MEIOTIC PROMOTERS AND THEIR USES

Abstract

The present invention relates to novel transcriptional promoters functional during meiosis. It thus provides novel tools, methods and compositions for the expression of proteins during meiosis in a eukaryotic cell, and more particularly in a plant cell.

Description

The present invention relates to tools, methods and compositions for the expression of proteins during meiosis in a eukaryotic cell, and more particularly in a plant cell. TECHNOLOGICAL BACKGROUND OF THE INVENTION In order to optimize plant production, the agricultural industry is constantly searching for plants with improved characteristics, particularly in terms of growth, yield, organoleptic properties, resistance to diseases or climatic hazards, or characteristics of importance in green chemistry or for biofuel production. Traditionally, a plant with specific properties can be obtained through sexual reproduction by crossing two parent strains with desirable characteristics and selecting a hybrid strain that provides the desired improvement. However, this method is unpredictable, and the selection process can be lengthy. Alternatively, genetically modifying the plant using recombinant DNA technology could also be considered. However, this modification may hinder its cultivation, whether for regulatory, health, or environmental reasons. A third alternative involves inducing a reassortment of paternal and maternal alleles in the genome during meiotic recombination. Meiotic recombination is an exchange of DNA between homologous chromosomes during meiosis. It is initiated by the formation of double-strand breaks in one or the other chromatid of the homologous chromosomes, followed by the repair of these breaks, using a chromatid from the homologous chromosome as a template. However, meiotic recombinations have the disadvantage of being distributed unevenly in terms of frequency and location along the chromosomes. Recent years have seen the emergence of new technologies that allow for influencing the frequency or positioning of meiotic recombination. It has been demonstrated that it is possible to modify the sites of double-strand break formation by expressing recombinant proteins during prophase of the first meiotic division (Pecina et al., 2002 Cell, 111, 173-184; WO 2016 / 120480). These new tools open up extremely promising prospects for targeted plant optimization through the reassortment of genes naturally present in the plant. Modulating meiotic events via the expression of recombinant proteins requires the use of promoters with transcriptional activity during this phase. Some such promoters have been described, such as the DMC gene promoter from Arabidopsis thaliana (Klimyuk and Jones. Plant J. 1997 Jan;11(1):1-14) or the SPO13 gene promoter from Saccharomyces cerevisiae (Buckingham et al., Proc Natl Acad Sci USA. 1990 Dec;87(23):9406-10). However, the available selection remains largely insufficient to cover all the intended applications. Therefore, there is a real need for new transcriptional promoters that allow the expression of proteins of interest during meiosis. SUMMARY OF THE INVENTION The present invention proposes a novel functional transcriptional promoter during meiosis. According to a first aspect, it relates to an isolated nucleic acid having functional transcriptional promoter activity during meiosis and comprising, or consisting of, a nucleotide sequence selected from the group consisting of the sequence SEQ ID NO: 1 and functional variants thereof, said functional variants comprising, or consisting of, - a sequence showing at least 70% identity with the sequence SEQ ID NO: 1; - a fragment of the SEQ ID NO: 1 sequence of at least 50 consecutive nucleotides, or - a sequence capable of hybridizing under conditions of low, medium or high stringency with the SEQ ID NO: 1 sequence where its complementary strand is located. Preferably, the nucleic acid according to the invention comprises, or consists of, a nucleotide sequence selected from the group consisting of the sequence SEQ ID NO: 1 and functional variants thereof having at least 80% identity with the sequence SEQ ID NO: 1. In particular, it may comprise, or consist of, a nucleotide sequence selected from the group consisting of the sequences SEQ ID NO: 1, 2, 3 or 4. In another aspect, the present invention relates to an expression cassette comprising a coding sequence operationally linked to a nucleic acid according to the invention. It also relates to an expression vector comprising a nucleic acid or an expression cassette according to the invention. The coding sequence may, in particular, code for a polypeptide of interest, preferably a reporter protein or a protein capable of modulating, preferably increasing, the frequency of meiotic recombination, a protein that modifies the structure of chromatin such as for example histone (de)acetylases or histone (de)methylases or a protein that modifies DNA methylation, Alternatively, the coding sequence codes a nucleic acid of interest, preferably an siRNA, an shRNA, an RNAi, a miRNA, an antisense RNA, a ribozyme, a DNAzyme or a guide RNA capable of targeting the action of a CRISPR-type endonuclease, preferably Cas9 or dCas9, at a specific sequence. According to another aspect, the present invention also relates to a non-human host cell transfected or transformed with a nucleic acid, an expression cassette or an expression vector according to the invention. In yet another aspect, the invention relates to a method, preferably an in vitro method, for expressing a coding sequence of interest in a non-human host cell during meiosis, comprising introducing into said cell an expression cassette or an expression vector according to the invention, said coding sequence being operationally linked to a nucleic acid according to the invention. It also relates to a method, preferably an in vitro method, for producing a multicellular plant organism expressing a coding sequence of interest during meiosis, comprising introducing into a plant cell an expression cassette or an expression vector according to the invention, said coding sequence being operationally linked to a nucleic acid according to the invention, and reconstituting said organism from said cell. Preferably, the host cell is a plant cell. The present invention also relates to a multicellular plant organism comprising an expression cassette or an expression vector according to the invention, as well as the use of a nucleic acid according to the invention to express a coding sequence of interest in a non-human host cell, preferably a plant cell, during meiosis. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1: Nucleotide sequence of the genomic region including the last intron, last exon, and 3”UTR of the ZMPHYC2 gene and the intergenic region upstream of ZmSpol1-1. The boxed sequences represent motifs conserved across different species Figure 2: Panicles. The panicles of homozygous mutant plants Zmspo11-1 bear far fewer anthers. Figure 3: Anthers. The anthers of homozygous mutant plants Zmspol1-1 are atrophied. Figure 4: Pollen. The anthers of homozygous mutant plants Zmspo11-1 contain many aborted pollen grains and almost no turgid pollen grains. Figure S: Panicles, Panicles of homozygous mutant plants Zmspo11-1 (WT / Homo) complemented by the transgene L1605 (TR Spol 1 / Homo) or by the transgene L1604 (TR Ubi / Homo). Figure 6: Anthers. Anthers of homozygous mutant plants Zmspo11-1 (WT / Homo) complemented by the transgene L1605 (TR Spol1 / Homo) or by the transgene L1604 (TR Ubi / Homo). Figure 7: Pollen. Pollen from the anthers of homozygous mutant plants Zmspol1-1 (WT / Homo) complemented by the transgene L1605 (TR Spo11 / Homo) or by the transgene L1604 (TR Ubi / Homo). DETAILED DESCRIPTION OF THE INVENTION This application describes the identification and characterization of plant-derived regulatory nucleic acid sequences that control the expression of a gene of interest in a eukaryotic cell, preferably a plant cell, during meiosis. The inventors have identified a nucleotide sequence upstream of the ZmSpoll-1 gene (GeneID NCBI: 100279325) from maize (Zea mays) that exhibits transcriptional promoter activity during meiosis. They have also demonstrated that this promoter is more efficient during meiosis than a strong constitutive promoter such as the ubiquitin promoter (ZMUBI). Definitions In this description, the terms "nucleic acid," "nucleic sequence," "polynucleotide," "oligonucleotide," and "nucleotide sequence" are used interchangeably and refer to a polymer of deoxyribonucleotides and / or ribonucleotides. These terms may include synthetic or semi-synthetic molecules. Recombinant nucleic acids, comprising non-natural bases or modified nucleotides, including, for example, a modified bond, a modified purine or pyrimidine base, or a modified sugar. The nucleic acid according to the invention can be obtained by any method known to those skilled in the art, for example, by chemical synthesis and / or by recombination and / or mutagenesis techniques. In some preferred embodiments, the nucleic acid according to the invention is a DNA molecule, preferably a double-stranded DNA molecule. This molecule can be obtained by recombinant techniques well known to those skilled in the art. As used here, the term "isolated" refers to biological material that has been removed from its natural environment. More specifically, the term "isolated nucleic acid" refers to a nucleic acid molecule that is separated from its adjacent nucleic acids when in its natural environment, i.e., within the genome from which it was isolated. The isolated nucleic acid may be included in a vector, genome, compound, or other component, yet remain isolated, as long as that component does not constitute its natural environment. As used here, the term "transcriptional promoter" refers to a regulatory element capable of initiating the transcription of a nucleic acid to which it is operationally bound. The activity of such a promoter can be assessed by any method known to those skilled in the art, and in particular by any method that quantifies the mRNA or protein obtained from the gene controlled by the promoter. For example, activity can be measured by assessing the amount of mRNA, for instance by Northern blot or RT-PCR, or by assessing the amount of protein translated, for instance by Western blot, ELISA, colorimetric assays, enzyme activity assays, or by using a reporter gene system. As used here, the expression "operationally linked" refers to nucleotide sequences that are combined / arranged in such a way that the function of one acts on the other. Thus, a transcriptional promoter and a nucleotide sequence, for example a coding sequence, are operationally linked when the expression of the nucleotide sequence is controlled by that promoter. The term "sequence identity percentage" or "identity percentage," as used here, refers to the percentage of identical nucleotides in a sequence of two polynucleotides. This percentage can be easily calculated by a person skilled in the art using a program. Sequence comparison computing. Sequence identity is determined by comparing sequences after aligning them, maximizing overlaps and identities while minimizing gaps. Specifically, sequence identity can be determined using one of the available global or local alignment mathematical algorithms. Sequences of similar lengths are preferably aligned using a global alignment algorithm (e.g., Needleman and Wunsch, 1970) that aligns sequences optimally along their entire length. Sequences of substantially different lengths are preferably aligned using a local alignment algorithm (e.g., Smith and Waterman, 1981; Altschul et al., 1997; Altschul et al., 2005).Alignments to determine the percentage of identity can be performed by any method known to a person skilled in the art, including using computer programs available on the internet (for example, http: / / blast.ncbi.nlm.nih.gov / or http: / / Www.ebi.ac.uk / Tools / emboss / ). Preferably, the value of the percentage of identity here refers to a value obtained with the EMBOSS Needle program which uses the Needleman-Wunsch global alignment algorithm with the default parameters, namely: Scoring matrix = BLOSUM62, Gap open = 10, Gap extend = 0.5, End gap penalty = false, End gap open = 10 and End gap extend = 0.5. According to a first aspect, the present application relates to a nucleic acid, preferably isolated, having functional transcriptional promoter activity during meiosis and comprising, or consisting of, a nucleotide sequence selected from the group consisting of the sequence SEQ ID NO: 1 and functional variants thereof. The nucleic acid according to the invention has functional transcriptional promoter activity during meiosis. This means that it is capable of initiating, during meiosis, the transcription of a nucleic acid to which it is operationally bound. Meiosis comprises two successive cell divisions. The first meiotic division is called reductional and includes the stages of prophase I, metaphase I, anaphase I, and telophase I. The second meiotic division is called equational and includes the stages of metaphase II, anaphase II, and telophase II. Preferably, the nucleic acid according to the invention has functional transcriptional promoter activity at least during prophase I of meiosis. According to a preferred embodiment, the nucleic acid according to the invention has a transcriptional promoter activity during meiosis, and more particularly during prophase I of meiosis, which is superior to that of a strong constitutive promoter. Preferably, the acid The nucleic acid according to the invention has a transcriptional promoter activity during meiosis that is superior to that of the ubiquitin gene promoter, and in particular the maize ubiquitin gene promoter (GenBank entry number: S94464, position 4-1997). The nucleic acid according to the invention is therefore preferably capable of inducing, during meiosis, and more particularly during prophase I of meiosis, the expression of a coding sequence of interest more efficiently than a strong constitutive promoter, in particular the ubiquitin gene promoter, and in particular the maize ubiquitin gene promoter. This characteristic can be evaluated by any method known to those skilled in the art, and in particular by the method described in the experimental section below. In one embodiment, the nucleic acid according to the invention comprises, or consists of, the sequence SEQ ID NO: 1. According to another embodiment, the nucleic acid according to the invention comprises, or consists of, a functional variant of the sequence SEQ ID NO: 1. As used here, the term "variant" refers to a nucleotide sequence that differs from the parent sequence (e.g., SEQ ID NO: 1) but retains its essential properties. The variant sequence may differ from the parent sequence by one or more substitutions, deletions, and / or insertions. The variant may be the same length as, or different from (shorter or longer than) the parent sequence. The term "functional variant" refers to a variant as defined above that retains the activity of the parent, in this case, functional transcriptional promoter activity during meiosis. According to one embodiment, the nucleic acid according to the invention comprises, or consists of, a functional variant of the SEQ ID NO: 1 sequence selected from the group consisting of - of a sequence exhibiting at least 70%, preferably at least 80%, identity with the sequence SEQ ID NO: 1; - a fragment of the SEQ ID NO: 1 sequence of at least 50 consecutive nucleotides, and - of a sequence capable of hybridizing under conditions of low, medium or high stringency with the SEQ ID NO: 1 sequence or its complementary strand. According to one embodiment, the nucleic acid according to the invention comprises, or consists of, a functional variant having a sequence having at least 70%, 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79%, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identity with the sequence SEQ ID NO: 1, preferably over the entire length of the sequence SEQ ID NO: 1. The nucleic acid according to The invention may differ from the sequence SEQ ID NO: 1 by up to 15, i.e. 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14 or 15, substitutions, insertions and / or deletions. According to another particular embodiment, the nucleic acid according to the invention comprises, or consists of, a functional variant that is a fragment of the SEQ ID NO: 1 sequence of at least 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, or 170 consecutive nucleotides. Preferably, the functional variant is a fragment of the SEQ ID NO: 1 sequence of at least 100 consecutive nucleotides. According to another particular embodiment, the nucleic acid according to the invention comprises, or consists of, a functional variant having a sequence capable of hybridizing under low, medium or high stringency conditions with the SEQ ID NO: 1 sequence or its complementary strand, preferably under medium or high stringency conditions, and more particularly preferred under high stringency conditions. As used here, the term "low stringency conditions" refers to pre-hybridization and hybridization at 42°C in 5X SSPE, 0.3% SDS, 200 µg / mL of denatured and sonicated salmon sperm DNA, and 25% formamide, followed by standard Southern blot procedures for 12 to 24 hours. The support is then washed three times for 15 minutes in 2X SSC, 0.2% SDS buffer at 