Plant enriched with amino acids, proteins and starch

Abstract

The present invention relates to a plant or plant cell that is genetically modified to overexpress a gene that codes for the D-3-phosphoglycerate dehydrogenase (PGDH1) protein, wherein PGDH1 comprises amino acids conserved between species and wherein said plant does not belong to the Arabidopsis thaliana species. The invention further relates to a method that comprises transforming wild plants or plant cells with a recombinant expression vector. The invention also relates to uses of the plant or plant cell for producing proteins, amino acids and / or starch.

Description

[0001] DESCRIPTION

[0002] PLANT ENRICHED IN AMINO ACIDS, PROTEINS AND STARCH

[0003] TECHNICAL SECTOR

[0004] The present invention relates generally to the field of genetically modified plants. In particular, the present invention relates to plants genetically modified to overexpress a gene encoding the protein D-3-phosphoglycerate dehydrogenase (PGDH1). These plants have a higher content of amino acids, proteins, and starch than non-transformed plants.

[0005] BACKGROUND OF THE INVENTION

[0006] Plant-based foods are considered healthy and can help prevent disease, but they lack sufficient protein content to maintain a balanced human diet. Cultivated plants, and especially cereals, are low in protein. Corn, for example, has a protein content of only 10%. This low protein content is exacerbated by climate change, as it has been observed that an increase in CO2 concentration increases carbohydrate content to the detriment of the protein content of plants (Mizokami et al. (2019); Myers et al. (2019)). This lack of protein content also occurs in livestock species, where the plant-based foods provided are enriched by the addition of amino acids, which increases livestock nutrition costs for farmers.

[0007] Furthermore, plant-based foods have advantages over animal-based foods. Excessive consumption of animal products, especially red meat and processed meats, a traditional source of protein in the human diet, can have negative effects on health, increasing the risk of diseases such as diabetes, heart disease, stroke, and cancer.

[0008] Furthermore, the production of animal-based proteins is much more expensive than that of plant-based proteins and has a much higher environmental cost. It is also one of the main causes of soil and water resource degradation. Increasing the nutritional value of plants by increasing their protein or carbohydrate content is of great interest, particularly in the agri-food industry. There is intense research into the search for alternative protein sources. Plant products with high protein or carbohydrate content can be the basis for developing new foods with added nutritional value that can be enriched with one or another metabolite according to needs.

[0009] The development of plants with greater efficiency in protein biosynthesis is critically needed because it can increase protein production at low economic and environmental costs from cereals and other protein-poor plant crops, and it can also contribute to improved health by reducing the need for excessive consumption of animal products. It can also help improve the nutrition of vulnerable populations with limited access to animal products and those with malnutrition (groups whose diet is based solely on cereals).

[0010] Humans and other monogastric animals cannot synthesize the so-called essential amino acids, which must be supplied by the diet. Among them, the most limiting amino acids in plants, and especially in cereals, with respect to the nutritional needs of humans and animals are lysine, methionine, threonine, and tryptophan, which negatively impacts the nutritional quality of plants. The development of plants with higher contents of some of these amino acids, such as lysine, methionine, and threonine, is essential.

[0011] Genetically modified plants developed to date have not achieved sufficiently satisfactory results. In some cases, genetically modified plants exhibited undesirable developmental changes.

[0012] DESCRIPTION OF THE INVENTION

[0013] For the purposes of the present invention, "complementary DNA (cDNA)" refers to a double-stranded DNA molecule, in which one of its strands constitutes a sequence completely complementary to the messenger RNA from which it was synthesized. It is used in plant transformation because, given the nature of its synthesis, it lacks introns. For the purposes of the present invention, "C3 metabolism plant" refers to a plant whose metabolic pathway for carbon fixation during photosynthesis is a 3-carbon pathway. In the 3-carbon pathway, CO2 is fixed directly in the Calvin cycle, without any prior fixation. The first stable product into which carbon is fixed in the Calvin cycle is 3-phosphoglycerate, a 3-carbon compound, which explains the name C3 metabolism.

[0014] For the purposes of the present invention, “C4 metabolism plant” refers to a plant whose metabolic pathway for carbon fixation during photosynthesis is a 4-carbon pathway or Hatch-Slack pathway. In the 4-carbon pathway, prior to the carboxylation of ribulose-1,5-bisphosphate catalyzed by the Rubisco enzyme, which produces 3-phosphoglycerate with three carbon atoms, a first carboxylation of phosphoenolpyruvic acid (PEP) occurs, which produces a four-carbon dicarboxylic acid (melic acid or aspartic acid) as a primary stable product. This type of plant minimizes the loss of CO2 during photorespiration.

[0015] The problem existing in the state of the art is to provide a genetically modified plant with improved efficiency in the biosynthesis of amino acids, proteins and starch.

[0016] Additionally, in particular, the problem existing in the state of the art is to provide a genetically modified plant with improved efficiency in the biosynthesis of amino acids, proteins and starch under conditions of high ambient CO2.

[0017] The present invention solves both technical problems by means of a plant genetically modified to over-express a gene encoding a protein D-3-phosphoglycerate dehydrogenase (PGDH1; EC 1.1.1.95), a protein of the phosphorylative pathway of serine biosynthesis.

[0018] Three enzymes that catalyze the conversion of D-3-phosphoglycerate to serine are involved in the phosphorylative pathway of serine biosynthesis: D-3-phosphoglycerate dehydrogenase (PGDH1; EC 1.1.1.95), phosphoserine aminotransferase (PSAT; EC 2.6.1.52), and phosphoserine phosphatase (PSP; EC 3.1.3.3). In Arabidopsis thaliana, there are three isoforms of the PGDH protein: PGDH1 isoform, encoded by the PGDH1 gene (also called EDA9), PGDH2 isoform, encoded by the PGDH2 gene (also called PGDH), and PGDH3 isoform, encoded by the PGDH3 gene (also called 3-PGDH). The three isoforms have an amino acid identity greater than 74%.

[0019] The present invention provides a genetically modified plant, not constituting a Plant Variety, or a genetically modified plant cell, to over-express a gene encoding a D-3-phosphoglycerate dehydrogenase (PGDH1) protein, wherein the amino acid sequence of said PGDH1 protein comprises the following amino acids: leucine at position 65; leucine at position 78; arginine at position 108; serine at position 109; threonine at position 111; alanine at position 142; alanine at position 143; alanine at position 162; glutamic acid at position 163; arginine at position 291; glycine at position 292; leucine at position 300; aspartic acid at position 315; valine at position 316; phenylalanine at position 317; glutamic acid at position 320; proline at position 321; proline at position 338; histidine at position 339; glycine at position 341; serine at position 343;threonine at position 344; glutamic acid at position 346; alanine at position 347; and glutamine at position 348; wherein said positions refer to the position in the amino acid sequence of the PGDH1 protein of Arabidopsis thaliana identified by the sequence SEQ ID NO: 1; and wherein said plant is not of the Arabidopsis thaliana species.

[0020] The amino acids in the preceding paragraph include conserved individual amino acids of the enzyme. These conserved individual amino acids can be grouped, in turn, into the following conserved domains of the enzyme, essential for its activity: leucine, at position 65; leucine at position 78; domain consisting of arginine and serine at positions 108 and 109 respectively; followed by threonine at position 111; alanine and alanine at positions 142 and 143, respectively; alanine and glutamic acid at positions 162 and 163, respectively; domain consisting of arginine and glycine at positions 291 and 292, respectively; followed by leucine at position 300; domain consisting of aspartic acid, valine and phenylalanine at positions 315, 316 and 317, respectively; followed by glutamic acid and proline at positions 320 and 321, respectively; and a domain consisting of proline and histidine at positions 338 and 339, respectively;followed by glycine at position 341; serine and threonine at positions 343 and 344, respectively; and finally, glutamic acid, alanine, and glutamine at positions 346, 347, and 348, respectively;

[0021] After performing an analysis of the sequences of plants (Arabidopsis thaliana, tomato and corn), bacteria (Escherichia coli and Mycobacterium tuberculosis) and mammals (Homo sapiens and Rattus norvegicus), the inventors have determined that the amino acids and domains of the previous paragraph are conserved in all the species studied, including bacteria and mammals, and are responsible for the D-3-phosphoglycerate dehydrogenase function, synthesizing serine, being conserved in all species, including bacteria and mammals. Since these domains are conserved in plants, bacteria and mammals, they have a high biological significance and a high functional importance.

[0022] The genetically modified plant or plant cell of the invention over-expresses a gene that codes for a D-3-phosphoglycerate dehydrogenase protein (PGDH1) with the amino acids and domains conserved in all the species studied, including bacteria and mammals, and is, due to this, an active protein for the D-3-phosphoglycerate dehydrogenase function, synthesizing serine.

[0023] In a preferred embodiment of the invention, the amino acid sequence of said PGDH1 protein further comprises the following amino acids: glycine at position 209; glycine at position 212; aspartate at position 256; and histidine at position 261; wherein said positions refer to the position in the amino acid sequence of the Arabidopsis thaliana PGDH1 protein identified by the sequence SEQ ID NO: 1.

[0024] Therefore, in a preferred embodiment, the amino acid sequence of said protein

[0025] PGDH1 comprises the following amino acids: leucine at position 65; leucine at position 78; arginine at position 108; serine at position 109; threonine at position 111; alanine at position 142; alanine at position 143; alanine at position 162; glutamic acid at position 163; glycine at position 209; glycine at position 212; aspartate at position 256; histidine at position 261; arginine at position 291; glycine at position 292; leucine at position 300; aspartic acid at position 315; valine at position 316; phenylalanine at position 317; glutamic acid at position 320; proline at position 321; proline at position 338; histidine at position 339; glycine at position 341; serine at position 343; threonine at position 344; glutamic acid at position 346; alanine at position 347; and glutamine at position 348;wherein said positions refer to the position in the amino acid sequence of the PGDH1 protein of Arabidopsis thaliana identified by the sequence SEQ ID NO: 1; and wherein said plant is not of the Arabidopsis thaliana species.

