Drought-resistant genes of maize and their use

Abstract

The present application relates to a corn drought-resistant gene and its application, and belongs to the field of genetic engineering. The present application obtains a corn ZmJAZ12 gene with drought resistance, and overexpression of ZmJAZ12 can further improve the drought resistance of corn.

Description

TECHNICAL FIELD

[0001] The present application relates to a corn drought resistance gene and its application, and belongs to the field of genetic engineering. BACKGROUND

[0002] In recent years, drought and other abiotic stresses have become one of the factors affecting the yield of corn. The mechanism of drought resistance of corn is very complex. Under stress conditions, corn plants regulate drought tolerance through various adaptive changes, which are manifested in stomatal regulation, plant hormone regulation, active oxygen scavenging, osmotic regulation and osmotic protection, and ion balance in the body. When stressed, corn plants use some adaptive mechanisms at the molecular level, such as regulating the opening and closing of leaf stomata and the water absorption and water retention capacity of root systems, to reduce the destructive effects of drought on cells. Therefore, the accumulation or inhibition of specific proteins in tissues such as leaves and roots and the up-regulation or down-regulation of many gene transcripts when stress occurs can help improve the drought resistance of corn.

[0003] JAZ protein is a unique protein in plants, belonging to the TIFY protein family and located in the nucleus. JAZ protein plays a core inhibitory factor role in the jasmonic acid (JA) signaling pathway in plants. The function of JAZ protein is diverse and redundant. There are as many as 39 members of the JAZ protein family in corn, and the functions of most of them are not clear.

[0004] The present application finds that the corn ZmJAZ12 gene is related to the drought resistance of corn through transcriptome and correlation analysis, and the overexpression of ZmJAZ12 can further improve the drought resistance of corn. SUMMARY

[0005] The purpose of the present application is to provide a method for improving the drought resistance of corn.

[0006] To achieve the above purpose, the present application adopts the following technical solutions:

[0007] The present application provides an application of a protein in regulating the drought resistance of corn, characterized in that the amino acid sequence of the protein is shown in SEQ ID NO. 1.

[0008] The present application also provides an application of a nucleic acid in regulating the drought resistance of corn, characterized in that the nucleic acid encodes the above-mentioned protein.

[0009] In some embodiments, the nucleotide sequence of the above-mentioned nucleic acid is shown in any one of SEQ ID NO. 2 or SEQ ID NO. 3.

[0010] The present application also provides a method for improving the drought resistance of corn, characterized in that the expression and / or activity of the above-mentioned protein is improved in corn, and a corn material with improved drought resistance is selected.

[0011] In some embodiments, the above method for improving protein expression and / or activity is driven by a high-activity promoter.

[0012] In some embodiments, the above high-activity promoter sequence is shown as SEQ ID NO. 4.

[0013] The present application also provides an expression cassette for improving drought resistance of corn, characterized in that the expression cassette is sequentially and operably linked by a corn ubiquitin gene promoter, a nucleic acid molecule encoding a protein sequence shown in SEQ ID NO. 1, and an Agrobacterium tumefaciens nopaline synthase gene terminator.

[0014] In some embodiments, the above corn ubiquitin gene promoter sequence is shown as SEQ ID NO. 4, the above nucleic acid molecule sequence encoding a protein sequence shown in SEQ ID NO. 1 is shown as SEQ ID NO. 2, and the above Agrobacterium tumefaciens nopaline synthase gene terminator sequence is shown as SEQ ID NO. 5.

[0015] Compared with the prior art, the present application has the beneficial effects that the present application finds that overexpression of ZmJAZ12 gene can improve the drought resistance of corn, and provides a new method for improving the drought resistance of corn and cultivating new drought-resistant corn varieties. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 Expression analysis of corn JAZ family members in response to drought stress. A: Corn JAZ family members and phylogenetic tree analysis. B: Expression analysis of corn JAZ family members in response to drought stress. C: Expression amounts of 6 genes in response to drought stress. FPKM: Fragments Per Kilobase of exon model per Million mapped fragments, representing gene expression amount. WW (normal watering), DT2 (soil moisture 30-35%), DT3 (soil moisture 20-25%), and DT4 (soil moisture 10-15%).

[0017] Figure 2 Physical map of expression vector pXG071-ZmJAZ12-T03. Each element is labeled on the map.

