Gene YL2 for improving photosynthesis and yield of rice and application of gene YL2

Abstract

The invention discloses a gene YL2 for improving photosynthesis and yield of rice and application thereof, and relates to the technical field of biology, the nucleotide sequence (1) of the gene YL2 is as shown in SEQ ID No.1 or SEQ ID No.2; or (2) a nucleotide sequence of a mutant, an allele or a derivative generated by adding, substituting, inserting or deleting one or more nucleotides. The invention also provides an encoding protein, a recombinant construct and a recombinant host cell of the gene YL2, and the expression quantity of the gene YL2 is improved by using various means to improve the photosynthesis and yield of rice and the heat resistance. The method has the beneficial effects that by increasing the expression quantity of the YL2 gene, the photosynthesis intensity and the yield per plant of the rice and the heat resistance of the rice can be improved. A gene resource is provided for cultivating a new variety of high-photosynthetic high-yield heat-resistant rice, and meanwhile, the gene has guiding significance for discussing molecular mechanism research of chlorophyll synthesis, chloroplast development and photosynthesis.

Description

Technical Field

[0001] The present invention belongs to the field of agricultural biotechnology, and specifically relates to a gene YL2 for improving rice photosynthesis and yield and its related molecular biological applications. Background Art

[0002] The yield of rice (Oryza sativa L.) is restricted by various physiological and environmental factors, among which photosynthesis efficiency is a key factor determining crop yield. Photosynthesis is the process by which plants use light energy to convert carbon dioxide and water into organic substances, and its efficiency directly affects plant growth, development, and yield formation. Chlorophyll is the core pigment of photosynthesis, participating in capturing light energy and driving photoreactions. The content and distribution of chlorophyll are one of the main factors affecting photosynthesis efficiency. However, due to the limitations of natural genetic variation and the complexity of the photosynthesis regulation mechanism, the progress of improving photosynthesis efficiency using traditional breeding methods is slow.

[0003] Currently, mining functional genes related to photosynthesis through molecular biology techniques and then improving the photosynthesis ability of crops through gene editing or transgenic means has become an important strategy for increasing crop yield. Some known photosynthesis-related genes, such as the Rubisco (ribulose-1,5-bisphosphate carboxylase / oxygenase) encoding gene and light-harvesting antenna protein gene, have been proven to be able to optimize photosynthetic efficiency. However, the improvement effects of these genes are often limited by the multi-level complex regulation of photosynthesis. In addition, the improvement of photosynthesis-related genes often requires balancing multiple parameters such as leaf morphology, biomass allocation, and light energy utilization efficiency, which poses higher requirements for in-depth research on gene functions.

[0004] In order to further explore new gene resources for enhancing photosynthesis efficiency, scientists have adopted various mutant screening techniques. Ion beam mutagenesis, as an efficient mutant creation method, can introduce random mutations into the plant genome, thereby obtaining a mutant population with significant trait changes. Compared with other mutagenesis methods, ion beam mutagenesis has significant advantages in terms of mutation efficiency and mutagenesis spectrum breadth, and has been widely used in the mining of rice functional genes. Summary of the Invention

[0005] The technical problem to be solved by the present invention is how to provide a gene for improving rice photosynthesis and yield, the protein encoded thereby, and applications.

[0006] The present invention solves the above technical problem by the following technical means:

[0007] The gene YL2 for improving rice photosynthesis and yield of the present invention is LOC_Os02g38820.

[0008] In the first aspect of the present invention, a gene YL2 for improving rice photosynthesis and yield is proposed. The nucleotide sequence of the gene YL2 includes:

[0009] (1) as shown in SEQ ID No.1 or SEQ ID No.2;

[0010] or (2) the nucleotide sequence of a mutant, allele or derivative generated by adding, substituting, inserting or deleting one or more nucleotides;

[0011] or (3) a nucleotide sequence that can hybridize with the nucleotide sequence shown in SEQ ID No.2 under stringent conditions and simultaneously encodes a protein with improved rice photosynthesis and yield.