[0026] The amino acids in the preceding paragraph also include individual conserved amino acids of the enzyme. These individual conserved amino acids can be grouped, in turn, into the following conserved domains of the enzyme: glycine and glycine at positions 209 and 212, respectively; aspartate and histidine at positions 256 and 261, respectively; and arginine and glycine at positions 291 and 292, respectively; followed by leucine at position 300.

[0027] In a preferred embodiment, the present invention provides a plant, not constituting a Plant Variety, or a genetically modified plant cell, to over-express a gene that codes for the protein D-3-phosphoglycerate dehydrogenase (PGDH1), in which the amino acid sequence of said PGDH1 protein has an identity of at least 65% with respect to the sequence of the PGDH1 protein of Arabidopsis thaliana (SEQ ID NO: 1) and in which said plant is not of the Arabidopsis thaliana species.

[0028] Overexpression of the gene encoding the D-3-phosphoglycerate dehydrogenase protein (PGDH1) leads to a significant increase in the amino acid, protein, and starch content of the modified plants. The PGDH1 protein is a protein of the phosphorylative serine biosynthesis pathway, which is a common pathway in all plants. Therefore, the present invention provides a solution for increasing the amino acid, protein, and starch content of numerous species of agricultural interest, including cereals. The present invention is especially relevant in the new conditions of climate change where high levels of ambient CO2 are expected. In fact, a very notable advantage of the present invention is that it increases protein and starch production under plant growth conditions where high CO2 concentrations exist.The increased protein production obtained is an unexpected result since an increase in CO2 concentration increases the starch content in plants while reducing their protein content. Under such high CO2 conditions, the present invention also manages to significantly increase most of the essential amino acids (leucine, isoleucine, phenylalanine, valine, threonine, lysine and methionine) in plants. This increase in the production of essential amino acids is an unexpected result given that, as indicated above, an increase in CO2 concentration reduces the protein content of plants (Myers et al. (2019)).

[0029] The results obtained by the inventors demonstrate that the present invention directs plant metabolism toward a higher content of some essential amino acids and in turn increases the generalized production of proteins and carbohydrates, and not just a higher production of a protein or a specific amino acid. In principle, therefore, the present invention covers any plant since the phosphorylative pathway of serine biosynthesis, in which PGDH1 is involved, is a general pathway for all of them.

[0030] Another advantage of the present invention is that, in contrast to other strategies in the state of the art, there is no reduction in the growth of the plant of the invention.

[0031] From all of the above, it follows that the present invention prevents the effects of climate change on the nutritional quality of crops and increases protein production at a low economic and environmental cost. Furthermore, the present invention allows for a reduction in the consumption of animal protein in humans and livestock.

[0032] Table 1 shows information about the sequences SEQ ID NO: 1-9. Table 1

[0033] The nucleotide sequence of the complementary DNA (cDNA) of the PGDH1 gene of Arabidopsis thaliana is the sequence SEQ ID NO: 8. The reference number of the nucleotide sequence of the PGDH1 gene of Arabidopsis thaliana in the database “The Arabidopsis Information Resource”, which is the reference database for Arabidopsis thaliana, is AT4G34200. The sequence SEQ ID NO: 8 corresponds to said sequence with reference number AT4G34200 in “The Arabidopsis Information Resource”. The nucleotide sequence of the PGDH1 gene of Arabidopsis thaliana encodes the PGDH1 protein, whose amino acid sequence is the sequence SEQ ID NO: 1. The reference number of the amino acid sequence of the PGDH1 protein of Arabidopsis thaliana in “National Center for Biotechnology Information” is NP_195146.1. The sequence SEQ ID NO: 1 corresponds to said sequence with reference number NP_195146.1 in the “National Center for Biotechnology Information”.The sequence SEQ ID NO: 2 corresponds to amino acids 61 to 348 of the PGDH1 protein of Arabidopsis thaliana.

[0034] In a preferred embodiment of the plant or plant cell of the invention, the amino acid sequence of the PGDH1 protein has an identity with respect to the sequence of the PGDH1 protein of Arabidopsis thaliana (SEQ ID NO: 1) of at least 66%, at least 67%, at least 68%, at least 69%, at least 70%, at least 71%, at least 72%, at least 73%, at least 74%, at least 75%, at least 76%, at least 77%, at least 78%, at least 79%, at least 80%, at least 81%, at least 82%, at least 83%, at least 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98% or at least 99%.

[0035] In another preferred embodiment of the plant or plant cell of the invention, said PGDH1 protein comprises a sequence that has an identity of at least 75% with respect to the sequence SEQ ID NO: 2.

[0036] Preferably, said PGDH1 protein comprises a sequence having an identity with respect to the sequence SEQ ID NO: 2 of at least 76%, at least 77%, at least 78%, at least 79%, at least 80%, at least 81%, at least 82%, at least

[0037] 83%, at least 84%, at least 85%, at least 86%, at least 87%, at least

[0038] 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least

[0039] 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least

[0040] 98% or at least 99%.

[0041] The inventors performed an analysis of the PGDH1 protein sequences in the plants Arabidopsis thaliana, tomato (Solanum lycopersicum), corn (Zea mays), and other species of agricultural interest. The results are shown in Table 2. In all the cases studied from different plant species, a sequence identity greater than 65% was found. Table 2

[0042] The inventors also performed an analysis of the sequences of amino acids 61 to 348 of the PGDH1 protein in the plants Arabidopsis thaliana, tomato (Solanum lycopersicum), corn (Zea mays), and other species of agricultural interest. The results are shown in Table 3. In all the cases studied from different plant species, a sequence identity greater than 75% was found.

[0043] Table 3 Additionally, the inventors have performed a sequence alignment of the PGDH1, PGDH2 and PGDH3 proteins from Arabidopsis thaliana, PGDH from tomato and PGDH from corn, which are shown in Figure 1. The analysis performed made it possible to determine that several amino acids of the PGDH1 protein are conserved in plants (Arabidopsis thaliana, tomato and corn), in bacteria (Escherichia coli and Mycobacterium tuberculosis) and in mammals (Homo sapiens and Rattus norvegicus). The sequence alignment of the PGDH1, PGDH2 and PGDH3 proteins from Arabidopsis thaliana, PGDH from Homo sapiens, PGDH from Escherichia coli, PGDH2 from rat (Rattus norvegicus) and PGDH1 from Mycobacterium tuberculosis are shown in Figure 7.These amino acids are the following: leucine at position 65; leucine at position 78; arginine at position 108; serine at position 109; threonine at position 111; alanine at position 142; alanine at position 143; alanine at position 162; glutamic acid at position 163; arginine at position 291; glycine at position 292; leucine at position 300; aspartic acid at position 315; valine at position 316; phenylalanine at position 317; glutamic acid at position 320; proline at position 321; proline at position 338; histidine at position 339; glycine at position 341; serine at position 343; threonine at position 344; glutamic acid at position 346; alanine at position 347; and glutamine at position 348.

[0044] The positions indicated in the previous paragraph refer to the position in the amino acid sequence of the PGDH1 protein of Arabidopsis thaliana.Therefore, in another preferred embodiment of the plant or plant cell of the invention, in said PGDH1 protein at least one of the amino acids is: leucine at position 65; leucine at position 78; arginine at position 108; serine at position 109; threonine at position 111; alanine at position 142; alanine at position 143; alanine at position 162; glutamic acid at position 163; arginine at position 291; glycine at position 292; leucine at position 300; aspartic acid at position 315; valine at position 316; phenylalanine at position 317; glutamic acid at position 320; proline at position 321; proline at position 338; histidine at position 339; glycine at position 341; serine at position 343; threonine at position 344; glutamic acid at position 346; alanine at position 347; and glutamine at position 348.

[0045] In another preferred embodiment of the plant or plant cell of the invention, the amino acid sequence of said PGDH1 protein comprises a sequence selected from the group consisting of: SEQ ID NO: 3, SEQ ID NO: 4, SEQ ID NO: 5, SEQ ID NO: 6 and SEQ ID NO: 7, which correspond to sequences of the PGDH1 protein conserved only in plants (they are conserved in Arabidopsis thaliana, tomato and corn), but not conserved in bacteria (Escherichia coli and Mycobacterium tuberculosis), nor in mammals (Homo sapiens and Rattus norvegicus).

[0046] In another preferred embodiment of the plant or plant cell of the invention, the amino acid sequence of said PGDH1 protein comprises a sequence selected from the group consisting of: SEQ ID NO: 16, SEQ ID NO: 17, SEQ ID NO: 18 and SEQ ID NO: 19. The sequences SEQ ID NO: 16, SEQ ID NO: 17, SEQ ID NO: 18 and SEQ ID NO: 19 correspond to:

[0047] - Amino acids 203 to 230 of the Arabidopsis thaliana PGDH1 protein (SEQ ID NO:

[0048] 16)

[0049] - Amino acids 251 to 273 of the Arabidopsis thaliana PGDH1 protein (SEQ ID NO:

[0050] 17)

[0051] - Amino acids 280 to 296 of the Arabidopsis thaliana PGDH1 protein (SEQ ID NO:

[0052] 18)

[0053] - Amino acids 530 to 603 of the Arabidopsis thaliana PGDH1 protein (SEQ ID NO:

[0054] 19)

[0055] In a more preferred embodiment of the plant or plant cell of the invention, the amino acid sequence of said PGDH1 protein is the sequence SEQ ID NO: 1.

