DE19503359C1 - Plants with increased tolerance towards stress - Google Patents

Abstract

The invention concerns plants with enhanced stress tolerance obtainable by introducing a nucleic acid which codes for a constitutively active transcription activator into a plant cell and by regenerating a transgenic plant. The plants concerned have higher levels of protective proteins under normal conditions than wild plant types.

Description

The present invention relates to a plant with elevated Stress tolerance with the features of claim 1, for their manufacture with the features of claim 1.

Heat occurs in all organisms, including plants shock proteins (HSP) in response to high temperatures or heat shock (HS) synthesized. The biological meaning This reaction, known as the HS response, is cellular proteins and structures during a stress phase and / or in the subsequent recovery phase. The HS answer can too by other abiotic stress factors (stressors) such. B. Heavy metals, arsenite or dryness are triggered. It the HS response is a general stress reaction on that the survival of the cell and thus the organism under unfavorable environmental conditions. The protective effect of HSPs relies primarily on minimizing the damage that by denaturing proteins due to exposure the stressors on the organism arise. Almost all HSP are molecular chaperones (see Tab. 1) that have a reversible bond with partially denatured proteins and thereby one enable correct renaturation (folding) of these molecules or accelerate. HSPs are able to share in denatu reduced protein due to the stress, or the Increase the proportion of correctly folded, biologically active proteins hen. More details on the role of heat shock proteins in plants are described by Vierling, E. in Annu. Rev. Plant Physiology Plant Mol. Biol. 1991, volume 42, pages 579-620.

Although, as stated above, all organisms in stress one HS answer show, this answer comes in a special in plants their importance. Plants can because of their bond least avoid environmental stress at the site or avoiding this and are most extreme the abiotic stress  sensors exposed. The small HSPs (HSP20 group with a molecular weight of approximately 17-20 kDa) important importance for the response of the plants to stress. These Proteins are highly expressed and there are several related ones Genes (a gene family). In contrast to other HSP groups (e.g. HSP70), there are no HSP20 or HSP20-like proteins even under normal conditions, e.g. B. in the normal reverse exercise temperature. Without environmental stress, HSP synthesized only in certain stages of plant development, this being especially in the late stages of pollen development and of embryogenesis (dessication phase of semen maturation) becomes.

However, there are no known plants in which under normal Stress-free conditions present noticeable levels of HSPs. In particular, no plants are known in which under stress free conditions a whole group of HSPs or even all HSPs in biologically relevant concentrations in the plant available.

The present invention was based on the technical problem To provide plants that have an increased stress tolerance, and especially on a variety of different stressors can react with increased tolerance.

This problem is solved by a plant with increased stress tolerance, containing at least a constitutively expressed and active transcription activator for the constitutive expression of at least one Protective protein, which is usually only induced by stress factors.

Another technical problem was a process ready to produce a plant with increased stress tolerance deliver.

According to the invention, this technical problem is solved by a Procedure comprising the steps:

• (a) Introducing a nucleic acid that is constitutive for a encoded active transcription activator into a plant cell, and
• (b) regenerating a transgenic plant from the one in step (a) plant cell produced.

Another technical problem was the provision of means for producing a plant with increased stress tolerance ranc.

This technical problem is solved by a nucleic acid, for a transcription that is constitutively active in the plant activator coded.

Fig. 1: Alternative models of regulation of the HS response in higher eukaryotes.

Fig. 2 Expression of the HSF-GUS fusion gene in transgenic Arabi dopsis.

• A) shows schematically the components of the gene fusion construct.
• B) shows the constitutive GUS activities in transgenic Arabi dopsis plants. The CIS activities were identified for each Construct in protein extracts from 30 individual transformants (F0) and their F1 descendants. The GUS activity was measured in pMol NAD / mg protein / minute.
• C) shows constitutive HSF and HSF-GUS (GH, HG) mRNAs Northern blot hybridization

Fig. 3 constitutive expression of HSP18 in transgenic Arabidopsis that overexpresses HSF fusion proteins.

