure diagram of the rice OsMOF gene.

[0033] Figure 2 It is the structural diagram of the functional domain of the rice OsMOF protein.

[0034] Figure 3 It is the structural diagram of the T-DNA insertion region of the OsMOF-pCAMBIA1306 expression vector.

[0035] Figure 4 It is the RTpcr verification of the OsMOF rice stable overexpression transformant line.

[0036] Figure 5 It is the germination phenotype of rice seeds overexpressing the OsMOF gene under improved salt stress.

[0037] Figure 6 It is the data of the germination traits of rice seeds overexpressing the OsMOF gene under improved salt stress.

[0038] Figure 7To improve the phenotype of the survival rate of rice seedlings under salt stress by overexpressing the OsMOF gene.

[0039] Figure 8 To improve the survival rate of rice seedlings under salt stress by overexpressing the OsMOF gene. Specific implementation manners

[0040] The following further elaborates on the present application in conjunction with the accompanying drawings and examples. It should be specifically noted that: for those conditions not specified in the following examples, they are carried out according to conventional conditions or the conditions recommended by the manufacturer. Except for special instructions, the raw materials used in the following examples can all be obtained from ordinary commercial sources.

[0041] Example 1 Construction of the OsMOF gene expression vector 1. Structure composition of the OsMOF gene and protein The rice OsMOF gene is located on chromosome 7 of rice. The full length of the genomic transcription region is 4891 bp, and the gene number is LOC_Os07g43360. The transcription structure diagram is as shown in Figure 1 shown. The full length of the transcription sequence is 1655 bp, of which the coding region is 1353 bp in full length, and the sequence is as shown in SEQ ID NO.1. This gene encodes 450 amino acids. The NCBI number of the OsMOF protein sequence is XP_015644713.1, and the amino acid sequence is as shown in SEQ ID NO.2. The rice OsMOF protein contains 1 RNA binding activity-knot (RNA binding activity) functional domain and 1 N-Acyltransferase superfamily (acetyltransferase activity) functional domain. The protein functional domain structure diagram is as shown in Figure 2 shown.

[0042] 2. Construction of the rice OsMOF gene expression vector 2.1 The full-length sequence of the transcription coding region of the OsMOF gene was amplified from the transcriptome cDNA of the indica rice variety Minghui 63 by the PCR method.

[0043] 2.2 Codon optimization was carried out on the bases at positions 1 bp - 294 bp in the OsMOF gene sequence. This codon optimization only involves codon base substitution, and the amino acids of the encoded product are the same as those of the codon-encoded product of the OsMOF gene with the gene number LOC_Os07g43360. The optimized base sequence is as shown by the bases at positions 1 - 294 bp in SEQ ID NO.3, the full-length coding region sequence of the OsMOF gene is as shown by the bases at positions 1 - 1353 bp in SEQ ID NO.3, and the amino acid sequence of the encoded product of the optimized sequence is as shown by the amino acids at positions 1 - 98 aa in SEQ IDNO.2.

[0044] 2.3 Optimize the full-length base sequence of the OsMOF gene and insert it downstream of the 35S constitutive promoter of the pCAMBIA1306 vector to obtain the OsMOF-pCAMBIA1306 expression vector. The T-DNA insertion region of this vector for plant transformation is as shown in Figure 3 shown.

[0045] Example 2 Transformation of the rice receptor with the OsMOF gene expression vector The rice material is the indica rice variety Minghui 63. The transformation receptor material is the callus induced from the mature embryos of this variety. The plant medium used in the transformation process is the MS basal medium, and the main components and formula are shown in Table 1. The transformation method is the Agrobacterium-mediated transformation method. The Agrobacterium strain is Agrobacterium tumefaciens LBA4404, and the microbial medium used for culturing Agrobacterium during the transformation process is the YEP medium.

[0046] Table 1 Plant medium for rice transformation Note: *All the above media contain 30 g / L sucrose + 2.5 g / L plant agar 1. Induction of rice callus 1.1 Remove the glumes from the seeds of the mature indica rice variety Minghui 63; 1.2 Under sterile conditions, soak in 70% ethanol for 5 min and wash with sterile water 3 - 5 times; 1.3 Soak in 0.1% mercuric chloride for 20 min and wash with sterile water 3 - 5 times; 1.4 Drain off all the moisture and inoculate the seeds onto the induction medium; 1.5 Incubate in the dark at 26°C. After 20 days, isolate the callus and subculture.