[0056] In a preferred embodiment, the plant or plant cell of the invention has a higher content of amino acids and / or proteins and / or starch than an untransformed plant or plant cell.

[0057] In a more preferred embodiment, the plant or plant cell of the invention has a content of at least 5% higher in amino acids and / or at least 5% higher in proteins and / or at least 5% higher in starch compared to an untransformed plant or plant cell.

[0058] In an even more preferred embodiment, the plant of the invention or the plant cell has a content that is at least 5% higher in amino acids and / or at least 5% higher in proteins and / or at least 5% higher in starch compared to an untransformed plant or plant cell, under cultivation conditions in which the CO2 concentration is at least 800 ppm. Currently, CO2 values ​​in the atmosphere are substantially lower than 800 ppm. However, in certain future scenarios, CO2 values ​​in the atmosphere could exceed 800 ppm.

[0059] In another preferred embodiment, the plant or plant cell of the invention is of a species of agronomic interest.

[0060] In a more preferred embodiment, the plant or plant cell of the invention is from a species with C3 metabolism. Preferably, the species with C3 metabolism is selected from among tomato and broccoli.

[0061] In a more preferred embodiment, the plant or plant cell is from a species with C4 metabolism. Preferably, the species with C4 metabolism is corn.

[0062] In another preferred embodiment of the plant or plant cell of the invention, the nucleotide sequence of the gene that codes for the PGDH1 protein has an identity of at least 65% with respect to the sequence SEQ ID NO: 8 or with respect to the sequence SEQ ID NO: 9.

[0063] Preferably, the nucleotide sequence of the gene encoding the PGDH1 protein has an identity with respect to the sequence SEQ ID NO: 8 or with respect to the sequence SEQ ID NO: 9 of at least 66%, at least 67%, at least 68%, at least 69%, at least 70%, at least 71%, at least 72%, at least 73%, at least 74%, at least 75%, at least 76%, at least 77%, at least 78%, at least 79%, at least 80%, at least 81%, at least 82%, at least 83%, at least 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98% or at least 99%.

[0064] In a more preferred embodiment of the plant or plant cell of the invention, the nucleotide sequence of the gene that codes for the PGDH1 protein is the sequence SEQ ID NO: 8 or the sequence SEQ ID NO: 9.

[0065] In another preferred embodiment of the plant or plant cell of the invention, the gene encoding the PGDH1 protein is operably linked to a constitutive promoter. Preferably, the promoter is selected from the constitutive promoter of the gene encoding maize ubiquitin and the constitutive promoter of the cauliflower mosaic virus 35S.

[0066] In another preferred embodiment, the plant of the invention does not suffer alteration in its growth as a plant, in relation to the growth, under identical cultivation conditions, of an untransformed plant of the same species.

[0067] In another preferred embodiment, the plant of the invention does not show an increase in root size relative to the root size of an untransformed plant.

[0068] In another preferred embodiment, the plant of the invention does not present an increase in the size of the aerial part in relation to the size of the aerial part of an untransformed plant.

[0069] The present invention also provides a recombinant expression construct comprising a gene encoding the D-3-phosphoglycerate dehydrogenase (PGDH1) protein, wherein the amino acid sequence of said PGDH1 protein has an identity of at least 65% with respect to the sequence SEQ ID NO: 1 and wherein the gene encoding the PGDH1 protein is operably linked to a constitutive promoter.

[0070] In a preferred embodiment of the recombinant expression construct of the invention, the constitutive promoter is selected from the constitutive promoter of the gene encoding corn ubiquitin and the constitutive promoter of the cauliflower mosaic virus 35S.

[0071] In another preferred embodiment of the recombinant expression construct of the invention, the nucleotide sequence of the gene encoding the PGDH1 protein has an identity of at least 65% with respect to the sequence SEQ ID NO: 8 or with respect to the sequence SEQ ID NO: 9.

[0072] Preferably, the nucleotide sequence of the gene encoding the PGDH1 protein has an identity with respect to the sequence SEQ ID NO: 8 or with respect to the sequence SEQ ID NO: 9 of at least 66%, at least 67%, at least 68%, at least 69%, at least 70%, at least 71%, at least 72%, at least 73%, at least 74%, at least 75%, at least 76%, at least 77%, at least 78%, at least 79%, at least 80%, at least 81%, at least 82%, at least 83%, at least 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98% or at least 99%.

[0073] In a more preferred embodiment of the recombinant expression construct of the invention, the nucleotide sequence of the gene encoding the PGDH1 protein is the sequence SEQ ID NO: 8 or the sequence SEQ ID NO: 9.

[0074] In another preferred embodiment of the method of the invention, the amino acid sequence of said PGDH1 protein comprises a sequence selected from the group consisting of: SEQ ID NO: 16, SEQ ID NO: 17, SEQ ID NO: 18 and SEQ ID NO: 19.

[0075] The present invention also provides a recombinant expression vector comprising the recombinant expression construct of the invention.

[0076] In a preferred embodiment of the recombinant expression vector of the invention, the nucleotide sequence of the gene that codes for the PGDH1 protein has an identity of at least 65% with respect to the sequence SEQ ID NO: 8 or with respect to the sequence SEQ ID NO: 9.

[0077] Preferably, the nucleotide sequence of the gene encoding the PGDH1 protein has an identity with respect to the sequence SEQ ID NO: 8 or with respect to the sequence SEQ ID NO: 9 of at least 66%, at least 67%, at least 68%, at least 69%, at least 70%, at least 71%, at least 72%, at least 73%, at least 74%, at least 75%, at least 76%, at least 77%, at least 78%, at least 79%, at least 80%, at least 81%, at least 82%, at least 83%, at least 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98% or at least 99%.

[0078] In a more preferred embodiment of the recombinant expression vector of the invention, the nucleotide sequence of the gene encoding the PGDH1 protein is the sequence SEQ ID NO: 8 or the sequence SEQ ID NO: 9. The present invention additionally provides a non-essentially biological process for obtaining a genetically modified plant, or a genetically modified plant cell, to over-express a gene encoding a D-3-phosphoglycerate dehydrogenase (PGDH1) protein, which comprises transforming the wild-type plants or the corresponding plant cells with an expression vector comprising a gene encoding the D-3-phosphoglycerate dehydrogenase (PGDH1) protein, wherein the amino acid sequence of said PGDH1 protein comprises the following amino acids: leucine at position 65; leucine at position 78; arginine at position 108; serine at position 109; threonine at position 111; alanine at position 142;alanine at position 143; alanine at position 162; glutamic acid at position 163; arginine at position 291; glycine at position 292; leucine at position 300; aspartic acid at position 315; valine at position 316; phenylalanine at position 317; glutamic acid at position 320; proline at position 321; proline at position 338; histidine at position 339; glycine at position 341; serine at position 343; threonine at position 344; glutamic acid at position 346; alanine at position 347; and glutamine at position 348; wherein said positions refer to the position in the amino acid sequence of the PGDH1 protein of Arabidopsis thaliana identified by the sequence SEQ ID NO: 1;and wherein said plant or plant cell is not of the species Arabidopsis thaliana. In a preferred embodiment of the method of the invention, the amino acid sequence of said PGDH1 protein further comprises the following amino acids: glycine at position 209; glycine at position 212; aspartate at position 256; and histidine at position 261; wherein said positions refer to the position in the amino acid sequence of the Arabidopsis thaliana PGDH1 protein identified by the sequence SEQ ID NO: 1.;

[0079] In a preferred embodiment, the present invention provides a non-essentially biological process for obtaining a genetically modified plant or a genetically modified plant cell comprising transforming the corresponding wild plants or plant cells with an expression vector comprising a gene encoding the protein D-3-phosphoglycerate dehydrogenase (PGDH1), wherein the amino acid sequence of said PGDH1 protein has an identity of at least 65% with respect to the sequence SEQ ID NO: 1 and wherein said plant or plant cell is not of the species Arabidopsis thaliana.

[0080] Preferably, the amino acid sequence of said PGDH1 protein has an identity with respect to the sequence SEQ ID NO: 1 of at least 66%, at least 67%, at least 68%, at least 69%, at least 70%, at least 71%, at least 72%, at least

[0081] 73%, at least 74%, at least 75%, at least 76%, at least 77%, at least

[0082] 78%, at least 79%, at least 80%, at least 81%, at least 82%, at least

[0083] 83%, at least 84%, at least 85%, at least 86%, at least 87%, at least

[0084] 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least

[0085] 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least

[0086] 98% or at least 99%.

[0087] The present invention also provides a non-essentially biological method for obtaining a genetically modified plant or a genetically modified plant cell comprising performing gene editing of the corresponding wild-type plants or plant cells so that they overexpress the gene encoding the protein D-3-phosphoglycerate dehydrogenase (PGDH1). Preferably, gene editing is a CRISPR-Cas9-based technology. In a preferred embodiment of the method of the invention, said PGDH1 protein comprises a sequence that has an identity of at least 75% with respect to the sequence SEQ ID NO: 2.Preferably, said sequence identity is at least 76%, at least 77%, at least 78%, at least 79%, at least 80%, at least 81%, at least 82%, at least 83%, at least 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98% or at least 99%.

[0088] In another preferred embodiment of the method of the invention, in said PGDH1 protein at least one of the amino acids is: leucine at position 65; leucine at position 78; arginine at position 108; serine at position 109; threonine at position 111; alanine at position 142; alanine at position 143; alanine at position 162; glutamic acid at position 163; arginine at position 291; glycine at position 292; leucine at position 300; aspartic acid at position 315; valine at position 316; phenylalanine at position 317; glutamic acid at position 320; proline at position 321; proline at position 338; histidine at position 339; glycine at position 341; serine at position 343; threonine at position 344; glutamic acid at position 346; alanine at position 347; and glutamine at position 348.