• A) shows the detection of HSP18 in Western blots.  
• B) shows the detection of HSP18 mRNA by means of Northern blot hybridization.
  WT = untransformed Arabidopsis; HG1, HG2, GH1, GH2 = a single transformant containing HSF-GUS or GUS-HSF.

"Increased stress tolerance" as used herein meant the fa ability of a plant according to the invention, under the influence of Stress factors less impact on their performance ability to show as the wild type plant or even the full one Maintain their performance. The increased Stress tolerance presumably rests without being tied to any theory to be on the presence of one or more protections proteins under normal conditions in an increased concentration on compared to the respective wild type plant. The performance The ability of a plant is shown, for example, in the wax speed, the stability of the characteristics, the Resistance to pathogens, quality and the Yield of crop products, nutrient efficiency, efficiency of water balance and behavior towards crop protection average.

"Transcription activator" as used herein means one regulatory protein that is in the active state of the transcript tion of certain genes stimulated. To do this, the transcript activator on certain sequences (so-called Responsive Ele ment) in the promoters of the Ge under his control recognize ne and / or their flanking regions (i), (ii) from them bind and (iii) initiate or promote the transcription of the genes other.

A transcription activator can act as a protein either in the active (derepressed) or inactive (repressed) state lie. The activator only stimulates the active state Transcription and thus the expression of the regulated genes.  

Examples of transcription activators in plants are wrote in K. D. Scharf, S. Rose, W. Zott, F. Schöffl and L. Nover in: The EMBO Journal, Volume 9, pp. 4495-4501 (1990).

"Constitutively expressed and active" means in connection with the Transcriptional activator that the activator is constantly d. H. under Normal conditions as under stress conditions, is expressed and is always in a form that ties in with the Control elements of DNA allowed.

"Heat shock factor (HSF)" is synonymous with the term "Heat shock transcription activator" that is in the active state via its DNA binding domain to the heat shock elements (HSE) binds in promoter sequences and thereby the transcription of the corresponding genes affected. Activation of the transcript tion activator to its DNA-binding form is for example wise by multimerization, such as trimerization, individual Ak tivator proteins.

A naturally occurring HSF in wild type plants needs for its activation by environmental stress, e.g. B. heat stress, he witnessed signal.

Genes that are regulated by HSF are e.g. B. the genes for Protective proteins, such as the heat shock proteins.

"Protective proteins" as used herein are gene products from Ge nen whose expression is regulated by HSF. To the well-known Protective proteins include heat shock proteins, which are mo lecular chaperones act in the cells and thereby others Proteins or biochemical and physiological processes in the Protect the cell from stress. Protective proteins can have zymatic activities, the biochemical reactions ka and thus protect cells and organisms Stress-related damage (e.g. due to oxidative stress, for For an overview, see [C.H. Foyer, P. Descourvieres and K.J. Kunert in: Plant, Cell and Environment, Vol. 17, pp. 507-523 (1994)], Anaero biose [Y. Yang, H.-B. Kwon, H.-P. Peng, M.-C. Shin in: Plant Phy  siology, volume 101, pp. 209-216 (1993)] regarding heavy metal toxicity [D. Neumann, O. Lichtenberger, D. Günther, K. Tschiersch and L. Nover in: Planta, Volume 194, pp. 360-367 (1994)] Photoinhibition [G. Schuster, D. Even, K. Kloppstech and J. Ohad in: The EMBO Journal, Volume 7, pp. 1-6 (1988)] and oxidative Stress [P. Mehlen, J. Briolag, L. Smith, C. Diaz-Latoud, M. Fa bre, D. Pauli, A.-P. Arrigo in: Eur. J. Biochemistry, volume 215, Pp. 277-284 (1993)]). These include a. also the Protei ne of the HSP20 family.

"Stress factors (stressors)" are biotic or abiotic factors gates that reduce the performance of a Plant can lead.

Such factors can be: Pathogen infestation (viruses, viroids, Fungi, bacteria, insects, nematodes), wounding, heat (especially during flower formation and during the seed row fe), cold (especially during germination), UV radiation, ho he light intensity, high concentration of heavy metal, salt and / or ozone, acidity, dryness and O₂ deficiency.