50°C. As used here, the term "medium stringency conditions" refers to pre-hybridization and hybridization at 42°C in 5X SSPE, 0.3% SDS, 200 µg / mL of denatured and sonicated salmon sperm DNA, and 35% formamide, followed by standard Southern blot procedures for 12 to 24 hours. The support is then washed three times for 15 minutes in 2X SSC, 0.2% SDS buffer at 55°C. As used here, the term "high stringency conditions" refers to pre-hybridization and hybridization at 42°C in SX SSPE, 0.3% SDS, 200 µg / mL of denatured and sonicated salmon sperm DNA and 0% formamide, followed by standard Southern blot procedures for 12 to 24 hours. The support is then washed three times for 15 minutes in 2X SSC, 0.2% SDS buffer at 65°C. According to preferred embodiments, the functional variants of the sequence SEQ ID NO: 1 include, preferably when aligned with SEQ ID NO: 1 by means of a global or local mathematical alignment algorithm, at least 1, 2, or 3 conserved motifs selected from the following motifs: - TTGN[A / T]GG, preferably TTGNAGG, and particularly preferably TTGAAGG, at positions 62 to 68 of SEQ ID NO: 1, - CGANCGA, preferably CGATCGA, in positions 115 to 121 of the SEQ ID NO: 1, - AAGCCNA, preferably AAGCCTA, in positions 94 to 100 of SEQ ID NO: 1, and - AAANNAAAA (SEQ ID NO: 7), preferably AAATCAAAA (SEQ ID NO: 8), in positions 152 to 161 of SEQ ID NO: 1. N can be A, T, Cou G Preferably, the functional variants include these 4 conserved motifs. These motifs are outlined in Figure 1. According to a particular embodiment, the nucleic acid according to the invention comprises, or consists of, a nucleotide sequence selected from the group consisting of SEQ ID NO: 2, 3 or 4 sequences and functional variants thereof, provided that these functional variants comprise (i) at least 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160 or 170 consecutive nucleotides of SEQ ID NO: 1, and / or (ii) comprise a sequence having at least 70%, 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79%, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98% or 99% identity with the SEQ ID NO sequence: 1. Preferably, the functional variants include at least 1, 2 or 3 of the conserved motifs mentioned above, preferably all 4 motifs. According to a preferred embodiment, the nucleic acid according to the invention comprises, or consists of, a nucleotide sequence selected from the group consisting of the sequence SEQ ID NO: 1 and functional variants thereof exhibiting at least 80% identity with the sequence SEQ ID NO: 1. In a second aspect, the present invention also relates to an expression cassette comprising a coding sequence of interest operationally linked to a nucleic acid according to the invention. As used here, the term "expression cassette" refers to a nucleic acid construct comprising a coding sequence and one or more control sequences required for the expression of said coding sequence. In particular, one of these control sequences is a nucleic acid according to the invention having promoter activity. Generally, the expression cassette comprises a coding sequence and regulatory sequences preceding (5' non-coding sequences) and following (3' non-coding sequences) the coding sequence. which is required for the expression of the gene product of interest. Thus, an expression cassette typically comprises a promoter sequence, a 5' untranslated region, a coding sequence, and a 3' untranslated region that usually contains a polyadenylation site and / or a transcription terminator. The expression cassette may also include additional regulatory elements such as, for example, enhancer sequences, a polylinker sequence to facilitate the insertion of a DNA fragment into a vector, and / or splicing signals. The expression cassette is usually included in a vector to facilitate cloning and transformation. Preferably, the expression cassette is a recombinant expression cassette, meaning that the nucleic acid according to the invention is functionally linked to a heterologous coding sequence. As used here, the term “heterologous” refers to a coding sequence that is different from the one to which the promoter is functionally linked in a natural genome. In particular, in some embodiments, the coding sequence of interest is not the ZmSpo1-1 gene (GeneID: 100279325) from maize (Zea mays). The coding sequence of interest operationally linked to a nucleic acid according to the invention can code for a polypeptide of interest or a nucleic acid of interest. According to one embodiment, the coding sequence of interest operationally linked to a nucleic acid according to the invention codes for a polypeptide of interest. The polypeptide of interest can be any polypeptide whose expression is desired during meiosis. In particular, the polypeptide of interest can be a reporter protein, a protein capable of modulating, preferably increasing, the frequency of meiotic recombination, a protein that modifies the structure of chromatin such as, for example, histone (de)acetylases or histone (de)methylases, and / or a protein that modifies DNA methylation. The reporter protein can be easily chosen by a person skilled in the art depending on the nature of the host cell and the detection technique. The reporter protein can be chosen, for example, from among fluorescent proteins, alkaline phosphatases, beta-glucuronidases, beta-galactosidases, beta-lactamases, or horseradish peroxidase. The protein capable of modulating the frequency of meiotic recombination can also be easily chosen by a person skilled in the art. The modulation can be a general increase in the frequency of recombination or a targeted increase, that is, an increase concerning a given genomic region. For example, this protein can be a protein obtained by fusing a Spol1 protein with a DNA-binding domain such as the transcription activator Gal4 (Pecina