[0018] Figure 3Drought resistance of ZmJAZ12 overexpressed maize. A: plant performance after drought treatment. WT: wild type control; OE1, OE2: two overexpression lines; Watered: normal water treatment; After drought: drought treatment. B: plant survival rate data statistics. CK: wild type control; OE1, OE2: two overexpression lines; * indicates significant difference. C: relative expression of ZmJAZ12. CK: wild type control; OE1, OE2: two overexpression lines. D: leaf water loss rate data statistics. OE1(+), OE2(+): two positive overexpression lines; OE1(-), OE2(-): negative controls isolated from two overexpression lines. DETAILED DESCRIPTION

[0019] The following definitions and methods are provided to better define the present application and to guide working practitioners in the art. Unless otherwise defined, terms are to be understood according to their common use by those of ordinary skill in the art. All patents, publications, scientific articles, and other public publications cited herein are incorporated by reference in their entirety.

[0020] As used herein, "maize" is any maize plant and includes all plant parts, including whole plants, plant cells, plant organs, plant protoplasts, plant cell and tissue cultures from which maize plants can be regenerated, plant cuttings, intact plants, plant cells that are intact, complete plant cells in a plant or plant part, such as embryos, pollen, ovules, seeds, leaves, flowers, branches, fruit, stems, roots, root tips, anthers, and the like, which can be regenerated into plants having all the characteristics of the described plants. Nucleic acids are written left to right in 5' to 3' orientation, unless otherwise indicated; amino acid sequences are written left to right in amino to carboxyl orientation, unless otherwise indicated. Amino acids can be referred to herein by either the commonly accepted single-letter codes, or by accepted three-letter codes. Similarly, nucleotides, or fragments of nucleotides, can be referred to by acceptably known single letter codes. Numeric ranges are inclusive of the numbers defining the range. As used herein, "nucleic acid" includes polynucleosides or polynucleotides in either single- or double-stranded form, and unless otherwise limited, includes known analogues of natural nucleotides that have similar binding properties as the reference nucleic acid and hybridize to single-stranded nucleic acids in a manner similar to naturally occurring nucleotides. As used herein, the term "encoding" or "encoded" with respect to a specified nucleic acid sequence is intended to mean that the nucleic acid sequence includes a code, or instructions, for making a specific protein. The code is in the form of a sequence of nucleotides that is translated into the amino acid sequence of the protein. As used herein, reference to "full-length sequence" with respect to a particular polynucleotide or its encoded protein refers to the entire nucleic acid sequence or the entire amino acid sequence having the native (non-synthetic) endogenous sequence. A full-length polynucleotide encodes a full-length, catalytically active form of the particular protein. The terms "polypeptide," "polypeptide," and "protein" are used interchangeably herein to refer to a polymer of amino acid residues. The term is used in its ordinary sense, including amino acid polymers in which one or more amino acid residues are artificial chemical mimics of a naturally occurring amino acid. The term also is used in its ordinary sense to include naturally occurring amino acid polymers. The terms "residue" or "amino acid residue" or "amino acid" are used interchangeably herein to refer to an amino acid that is incorporated into a protein, polypeptide, or peptide (collectively "protein"). The amino acid can be a naturally occurring amino acid, and unless otherwise limited, can include known analogs of naturally occurring amino acids that can function in a manner similar to the naturally occurring amino acid.

[0021] The term "trait" refers to a physiological, morphological, biochemical, or physical characteristic of a plant or a particular plant material or cell. In some cases, the characteristic is visible to the human eye, such as seed or plant size, or can be measured by biochemical techniques, such as detecting protein, starch, or oil content of seeds or leaves, or by observing metabolic or physiological processes, for example, by measuring tolerance to water deprivation or specific salt or sugar or nitrogen concentrations, or by observing expression levels of one or more genes, or by agronomic observations such as osmotic stress tolerance or yield.

[0022] A "transgene" refers to any cell, cell line, callus, tissue, plant part or plant having a genome that has been altered as a result of the presence of heterologous nucleic acid, such as a recombinant DNA construct. The term "transgene" as used herein encompasses those initial transgenic events as well as those derived from the initial transgenic event through sexual crosses or asexual reproduction and does not encompass genomic (chromosomal or extrachromosomal) alterations made by conventional plant breeding methods or by naturally occurring events such as random cross-fertilization, non-recombinant viral infection, non-recombinant bacterial transformation, non-recombinant transposition or spontaneous mutation.

[0023] A "plant" includes references to whole plants, plant organs, plant tissues, plant seeds and plant cells, and progeny of the same. Plant cells include, but are not limited to, cells from seeds, suspension cultures, embryos, meristematic regions, callus tissue, leaves, roots, shoots, gametophytes, sporophytes, pollen, and microspores. "Progeny" encompasses the genetic progeny of a plant.