[0012] Stringent conditions refer to placing the hybridization membrane in pre-hybridization solution (0.25 mol / L sodium phosphate buffer, pH 7.2, 7% SDS) at 65°C for 30 minutes; discarding the pre-hybridization solution, adding hybridization solution (0.25 mol / L sodium phosphate buffer, pH 7.2, 7% SDS, isotope-labeled nucleotide fragment), and hybridizing at 65°C for 16 hours; discarding the hybridization solution, adding washing solution I (20 mmol / L sodium phosphate buffer, pH 7.2, 0.1% SDS), washing the membrane at 65°C twice, 10 - 15 minutes each time; adding washing solution II (10 mmol / L sodium phosphate buffer, pH 7.2, 0.1% SDS), and washing the membrane at 65°C for 10 - 15 minutes.

[0013] The present invention uses heavy ion irradiation to irradiate the Chinese japonica rice variety Wuyunjing 7 (WYJ7) to obtain a yellow leaf yl2 (yellow leaf) mutant with yellowing leaf color, reduced chlorophyll content, decreased photosynthetic rate, and reduced yield.

[0014] By constructing a genetic analysis population of the yl2 mutant and analyzing its genetic behavior, the present invention finds that the yellowing leaf phenotype of the yl2 mutant is recessively controlled by the mutated single gene YL2.

[0015] YL2 encodes an oligopeptidase and plays an important role in the development of chloroplasts in rice leaves and the photoprotection mechanism of photosystems in plants. In allelic variations of YL2 and loss-of-function mutants generated by gene editing, the leaf color turns yellow, the chlorophyll content decreases significantly, the photosynthetic rate decreases, and the yield decreases.

[0016] The gene YL2 provides theoretical support for clarifying the synthesis and development of chloroplasts in rice leaves and the improvement of rice photosynthesis at the molecular level in the future.

[0017] In the second aspect of the present invention, a protein encoded by the above gene YL2 is proposed. The amino acid sequence of the protein encoded by the gene YL2 includes:

[0018] (1) as shown in SEQ ID No.3;

[0019] or (2) an amino acid sequence that is different from the amino acid sequence shown in SEQ ID No.3 due to substitution, deletion, and / or insertion of one or more (such as 1 - 25, 1 - 20, 1 - 15, 1 - 10, 1 - 5, 1 - 3) amino acid residues;

[0020] or (3) an amino acid sequence having at least 70%, preferably at least 80%, more preferably at least 90%, especially at least 95% or 98% or 99% identity with the amino acid sequence shown in SEQ ID No.3;

[0021] or (4) an active fragment of the amino acid sequence described in any one of (1) - (3) above.

[0022] The third aspect of the present invention provides a recombinant construct, which contains the nucleotide sequence of the rice leaf color control gene YL2, and the vector used for the recombinant construct is a cloning vector or an expression vector for expressing the nucleotide.

[0023] The fourth aspect of the present invention provides a recombinant host cell, including a host cell containing the above - mentioned recombinant construct, or a polynucleotide sequence containing the above - mentioned gene YL2 in its genome.

[0024] Preferably, the host cell can be selected from plant cells or microbial cells, such as Escherichia coli cells or Agrobacterium cells, preferably plant cells, and most preferably rice cells. The cell can be isolated, in vitro, cultured, or a part of a plant.

[0025] Preferably, the host cell is a microbial cell.

[0026] Preferably, the microbial cell is an Escherichia coli cell or an Agrobacterium cell.

[0027] The fifth aspect of the present invention provides the application of the above - mentioned YL2 gene in improving rice photosynthesis and / or yield breeding, by increasing the expression level of the YL2 gene in rice to increase the photosynthesis ability and the yield per plant of rice

[0028] The sixth aspect of the present invention provides a cultivation method for improving rice photosynthesis and yield, including the following steps: constructing an over - expression vector of YL2, and using transgenic means to transfer the YL2 over - expression vector into a normal rice variety.

[0029] or

[0030] Perform haplotype analysis on the YL2 gene in natural populations to clarify the relationship between the corresponding haplotypes and the expression level of the YL2 gene. Then, transfer the high-expression YL2 haplotype into the rice variety to be transferred using the method of hybridization and backcrossing. That's all.

[0031] The seventh aspect of the present invention provides the application of the YL2 gene or the protein encoded thereby in improving plant stress resistance.