[0047] 2. Transformation of the vector plasmid into Agrobacterium 2.1 Take 200 μl of Agrobacterium competent cells, add 1 μg of the vector plasmid, mix well, and place on ice for 5 min; 2.2 Freeze the mixture in liquid nitrogen for 5 min, then incubate in a water bath at 37°C for 5 min; 2.3 Add liquid YEP medium to dilute to 1 ml and culture with shaking at 28°C for 4 h; 2.4 Centrifuge at 5000 rpm for 2 min to enrich the bacterial solution, remove 900 μl of the supernatant, resuspend the bacterial solution and spread it on a YEP solid plate containing rifampicin and kanamycin, and culture at 28°C for 2 - 3 days to obtain transformant monoclonal colonies; 2.5 Pick monoclonal colonies for shaking culture, identify positive transformation clones, add 20% glycerol, and quickly freeze in liquid nitrogen and store at -80°C.

[0048] 3. Obtaining Transformed Rice Lines by Agrobacterium-mediated Transformation 3.1 Agrobacterium was cultured in YEP liquid medium at 28°C with shaking at 200 rpm until the OD value reached 0.6 - 0.8. 40 μl of AS (acetosyringone) was added to every 40 ml of the bacterial solution.

[0049] 3.2 The callus granules were soaked in the prepared Agrobacterium bacterial solution for 20 - 30 min, and shaken constantly during this period.

[0050] 3.3 The callus pieces were taken out, blotted dry on sterile filter paper to remove excess bacterial solution, and transferred to the co-culture medium. A layer of sterile filter paper was laid on the surface of the medium, and the callus was not in direct contact with the medium on the filter paper. It was cultured in the dark at 26°C for 6 days.

[0051] 3.4 The callus pieces were taken out, washed 3 - 5 times with sterile water, and then washed 2 - 3 times with sterile water containing rifampicin (50 mg / L) and kanamycin (50 mg / L). After blotting dry the excess water with sterile filter paper, the callus was transferred to the primary screening medium.

[0052] 3.5 The transformed callus was subjected to two rounds of primary and secondary screening, and cultured in the dark at 26°C for about 20 days.

[0053] 3.6 The callus was transferred to the differentiation medium and cultured under the condition of 26°C with 16 h of light per day for differentiation.

[0054] 3.7 After green seedlings were differentiated, the small seedlings were transferred to the rooting medium.

[0055] 3.8 When the differentiated seedlings grew to about 10 cm in height and had strong root growth, they were acclimatized to the environment with the lid open for about 7 days. Then they were removed from the rooting medium, the residual medium was washed off, and transplanted to the greenhouse or field.

[0056] 3.9 The candidate transformed plants were detected by PCR amplification to obtain positive T0 generation plants containing the OsMOF transformation fragment, and multiplied by generations in the field.

[0057] 3.10 The OsMOF homozygous lines were obtained, the total RNA of the transformed lines was extracted, reverse transcribed into cDNA, and the expression level of OsMOF was detected by RT-PCR using OsMOF gene-specific primers to verify the positive rice lines with stable overexpression of the OsMOF gene. The RT-PCR identification results of the positive transformed lines are as Figure 4 shown.

[0058] Example 3 Salt Tolerance Traits of Rice Lines with OsMOF Gene Expression 1. Improvement of Germination Traits of Rice Seeds under Salt Stress in Rice Lines with Overexpression of the OsMOF Gene Take wild-type control strain and OsMOF overexpression strain of rice seeds. After breaking dormancy by treating with high temperature at 50 °C for 2 days, place the seeds in a petri dish lined with a 9-cm round filter paper and add 15 ml of NaCl solution with concentrations of 0, 40, 80, and 120 mM respectively. Record the seed germination situation every day. Take the root length or shoot length > 1 / 2 of the seed length as the standard to record the number of germinated seeds per day, and take pictures to record the seed germination situation and measure the shoot length on the 12th day of the experiment.

[0059] Compared with the seeds of the wild-type control strain, the rice seeds of the OsMOF overexpression strain showed a better phenotype of shoot germination and growth under the treatment of the same higher salt concentration and the same germination days ( Figure 5 ).

[0060] In terms of statistical analysis of germination traits, after the same time under the treatment of the same salt concentration, the seeds of the OsMOF overexpression strain had a higher germination rate, a longer shoot length, and a better growth condition. As Figure 6 shown, after treatment with 40 mM, 80 mM, and 120 mM salt concentrations, the germination rate of the OsMOF overexpression strain increased significantly, and its average shoot length increased significantly, indicating that the germination process of the seeds of the OsMOF overexpression strain was less affected by salt stress, suggesting that OsMOF promotes the tolerance of rice to salt stress at the seed germination stage.