et al, 2002 Cell, 111, 173-184), the ZF (Zinc Finger) domain or the TALE (Transcription Activator-Like Effector) domain, or a protein obtained by fusing a Spol 1 protein with a Cas9 domain, preferably a "dead Cas9" or dCas9 domain lacking nuclease activity, and used in combination with a guide RNA capable of targeting a specific sequence (WO 2016 / 120480). According to another embodiment, the coding sequence of interest, operationally linked to a nucleic acid according to the invention, codes for a nucleic acid of interest. The nucleic acid of interest can be any nucleic acid whose expression is desired during meiosis. In particular, the nucleic acid of interest can be an siRNA, a shRNA, an RNAi, a miRNA, an antisense RNA, a ribozyme, a DNAzyme, or a guide RNA capable of targeting the action of a CRISPR-type endonuclease, preferably Cas9 or dCas9, to a specific sequence. The coding sequence of interest operationally linked to a nucleic acid according to the invention can code for one or more molecules of interest, i.e. for one or more polypeptides of interest and / or one or more nucleic acids of interest. The expression cassette according to the invention may comprise one or more coding sequences of interest operationally linked to the nucleic acid according to the invention. All embodiments relating to other aspects of the invention are also considered in this aspect. In a third aspect, the present invention also relates to a vector comprising a nucleic acid according to the invention or an expression cassette according to the invention. As used here, the term "vector" refers to a nucleic acid molecule used as a vehicle to transfer genetic material, and in particular to deliver nucleic acid into a host cell, either in vitro or in vivo. The vector may be DNA or RNA, circular or non-circular, single- or double-stranded. Vectors include, but are not limited to, plasmids, phasmids, cosmids, transposable elements, viruses, and artificial chromosomes (e.g., YACs). Vectors can be constructed using standard molecular biology techniques well known to those skilled in the art. Advantageously, the vector according to the invention is a plant vector, that is to say, a vector capable of transforming a plant cell. Examples of plant vectors are described in the literature, among which we can cite in particular the T-DNA plasmids of A. tumefaciens pBIN19 (Bevan et al, 1984, Nucleic Acids Research, vol. 12: 8711-8721), the vector pPZP100 (Hajdukiewicz et al. 1994, Plant Mol. Biol. 25: 989-994), the vectors of the pPCAMBIA series (R. Jefferson, 1987, Plant Mol. Biol. Rep. 5:387-405) or the vectors described in the articles by Karimi et al. (Plant Physiology; 2007, 145(4): 1183-91, and Plant Physiology; 2007, 145(4): 1144-54) which are more specific to monocots. The vectors according to the invention may further comprise one or more bacterial and / or eukaryotic origins of replication. In particular, it may comprise a bacterial origin of replication allowing its selection during the cloning steps, for example, a functional origin of replication in *Ae. coli*, and another origin of replication used during transfer into the plant cell, for example, a functional origin of replication in *Agrobacterium tumefaciens*. The vector may further comprise elements allowing its selection in a bacterial or eukaryotic host cell, such as, for example, an antibiotic resistance gene, a gene allowing the complementation of auxotrophy, or a gene conferring herbicide tolerance. Such elements are well known to those skilled in the art and are widely described in the literature. The expression vector may also include one or more sequences allowing targeted insertion of the vector, expression cassette or nucleic acid according to the invention into the genome of a host cell. All embodiments relating to other aspects of the invention are also considered in this aspect. In another aspect, the present invention relates to the use of a nucleic acid, an expression cassette, or an expression vector according to the invention to transform or transfect a host cell. It also relates to a host cell transformed or transfected by at least one nucleic acid, an expression cassette, or an expression vector according to the invention. As used here, the term "host cell" refers to a prokaryotic cell or a non-human eukaryotic cell. Preferably, the host cell is a non-human eukaryotic cell chosen from a yeast, plant, fungal, or animal cell. In a particularly preferred manner, the host cell is a plant cell. According to some embodiments, this term also encompasses plant protoplasts. In a preferred embodiment, the host cell is a plant cell. In particular, the host cell can be a plant cell selected from the group consisting of cereals such as maize, rice, wheat, barley, sorghum, millet, oats and rye, sunflower, rapeseed, model plants such as Arabidopsis thaliana or Brachypodium dystachion, vegetables such as tomato, pepper, chili pepper, cabbage, cauliflower or lettuce, legumes such as broad beans, kidney beans, lentils, split peas, chickpeas, soybeans, fava beans or alfalfa, cotton, sugar plants such as sugar cane or beetroot, and fruit plants such as citrus fruits (e.g., lemons, oranges or grapefruits), berries (e.g., strawberries, currants, raspberries or grapes), pome fruits (e.g., apples or pears),Stone fruits (e.g., apricots, cherries, or peaches) or nuts (e.g., hazelnuts or walnuts). Preferably, the host cell is a maize cell. The host cell can be transformed / transfected in a transient or stable manner. The nucleic acid, cassette, or vector according to the invention can be contained within the cell in a non-integrated form or integrated into the genome. The techniques for transfection or transformation of host cells are well known to those skilled in the art. In particular, plant transgenesis techniques are