[0032] Preferably, the stress resistance is heat resistance. When the expression level of the YL2 gene decreases or the YL2 gene mutates, the stress resistance of the plant significantly decreases; when the expression level of the YL2 gene is upregulated and / or the activity of the protein encoded by YL2 increases, the stress resistance of the plant increases.

[0033] The beneficial effects of the present invention are as follows:

[0034] 1. The present invention isolated and identified a gene YL2 that controls rice leaf color through map-based cloning. Through phenotypic analysis of the materials and genetic complementation experiments, it was confirmed that the YL2 gene functions in rice leaf regulation and the formation and development of chloroplasts.

[0035] 2. The present invention provides the application of the rice gene YL2 in improving rice photosynthesis and yield. The YL2 gene provided by the present invention also has an obvious effect on plant heat resistance. Inhibiting the expression and function loss of this gene significantly reduces the photosynthesis, yield, and heat resistance of rice. Increasing the expression of the YL2 gene significantly improves the photosynthesis, yield, and heat resistance of rice. Therefore, introducing the YL2 gene into plants for overexpression can lead to plants with improved photosynthesis, yield, and heat resistance, thereby enabling the cultivation of transgenic plants with high photosynthesis, high yield, and stress resistance. The YL2 gene and the encoded protein can be applied to plant genetic improvement. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 Comparison diagram of the plant types of wild-type WT and yl2 mutants in Example 1 of the present invention;

[0037] Figure 2 Comparison diagram of the leaves of wild-type WT and yl2 mutants in Example 1 of the present invention;

[0038] Figure 3 Comparison diagram of the chlorophyll content of wild-type WT and yl2 mutants in Example 1 of the present invention;

[0039] Figure 4 Comparison diagram of the photosynthetic rates of wild-type WT and yl2 mutants in Example 1 of the present invention;

[0040] Figure 5 Comparison diagram of the yield per plant of wild-type WT and yl2 mutants in Example 1 of the present invention;

[0041] Figure 6 This is a comparison diagram of the chloroplast transmission electron micrographs of the wild-type WT and yl2 mutants in Example 1 of the present invention;

[0042] Figure 7 This is the gene mapping diagram of YL2 in Example 2 of the present invention;

[0043] Figure 8 This is the sequencing alignment peak diagram of the YL2 gene of the wild-type WT and yl2 mutants in Example 2 of the present invention;

[0044] Figure 9 This is the protein mutation comparison diagram of the YL2 gene of the wild-type WT and yl2 mutants in Example 2 of the present invention;

[0045] Figure 10 This is the genetic complementation diagram of the YL2 gene in the yl2 mutant map in Example 2 of the present invention;

[0046] Figure 11 This is the CRISPR-Cas9 editing sequencing peak diagram of the YL2 gene in Example 2 of the present invention;

[0047] Figure 12 This is the comparison of the YL2 gene editing and its wild-type WT plant type diagram in Example 2 of the present invention;

[0048] Figure 13 This is the analysis diagram of the expression pattern of the YL2 gene in Example 2 of the present invention;

[0049] Figure 14 This is the subcellular localization diagram of the protein encoded by the YL2 gene in Example 2 of the present invention;

[0050] Figure 15 This is the overexpression plant type diagram of the YL2 gene in Example 3 of the present invention;

[0051] Figure 16 This is the comparison diagram of the photosynthetic rate of the overexpression of the YL2 gene in Example 3 of the present invention;

[0052] Figure 17 This is the comparison diagram of the yield of the overexpression of the YL2 gene in Example 3 of the present invention;

[0053] Figure 18 This is the comparison diagram of the high-temperature stress phenotypes of the wild-type WT and yl2 mutants in Example 3 of the present invention. Detailed implementation manners

[0054] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts fall within the protection scope of the present invention.

[0055] The test materials, reagents, etc. used in the following embodiments can be obtained from commercial channels without special instructions.

[0056] For those not specifying specific techniques or conditions in the embodiments, they can all be carried out according to the techniques or conditions described in the literature in this field or according to the product specifications. Without special instructions, the quantitative tests in the following embodiments are all set with more than three repeated experiments, and the results are averaged.