[0089] In another preferred embodiment of the method of the invention, the amino acid sequence of said PGDH1 protein comprises a sequence selected from the group consisting of: SEQ ID NO: 3, SEQ ID NO: 4, SEQ ID NO: 5, SEQ ID NO: 6 and SEQ ID NO: 7.

[0090] In another preferred embodiment of the method of the invention, the amino acid sequence of said PGDH1 protein is the sequence SEQ ID NO: 1.

[0091] In another preferred embodiment of the method of the invention, the plant or plant cell is of a species of agronomic interest.

[0092] In another preferred embodiment of the method of the invention, the plant or plant cell is from a species with C3 metabolism. Preferably, the species with C3 metabolism is selected from among tomato and broccoli.

[0093] In another preferred embodiment of the method of the invention, the plant or plant cell is from a species with C4 metabolism. Preferably, the species with C4 metabolism is corn.

[0094] In another preferred embodiment of the method of the invention, the nucleotide sequence of the gene that codes for the PGDH1 protein has an identity of at least 65% with respect to the sequence SEQ ID NO: 8 or with respect to the sequence SEQ ID NO: 9.

[0095] Preferably, the nucleotide sequence of the gene encoding the PGDH1 protein has an identity of at least 65% with respect to the sequence SEQ ID NO: 8 or with respect to the sequence SEQ ID NO: 9 of at least 66%, at least 67%, at least 68%, at least 69%, at least 70%, at least 71%, at least 72%, at least 73%, at least 74%, at least 75%, at least 76%, at least 77%, at least 78%, at least 79%, at least 80%, at least 81%, at least 82%, at least 83%, at least 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98% or at least 99%. In a more preferred embodiment of the method of the invention, the nucleotide sequence of the gene encoding the PGDH1 protein is the sequence SEQ ID NO: 8 or the sequence SEQ ID NO: 9.

[0096] The present invention also provides the use of the plant of the invention, the plant cell of the invention, the recombinant expression construct of the invention, or the recombinant expression vector of the invention, for the production of proteins, amino acids and / or starch.

[0097] In a preferred embodiment of the use of the invention, the plant cell or plant is grown under conditions in which the CO2 concentration is at least 800 ppm.

[0098] In relation to the sequence identity percentages of the present invention, the expert can determine whether a sequence has at least a certain percentage of identity with respect to a sequence of the present invention, using sequence alignment computer programs known in the state of the art.

[0099] For example, herein, a problem sequence is understood to have at least 65% identity to a reference sequence of the invention when the sequence can include up to 35 different residues for every 100 residues of the reference sequence, whether by deletion, insertion, or substitution. This extends analogously to the other identity percentages described herein.

[0100] Throughout the description and claims, the terms "comprises," "comprising," and their variants are not limiting in nature and, therefore, are not intended to exclude other technical features. The terms "comprises," "comprising," and their variants, throughout the description and claims, specifically include the terms "consists of," "consisting of," and their variants.

[0101] As used in this description and the claims, the singular forms "the" and "the" include references to the plural forms unless the content clearly indicates otherwise. Unless otherwise defined, all technical and scientific terms used throughout the description and claims have the same meaning as that commonly understood by a person skilled in the art.

[0102] BRIEF DESCRIPTION OF THE DRAWINGS

[0103] Figure 1. Sequence alignment of the PGDH1, PGDH2, and PGDH3 proteins from Arabidopsis thaliana, tomato PGDH, and maize PGDH. Domains conserved across the plant species studied are highlighted in light gray, and domains conserved even in mammals (rat and human) are highlighted in dark gray; the PGDH protein sequences from these two mammalian species are not shown in the figure.

[0104] Figure 2. Phenotypic characterization of triple overexpressing (TriOex) and overexpressing (Oex PGDH1) lines of 14-day-old Arabidopsis thaliana seedlings grown in vitro under ambient CO2 (400 ppm) (A and B) and high CO2 (2500 ppm) (C and D) conditions. For both conditions, shoot fresh weight (A and C) and primary root length (B and D) were measured. Values ​​represent the mean ± SE (n > 100). (*) indicates significant differences with respect to the wild-type control (WT; T-test, P < 0.05).

[0105] Figure 3. Analysis of starch (A and B) and protein (C and D) contents under ambient CO2 (400 ppm; white bars) and high CO2 (2500 ppm; grey bars) conditions in shoots (A and C) and roots (B and D) of 14-day-old Arabidopsis thaliana TriOex and Oex PGDH1 plants grown in vitro. Values ​​represent the mean ± SE (n = 12 biological replicates). (*) represents significant differences with respect to the wild-type control (WT; T-test, P < 0.05).

[0106] Figure 4. Analysis of starch (A, B, and C) and protein (D, E, and F) contents under ambient CO2 conditions in leaves (A and D), stems (B and E), and grain (C and F) of ZmOex PGDH1 maize plants, either in individual lines (ZmOex PGDH 1-22, ZmOex PGDH 1-27, and ZmOex PGDH1-31) or in all lines (ZmOex PGDH1). The material comes from plants grown in a greenhouse for 20 days (leaves and stems) or at the end of the biological cycle in the case of grain. The values ​​represent the mean ± SE (n > 12 biological replicates). (*) represents significant differences with respect to the wild-type control plants (WT; T-test, P < 0.05). Figure 5. Relative expression of the Arabidopsis thaliana PGDH1 gene in different organs of three transgenic maize lines (ZmOex PGDH1-22, ZmOex PGDH1-27, and ZmOex PGDH1-31). Bars represent mean ± SE (n > 6 biological replicates). (*) represents significant differences with respect to the wild-type control (WT; T-test, P < 0.05).

[0107] Figure 6. Relative shoot weight of 22-day-old plants of three transgenic maize lines overexpressing the PGDH1 gene compared with the wild-type control (WT). Data are from individual transgenic lines (ZmOex PGDH1-22, ZmOex PGDH1-27, and ZmOex PGDH1-31) or from all lines (ZmOex PGDH1). Bars represent the mean ± SE (n > 15 biological replicates). (*) represents significant differences with respect to the wild-type control (WT; T-test, P < 0.05).

[0108] Figure 7. Sequence alignment of Arabidopsis thaliana PGDH1 (AtPGDHI), Arabidopsis thaliana PGDH2 (AtPGDH2), Arabidopsis thaliana PGDH3 (AtPGDH3), Homo sapiens PGDH (HmPGDH), Escherichia coli PGDH (EcPGDH), rat PGDH1 (RnPGDHI), and Mycobacterium tuberculosis PGDH1 (MtPGDHI) proteins.

[0109] DESCRIPTION OF IMPLEMENTATION MODES

[0110] Example 1. Materials and methods

[0111] Plant material and growing conditions

[0112] Wild-type Arabidopsis thaliana plants, ecotype Columbia, were used as the starting plant material. These wild-type seeds were used as the genetic background for obtaining over-expressing lines. The seeds to be sterilized were placed in a 1.5 mL tube and two successive washes of 15 minutes each were performed, with continuous agitation, with 1 mL of a 70% ethanol solution and 0.05% SDS (Sodium Dodecyl Sulfate, SIGMA, Ref. 1667289). Once these two washes were completed, the final solution was discarded and replaced with 1 mL of a 70% ethanol solution, and the seeds were again kept agitated for 5 minutes. After these 5 minutes, the seeds were placed and allowed to dry on sterile filter paper inside a horizontal laminar flow cabinet under sterile conditions. Once dry, the seeds were sown in the appropriate culture medium or stored at 4°C until use in a sterile 1.5 mL tube.For the in vitro cultivation of Arabidopsis thaliana, round or square plates of 12 cm each side were used, containing a culture medium composed of 0.9 g / L of a preparation from Duchefa Biochemie (Ref. P03769-05), 0.9 g / L of MES (2-N-morpholinoethanesulfonic acid, SIGMA, Ref. 32K5465), 8 g / L of agar (Pronadisa, Ref. SB090321), and the pH adjusted to 5.7 [adjusted with Tris (tris(hydroxymethyl) aminomethane; Sigma, Ref. T6066) or KOH]. This medium was designated as MS1 / 5. Once inoculation was carried out under sterile conditions, the plates were sealed with Micropore Hypoallergenic porous tape (3M Micropore TM, Ref. 1530-0 for round plates and Ref. 1530-1 for square plates), which allows gas exchange but maintains humidity inside the plates.

[0113] Before being transferred to growth chambers (Sanyo-MLR-351 H or Ibercex H-900) for germination, the seeds sown on the plates were stratified for 3-4 days at 4°C to promote and synchronize germination. The culture remained for the appropriate days for each experiment at a temperature of 22-25°C, relative humidity 40-60%, a long-day photoperiod (16 h of light and 8 h of darkness) and a light intensity of 120 pmol m' 2 s' 1 . When in vitro cultivation under high CO2 conditions was required, plants were grown at a CO2 concentration of 2000 or 2500 ppm under the same light and humidity conditions.

[0114] Plants of agricultural interest and C4 photosynthetic metabolism have also been used. Specifically, maize (Zea mays) variety B104 plants were used to generate transgenic lines. This variety was supplied by the Plant Transformation Service of Iowa State University, where the first generation of transgenic maize plants was obtained. From this starting material, at least three more generations were obtained until transgenic lines with a single homozygous insertion were obtained, as indicated below.