[0024] In this application, the words "comprise," "comprises," or "comprising" are used in their inclusive sense, meaning that additional elements, numbers, or steps can be included. A "subject plant" or "subject plant cell" refers to a plant or plant cell in which a genetic modification has taken effect, or a progeny cell of such a plant or cell that contains the modification. A "control" or "control plant" or "control plant cell" provides a reference point for measuring phenotypic changes in a subject plant or plant cell.

[0025] A negative or control plant can include, for example: (a) a wild-type plant or cell, i.e., a plant or cell having the same genotype as the starting material for a genetic modification that produced the subject plant or cell; (b) a plant or plant cell having the same genotype as the starting material but that has been transformed with an empty construct, i.e., a construct that has no known effect on the trait of interest, such as a construct comprising a marker gene; (c) a plant or plant cell that is a non-transformed segregant of the subject plant or plant cell; (d) a plant or plant cell that is genetically identical to the subject plant or plant cell but that has not been exposed to a condition or stimulus that induces expression of the gene of interest; or (e) the subject plant or plant cell itself, under conditions in which the gene of interest is not expressed.

[0026] Those skilled in the art will readily recognize, for example, that advances in the field of molecular biology, such as site-specific mutagenesis and random mutagenesis, polymerase chain reaction methods, and protein engineering techniques, provide a wide range of appropriate tools and procedural steps for modifying or engineering the amino acid sequence and potentially the genetic sequence of a protein of interest in agriculture.

[0027] In some embodiments, the nucleotide sequences of the application can be altered to make conservative amino acid substitutions. Principles and examples of conservative amino acid substitutions are further described below. In certain embodiments, the nucleotide sequences of the application can be altered without changing the amino acid sequence, e.g., codons preferred by monocots can be substituted for codons encoding the same amino acid sequence without changing the amino acid sequence encoded by the nucleotide sequence. In some embodiments, portions of the nucleotide sequences in the application are replaced with different codons that encode the same amino acid sequence, thereby altering the nucleotide sequence while not changing the amino acid sequence it encodes. Conservative variants include those sequences that encode the same amino acid sequence of a protein of the embodiments due to the degeneracy of the genetic code. In some embodiments, portions of the nucleotide sequences in the application are replaced according to monocot-preferred codons. Those of skill in the art will recognize that amino acid additions and / or substitutions generally are based on the relative similarity of the amino acid side chains, for example, as is shown by the hydrophilicity, charge, size, and the like. Exemplary amino acid substitution groups that take various of the foregoing considerations into account are well-known in the art and include: arginine and lysine; glutamate and aspartate; serine and threonine; glutamine and asparagine; and valine, leucine, and isoleucine. Guidance in appropriate amino acid substitutions that do not affect the biological activity of the protein of interest can be found in the model of Dayhoff et al. (1978) Atlas of Protein Sequence and Structure (Natl. Biomed. Res. Found., Washington, D.C.), incorporated herein by reference. Conservative substitutions can be made, such as replacing one amino acid with another amino acid of similar properties. Identification of sequence identity includes hybridization techniques. For example, all or a portion of a known nucleotide sequence is used as a hybridization probe to selectably hybridize to other corresponding nucleotide sequences present in a population of cloned genomic DNA fragments or cDNA fragments from a selected organism (i.e., a genomic or cDNA library). The hybridization probe can be a genomic DNA fragment, a cDNA fragment, an RNA fragment, or other oligonucleotide, and can be labeled with a detectable group, such as32P, or other detectable marker. Thus, for example, a hybridization probe can be prepared by labeling a synthetic oligonucleotide based on an embodiment sequence. Methods for preparing hybridization probes and constructing cDNA and genomic libraries are generally known in the art. The hybridization of the sequences can be performed under stringent conditions. As used herein, the term "stringent conditions" or "stringent hybridization conditions" means conditions under which a probe will hybridize to its target sequence to a detectably greater degree than to other sequences (e.g., at least 2-fold, 5-fold, or 10-fold background).Stringency conditions are sequence dependent, and are different under different circumstances. By controlling hybridization stringency and / or controlling wash conditions, one can identify target sequences that are 100% complementary to the probe (homologous probe method). Alternatively, one can adjust stringency conditions to allow some sequence mismatch, in order to detect lower degrees of similarity (heterologous probe method). Typically, the probe is less than about 1000 or 500 nucleotides in length. Typically, stringency conditions are conditions under which the salt concentration is less than about 1.5 M Na ion, typically about 0.01 to 1.0 M Na ion concentration (or other salts) at pH 7.0 to 8.3 and the temperature is that at which DNA is normally melted (about 50°C for a 1 kb DNA fragment; about 60°C for a 0.1 kb DNA fragment; and about 65°C for a 0.05 kb DNA fragment). Stringent conditions can also be achieved with the addition of destabilizing agents such as formamide. Exemplary low stringency conditions include hybridization in 30 to 35% formamide, 1 M NaCl, 1% SDS at 37°C, with a wash in 0.1 x to 0.2 x SSC at 37°C. Exemplary moderate stringency conditions include hybridization in 40 to 45% formamide, 1 M NaCl, 1% SDS at 37°C, with a wash in 0.1 x to 0.2 x SSC at 55°C. Exemplary high stringency conditions include hybridization in 50% formamide, 1 M NaCl, 1% SDS at 37°C, with a wash in 0.1 x to 0.2 x SSC at 60 to 65°C. Optionally, the wash buffer can include about 0.1% to about 1% SDS. The duration of hybridization is typically less than about 24 hours, often about 4 to about 12 hours. Specificity is typically dependent on the length of the probe and the degree of mismatching, with longer probes and less mismatching being more specific. The degree of mismatching can be controlled by the length of the probe and the temperature of hybridization. The Tm (temperature of melting) of a DNA-DNA hybrid can be approximated from the equation of Meinkoth and Wahl (1984) Anal. Biochem. 138:267-284: Tm = 81.5°C + 16.6(log M) + 0.41(%GC) - 0.61(%formamide) - 500 / L; where M is the molarity of monovalent cations, %GC is the percentage of guanosine and cytosine nucleotides in the DNA, "%formamide" is the percentage of formamide in the hybridization solution, and L is the length of the hybrid in base pairs. Tm is the temperature at which 50% of the complementary target sequence will hybridize with a perfectly matched probe, at the specified ionic strength and pH. Washes are typically carried out at least to the point of equilibrium, and to a low background level of hybridization, such as for 2 hours, 1 hour, or 30 minutes. Each 1% of mismatch corresponds to a decrease in Tm of about 1°C; thus, one can adjust the Tm, hybridization, and / or wash conditions to hybridize with sequences of the desired degree of identity. For example, if sequences of >90% identity are desired, one can decrease the Tm by 10°C.Typically, stringency conditions are chosen to be about 5°C lower than the Tmof specific sequences and their complements under the conditions of the particular nucleic acid hybridization or cleavage reaction. However, under very stringent conditions, hybridization and / or washing can be performed at 4°C lower than the Tm; under moderately stringent conditions, at 6°C lower than the Tm; and under low stringency conditions, at 11°C lower than the Tm.