[0057] Example 1:

[0058] Phenotypic analysis of rice yellow leaf mutant yl2

[0059] (1) Agronomic trait analysis

[0060] Using heavy ion 12 C 6+ mutation (energy 80 MeV, dose 120 Gy) of japonica rice variety Wuyunjing 7 (WYJ7) to obtain the yl2 mutant. The phenotypic characteristics of this mutant are: slightly reduced plant height, yellowing of leaves, significantly reduced chlorophyll content in leaves, decreased photosynthetic rate, and reduced yield per plant. As Figures 1 - 5 shown.

[0061] (2) Genetic analysis of yl2 mutant

[0062] To study the molecular mechanism of the formation of yellowing leaves in the yl2 mutant, genetic analysis was first carried out on it. A backcross population was constructed by crossing the yl2 mutant with the wild-type Wuyunjing 7. Among the 344 F2 generation segregation populations, 82 plants had yellow leaf phenotypes and 262 plants had normal leaf colors. The segregation ratio of the number of yellow leaves to normal leaf colors was in line with 1:3 (χ 2 [1:3] = 0.256 < χ 2 0.05 = 3.84; P > 0.05). By crossing the yl2 mutant with indica rice variety 93-11, among the 640 F2 generation segregation populations, 169 plants had yellow leaf phenotypes and 471 plants had normal leaf colors. The segregation ratio of the number of yellow leaves to normal leaf colors was in line with 1:3 (χ 2 [1:3] = 0.24 < χ 20.05 = 3.84; P > 0.05). The above results indicate that the yellow leaf phenotype of the yl2 mutant is controlled by a single recessive gene and is not affected by the genetic background.

[0063] (3) Observation of chloroplasts by transmission electron microscopy

[0064] To further study the mechanism of yellowing leaf color formation in the yl2 mutant, the leaves of the wild type and the yl2 mutant were ultrathin sectioned and observed by transmission electron microscopy. It was found that the number of thylakoids in the chloroplasts of the yl2 mutant was significantly reduced. This indicates that the reduction in the number of thylakoids in the chloroplasts is the cause of the yellowing leaf color phenotype of the yl2 mutant, as Figure 6 shown.

[0065] Example 2:

[0066] Gene mapping of rice yellowing gene YL2

[0067] (1) Construction of mapping population

[0068] The yl2 mutant was crossed with indica rice varieties such as 93-11, Minghui 63, and Huajingxian 74. The F1 generations of different hybrid combinations were self-crossed to obtain seeds of the segregating population. These seeds were planted in the field, and individual plants with the yellow leaf phenotype were selected as mapping individuals. About 100 mg of leaves were taken from each individual plant for DNA extraction.

[0069] (2) Screening of simple sequence repeat (SSR) polymorphisms

[0070] SSR primers reported to be evenly distributed on 12 rice chromosomes were used to screen for polymorphisms between the yl2 mutant and 93-11. Polymorphic SSR primers were obtained for the next experiment.

[0071] (3) Mapping of the YL2 gene

[0072] First, 21 randomly selected individual plants with the yellow leaf phenotype in the segregating population constructed by the yl2 mutant and 93-11 were used for the preliminary mapping of the YL2 gene. The polymorphic SSR primers obtained by screening were used for linkage analysis of these 21 individual plants. The results showed that the molecular markers BSR18 and BSR29 on chromosome 2 were significantly linked to the mutant gene, as Figure 7 shown. Recombinants in the figure indicate recombinants. It was further determined that the YL2 gene is located between BSR21 and BSR25, and this interval is approximately 3.06 Mb.

[0073] To further narrow down the mapping interval of the YL2 gene, more polymorphic primers were searched for between the BSR21 and BSR25 molecular markers (the primer sequences used for YL2 gene mapping are shown in Table 1), and the number of the mapping population was expanded. Linkage analysis was performed on a larger mapping population. As Figure 7 shown, Recombinants in the figure represent recombinants. Finally, the YL2 gene was finely mapped within a region of approximately 60 kb between the Indel markers B7 and B8.