[0061] 2.Improving the survival rate of rice seedlings under salt stress in the rice lines overexpressing the OsMOF gene Take wild-type control strain and OsMOF overexpression strain of rice seeds. After breaking dormancy by treating with high temperature at 50 °C for 2 days, soak the seeds in 0.5% hydrogen peroxide for two days to promote germination. Place the germinated seeds in 20-fold diluted MS culture solution for hydroponics for 14 days until most of the seedlings grow to the three-leaf stage, and then use 140 mM NaCl solution for hydroponics for 7 days for salt stress treatment. After the salt stress treatment, change back to 20-fold diluted MS culture solution for hydroponics for 7 days to allow the surviving seedlings to recover, and distinguish and count the dead seedlings. Take pictures to record the phenotype and count the seedling survival rate 7 days after the recovery treatment.

[0062] Observing the phenotypes of rice seedlings before salt stress treatment and after the end of the recovery treatment, it can be seen that after the end of the recovery treatment, the growth and survival of the rice seedlings of the OsMOF overexpression strain were better ( Figure 7 ).

[0063] The statistical analysis results of the survival rate showed that the survival rates of the seedlings of the three independent transgenic lines of the OsMOF overexpression strain were significantly higher than those of the wild-type control strain under the treatment of 140 mM salt concentration ( Figure 8 ). After treatment with the same concentration of salt stress, the rice seedlings of the OsMOF overexpression strain showed a better survival state and a higher survival rate. Therefore, the OsMOF protein can promote the enhancement of the salt stress tolerance of rice seedlings at the three-leaf stage.

[0064] This specific embodiment is only an interpretation of the present application and does not limit the present application. After reading this specification, those skilled in the art can make modifications to this embodiment that do not contribute creatively as needed, but as long as it is within the scope of the claims of the present application, it is protected by the patent law.

Claims

1. Application of OsMOF protein in improving salt tolerance traits of rice, characterized in that, The OsMOF protein is any one of the following (a)-(c): (a) A protein composed of the amino acids shown in SEQ ID NO.2; (b) A protein derived from (a) with the same function, in which the amino acids shown in SEQ ID NO.2 are substituted and / or deleted and / or added by one or several amino acid residues; (c) A protein or its derivative with at least 85% sequence identity and the same function as (a), which is derived from other varieties of rice or other species.

2. The application according to claim 1, wherein The improved salt tolerance traits of the rice include improving the germination traits of rice seeds under salt stress and the survival rate of rice seedlings under salt stress conditions.

3. Use of the gene encoding the OsMOF protein described in claim 1 in improving the salt tolerance trait of rice, characterized in that, The gene sequence is any one of the following (d)-(f): (d) A DNA molecule whose coding region is the sequence shown in SEQ ID NO.1; (e) A DNA molecule that hybridizes with the DNA sequence defined in (d) under stringent conditions and encodes a protein with the same function; (f) A DNA molecule with at least 90% sequence identity to the DNA sequence defined in (d) and encodes a protein with the same function.

4. The application according to claim 3, wherein The improved salt tolerance traits of the rice include improving the germination traits of rice seeds under salt stress and the survival rate of rice seedlings under salt stress conditions.

5. The application of the recombinant vector containing the OsMOF gene described in claim 3 in improving the salt tolerance traits of rice.

6. The application according to claim 5, characterized in that, The recombinant vector is a vector in which the coding gene of the OsMOF protein is inserted downstream of the 35S constitutive promoter of the pCAMBIA1306 vector.

7. The application according to claim 5, wherein The improved salt tolerance traits of the rice include improving the germination traits of rice seeds under salt stress and the survival rate of rice seedlings under salt stress conditions.

8. The application of the expression cassette, transgenic cell line or recombinant bacterium containing the coding gene of the OsMOF protein described in claim 3 in improving the salt tolerance traits of rice.

9. The application according to claim 8, wherein The improved salt tolerance traits of the rice include improving the germination traits of rice seeds under salt stress and the survival rate of rice seedlings under salt stress conditions.

10. A method for improving the salt tolerance trait of rice, characterized in that, Construct the recombinant vector described in claim 4, transform the recombinant vector into a rice receptor, and obtain a rice transformant line with overexpression of the OsMOF gene.

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