[0115] The corn seeds were manually separated from the cob, cleaned, and surface sterilized (to eliminate possible spores and fungi) with two successive 5-minute washes in alcoholic solutions. First, the seeds were placed in 250 mL flasks and sterilized with gentle shaking, followed by a first wash with 70% ethanol containing 0.05% SDS for 5 minutes. After 5 minutes, this solution was removed, and a second wash was performed with 70% ethanol for another 5 minutes. After this time, the seeds were placed on filter paper and allowed to dry inside a laminar flow cabinet. Once dry, the seeds were stored in paper bags at 4°C until use.To obtain maize leaf, stem, and root material, seeds were sown in polystyrene pots containing expanded perlite with a particle size of 1–5 mm (Projar), placed in trays, and watered with nutrient solution. After one week, the seeds had germinated, and the seedlings had two or three leaves. Leaf, stem, and root material were collected after two weeks. To harvest the grain, the plants had to complete their life cycle. To do this, two-week-old seedlings were transplanted into 35-liter pots containing a Kekkila substrate and perlite in a 3:1 (v / v) ratio, respectively.

[0116] The pots were watered once or twice a week with a nutrient solution, depending on their water requirements. After a few months, the plants developed male inflorescences (from which we collected pollen) and female inflorescences (which self-pollinated) to obtain the grain. When a small, unopened ear of corn (a female inflorescence) appeared from the axil of a leaf, it was quickly covered with a paper bag to prevent unwanted crossbreeding. Since in some cases there is a slight time lag between the development of the male flower, which develops first, and the female flower, pollen was collected from each plant individually and stored at 4°C until use. When the female flower developed and the filamentous stigmas appeared, each flower was pollinated with pollen from the same plant, allowing it to fall onto the stigmas.Self-pollination of the plants lasted until the male inflorescence produced pollen or while the stigmas were receptive.

[0117] The growth conditions in the greenhouse were long day (16 h of light and 8 h of darkness), with an approximate light intensity of 130 pmol nr 2 s' 1 , 50–70% relative humidity, and a temperature of around 28°C during the day and around 25°C at night. Natural light was supplemented with artificial light (sodium vapor lamps and mercury vapor lamps) when necessary.

[0118] Cloning and transformation of plants

[0119] The PGDH1 cDNA was introduced into the plant expression plasmid pMDC83 using Gateway® technology, which is based on att recombination sites, using the recombinase enzyme from the INVITROGEN Gateway® LR Clonase® II enzyme mix kit (Ref. 11791-100). Plasmid pMDC83 allows the expression of PGDH1 in plants under the control of the strong cauliflower mosaic virus promoter (pMDC83 Pro35S:PGDH1-GFP). Plasmid pMDC83 carries the green GFP fusion protein, which is in reading frame with the introduced DNA.

[0120] Triple over-expressing plants of three genes encoding the three enzymes involved in the phosphorylative pathway of serine biosynthesis, D-3-phosphoglycerate dehydrogenase (PGDH1), phosphoserine aminotransferase (PSAT1) and phosphoserine phosphatase (PSP), have also been obtained. The construction for obtaining plants over-expressing the PSAT1 gene consisted of cloning the coding part of said gene into plasmid pMDC86 to obtain plasmid pMDC86 Pro35S:PSAT1-GFP. Plasmid pMDC86 is similar to pMDC83 described above except for the plant selection agent, which in plasmid pMDC83 provides tolerance to hygromycin and in plasmid pMDC86 provides tolerance to BASTA. The PSAT1 gene does not contain introns, so BAG F8D20 was used to amplify its coding region by PCR.The resulting PCR product, using primers PSAT1+1 For and PSAT1+1270 Rev (Table 4), was cloned into the pCR8 / GW / T0P0 plasmid from the INVITROGEN pCR®8 / GW / T0P0® TA Cloning Kit (Ref. K2500-20), and competent Escherichia coli DH5a cells were subsequently transformed with said plasmid.

[0121] Table 4 shows the primers used in the examples of the invention.

[0122] Table 4

[0123] After verifying the sequence of interest was free of mutations by sequencing, this coding region was subcloned into plasmid pMDC86 using Gateway® technology. Plasmid pMDC86 carries the green GFP fusion protein, which is in reading frame with the inserted DNA. The generated plasmid pMDC86 Pro35S:PSAT1-GFP was also checked by sequencing, but in this case, only the insertion regions were sequencing to confirm that the GFP was in reading frame with the coding region of the PSAT1 gene. Finally, this construct was introduced into Agrobacterium tumefaciens strain GV3101 to transform Arabidopsis thaliana plants.

[0124] The construction of the PSP1 gene was also designed under the control of the 35S promoter and linked to the gene that codes for the GFP protein in plasmid pMDCIOO. Plasmid pMDC100 was chosen to obtain this construction because it provides tolerance in plants to kanamycin, and despite having recombination sites of the Gateway® system, the cloning of the sequences inside was done by restriction enzymes. The Pro35S:PSP1-GFP fragment was obtained by PCR amplification using primers 2x35S -786 For and T-Nos +322 fig / ll Rev (Table 4) from the pMDC83 Pro35S:PSP1-GFP construct. After checking by electrophoresis with an aliquot of the PCR that the amplified fragment had the appropriate size and there were no nonspecific bands, the rest of the PCR reaction was purified and digested with the restriction enzyme Hind\\\, generating an amplicon with a cohesive 5' end Hind\\\ and a blunt 3' end.On the other hand, plasmid pMDCIOO was digested with Hind\\\ and Ec / 136ll (which generates a blunt end). Thus, by purifying the correct band, separated on an electrophoresis gel, the entire region between the attR1 and attR2 recombination regions was eliminated in pMDCIOO and replaced with the Pro35S:PSP1-GFP fragment. In this way, plasmid pMDCIOO was obtained, which confers kanamycin resistance in plants and carries the PSP1 gene under the control of the 35S promoter and linked to GFP (pMDCIOO Pro35S:PSP1-GFP). After confirming that the insertion edges were correct by sequencing, this plasmid was introduced into the A. tumefaciens strain GV3101 to transform Arabidopsis thaliana plants.

[0125] Arabidopsis thaliana plants were transformed using the floral dip method. Several independent transgenic lines were generated from individuals homozygous for the transgene and with a single insertion.

[0126] To obtain the triple over-expressing lines, we started from plants that over-expressed the PGDH1 gene, whose selection agent is the gene for resistance to the antibiotic hygromycin. Two constructs were designed, as previously mentioned, to over-express the genes encoding the enzymes phosphoserine aminotransferase (PSAT) and phosphoserine phosphatase (PSP) in Arabidopsis thaliana. These two enzymes participate in the second and third reactions of the phospholipid pathway of serine biosynthesis, respectively, while the PGDH1 enzyme participates in the first. The two constructs obtained for this purpose have been designed with two different plasmids, each of which presents a different selection agent (BASTA for the plasmid expressing the PSAT1-containing transgene and kanamycin for the plasmid expressing the PSPT transgene) and also, in turn, different from the selection agent of the PGDH1 over-expressing lines (hygromycin).The presence of different selection agents in each of the over-expressing lines made it easier to obtain triple over-expressing lines by using antibiotic selection during seed germination.

[0127] With each of these constructs, two PGDH1 gene overexpressing lines named Oex PGDH1-L1 and Oex PGDH1-L2 were transformed. With this strategy, and for each of the oex PGDH1 lines, plants overexpressing PSAT1 and PGDH1 were obtained, on the one hand, and plants overexpressing PSP1 and PGDH1, on the other. From double homozygous overexpressing plants, crosses were made until homozygous overexpressing plants for the three transgenes were obtained. The identification of these homozygous lines for each of the three genes was possible thanks to the different selection agents used.

[0128] A construct was also made to express the Arabidopsis thaliana PGDH1 cDNA in maize. This construct consisted of cloning the coding portion of the PGDH1 gene, linked to the GFP protein sequence, into plasmid pMCG1005 (obtained from Iowa State University). The PGDH1-GFP fragment was obtained from plasmid pMDC83 Pro35S:PGDH1-GFP by PCR using primers EDA9GFP Xbal Avril For and EDA9GFP Spel Rev (Table 4). After verifying by electrophoresis that the fragment was approximately 2656 bp in size, the amplicon was purified and digested with the restriction enzyme Spel to generate a Spel fragment that was cohesive on one side and blunt on the other. On the other hand, plasmid pMCG1005 was digested with Spel and Stu\ (the latter enzyme generates a blunt end) to remove the Waxy-a rice intron.After purifying the fragment corresponding to the plasmid (13220 bp), it was ligated with the PGDH1-GFP fragment to obtain the construct pMCG1005 ProUbi:PGDH1-GFP. This formed plasmid confers resistance to BASTA in plants and, after confirming that the sequence introduced in the plasmid was correct by sequencing, said plasmid was sent to the plant transformation service of the Iowa State University so that they could obtain transformed corn plants and send them to us. The corn seeds obtained from plants transformed by the pMCG1005 ProUbi:PGDH1-GFP gene construct, from the plant transformation service of the Iowa State University, were received and the plants that presented a single copy of the transgene were identified and isolated.These seeds sent came from the transgenic plants regenerated after the transformation, so according to the terminology normally used in Arabidopsis thaliana, they would correspond to the segregating generation T2 (where the lines that present a copy of the transgene are identified by a 3:1 ratio).

[0129] T2 seeds for each independent line were sown, and after germination, BASTA tolerance assays and diagnostic PCRs were performed to identify transgenic plants and syngeneic controls. The results were used to establish segregation and, therefore, determine how many T-DNA insertions the parental plants had. After this assay, lines with one insertion were identified, along with plants that were BASTA tolerant and PCR-positive (and therefore contained the transgene of interest; these plants could already be homozygous or heterozygous, but the assays performed prevented us from distinguishing them). These selected plants, after growing and flowering, were self-pollinated to obtain the next generation of seeds. Once these seeds were obtained, they were sown again and analyzed to identify homozygous seed batches (which would be those 100% tolerant or PCR+, since their parent was homozygous).