"Wild type plant" herein means a plant that is normal Stress tolerance shows and the starting plant or plants cell for the inventive method provides.

"Fusion protein" as used herein means a fusion pro tein from a transcription activator and at least one white ther protein component, which is usually not in the ent speaking transcription activator occurs. The fusion protein possesses the DNA-binding property of the transcription assets tors and possibly other properties due to the further pro stone component. The activator component of the fusion protein has the ability to bind and regulate DNA Transcription of the genes under his control, and he can the foreign protein portion at its N-terminus, C-terminus and / or wear within the protein chain. The includes Foreign protein content preferably about 500-600 amino acids.  

"Increased level of protective protein" means that the invented Plant according to the invention with increased stress tolerance one or more Contains protective proteins in a concentration that is higher than in the comparable wild type with normal stress tolerance. On increased level is already present, for example, when the Plant with increased stress tolerance under stress-free conditions a concentration of protective proteins reached 5% before preferably about 15-20% or more of the concentration of protection pro teins corresponds to stressful conditions.

"Normal conditions" as used herein means that none "Stress factors", as explained above, act on the plant. There will be a transition from normal conditions to stress conditions caused, for example, by a temperature increase of approx. 20-25 ° C (normal) to approx. 37 ° C (stress). Stress reactions can but also at lower and / or higher temperatures than 37 ° C.

An important switching point for the regulation of the HS response, ie the HSP synthesis, is the transcription of the HSPs. The coordinated expression of the HSPs is brought about by the central regulator, ie the HS transcription factor (HSF). The HSF thus plays a key role in initiating the HS response. This function consists of knowing and binding heat shock promoters and stimulating the transcription of the HS genes (which code for HSP). This principle of regulation is served in all higher eukaryotes, including plants (see FIG. 1). The central regulatory protein HSF is constitutive (ie permanent), but it is inactive under normal or optimal growth conditions with regard to its ability to bind to DNA and to activate the transcription of the HS genes. Stress on the plant has the consequence that the HSF is activated, ie it gains its ability to bind DNA and activate the transcription of the HS genes, and this in turn leads to the increased production of HSPs. The activation of HSF often correlates with a trimerization or multi-merization of HSF monomers. The HSF trimers bind to conserved HS promoter elements (referred to as HSE, which contain the Konsen susmotiv [nGAAnnTTCn] _n ). The transcripts of the HS genes generated in this way are then preferably translated during a heat shock and enriched in relatively large amounts, with the result that, under stress, a high level of HSPs and other protective proteins is present in the plant.

One way to influence the HS response shone through given the ectopic overexpression of HSF. Here should have an HSF gene under the control of a strong constituti ven promoters to overexpression of the HSF and consequently to an increased transcription of the HS genes with the consequence of a lead to increased HSP levels. As surprised by the inventors however, this approach did not lead to one Overexpression of the HSPs.

In contrast, however, was found within the scope of the present invention that an increased level of protective proteins in a plant ze is obtained under normal conditions when the plant Contains transcription activator, preferably an HSF, which is constitutively expressed and constitutively in the active state is present, so that this plant con at least one protective protein expressed tripitatively. Preferably in such a plant however, several protective proteins, such as the Mit members of the HSP20 family, as well as HSP70 and superoxide dismutase, at the same time under the influence of the transcription activator kon expressed tripitatively. The constitutive expression of the Schutzpro teine can even affect all of the plant's protective proteins.

The increased stress tolerance of such a manipulated plant rests, but is not bound to a theory, probably on an increased concentration of one or more protections proteins already under normal conditions, so that when they occur of a stress factor already protective proteins in large quantities lie to immediately minimize the damage z. B. by De Naturation of proteins arise due to the stress situation. Such a plant with increased stress tolerance already has under normal conditions, d. H. stress-free conditions, a  Levels of at least one protective protein that is approximately 5% of the Level of protective protein that is at a full under Stress plant is built. Preferably, the plant according to the invention already under normal conditions approx. 15-20% or more of a plant's stress protein level Stress conditions, with members being particularly preferred of the HSP20 family under normal conditions already 20% of the maxi paint mirror under stress conditions.