well known and include, for example, the use of the bacterium Agrobacterium tumefaciens, electroporation, direct transfer, biolistic techniques, etc. A commonly used technique relies on the bacterium Agrobacterium tumefaciens, which essentially involves introducing the construct of interest (nucleic acid, cassette, vector, etc.) into the bacterium A. fumefaciens, and then exposing this transformed bacterium to appropriate explants of the chosen plant. The introduction of the expression cassette into the bacterium is typically achieved using a plasmid with a disarmed T-DNA as a vector, which can be transferred into the bacterium, for example, by heat shock. Incubating the transformed bacterium with the appropriate explants allows the transfer of the T-DNA containing the expression cassette into the genome of the disc cells. These disc cells can then be cultured under suitable conditions to reconstitute a transgenic plant whose cells include the construct of interest. the invention. For more details or variants of the implementation of the transformation technique by A. tumefaciens, one can refer for example to Horsch et al., (1985) Science 227:1229-1231, Hooykaas and Schilperoort (1992) Plant Mol. Biol. 19:15-38 or Ishida et al. (2007) Nat Protoc, 2(7):1614-21. Another plant transformation technique is based on the projection of microparticles (typically microbeads) to which genetic constructs are attached, directly onto plant cells, followed by the culture of these cells to reconstitute a transgenic plant. The particles used are typically gold particles, which are typically projected using a particle gun (see, in particular, Russell et al., In Vitro Cell. Dev. Biol., 1992, 28P, p. 97-105 and Klein et al. Plant Physiol. 1989 Sep;91(1):440-4). The microinjection technique essentially consists of injecting genetic constructs into plant embryos or protoplasts, and then culturing these tissues to regenerate complete plants. Other plant transgenesis techniques are well known, or other protocols implementing the above techniques are described in the prior art (Siemens, J and Schieder, 1996, Plant Tiss. Cult. Biotechnol. 2:66-75) and can be applied to the present invention. All embodiments relating to other aspects of the invention are also considered in this aspect. In another aspect, the present invention relates to a method for expressing a coding sequence of interest in a host cell during meiosis, comprising introducing into said cell an expression cassette or an expression vector according to the invention, said coding sequence being operationally linked to a nucleic acid according to the invention. It also relates to the use of a nucleic acid according to the invention for expressing a coding sequence of interest in a host cell during meiosis. All embodiments relating to other aspects of the invention are also considered in this aspect. In yet another aspect, the present invention relates to a multicellular plant organism, comprising an expression cassette or a vector according to the invention. It concerns also a method for producing a multicellular plant organism expressing a coding sequence of interest during meiosis, comprising introducing into a plant cell an expression cassette or a vector according to the invention, said coding sequence being operationally linked to a nucleic acid according to the invention, and reconstituting said organism from said cell. Optionally, the process may also include a step of selecting organisms containing the cassette or vector according to the invention. This selection can be carried out by any method known to those skilled in the art, in particular by DNA amplification methods using primers targeting a specific sequence of the cassette or vector. The process may also include a step of crossing the resulting organisms with each other or with other plants of the same or different species. Following this crossing, it is possible to select organisms containing the cassette or vector according to the invention. The introduction of the cassette or vector according to the invention into the cell can be carried out by any means known to a person skilled in the art, for example by one of the methods described above. As used here, the term "plant multicellular organism" refers to an entire plant, plant parts such as flowers, seeds, leaves, stems, fruits, pollen, tubers, wood, or multicellular structures such as calluses, plant organs, especially meiotic panicles and meiotic epis, or immature embryos (e.g., explants used for transgenesis). In some preferred embodiments, the plant multicellular organism is an entire plant or a seed. The reconstitution of a multicellular plant organism as defined above from a transfected or transformed plant cell uses routine techniques well known to those skilled in the art. All embodiments relating to other aspects of the invention are also considered in this aspect. The methods according to the invention can be in vitro, in vivo, or ex vivo. Preferably, the methods according to the invention are in vitro methods. The following examples are presented for illustrative purposes only and are not exhaustive. EXAMPLES The inventors identified a functional transcriptional promoter during meiosis and demonstrated that the use of this promoter enabled the expression of a fusion protein comprising a ZmSpo1 1-1 domain and a DNA-binding domain during meiosis. The ZmSpo11-1 gene carries the identifier GRMZM2G129913_T04 (gene model T04 of the GRMZM2G129913 gene) in version 3 of the maize B73 genotype reference sequence. In the genome of this genotype, the ZmPHYC2 gene (GRMZM2G129889 T01) is unusually close to ZmSpol 1-1, with only 162 bp between the end of the predicted 3' UTR of ZmPHYC2 and the beginning of the predicted S' UTR of ZmSpol 1-1. To facilitate cloning of the promoter region, an internal Ncol