[0074] Table 1: Primers used for YL2 gene mapping

[0075]

[0076] (4) Obtaining candidate genes and cloning of the YL2 gene

[0077] Genes in the fine mapping interval were sequenced and compared with the wild type. It was found that there was a 2-bp base deletion (AG deletion) in the first exon of the LOC_Os02g38820 gene( Figure 8 ), which ultimately led to changes in the translated amino acid sequence and premature termination( Figure 9 ). Therefore, it was speculated that the LOC_Os02g38820 gene was the candidate gene controlling the leaf yellowing phenotype of this mutant.

[0078] (5) Functional complementation verification of the YL2 gene

[0079] To verify that LOC_Os02g38820 is the YL2 gene, using the leaves of the wild type as materials, RNA was extracted and reverse transcribed and amplified to obtain cDNA. An expression vector pYL2F of LOC_Os02g38820 driven by its own promoter (a 3000-bp fragment upstream of ATG) was constructed. The pYL2F expression vector was transferred into the yl2 mutant, and the leaves of the obtained positive transgenic T0 generation plants all recovered to the normal leaf color level, and the chlorophyll content also recovered to the wild type level. As Figure 10 shown. This result proved that the LOC_Os02g38820 gene is the YL2 gene.

[0080] The primers used for constructing the expression vector pYL2F are as follows:

[0081] pYL2-F: 5’-cggaattcGACCACTGTGCTCGCAGATC-3’ (SEQ ID No.24)

[0082] pYL2-R: 5’-cgggtaccTGAAACCTCCTATTCCGGTC-3’ (SEQ ID No.25)

[0083] YL2-CDS-F: 5’-cgggtaccATGGAGGTGGTGGGCGGCGT-3’ (SEQ ID No.26)

[0084] YL2-CDS-R: 5’-cgggatccTCAGCTCTCCGTTTTGATCC-3’ (SEQ ID No.27)

[0085] The construction method of the expression vector pYL2F includes the following steps:

[0086] (a) Using the pYL2-F and pYL2-R primers, with the DNA of wild-type Wuyunjing 7 as a template, the amplified PCR product is double-digested with the restriction endonucleases EcoRI and KpnI. At the same time, the pCAMBIA2300 backbone is double-digested with this enzyme, and then the amplified pYL2 fragment is inserted into the pCAMBIA2300 vector using T4 ligase to obtain the intermediate vector pCAMBIA2300-pYL2.

[0087] (b) Using the YL2-CDS-F and YL2-CDS-R primers, with the cDNA of wild-type Wuyunjing 7 as a template, the amplified PCR product is double-digested with the restriction endonucleases KpnI and BamHI. At the same time, the intermediate vector pCAMBIA2300-pYL2 obtained in step (1) is double-digested with this enzyme, and then the amplified YL2-CDS fragment is inserted into the pCAMBIA2300-pYL2 vector using T4 ligase to obtain the final vector pCAMBIA2300-pYL2::YL2, and this vector is designated as pYL2F.

[0088] Similarly, the CRISPR / Cas9 technology is used to edit the LOC_Os02g38820 gene to create mutants with a loss of function of the LOC_Os02g38820 gene. Among several independent homozygous lines with the LOC_Os02g38820 gene knocked out, all showed the phenotypes of leaf chlorosis, reduced chlorophyll content, decreased photosynthesis, and reduced yield per plant, which were consistent with the yl2 mutant phenotypes, further indicating that LOC_Os02g38820 is the YL2 gene.

[0089] The construction and transformation method of the CRISPR / Cas9 vector is as follows:

[0090] According to the gDNA sequence of the YL2 gene, the following target primers are designed:

[0091] YL2-CRISPR-U3: 5’-GTCGCTGAGCGCGTCTTCGCCGG-3’ (SEQ ID No.28)

[0092] For the specific construction method, please refer to the article published by Professor Liu Yaoguang of South China Agricultural University (A robust CRISPR / Cas9 system for convenient, high-efficiency multiplex genome editing in monocot and dicot plants. (2015) Molecular Plant, 8(8): 1274-1284). The vector was introduced into WYJ7 by Agrobacterium-mediated transformation (rice transformation was completed by the applicant's laboratory). Comparative phenotypic analysis of wild-type and transgenic rice found that in the homozygous line crispr-yl2 with the YL2 gene knocked out (the sequencing peak map of the mutation site is as Figure 11 ), the leaves showed a yellowing phenotype ( Figure 12 ).