[0028] In some embodiments, fragments of the nucleotide sequences and the amino acid sequences they encode are also included. As used herein, the term "fragment" refers to a portion of the nucleotide sequence of a polynucleotide or a portion of the amino acid sequence of a polypeptide of the embodiments. Fragments of the nucleotide sequences can encode protein fragments that retain the biological activity of the native or corresponding full-length protein and thus have the protein activity. Mutant proteins include biologically active fragments of native proteins that comprise contiguous amino acid residues that retain the biological activity of the native protein. Some embodiments also include transformed plant cells or transgenic plants comprising at least one nucleotide sequence of the embodiments. In some embodiments, plants are transformed using an expression vector comprising at least one nucleotide sequence of the embodiments operably linked to a promoter that drives expression in plant cells. Transformed plant cells and transgenic plants represent plant cells or plants that comprise a heterologous polynucleotide within the genome. Generally, the heterologous polynucleotide is stably integrated within the genome of the transformed plant cell or transgenic plant such that the polynucleotide is passed to progeny. The heterologous polynucleotide can be integrated into the genome either alone or as part of an expression vector. In some embodiments, plants contemplated by the present application include plant cells, plant protoplasts, plant cell tissue cultures from which plants can be regenerated, plant calli, plant clumps, and plant cells that are intact plants or parts of plants, such as embryos, pollen, ovules, seeds, leaves, flowers, branches, fruit, kernels, ears, cobs, husks, stalks, roots, root tips, anthers, and the like. The present application also includes plant cells, protoplasts, tissues, calli, embryos, and flowers, stems, fruits, leaves and roots of the transgenic plants or their progeny that originate plant cells that have been transformed with the nucleotide sequences of the present application and that, at least partially, comprise the nucleotide sequences of the present application.