A so-called heat shock factor is preferably considered as the activator of the protective proteins. These transcription activators (transcription factors) usually bind to conserved elements within the HS promoters, which often have the consensus motif [nGAAnnTTCn] _n . An example of such a heat shock factor from plants is the Arabidopsis heat shock factor (cf. Hübel, A. and Schöffl, F. in Plant Molecular Biology, volume 26, pages 353-362 (1994). Further heat shock factors are known to the person skilled in the art well known from the prior art, as described, for example, in KD Scharf, T. Materna, E. Treuter and L. Nover in: L. Nover (ed.) Plant Promotors and Transcription Factors, pp. 121-158, Springer Verlag, Berlin-Heidelberg (1994).

As stated above, the transcriptional activator is in wild Type plants either not at all under normal conditions before, or in a form that the DNA binding, in particular binding to HSE, not allowed. As part of the present Invention could be shown that such an inactive Transcription activator in a constitutively active transcript tion activator by manipulating its native, inactive Structure can be converted, preferably by modification the protein sequence. The techniques for changing a given one Protein sequences are well known to those skilled in the art known, as described for example in Sambrook, J. et al., Molecular Cloning, Cold Spring Harbor Laboratory Press (1989). The inactive transcription activator is modified with the aim of giving the activator a constitutive DNA binding ability to rent.  

A preferred modification of an HSF to activate it is the fusion with another protein (foreign protein), the Foreign protein preferably at the N-terminus or C-terminus of the HSF is merged. Suitable fusion partners for an HSF are for example β-glucuronidase, as well as other so-called reports terproteins, for example luciferase, structural or enzyme pro teine, as well as proteins that are used for the selection of Zel oils, tissues and plants with a modified HSF are. Neomycin phosphotransfera are particularly suitable for this se II, phosphinothricin acetyltransferase and hygromycinphos photransferase. Furthermore, the HSF can also be attached any other, including synthetic proteins modified the.

Whether a modification of the inactive HSF was carried out in has converted a constitutively active HSF, can simply be there by being found that the modified HSF to that effect it is examined whether it has the ability to bind DNA under Nor painting conditions through the modification. This capable speed for DNA binding can be with from the prior art known conventional methods, such as with the gel retardation assays familiar to the person skilled in the art, such as be wrote in D.D. Mosser, N.G. Theodorakis and R.J. Morimoto in: Molecular & Cellular Biology, Vol. 8, pp. 4736-4744 (1988).

Plants are preferred as a plant with increased stress tolerance from the family of the Brassicaceae, the class of the Magnoliatae and the class of the Lilietae, with members being particularly preferred that of the genera Brassica, Beta, Solanum, Lycopersicum, Helian thus, Glycine, Zea, Hordeum, Triticum, Secale and Oryza.

The increased stress tolerance of the plants according to the invention shows themselves in their ability, when exposed to stress factors ih to maintain your full capacity, at least ever however, they show less under given stress conditions Impairment of their full performance as the game  Type plant from which the plant according to the invention originated is.

The performance of a plant is shown, for example in their growth rate, the stability of the characteristic expression, seeds and fruit substance, resistance towards pathogens, the quality and the yield of the harvest pro products, the nutrient efficiency, the efficiency of the water balance and compatibility with crop protection products.

The plants according to the invention preferably show a verbes stress tolerance to at least one of the biotic Stress factors such as pathogen infestation (e.g. viruses, Viroi de, fungi, bacteria, insects, nematodes), and / or abiotic Stress factors, wounding, heat (especially with the flowers training and during fruit and seed ripening), cold (especially during germination), UV radiation, high light intensities, high concentrations of heavy metals, of salt and of ozone, acidity, drought, and O₂ deficiency. Especially plants with an increased tolerance to several are preferred of the stress factors mentioned, very particularly preferred they are more tolerant of all stress factors.