[0130] Since the maize life cycle is between 6 and 7 months, the data presented are from some heterozygous lines and, in some cases, from homozygous lines. In grain analyses, where sufficient seeds were not available, pools of two or three lines were created. Lines that overexpress the PGDH1 gene were designated ZmOex PGDH1.

[0131] Measures of protein and starch content

[0132] Total soluble protein content was determined using Bradford reagent (Bio-Rad, 500-0006). Starch content was determined using the Enzytec kit (r-biopharm). In both cases, two-week-old rosette leaves of Arabidopsis thaliana were used. In the case of corn, leaves, stems, or seeds were used, and the protocol was optimized for each material. Example 2. Characterization of Arabidopsis thaliana plants overexpressing the Arabidopsis thaliana PGDH1 gene

[0133] The contents of free amino acids, starch and proteins were analyzed in the over-expressing lines of the PGDH1 protein of Arabidopsis thaliana both under ambient CO2 conditions and under high CO2 conditions (2500 ppms of CO2) where the activity of the Glycolate pathway associated with photorespiratory activity is lower. Lines that over-express the PGDH1 gene (Oex PGDH1-L1 and Oex PGDH1-L2) and lines that overexpressed the three enzymes of the PGDH1, PSAT1 and PSP pathway (Tr¡Oex1-40, Tr¡Oex2-4, Tr¡Oex2-47 and Tr¡Oex2-49) were used.

[0134] First, we studied whether overexpression of the Arabidopsis thaliana PGDH1 protein had a negative effect on plant growth. In four of the six overexpressing lines grown in vitro and cultured under ambient CO2 conditions, no significant differences in shoot growth were observed compared to the wild-type control line (WT), and only the triple overexpressing line Tr¡Oex2-49 and the Oex PGDH1-L2 line from which it is derived showed reduced shoot growth (Figure 2A). A reduction in the growth of the main root (between 10 and 20%) was also observed in three of the six characterized lines (Tr¡Oex2-4, Tr¡Oex2-49 and the Oex PGDH1-L2 line from which they are derived) (Figure 2B).

[0135] In vitro phenotypic characterization assays were also performed under high CO2 conditions to study the role of the Arabidopsis thaliana protein PGDH1 when the glycolate pathway associated with photorespiration is less active. In this assay, no significant differences were observed in the growth of the shoots in any of the TriOex lines compared to the control. Only a decrease in the weight of the shoots of around 25% was observed in the Oex PGDH1-L2 line (Figure 2C). In contrast to what occurred under ambient CO2 conditions, a significant increase in the length of the primary root was observed in three lines when compared to the control (Tr¡Oex1-40, Tr¡Oex2-47 and Tr¡Oex2-49), with an increase of 7-12% of the primary root compared to the control (Figure 2D).

[0136] With these results we conclude that it is possible to obtain over-expressing lines of the Arabidopsis thaliana PGDH1 protein without having a negative effect on the growth of Arabidopsis thaliana and that over-expression can even have a positive effect on growth under high CO2 culture conditions. Metabolomic analysis of the over-expressing lines of the Arabidopsis thaliana PGDH1 protein showed an increase in serine content accompanied by a generalized increase in other amino acids in most of the over-expressing lines, mainly in the aerial part but also in the roots, among which threonine, valine, asparagine, aspartate, glutamate and glutamine stand out (Table 5 and Table 6) suggesting that serine levels are essential to control the homeostasis of the rest of the amino acids in the plant, and therefore of the processes associated with it, mainly protein synthesis.Of all of them, the most interesting are valine and threonine because they are essential amino acids, but especially threonine because it is considered one of the four essential amino acids that limit the nutritional quality of plants.

[0137] Tables 5 and 6 show the amino acid levels in the shoots (Table 5) and roots (Table 6) of the PGDH1 gene overexpressing lines (OexPGDH1-L1 and OexPGDH1-L2) and the triple overexpressing lines (ThOex1-40, Tr¡Oex2-4, Tr¡Oex2-47 and Tr¡Oex2-49) compared to the wild-type plant line (WT) under ambient CO2 conditions (aCÜ2; 400 ppm). The data represent relative values ​​normalized with respect to the mean calculated for the WT (mean ± SE of at least 6 independent determinations). Values ​​that are significantly different from the wild-type control plants (WT) are highlighted in bold (T-test, P < 0.05).

[0138] Table 5

[0139] Table 6 Metabolomic analysis was also performed on plants grown under high CO2 concentrations. In this case, a generalized increase in virtually all amino acids was observed in the aerial parts of the overexpressing lines, with particular attention to the essential amino acids isoleucine, leucine, lysine, phenylalanine, methionine, and valine (Table 7). An increase in phenylalanine and threonine was also observed in roots (Table 8).

[0140] Tables 7 and 8 show the amino acid levels in the shoots (Table 7) and roots (Table 8) of the PGDH1 gene overexpressing lines (OexPGDH1-L1 and OexPGDH1-L2) and the triple overexpressing lines (Tr¡Oex1-40, Tr¡Oex2-4, Tr¡Oex2-47 and Tr¡Oex2-49) compared to the wild type (WT) plant line under high humidity conditions.

[0141] CO2 (eCÜ2; 2500 ppm). Data represent relative values ​​normalized to the mean calculated for wild-type (WT) plants (mean ± SE of at least 6 independent determinations). Values ​​significantly different from the wild-type (WT) plant are highlighted in bold (T-test, P < 0.05).

[0142] Table 7 Table 8

[0143] These results indicate that the effect of over-expression of the Arabidopsis thaliana PGDH1 protein on amino acid content is especially relevant under high CO2 conditions in the aerial part, since under these conditions the levels of some amino acids, such as the essential amino acids isoleucine, leucine, lysine, methionine, phenylalanine, valine or threonine are reduced in control plants compared to ambient CO2 conditions (Table 9). Table 9 shows the amino acid levels in the aerial part of the control line (WT), the PGDH1 gene overexpressing lines (OexPGDH1-L1 and OexPGDH1-L2) and the triple overexpressing lines (Tr¡Oex1-40, Tr¡Oex2-4, Tr¡Oex2-47 and Tr¡Oex2-49) under high CO2 conditions (eCÜ2; 2500 ppm) compared to the wild-type plant (WT) grown under ambient CO2 conditions (aCÜ2; 400 ppm).The data represent relative values ​​normalized to the mean calculated for the wild-type (WT) plant in ambient CO2 (mean ± SE of at least 6 independent determinations). Values ​​significantly different from the wild-type (WT) plant are highlighted in bold (T-test, P < 0.05). Table 9.

[0144] The levels of starch and proteins in the over-expressing lines of the PGDH1 protein of Arabidopsis thaliana were quantified under ambient CO2 conditions and under high CO2 conditions.

[0145] Under ambient CO2 conditions, a significant increase in starch content was observed in the aerial parts of four of the over-expressing lines analyzed (Tr¡Oex2-47, Tr¡Oex1-40, Oex PGDH1-L1, and Oex PGDH1-L2) (Figure 3A). This increase could be observed in the aerial parts of all over-expressing lines when the plants were grown under high CO2 conditions (Figure 3A). No significant differences were observed in roots between over-expressing plants and controls under any of the conditions tested (Figure 3B). Under culture conditions in the presence of high concentrations of high CO2, plants synthesize and store more starch to the detriment of protein content. This is partly due to the fact that the Rubisco enzyme acts mainly with carboxylase activity, so that all the D-3-phosphoglycerate formed enters the Calvin cycle to synthesize sugars.It was found that both control plants and over-expressors of the Arabidopsis thaliana PGDH1 protein had higher starch content under these conditions, but the over-expressors always showed higher levels than the controls (Figure 3). Furthermore, all lines showed lower protein content under these high CO2 conditions, but this reduction in protein content was lower in the over-expressor lines than in the controls in both shoots and roots (Figure 3C and Figure 3D). Thus, plants over-expressing the Arabidopsis thaliana PGDH1 protein had higher protein content than the controls both under ambient CO2 conditions and under high CO2 conditions (Figure 3C and Figure 3D). Furthermore, under high CO2 conditions, the protein content in the over-expressor lines was similar to or even higher than the value in the control under ambient CO2 conditions (Figure 3C and Figure 3D).

[0146] The results obtained demonstrate that the stimulatory effect of overexpression of the Arabidopsis thaliana protein PGDH1 on amino acid metabolism also involves an increase in protein content in the overexpressing Arabidopsis thaliana lines and, surprisingly, a higher starch content compared to the control, without affecting plant growth. On the one hand, the higher serine content of the phosphorylative pathway of serine biosynthesis can stimulate the synthesis of the rest of the amino acids that activate protein synthesis. On the other hand, the higher serine content of the phosphorylative pathway of serine biosynthesis would imply that a lower content of photorespiratory serine leaves the cycle and is recycled back to D-3-phosphoglyceride, thus increasing sugar assimilation and ultimately being stored as starch.

[0147] The results also demonstrate that rising atmospheric CO2 levels affect carbon and nitrogen homeostasis, favoring carbohydrate metabolism and reducing amino acid and protein metabolism. The effect of the phosphorylative serine biosynthesis pathway on carbohydrate / protein homeostasis is more evident under conditions of climate change. The results demonstrate that genetic engineering of the phosphorylative serine biosynthesis pathway is extremely useful as a strategy for increasing plant nutritional quality, especially under conditions of reduced photorespiratory activity associated with rising atmospheric CO2.