[0029] The term "amplification" in the context of nucleic acid amplification is any process in which additional copies of a selected nucleic acid (or its transcribed form) are produced. General amplification methods include various polymerase-based replication methods, including the polymerase chain reaction (PCR), ligase-mediated methods such as ligase chain reaction (LCR), and RNA polymerase-based amplification (e.g., by transcription) methods.

[0030] The following examples are intended to illustrate the present application but not to limit the scope of the present application. Modifications or substitutions of the methods, steps or conditions of the present application are possible without departing from the spirit and scope of the present application. Unless otherwise specified, the examples are performed according to the conventional experimental conditions, such as Sambrook et al. Molecular Cloning: A Laboratory Manual, 2001, or according to the conditions suggested by the manufacturer. Unless otherwise specified, the chemical reagents used in the examples are conventional commercially available reagents, and the technical means used in the examples are conventional means known to those skilled in the art.

[0031] Example 1 Identification of drought resistance genes in maize

[0032] The present application uses high-density SNP markers in association population materials and survival rate data of 368 maize inbred lines under drought treatment conditions to perform association analysis on maize drought resistance candidate genes. The survival rate of drought seedlings is used as the phenotypic data, and the SNP markers have a total of 525105 (MAF>0.05), of which multiple are related to JAZ family member genes (Table 1).

[0033] The present application further analyzes maize JAZ family member genes by B73 transcriptome under different gradient drought conditions. Different gradient droughts are selected to treat WW (normal watering), DT2 (soil moisture is 30-35%), DT3 (soil moisture is 20-25%) and DT4 (soil moisture is 10-15%) (for reference Plant J, 2019, 98(4): 697-713), and it is found that six JAZ family members significantly affect their expression levels after drought Figure 1 ), of which the expression level of ZmJAZ12 gene is the most significant, indicating that ZmJAZ12 (LOC number in B73 reference genome is Zm00001d027900 or GRMZM5G838098) is a gene related to maize drought resistance.

[0034] Table 1 Partial JAZ genes with significant signals after GWAS analysis

[0035]

[0036] Example 2 Overexpression of ZmJAZ12 gene

[0037] Since ZmJAZ12 (genomic sequence is shown as SEQ ID NO. 3) has multiple transcripts, ZmJAZ12-T3 is selected to construct an overexpression vector. The specific construction process is as follows:

[0038] The pXG071 plasmid was digested with BamHI and HindIII, and the vector fragment was recovered. The artificially synthesized ZmJAZ12T03 (as shown in SEQ ID NO. 2) was designed to have BamHI and HindIII digestion sites, and was ligated into the BamHI and HindIII sites of the vector pXG071 to construct a plant expression vector, named pXG071-ZmJAZ12-T03. The vector contains one independent T-DNA region, which includes the ZmJAZ1T03, red fluorescent marker Dsred and bar gene expression cassette. Among them, ZmJAZ12T03 is driven by the ubiquitin promoter Ubi from corn (containing the ubiquitin 5'UTR region and the first intron, the sequence is shown in SEQ ID NO. 4) (the terminator uses the nopaline synthase gene terminator Nos polyA of Agrobacterium tumefaciens, the sequence is shown in SEQ ID NO. 5). pXG071-ZmJAZ12-T03 was transformed into Agrobacterium EHA105, which was used for subsequent experiments of Agrobacterium-mediated transformation of corn young embryos and callus.

[0039] Agrobacterium EHA105 containing pXG071-ZmJAZ12-T03 was plated on YEP solid medium and incubated at 28°C in the dark for 1-3 days. The cultured Agrobacterium was scraped off the plate and resuspended, and the OD550 was adjusted to 0.3 to prepare an infection solution for standby.

[0040] The corn y822 (a corn inbred line selected by Jilin Academy of Agricultural Sciences) young ear 9-12 days after pollination was taken, the bract was peeled off, and 75% alcohol was used for disinfection for 10 min. The young embryos were taken out and placed in a centrifuge tube containing 2 mL of resuspension solution, 100 young embryos per tube, for standby.

[0041] When infected, the resuspension solution was discarded, 2 mL of infection solution was added, and the centrifuge tube was gently inverted several times to mix, and then was left still at room temperature in the dark for 5 min. After the infection was completed, the young embryo shield was inoculated in the co-culture medium with the shield facing up, and was incubated at 20°C in the dark for 3 days. Then it was transferred to the resting medium and incubated at 28°C in the dark for 7 days. Then it was transferred to the selection medium S1 containing 1.5 mg / L of double propanolamine, and was incubated at 28°C in the dark for 2 weeks. If the initial callus has been obtained, it is transferred to the screening medium S2 containing 3 mg / L of double propanolamine, and the S2 medium is replaced every two weeks.