[0093] (6) Functional analysis of the YL2 gene

[0094] Gene annotation analysis showed that the YL2 gene encodes an oligopeptidase. To study the molecular mechanism of YL2's involvement in rice leaf color regulation, first, the expression pattern of the YL2 gene was analyzed. RNA from different tissues at different growth stages of rice was extracted, reverse-transcribed into cDNA, and quantitative analysis of the YL2 gene in these tissues was performed by quantitative PCR. The results showed that the YL2 gene was mainly expressed in leaves and leaf sheaths, while the expression levels in roots and young panicles were extremely low ( Figure 13 ), which was also consistent with the function of YL2 in regulating leaf color, further indicating that mutations in the YL2 gene would affect changes in rice leaf color. The subcellular localization of the protein encoded by a gene determines the function of the protein. To study the function of the protein encoded by the YL2 gene, subcellular localization analysis of the YL2 protein was performed, and the result showed that the YL2 protein was localized in chloroplasts ( Figure 14 ), which was consistent with the function of YL2 in participating in chloroplast synthesis, further verifying that the YL2 gene mutant affects chlorophyll synthesis and chloroplast development.

[0095] Example 3:

[0096] Overexpression of the YL2 gene improves rice photosynthesis and yield

[0097] Considering that mutations in the YL2 gene cause the yellowing of rice leaves, a decrease in chlorophyll content, and a significant decrease in photosynthesis and yield. Increasing the expression level of the YL2 gene may improve rice photosynthesis and yield. Therefore, a YL2 overexpression vector was constructed and introduced into WYJ7 by Agrobacterium-mediated transformation (rice transformation was completed by the applicant's laboratory). The positive overexpression transgenic plants significantly showed dark green leaves ( Figure 15), the photosynthetic rate increases ( Figure 16 ), and finally the yield per plant increases ( Figure 17 ). Therefore, increasing the expression level of the YL2 gene can improve rice photosynthesis and yield. In addition, it was found that the YL2 overexpression transgenic has obvious heat tolerance. Using high-temperature treatment, the yl2 mutant died significantly, while the YL2 overexpression significantly showed good heat tolerance ( Figure 18 ).

[0098] All primers for the YL2 gene overexpression vector are as follows:

[0099] YL2-OE-F: 5’-cgggtaccATGGAGGTGGTGGGCGGCGT-3’ (SEQ ID No.29)

[0100] YL2-OE-R: 5’-cgggatccTCAGCTCTCCGTTTTGATCC-3’ (SEQ ID No.30)

[0101] The method for constructing the expression vector p35S::YL2 includes the following steps:

[0102] Using the YL2-OE-F and YL2-OE-R primers, with the cDNA of wild-type Wuyunjing 7 as a template, the amplified PCR product was double-digested with the KpnI and BamHI restriction endonucleases. At the same time, the pCAMBIA2300 backbone was double-digested with these enzymes, and then the amplified YL2-CDS fragment was inserted into the pCAMBIA2300 vector using T4 ligase to obtain the final vector pCAMBIA2300-p35S::YL2, and this vector was designated as p35S::YL2.

[0103] SEQ ID No.1 CDS sequence of the YL2 gene

[0104] ATGGAGGTGGTGGGCGGCGTGTCGTCGCTGAGCGCGTCTTCGCCGGCGCCGGCGCGGGCGCGGCTGCGGCAGCTGTCGCCCGGCGAGGCGAGCGGCGGGGGGAGCTTCCTGCTGATGAGGACGGCGCCGAGGAGCAGGCTGCAGGCGGCGGCGAGGCCGGCGAGGCGGGCGGCGCTGGTGGTGGAGGCGAGGGGGAGGGGGTGGTCGGACCGGCGGTCCCAGCAGCAGCGCATGCCGCAGCTGCCCAAGATCGAGGACGACGGCAACCCGCGCTTCGTCATCTTCATCCGCACCGCCAATGTGTACTTCTGGTACCCGCTCAACATCGTCACCGGCGGCACGACGGCGAAGATCATGCTCGCGGCGAAGGACAACTTCCTCGGAAAGTACATCTACAAGGACACGCTCGCCAGGAACCTTGCCGCTGTCATCTACAAAGATGAGGATGACATAATAGACACAGCAAAAGAGCAGTACAGGGTGCTGAAGACCGACAATGAGTTTCGATATGGCTACAAAGTTGTGGAGAATGGGAACCTGAGGTCTGCGCTGACGACAAGTAATGTGATCGAACTCCCAAAGAAAGAAGAGCTCAAAACTGTGGTTGACAAGGTGAAGGACTTCTTCGGCGACGTAACCTCTGGCGCCAAAGAGTCGTTTGCGCAGATTACAGGATCTGTCAGCGCAGAGGCAGAAGCGCCAGTGGAGGAAGAGAAGCCCTGGGTGAAGAGGCGAAACGAGAGGAAGCGGAAACAGAAGGAGAAGCAGAACCAGAAGCAGGGGATCAGTAAGTAAAGAAACGGAGAGCTGA