[0148] Example 3. Characterization of corn plants that over-express the Arabidopsis PGDH1 gene th al i an a

[0149] The contribution of overexpression of the Arabidopsis thaliana PGDH1 protein to the C4 metabolism of maize was studied. Maize exhibits a lower photorespiratory rate than Arabidopsis thaliana and therefore lower glycolate pathway activity. The starch and protein contents of transgenic maize plants overexpressing the Arabidopsis thaliana PGDH1 gene (ZmOex PGDH1) grown in a greenhouse at ambient CO2 concentrations were analyzed. Results were obtained not only from leaves and roots, but also from stems of three ZmOex PGDH1 lines (ZmOex PGDH1-22, ZmOex PGDH1-27, and ZmOex PGDH1-31) and the control line (WT).

[0150] Regarding starch, in heterozygous maize plants for the PGDH1 transgene, two of the over-expressing lines of the PGDH1 protein from Arabidopsis thaliana (ZmOex PGDH1-22 and ZmOex PGDH1-27) significantly increased their content in both leaves and stems compared to the control (Figure 4A and Figure 4B). A third line also increased starch content in stems (ZmOex PGDH1-31). This increase ranged from 8% to 61% depending on the line, indicating that there is a lot of variability between lines. In order to make the statistical analysis more robust, all over-expressing lines were analyzed together (ZmOex PGDH1), and they were compared with the control lines. A significant increase in starch content was observed in the over-expressing lines compared to the controls, around 29% in leaves and 42% in stems.

[0151] Regarding proteins, in heterozygous maize plants for the PGDH1 transgene, all lines showed a higher content than the controls in leaves and stems, ranging between 5% and 25% with respect to the control, although it was only significant in one line in stems (Figure 4D and Figure 4E).

[0152] Therefore, after obtaining homozygous maize lines for the PGDH1 transgene, new experiments were performed and one line showed a significant increase in protein content in leaves and three lines with a significant increase in stems (Table 10). The combined analysis of all lines showed a significant increase of between 9 and 18% in protein content in leaves and stems, respectively. Table 10 shows the protein content in leaves and stems of maize plants that overexpressed the PGDH1 gene from Arabidopsis thaliana. Data are from either individual lines (ZmOex PGDH1-22 and ZmOex PGDH1-27 and ZmOex PGDH1-31) or from all lines (ZmOex PGDH1). The material comes from plants grown in a greenhouse for 15 days under ambient CO2 conditions. Values ​​represent the mean of the percentage of wild plant control (WT) ± SE (n > 30 biological replicates).(*) represents significant differences with respect to the wild control (WT; T-test, P < 0.05).

[0153] Table 10

[0154] Finally, the starch and protein content of the maize grains from the lines overexpressing the Arabidopsis thaliana PGDH1 protein was determined. As in previous cases, and to increase the robustness of the statistical analysis, the data from the three overexpressing lines were compared together. In the case of starch, a significant increase of 6.7% was observed. In protein, only a 2.6% increase was observed, which was not significant (Figure 4). The higher percentage increases in stems and leaves compared to the grain can be partly attributed to the fact that some of the mother plants were not homozygous, and therefore some of the grains from these lines will not be transgenic. Repeating these experiments using grains from homozygous lines improved these results.Thus, the protein content also increased significantly in the grain in one of the lines studied by 5%, while in the other two the increase was between 2 and 3% (Table 10).

[0155] An analysis of gene expression of the PGDH1 gene in transgenic lines indicated that lines ZmOex PGDH1-27 and ZmOex PGDH1-31 showed the highest levels of transgene expression in all studied organs (Figure 5). Additionally, the contribution of overexpression of the PGDH1 protein from Arabidopsis thaliana under high CO2 conditions in a species with C4 photosynthetic metabolism, such as maize, was studied. Plants with C4 photosynthetic metabolism initially have a lower photorespiratory rate than plants with C3 metabolism, but not zero, so it is important to understand the effects of the PGDH1 protein from Arabidopsis thaliana on this type of metabolism both under ambient CO2 and under high CO2. To this end, protein content was analyzed in transgenic maize plants that overexpress the PGDH1 gene in homozygosity of Arabidopsis thaliana (ZmOex PGDH1).In this case, results were obtained in leaves and stems of three ZmOex PGDH1 lines (ZmOex PGDH1-22, ZmOex PGDH1-27 and ZmOex PGDH1-31) together with the control line of wild plants (WT).

[0156] Regarding protein content, all lines showed higher protein content than controls in leaves, ranging from 14% to 22% in the best case (Table 11). In stems, the lines with the highest level of PGDH1 expression also showed a significant increase in protein content, ranging from 17% to 38% higher than in controls (Table 11). An analysis of all overrepressor lines as a whole (ZmOex PGDH1) with respect to the wild-type control (WT) is also presented. In this case, protein content in leaves and stems significantly increased by 18% and 20%, respectively, compared to the wild-type control (WT) (Table 11). Data are obtained either from individual lines (ZmOex PGDH1-22, ZmOex PGDH1-27, and ZmOex PGDH1-31) or from all lines combined (ZmOex PGDH1). The material comes from plants grown in a greenhouse for 15 days in the presence of 2000 ppm of CO2.Values ​​represent the mean of 1% relative to the wild-type plant control (WT) ± SE (n > 30 biological replicates). (*) represents significant differences relative to the wild-type plant control (WT; T-test, P < 0.05).

[0157] Table 11 It is important to note that the increase in protein content occurred without a significant reduction in shoot growth in two of the overexpressing lines, as shown in Figure 6. Only the ZmOex PGDH1-31 line showed a 15% reduction in growth. However, this reduction was smaller than the 22% and 39% increases in protein content in leaves and stems, respectively, in this line.

[0158] Total elemental content was measured in control and overexpressing (Oex) lines of maize PGDH1 (Zm OexPGDH1-L2 and L3; see Table 12). For these experiments, only the two overexpressing lines showing the highest protein levels in leaves and stems were chosen. The most pronounced changes were observed under elevated CO2 conditions (eCÜ2). Under these elevated CO2 conditions, total nitrogen content in the leaves of wild-type (WT) plants decreased, while carbon content increased (Table 12). In stems, total nitrogen also decreased in wild-type plants when grown under elevated CO2 conditions. These changes translated into a significant decrease in the nitrogen / carbon ratio in both organs.Furthermore, higher nitrogen (in leaves and stems) and sulfur (in leaves) contents were found in Oex lines compared to wild-type plants when plants were grown under elevated CO2 conditions, leading to higher nitrogen-to-carbon (in leaves and stems) and sulfur-to-carbon (in leaves) ratios in Oex lines compared to controls (Table 12). Taken together, these results confirmed the role of PGDH1 protein in maize nitrogen homeostasis and show that this effect is more pronounced under elevated CO2 conditions. Therefore, these results corroborate that genetically engineering the serine biosynthesis phosphorylative pathway improves crop nitrogen content.

[0159] Table 12 shows the carbon, nitrogen, and sulfur contents (mg / g dry weight) and nitrogen / carbon and sulfur / carbon ratios in leaves and stems of PGDH1-overexpressing maize lines (Zm OexPGDH1-L2 and L3) grown under ambient CO2 or elevated CO2 conditions compared to wild-type plants. The mean of the two overexpressing lines (Zm OexPGDHI) is also shown. Values ​​represent the mean ± SE of at least 6 groups of three plants per line. Different letters indicate significant differences between lines (P < 0.05) under the same growth conditions; significant differences between growth conditions according to the Student t test are represented by * (P < 0.05). aCO2, ambient CO2 conditions; eCO2, elevated CO2 conditions; WT, wild-type plants. Table 12

[0160] Example 4. Characterization of broccoli plants that overexpress the Arabidopsis PGDH1 gene th al i an a

[0161] A construct expressing the Arabidopsis thaliana PGDH1 cDNA in broccoli plants was prepared and inserted into a plasmid. This plasmid was used to transform broccoli plants.

[0162] The contribution of overexpression of the Arabidopsis thaliana PGDH1 protein to broccoli plants, a species with C3 metabolism, was studied. Protein content was analyzed in transgenic broccoli plants in three lines overexpressing the Arabidopsis thaliana PGDH1 gene.

[0163] All over-expressing lines in the T1 generation showed higher protein content in the shoot portion than the controls, between 8% and 17%. Table 13 shows the analysis of all over-expressing lines (Bo Oex PGDH1) compared to the wild-type control (WT). In this case, the protein content of the shoot portion of the over-expressing lines increased significantly by an average of 12% compared to the wild-type control (WT) (Table 13). The material was obtained from plants grown in pots with perlite and Hoagland nutrient solution in a growth chamber for 45 days in the presence of 2000 ppm CO2. The values ​​represent the mean percentage of the wild-type control (WT) ± SE (n > 12 biological replicates). (*) represents significant differences compared to the wild-type control (WT; T-test, P < 0.05).

[0164] Table 13

[0165] LISTA DE REFERENCIAS BIBLIOGRÁFICAS Mizokami et al. (2019). Elevated CO2-induced changes in mesophyll conductance and anatomical traits in wild type and carbohydrate-metabolism mutants of Arabidopsis. J Exp Bot.;70(18):4807-4818. doi: 10.1093 / jxb / erz208

[0166] Myers et al. (2019). Increasing CO2 threatens human nutrition. Nature;510(7503): 139-42. doi: 10.1038 / nature13179. Erratum in: Nature (2019);574(7778):E14.

Claims

CLAIMS 1. A plant genetically modified to over-express a gene encoding a D-3-phosphoglycerate dehydrogenase (PGDH1) protein, wherein the amino acid sequence of said PGDH1 protein comprises the following amino acids: leucine at position 65; leucine at position 78; arginine at position 108; serine at position 109; threonine at position 111; alanine at position 142; alanine at position 143; alanine at position 162; glutamic acid at position 163; arginine at position 291; glycine at position 292; leucine at position 300; aspartic acid at position 315; valine at position 316; phenylalanine at position 317; glutamic acid at position 320; proline at position 321; proline at position 338; histidine at position 339; glycine at position 341; serine at position 343; threonine at position 344; glutamic acid at position 346; alanine at position 347; and glutamine at position 348;wherein said positions refer to the position in the amino acid sequence of the PGDH1 protein of Arabidopsis thaliana identified by the sequence SEQ ID NO: 1; and wherein said plant is not of the Arabidopsis thaliana species.