restriction site was eliminated by point mutation, thus maintaining a single Ncol site at the 3' end of the fragment, which overlaps the START codon of ZmSpol1-1. An I-Scel restriction site was added at the 5' end. The sequence used in the clonings described below, which includes the ZmSpol 1-1 promoter, is shown in Figure 1. A phylogenetic analysis involving several cereal species, namely Zea mays, Sorghum bicolor, Setaria italica, Oryza sativa japonica, Brachypodium distachyon, Triticum aestivum, Saccharum officinarum, and Hordeum vulgare, revealed a strong divergence in sequences at the intergenic region and the presence in this region of four conserved motifs: TTGX[A / T]GG, CGAXCGA, AAGCCXA, and AAAAXXAAAA (SEQ ID NO: 7). These motifs are outlined in Figure 1. Plasmid constructs A cassette containing the chimeric gene TAL-ZmSpol1-1, positioned under the control of the ZmSpol 1-1 promoter within SEQ ID NO: 5 (Figure 1), was inserted into a plasmid to generate plasmid L1605. The TAL domain is a DNA-binding domain designed to recognize the sequence 5'-TGGTTCTGTGACTACAAGTACAATG-3' (SEQ ID NO: 6). Its coding sequence was placed in-frame upstream of the ZmSpol11-1 cDNA, with a 36 bp stop codon-free spacer joining the two. An 18 bp sequence encoding a 6-His tag was added in-frame to the end of the ZmSpol 1-1 gene, just before the stop codon. A plasmid L1604 was obtained in a similar manner and contained a cassette comprising the chimeric gene TAL-ZmSpo11-1 placed under the control of the strong constitutive promoter of the maize ubiquitin gene, ZMUBI (GenBank entry number: S94464). Plasmid L1604 is identical to plasmid L1605 except that the ZMUBI promoter replaces the ZmSpol1-1 promoter. Mutant Zmspoll-1 The inventors used a maize plant containing a mutation consisting of a deletion of part of the ZmSpol1-1 gene (provided by Arnaud Ronceret). This mutant exhibits numerous defects in recombination, chromosome pairing, and synapses during meiosis, and shows complete male sterility and almost complete female sterility. Male flowering and pollen production of plants heterozygous and homozygous for this deletion were characterized at the panicle, anther and pollen levels. It has thus been shown that the panicles of mutant plants bear far fewer anthers, and that the anthers of mutant plants are atrophied and contain many aborted pollen grains and almost no turgid pollen grains (Figures 2 to 4). Transgenic plants containing the ZmSpoll-1 promoter The maize genotype A188 was transformed with plasmids L1604 and L1605 according to the standard protocol of Ishida et al (Nat Protoc. 2007;2(7):1614-21), For each construct, a single transformation event was obtained, each time represented by two plants derived from the same callus. TO plants carrying either the L1604 plasmid (ZMUBI promoter) or the L1605 plasmid (ZmSpol1-1 promoter) were crossed with the Zmspo11-1 mutant. Zmspoll-1 mutant complementation! To test the complementation of the Zmspol1-1 mutant by the L1604 transgene (ZmUBI promoter - TAL-ZmSpol 1-1 fusion protein) or L1605 transgene (ZmSpol 1-1 promoter - TAL-ZmSpol 1-1 fusion protein), the TO plants were crossed with heterozygous plants carrying the Zmspol 1-1 mutation. The T1 seedlings resulting from these crosses were genotyped to identify seedlings carrying both the transgene and the mutation. Plants hemizygous for the transgene and hemizygous for the Zmspo11-1 mutation were self-fertilized. T2 seedlings from self-fertilization were genotyped. Seedlings homozygous for the Zmspo! 1-1 mutation and (i) carrying the L1604 transgene (ZMUBI promoter - TAL-ZmSpo11-1 fusion protein), (ii) carrying the L1605 transgene (ZmSpo11-1 promoter - TAL-ZmSpol 1-1 fusion protein), or (iii) not carrying a transgene, were selected for phenotypic analysis. The results of this analysis are presented in Figures 5 to 7 and show that - the panicles of homozygous mutant plants complemented by the L1605 transgene (ZmSpol1-1 promoter - TAL-ZmSpol1-1 fusion protein) bear a normal number of anthers, whereas complementation by the L1604 transgene (ZMUBI promoter - TAL-ZmSpol1-1 fusion protein) only slightly increases the number of anthers in the mutant (WT / Homo), -the anthers of homozygous mutant plants without complementation (WT / Homo) or complemented by L1604 (ZMUBI promoter - TAL-ZmSpol 1-1 fusion protein) are atrophied, while the anthers complemented by L1605 (ZmSpol 1-1 promoter - TAL-ZmSpol 1-1 fusion protein) are normal (turgid), - the anthers of homozygous mutant plants without complementation (WT / Homo) or complemented by L1604 (promoter ZmUBI - fusion protein TAL-ZmSpol1-1) contain many aborted pollen grains and almost no turgid pollen grains, whereas the anthers complemented by L1605 (promoter ZmSpol 1-1 - fusion protein TAL-ZmSpol 1-1) contain normal amounts of turgid pollen. The Spoll-1 gene is recognized in many eukaryotic species as essential for meiotic recombination (Grelon et al. EMBO J. 2001 Feb 1;:20(3):589-600; Stacey et al. Plant J. 2006 Oct;48(2):206-16) and the SPO11-1 protein as necessary to initiate recombination by a double-strand break in DNA (Shingu et al. FEBS J. 2010 May;277(10):2360-74; Hartung et al. Plant Cell. 2007 Oct;19(10):3090-9) within a protein complex formed with SPOI1-2 and TOPOVIB (Vrielynck et al. Science. 2016 Feb 26;351(6276):939-43). Spol 1-1 mutants are characterized by meiotic aberrations leading to sterility. The fact that a TAL-ZmSpo11-1 fusion protein under the control of a promoter according to the invention present in the L1605 plasmid complements the mutation Zmspol1-1 demonstrates that this promoter is functional during meiosis. Furthermore, the results obtained also show that this promoter allows for a higher level of expression during meiosis than that obtained with a strong constitutive promoter such as the ubiquitin promoter.