[0042] When the resistant callus obtained by screening is proliferated to about 2 cm in diameter, it is transferred to dark differentiation medium and cultured at 25°C in the dark for 2-3 weeks. The embryo sheath obtained by differentiation is transferred to light differentiation medium and cultured at 25°C under light for 2 weeks. When the embryo sheath forms complete seedlings and roots, the seedlings are transferred into culture bottles for root promotion and seedling strengthening. After 10 days, the seedlings are transplanted into nutrient pots and cultured in an indoor greenhouse. After the seedlings grow 1-2 new leaves, they are transplanted into large flowerpots and transferred to a large greenhouse, and then daily management is performed according to the conventional method. After the tassels are powdery, self-pollination is performed.

[0043] Example 3 Drought resistance identification of corn

[0044] The transgenic corn and the control are planted in Gongzhuling Transgenic Test Base of Jilin Academy of Agricultural Sciences, and PCR detection is performed on all materials to determine whether they are transgenic corn.

[0045] In the drought survival rate test of corn seedlings, the seeds are grown in the greenhouse soil under normal watering conditions until they grow to the three-leaf stage and stop watering. The ZmJAZ12T03 overexpression materials and negative control seedlings that have developed well in the plate are transplanted into the same pot to ensure that they grow under the same environmental conditions. Nine overexpression materials and control materials are transplanted respectively to further ensure the consistency of the growth conditions. After the materials grow for half a month, i.e., when the corn is in the three-leaf one-heart stage, their growth state is recorded by taking photos, and watering is stopped to simulate drought stress conditions. The wilting state of the leaves is observed and recorded every day. When the overexpression materials and the control materials show obvious growth differences, a rewatering treatment is performed, and then their growth conditions are observed and recorded after one day, and the survival rate is counted.

[0046] The experimental results show that, by comparing multiple different transformants and combining phenotype and agronomic trait data analysis, it is found that the transgenic corn overexpressing ZmJAZ12T03 shows lower leaf water loss rate and significantly increased drought survival rate at the seedling stage than the non-transgenic control (see Figure 2 ), and under the same drought and rewatering treatment conditions, the corn plants show yellowing and death at the leaf tip under drought conditions. Among them, the transgenic material of OE1 survives more than 5 plants after rewatering, while the negative control material almost all dies. It is shown that ZmJAZ12T03 has drought resistance function.

[0047] Although the present application has been described in detail by the general description and specific embodiments above, some modifications or improvements can be made on the basis of the present application, which is obvious to those skilled in the art. Therefore, these modifications or improvements made on the basis of not deviating from the spirit of the present application are within the scope of the present application claimed.

Claims

1. The use of overexpression of a protein in improving drought tolerance in maize, characterized in that, The amino acid sequence of the protein is shown as SEQ ID NO.

1.

2. Use of overexpression of a nucleic acid in improving drought tolerance in maize, characterized in that, The nucleic acid encodes the protein as claimed in claim 1.

3. Use according to claim 2, characterized in that, The nucleotide sequence of the nucleic acid is shown as SEQ ID NO.

2.

4. A method of increasing drought tolerance in maize, comprising, Increasing the expression of the protein as claimed in claim 1 in corn, and selecting corn material with increased drought resistance.

5. The method of claim 4, wherein, The method for increasing the expression of the protein is to use a high-activity promoter to drive the nucleic acid molecule encoding the protein.

6. The method of claim 5, wherein, The high-activity promoter sequence is shown as SEQ ID NO.

4.

7. Use of an expression cassette in improving drought tolerance in maize, characterized in that, The expression cassette is sequentially and operably linked by a corn ubiquitin gene promoter, a nucleic acid molecule encoding the protein sequence shown as SEQ ID NO. 1, and an Agrobacterium tumefaciens nopaline synthase gene terminator.

8. Use according to claim 7, characterized in that, The corn ubiquitin gene promoter sequence is shown as SEQ ID NO. 4, the nucleic acid molecule sequence encoding the protein sequence shown as SEQ ID NO. 1 is shown as SEQ ID NO. 2, and the Agrobacterium tumefaciens nopaline synthase gene terminator sequence is shown as SEQ ID NO. 5.

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