Preferred plants according to the invention are already under stress free conditions, d. H. under conditions in which the Do not plant any of the above Stress factors are exposed (Normal conditions), an elevated level of at least one Protective protein, but preferably several protective proteins. The presence of an elevated level of protective protein can be simply determine that the level of protective proteins is determined in a plant according to the invention and this The content is compared with the protective protein content of the game type plant. The protective proteins can be from the state of the Technology known conventional methods from the plants iso and quantify.  

As a vehicle for introducing a constitutive active trans Krtionstionsaktivators in the plant is a nucleic acid ver applies, which codes for the desired transcription activator.

The nucleic acid represents a DNA, for example in the form of egg nes plasmid, which is used in plants by known methods can be brought. For example, comes as a suitable one Plasmid the Ti plasmid from the Agrobacterium tumefaciens in Be or it becomes one of the known techniques for direct DNA transfer used.

The nucleic acid introduced into the plant preferably codes se for a constitutively active HSF, with be as the active form a fusion protein of an HSF and an is particularly preferred another protein or protein fragment.

The introduced nucleic acid itself preferably contains the for the expression of the desired transcription activator required regulatory elements, whereby those for the express sion required in plants in the prior art nik are known and described. Alternatively, the on also brought nucleic acid under the control of already in the Plant cell brought existing regulatory elements will. F. Schöffl, M. Rieping and G. Baumann in: Developmental Genetics, Volume 8, pp. 365-374 (1987) describes the constitutive Expression of an HS gene under the control of the CaMV-35S promoter in tobacco.

The procedures for introducing a nucleic acid into a plant cells are well known to those skilled in the art. Regeneration too a whole plant from a plant cell, transfor mated with a nucleic acid, is familiar to the person skilled in the art and can with conventional methods from the prior art.

The plants according to the invention are produced by incorporation gene of a nucleic acid that is necessary for a constitutively active trans encoding activator, into a plant cell, and rain  the transgenic plant with the nucleic acid transformed plant cell.

All measures to produce a transgenic plant are known from the prior art. Usually after the Introducing a nucleic acid into plant cells after those Selected plant cells that have taken up the nucleic acid ben and express it stably. These transformants become then stimulate a whole plant using conventional methods nerated. It is particularly advantageous if the for selection selection of the appropriately transformed plants marker is provided by the foreign protein, which is called Fu sion partner of the HSF.

The plants of the invention are of great use on the Field of agriculture, especially where under difficult Growing conditions, d. H. under the influence of stress factors Plants need to be grown.

The following examples illustrate the invention. In doing so most experiments with Arabidopsis thaliana performed the known to be a popular model system for crops represents. This model embodies all the important genetic, physiological, biochemical and molecular properties herer plants. In particular, this plant represents a model sy stem for the regulation of the HS response in crop plants.

The heat shock factor from Arabidopsis, ATHSF1

The heat shock factor is expressed constitutively, but its Activation for DNA binding is strictly due to induction Heat bound (at 37 ° C), and activation requires that Transition from monomers to trimers. ATHSF1 is detailed wrote in Hübel, A. and Schöffl, F. in Plant Molecular Biolo gy, vol. 26, pages 353-362 (1994).

Manufacture of constitutively active ATHSP1

Two types of gene fusion products, HSF-GUS (HG) and GUS-HSF (GH), were made as shown in Fig. 2A. The fusions were constitutively expressed using the CaMV 35S promoter in transgenic Arabidopsis plants. It does not matter for the activity of the fusion product whether ATHSF1 was fused with the foreign protein at the N- or at the C-terminus. The construct used for transformation was prepared by subcloning ATHSF1 cDNA in the plant vector BIN19, which contains the glucoronidase (GUS) reporter gene under the control of the constitutive CAMV35S promoter, and the termination sequence of the nopaline synthase (NOS-ter) . The ATHSF1 portion was missing 15 amino acids at the C-terminus in the HSF-GUS fusion and 5 amino acids at the N-terminus in the GUS-HSF fusion. In the GUS-HSF fusion, the GUS content is reduced by 5 amino acids at the C-terminus.