Claims

Claims 1. A recombinant expression cassette comprising a nucleic acid operably linked to a heterologous coding sequence, said nucleic acid having functional transcriptional promoter activity during meiosis and comprising, or consisting of, a nucleotide sequence selected from the group consisting of the sequence SEQ ID NO: 1 and functional variants thereof, said functional variants comprising, or consisting of, - a sequence having at least 70% sequence identity over the entire length of the sequence SEQ ID NO: 1; or - a fragment of the sequence SEQ ID NO: 1 of at least 110 consecutive nucleotides.

2. Expression cassette according to claim 1, characterized in that the nucleic acid comprises, or consists of, a nucleotide sequence selected from the group consisting of the sequence SEQ ID NO: 1 and functional variants thereof having at least 80% sequence identity over the entire length of the sequence SEQ ID NO:

1.

3. Expression cassette according to claim 1, characterized in that the nucleic acid comprises, or consists of, a nucleotide sequence selected from the group consisting of the sequences SEQ ID NO: 1, 2, 3 or 4.

4. Expression cassette according to any one of claims 1 to 3, characterized in that the coding sequence encodes a polypeptide of interest, preferably a reporter protein or a protein capable of modulating, preferably increasing, the frequency of meiotic recombinations, a protein which modifies the structure of chromatin such as for example histone (de)acetylases or histone (de)methylases or a protein which modifies DNA methylation.

5. Expression cassette according to any one of claims 1 to 3, characterized in that the coding sequence codes for a nucleic acid of interest, preferably an siRNA, an shRNA, an RNAi, miRNA, antisense RNA, ribozyme, DNAzyme or guide RNA capable of targeting the action of a CRISPR-type endonuclease, preferably Cas9 or dCas9, at a specific sequence.

6. Expression vector comprising an expression cassette according to any one of claims 1 to 5.

7. Non-human host cell transfected or transformed with an expression cassette according to any one of claims 1 to 5, or an expression vector according to claim 6, and containing said expression cassette or said vector in integrated or non-integrated form in the genome.

8. An in vitro method for expressing a coding sequence of interest in a non-human host cell during meiosis, comprising introducing into said cell an expression cassette according to any one of claims 1 to 5, or an expression vector according to claim 6, said coding sequence being operably linked to a nucleic acid as defined in any one of claims 1 to 3.

9. A method of producing a multicellular plant organism expressing a coding sequence of interest during meiosis, comprising introducing into a plant cell an expression cassette according to any one of claims 1 to 5, or an expression vector according to claim 6, said coding sequence being operably linked to a nucleic acid as defined in any one of claims 1 to 3, and reconstituting said organism from said cell.

10. Cell according to claim 7 or method according to claim 8, characterized in that the host cell is a plant cell.

11. A plant multicellular organism comprising an expression cassette according to any one of claims 1 to 5, or an expression vector according to claim 6.

12. Use of a nucleic acid as defined in any one of claims 1 to 3 for expressing a heterologous coding sequence of interest in a non-human host cell, preferably a plant cell, during meiosis.

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