[0105] SEQ ID No.2 YL2 gene gDNA sequence

[0106]

[0107] SEQ ID No. 3 YL2 protein sequence

[0108] MEVVGGVSSLSASSPAPARARLRQLSPGEASGGGSFLLMRTAPRSRLQAAARPARRAALVVEARGRGWSDRRSQQQRMPQLPKIEDDGNPRFVIFIRTANVYFWYPLNIVTGGTTAKIMLAAKDNFLGKYIYKDTLARNLAAVIYKDEDDIIDTAKEQYRVLKTDNEFRYGYKVVENGNLRSALTTSNVIELPKKEELKTVVDKVKDFFGDVTSGAKESFAQITGSVSAEAEAPVEEEKPWVKRRNERKRKQKEKQNQKQGIKTES

[0109] 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 foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A gene YL2 for improving rice photosynthesis and yield, characterized in that: The nucleotide sequence of the gene YL2 includes: (1) as shown in SEQ ID No.1 or SEQ ID No.2; or (2) the nucleotide sequence of a mutant, allele or derivative generated by the addition, substitution, insertion or deletion of one or more nucleotides; or (3) can hybridize with the nucleotide sequence shown in SEQ ID No. 2 under stringent conditions and simultaneously encode a nucleotide sequence that can improve rice photosynthesis and yield.

2. The protein encoded by gene YL2 according to claim 1, characterized in that: The amino acid sequence of the protein encoded by the gene YL2 includes: (1) as shown in SEQ ID No. 3; or (2) an amino acid sequence that differs from the amino acid sequence shown in SEQ ID No. 3 due to substitution, deletion and / or insertion of one or more amino acid residues; or (3) an amino acid sequence that is at least 70%, preferably at least 80%, more preferably at least 90%, especially at least 95%, 98% or 99% identical to the amino acid sequence shown in SEQ ID No. 3; or (4) an active fragment of the amino acid sequence described in any one of (1) to (3) above.

3. A recombinant construct, characterized in that: The recombinant construct contains the nucleotide sequence of the gene YL2 according to claim 1, and the vector used in the recombinant construct is a cloning vector or an expression vector for expressing the nucleotide.

4. A recombinant host cell, characterized in that: A host cell comprising the recombinant construct of claim 3, or comprising the nucleotide sequence of the gene YL2 of claim 1 in its genome.

5. The recombinant host cell according to claim 4, characterized in that: The host cell is a microbial cell.

6. Use of the gene YL2 according to claim 1 in breeding for improving rice photosynthesis and / or yield.

7. The use according to claim 6, characterized in that: Increasing the expression of the YL2 gene in rice increases the rice's photosynthesis capacity and single-plant yield.

8. Use of the gene YL2 or the protein encoded by it according to claim 1 in improving plant stress resistance.

9. The use according to claim 8, characterized in that: Increasing the expression of the YL2 gene in rice can increase the heat tolerance of rice.

10. A method for improving rice photosynthesis and yield, characterized in that: The following steps are involved: Construct a YL2 overexpression vector, and use transgenic methods to transfer the YL2 overexpression vector into normal rice varieties; or Conduct haplotype analysis on the YL2 gene in natural populations, clarify the relationship between the corresponding haplotype and the expression level of the YL2 gene, and use the hybridization method to transfer the highly expressed YL2 haplotype into the rice variety to be bred.

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