Expression of the fusions in Arabidopsis

The GUS activities were determined for each construct in Pro extracts from 30 different transformants (F0) and the F1 successor generation. GUS activity was measured in pmoles NAD / mg protein / minute.

Arabidopsis thaliana (Columbia ecotype) was treated with Agrobacterium tumefaciens, containing the vector plasmids derived from BIN19, with the aid of Valvekens, M. van Montagu and M. van Lÿsebet tens in: Proceedings of the National Academy of Science, USA, volume 85, p 5536-5540 (1988). F1 seeds were generated from self-transformants and GUS activities were determined in the leaf tissue protein extracts using the fluorescence method as described by RA Jefferson, TA Kavnagh and MW Bevan in: The EMBO Journal, Vol. 6, p. 3901- 3907 (1987). The GUS activities found are shown in Fig. 1B.

Furthermore, the mRNA levels of HSF and the HSF fusions were determined in the wild type as well as in the transgenic Arabidopsis. For this purpose, the total RNA was isolated from the leaf tissue of individual transformants and from wild type plants following or without heat stress (HS) at 37 ° C. for 3 hours. The RNAs were analyzed by Northern blot hybridization using 30 µg total RNA / lane and a 32 P-labeled ATHSF1 cDNA sample as described by Severin and Schöffl in K. Severin and F. Schöffl in: Plant Molecular Biology, Vol. 15, pp. 827-833 (1990). The mRNA levels of the chimeric genes were significantly increased compared to the levels of the authentic ATHSF1 transcript, as can be seen from FIG. 1C. These data show that the chimeric HSFs are stably expressed in the transgenic plants in addition to the endogenous wild-type ATHSF1.

Constitutive HSP synthesis

So far 5 genes are known for the small HSP in Arabidopsis, 3 for class I (which also includes the HSP18 tested below), 2 for class II (see Vierling, E. see above). mRNAs within one Family are so well preserved that they hybridize cross-react.

The constitutive expression of HSP18 in transgenic Arabidopsis that overexpress HSF fusion proteins is shown in FIG. 3.

For Western blot analysis, the proteins were isolated without or following an HS (cf. also FIG. 1) by rapidly homogenizing leaf tissue in buffers containing 8 M urea. Analysis samples (30 µg / lane) were subjected to SDS-PAGE and transferred to nitrocellulose using the electroblot method. HSP18 was detected by an antibody which was directed against a recombinant Arabidopsis HSP17.6. The gene sequence for HSP17.6 is described in KW Helm and E. Vierling in: Nucleic Acids Research, Volume 17, p. 7995 (1989). The bands were visualized by incubation with mouse anti-chicken IgG to which alkaline phosphatase was coupled and staining with the nitrotetrazolium blue / 5-bromo-4-chloro-3-indolyl-phosphate system as described in E. Engvall and PJ Perlmann in: Journal of Immunology, Volume 109, p. 129 (1972).

The Northern blot hybridizations were carried out as described above wrote in K. Severin and F. Schöffl in: Plant Molecular Bio logy, vol. 15, pp. 827-833 (1990).

The result of the HSP expression studies shows that no HSP18mRNA is detectable in the wild type (WT) at room temperature (RT). Antisera directed against recombinant HSP18 from Arabidopsis can be used to detect constitutively expressed small HSPs in the transgenic plants. The antisera, whether they are directed against an individual HSP, recognize all members of an HSP family because of the strong conservation of the HSP structure. In the Western blot, there is a clear difference between WT (no expression) and transgenic plants at RT. The level of constitutively expressed HSP found in the transgenic plants at room temperature is approximately 15-20% of the amount of HSPs induced by HS (determined using immunodiffusion). This corresponds to approximately 1-2 ng HSP18 / µg total protein. After a heat shock, the amount of small HSP in the transgenic plants increases to the value which is also achieved in the heat-induced wild type (cf. FIG. 3).

The mRNA levels for HSP70, the most conserved of all protection pro teine, are also in HSF-GUS (GUS-HSF) transgenic plants strongly constitutive increased compared to the non-induced Wild type. This shows that the constitutive stress response is not is limited to the small HSP, but also HSP70 and includes other HSPs. In other words, this means that the con tripitatively active HSF induced a range of HSPs.