2. The plant according to claim 1, wherein the amino acid sequence of said PGDH1 protein further comprises the following amino acids: glycine at position 209; glycine at position 212; aspartate at position 256; and histidine at position 261; wherein said positions refer to the position in the amino acid sequence of the Arabidopsis thaliana PGDH1 protein identified by the sequence SEQ ID NO:

1.

3. The plant according to claim 1 or 2, wherein the amino acid sequence of said PGDH1 protein further has an identity of at least 65% with respect to the sequence SEQ ID NO:

1.

4. The plant according to any of claims 1 to 3, wherein the amino acid sequence of said PGDH1 protein also has an identity of at least 75% with respect to the sequence SEQ ID NO:

1.

5. The plant according to any of claims 1 to 4, wherein, in addition, the amino acid sequence of said PGDH1 protein also has an identity of at least 85% with respect to the sequence SEQ ID NO:

1.

6. The plant according to any of claims 1 to 5, wherein, in addition, the amino acid sequence of said PGDH1 protein also has an identity of at least 95% with respect to the sequence SEQ ID NO:

1.

7. The plant according to any one of claims 1 to 6, wherein the amino acid sequence of said PGDH1 protein further comprises a sequence selected from the group consisting of: SEQ ID NO: 3, SEQ ID NO: 4, SEQ ID NO: 5, SEQ ID NO: 6 and SEQ ID NO:

7.

8. The plant according to any one of claims 1 to 7, wherein the amino acid sequence of said PGDH1 protein further comprises a sequence selected from the group consisting of: SEQ ID NO: 16, SEQ ID NO: 17, SEQ ID NO: 18 and SEQ ID NO:

19.

9. The plant according to any one of claims 1 to 8, wherein the amino acid sequence of said PGDH1 protein is the sequence SEQ ID NO:

1.

10. The plant according to any of claims 1 to 7, wherein the plant is of a species of agronomic interest.

11. The plant according to any one of claims 1 to 8, wherein the plant is of a species with C3 metabolism.

12. The plant according to claim 9, wherein the plant is selected from tomato and broccoli.

13. The plant according to any one of claims 1 to 8, wherein the plant is of a species with C4 metabolism.

14. The plant according to claim 11, wherein the plant is corn.

15. The plant according to any one of claims 1 to 12, wherein the gene encoding the PGDH1 protein is operably linked to a constitutive promoter.

16. The plant according to claim 13, wherein the constitutive promoter is selected from the constitutive promoter of the gene encoding maize ubiquitin and the constitutive promoter of the cauliflower mosaic virus 35S.

17. A plant cell genetically modified to over-express a gene encoding a D-3-phosphoglycerate dehydrogenase (PGDH1) protein, wherein said cell is genetically modified with an expression vector comprising a gene encoding a D-3-phosphoglycerate dehydrogenase (PGDH1) protein, wherein the amino acid sequence of said PGDH1 protein comprises the following amino acids: leucine at position 65; leucine at position 78; arginine at position 108; serine at position 109; threonine at position 111; alanine at position 142; alanine at position 143; alanine at position 162; glutamic acid at position 163; arginine at position 291; glycine at position 292; leucine at position 300; aspartic acid at position 315; valine at position 316; phenylalanine at position 317; glutamic acid at position 320; proline at position 321; proline at position 338; histidine at position 339; glycine at position 341; serine at position 343; threonine at position 344; glutamic acid at position 346; alanine at position 347; and glutamine at position 348; wherein said positions refer to the position in the amino acid sequence of the PGDH1 protein of Arabidopsis thaliana identified by the sequence SEQ ID NO: 1; and wherein said cell is not of Arabidopsis thaliana.

18. The cell according to claim 17, wherein the amino acid sequence of said PGDH1 protein further comprises the following amino acids: glycine at position 209; glycine at position 212; aspartate at position 256; and histidine at position 261; wherein said positions refer to the position in the amino acid sequence of the Arabidopsis thaliana PGDH1 protein identified by the sequence SEQ ID NO:

19. The cell according to claim 17 or 18, wherein the amino acid sequence of said PGDH1 protein further has an identity of at least 65% with respect to the sequence SEQ ID NO:

1.

20. The cell according to any of claims 17 to 19, wherein the amino acid sequence of said PGDH1 protein further has an identity of at least 75% with respect to the sequence SEQ ID NO:

1.

21. The cell according to any of claims 17 to 20, wherein the amino acid sequence of said PGDH1 protein further has an identity of at least 85% with respect to the sequence SEQ ID NO:

1.

22. The cell according to any of claims 17 to 21, wherein the amino acid sequence of said PGDH1 protein also has an identity of at least 95% with respect to the sequence SEQ ID NO:

1.

23. The cell according to any one of claims 17 to 22, wherein the amino acid sequence of said PGDH1 protein further comprises a sequence selected from the group consisting of: SEQ ID NO: 3, SEQ ID NO: 4, SEQ ID NO: 5, SEQ ID NO: 6 and SEQ ID NO:

7.

24. The cell according to any one of claims 17 to 23, wherein the amino acid sequence of said PGDH1 protein further comprises a sequence selected from the group consisting of: SEQ ID NO: 16, SEQ ID NO: 17, SEQ ID NO: 18 and SEQ ID NO:

19.

25. The cell according to any one of claims 17 to 24, wherein the amino acid sequence of said PGDH1 protein is the sequence SEQ ID NO:

1.

26. The cell according to any of claims 17 to 25, wherein the cell is of a species of agronomic interest.

27. The cell according to any one of claims 17 to 26, wherein the cell is from a plant species with C3 metabolism.

28. The cell according to claim 27, wherein the plant is selected from tomato and broccoli.

29. The cell according to any one of claims 17 to 26, wherein the cell is from a plant species with C4 metabolism.

30. The cell according to claim 29, wherein the plant is corn.

31. A method for obtaining a genetically modified plant or a genetically modified plant cell to over-express a gene encoding a D-3-phosphoglycerate dehydrogenase (PGDH1) protein, comprising transforming the corresponding wild-type plant or plant cell with an expression vector comprising a gene encoding a D-3-phosphoglycerate dehydrogenase (PGDH1) protein, wherein the amino acid sequence of said PGDH1 protein comprises the following amino acids: leucine at position 65; leucine at position 78; arginine at position 108; serine at position 109; threonine at position 111; alanine at position 142; alanine at position 143; alanine at position 162; glutamic acid at position 163; arginine at position 291; glycine at position 292; leucine at position 300; aspartic acid at position 315; valine at position 316; phenylalanine at position 317; glutamic acid at position 320;proline at position 321; proline at position 338; histidine at position 339; glycine at position 341; serine at position 343; threonine at position 344; glutamic acid at position 346; alanine at position 347; and glutamine at position 348; wherein said positions refer to the position in the amino acid sequence of the Arabidopsis thaliana PGDH1 protein identified by the sequence SEQ ID NO: 1; and wherein said plant or plant cell is not of the Arabidopsis thaliana species.

32. The method according to claim 31, wherein the amino acid sequence of said PGDH1 protein further comprises the following amino acids: glycine at position 209; glycine at position 212; aspartate at position 256; and histidine at position 261. wherein said positions refer to the position in the amino acid sequence of the Arabidopsis thaliana PGDH1 protein identified by the sequence SEQ ID NO:

1.

33. The method according to claim 31 or 32, wherein the amino acid sequence of said PGDH1 protein further has an identity of at least 65% with respect to the sequence SEQ ID NO:

1.

34. The method according to any of claims 31 to 33, wherein the amino acid sequence of said PGDH1 protein also has an identity of at least 75% with respect to the sequence SEQ ID NO:

1.

35. The method according to any of claims 31 to 34, wherein the amino acid sequence of said PGDH1 protein also has an identity of at least 85% with respect to the sequence SEQ ID NO:

1.

36. The method according to any of claims 31 to 35, wherein the amino acid sequence of said PGDH1 protein also has an identity of at least 95% with respect to the sequence SEQ ID NO:

1.

37. The method according to any of claims 31 to 36, wherein the amino acid sequence of said PGDH1 protein further comprises a sequence selected from the group consisting of: SEQ ID NO: 3, SEQ ID NO: 4, SEQ ID NO: 5, SEQ ID NO: 6 and SEQ ID NO:

7.

38. The method according to any of claims 31 to 37, wherein the amino acid sequence of said PGDH1 protein further comprises a sequence selected from the group consisting of: SEQ ID NO: 16, SEQ ID NO: 17, SEQ ID NO: 18 and SEQ ID NO:

19.

39. The method according to any of claims 31 to 38, wherein the amino acid sequence of said PGDH1 protein is the sequence SEQ ID NO:

1.

40. The method according to any of claims 31 to 39, wherein the plant or plant cell is of a species of agronomic interest.

41. The method according to any one of claims 31 to 40, wherein the plant or plant cell is of a species with C3 metabolism.

42. The method according to claim 41, wherein the plant or plant cell is selected from tomato and broccoli.

43. The method according to any one of claims 31 to 40, wherein the plant or plant cell is of a species with C4 metabolism.

44. The method according to claim 43, wherein the plant or plant cell is corn.

45. Use of the plant of claims 1 to 16, or of the plant cell of any of claims 17 to 30, for the production of proteins, amino acids and / or starch.

46. ​​Use according to claim 45, wherein the plant cell or plant is grown under conditions in which the CO2 concentration is at least 800 ppm.

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