Constitutive activity of the HSF fusion proteins and HSF interactions

Depression of HSF activity expressed in Arabidopsis fusion proteins (HSF-GUS and GUS-HSF) were able to do three things Experiments are proven:

• 1. The HSF fusion proteins are constituted by trimerization.
• 2. The HSF fusion proteins bind constitutively to HSE sequences.
• 3. The heat shock proteins are expressed constitutively.

It has been shown that at normal temperature (20-25 ° C), i.e. H. under stress-free conditions that HSF fusion proteins are active, the naturally occurring HSF is however inactive. Only after an HS can also observe the activity of the naturally occurring ATHSF1 be respected.

Transferability of HSF activation from Arabidopsis to others plants

He described the HSF-GUS or GUS-HSF gene constructs described above leave the heterologous expression in plants other than Arabi dopsis. The fusion products from Arabidopsis lead to constitutive expression of HSPs in heterologous plants.

Furthermore, the plants can be found in plants other than Arabidopsis corresponding HSFs in a manner analogous to that detailed above activate activation in Arabidopsis, too that there is a constitutive expression of the HSPs by the ho mologically constitutive active HSFs comes.  

Table 1

Biochemical and functional properties of HS proteins

Claims (21)

1. Plant with increased stress tolerance, containing at least one egg a constitutively expressed and active transcription activator for the constitutive expression of at least one protection pro tein, which is usually only induced by stress factors. 2. Plant according to claim 1, characterized in that the Transcription activator is a heat shock factor (HSF). 3. Plant according to claim 2, characterized in that the Transcription activator a fusion protein from an HSF and egg another protein. 4. Plant according to one of claims 1 to 3, characterized records that the plant is selected from the family of Brassicaceae, the class of Magnoliatae and the class of Liliatae. 5. Plant according to claim 4, characterized in that the Plant is selected from the genera Brassica, Beta, Sola num, Lycopersicum, Helianthus, Glycine, Zea, Hordeum, Triticum, Secale and Oryza. 6. Plant according to one of claims 1 to 5, characterized net that the plant shows increased stress tolerance compared to the Stress factors Pathogen infestation, wounding, heat, cold, UV radiation, high light intensity, high concentration of heaviness tall, salt and / or ozone, acidity, dryness and / or O₂ deficiency. 7. Plant according to one of claims 1 to 6, characterized records that the plant egg even under stress-free conditions has an elevated level of at least one protective protein. 8. Plant according to claim 7, characterized in that the The level of several protective proteins is increased.   9. Nucleic acid, which is constitutive for a plant tive transcription activator encoded. 10. Nucleic acid according to claim 9, characterized in that the nucleic acid is a DNA. 11. Nucleic acid according to one of claims 9 or 10, characterized ge indicates that the encoded transcription activator is an HSF is. 12. Nucleic acid according to one of claims 9 to 11, characterized ge indicates that the encoded transcription activator is a Fu is a protein from an HSF and another protein. 13. Nucleic acid according to one of claims 9 to 12, characterized ge indicates that they continue to have one or more regulatory Elements included for the expression of the coding sequence in a plant. 14. Plant cell containing a nucleic acid according to one of the Claims 9 to 13. 15. Plant that from a plant cell according to claim 14 he is stable. 16. A method for producing a plant with increased stress tolerance, comprising the steps:

• a) introducing a nucleic acid, which codes for a constitutively active transcription activator, into a plant cell, and
• b) Regeneration of a transgenic plant from the plant cell produced in step a).

17. The method according to claim 16, characterized in that the Nucleic acid is a DNA.   18. The method according to claim 16, characterized in that the Nucleic acid is an RNA. 19. The method according to any one of claims 16 to 18, characterized ge indicates that the transcription activator is an HSF. 20. The method according to any one of claims 16 to 19, characterized ge indicates that the transcriptional activator is a fusion protein is made up of an HSF and another protein. 21. The method according to claim 20, characterized in that the additional protein serves simultaneously as a selection marker.