The occurrence of spring forms in tetraploid Timopheevi wheat is associated with variation in the first intron of the <Emphasis Type="Italic">VRN-A1</Emphasis> gene

Background

Triticum araraticum and Triticum timopheevii are tetraploid species of the Timopheevi group. The former includes both winter and spring forms with a predominance of winter forms, whereas T. timopheevii is considered a spring species. In order to clarify the origin of the spring growth habit in T. timopheevii, allelic variability of the VRN-1 gene was investigated in a set of accessions of both tetraploid species, together with the diploid species Ae. speltoides, presumed donor of the G genome to these tetraploids.

Results

The promoter region of the VRN-A1 locus in all studied tetraploid accessions of both T. araraticum and T. timopheevii represents the previously described allele VRN-A1f with a 50 bp deletion near the start codon. Three additional alleles were identified namely, VRN-A1f-del, VRN-A1f-ins and VRN-A1f-del/ins, which contained large mutations in the first (1^st) intron of VRN-A1. The first allele, carrying a deletion of 2.7 kb in a central part of intron 1, occurred in a few accessions of T. araraticum and no accessions of T. timopheevii. The VRN-A1f-ins allele, containing the insertion of a 0.4 kb MITE element about 0.4 kb upstream from the start of intron 1, and allele VRN-A1f-del/ins having this insertion coupled with a deletion of 2.7 kb are characteristic only for T. timopheevii. Allelic variation at the VRN-G1 locus includes the previously described allele VRN-G1a (with the insertion of a 0.2 kb MITE in the promoter) found in a few accessions of both tetraploid species. We showed that alleles VRN-A1f-del and VRN-G1a have no association with the spring growth habit, while in all accessions of T. timopheevii this habit was associated with the dominant VRN-A1f-ins and VRN-A1f-del/ins alleles. None of the Ae. speltoides accessions included in this study had changes in the promoter or 1^st intron regions of VRN-1 which might confer a spring growth habit. The VRN-1 promoter sequences analyzed herein and downloaded from databases have been used to construct a phylogram to assess the time of divergence of Ae. speltoides in relation to other wheat species.

Conclusions

Among accessions of T. araraticum, the preferentially winter predecessor of T. timopheevii, two large mutations were found in both VRN-A1 and VRN-G1 loci (VRN-A1f-del and VRN-G1a) that were found to have no effect on vernalization requirements. Spring tetraploid T. timopheevii had one VRN-1 allele in common for two species (VRN-G1a), and two that were specific (VRN-A1f-ins, VRN-A1f-del/ins). The latter alleles include mutations in the 1^st intron of VRN-A1 and also share a 0.4 kb MITE insertion near the start of intron 1. We suggested that this insertion resulted in a spring growth habit in a progenitor of T. timopheevii which has probably been selected during subsequent domestication. The phylogram constructed on the basis of the VRN-1 promoter sequences confirmed the early divergence (~3.5 MYA) of the ancestor(s) of the B/G genomes from Ae. speltoides.

     

Use of foreign genetic variability to improve the quality of wheat grain

Foreign genetic variability, which is represented by different wild-growing relatives of wheat such as Ae. umbellulata (UU, 2n = 14), Ae. cylindrica (CCDD, 2n = 28), Ae. tauschii (DD, 2n = 14), Ae. ventricosa (DDUnUn, 2n = 28), Ae. variabilis (UUSS, 2n = 28), and T. palmovae (AADD, 2n = 28) is used in interspecies crossings with the wheat cultivar T. aestivum for the purpose of transferring exotic Gli/Glu alleles into the genome of the crop. As a result, a series of new exotic Gli/Glu alleles is introgressed into the genome of wheat cultivar. An essential negative as well as positive influence of the wild exotic alleles on the baking quality indicators of the flour and the consistency of the wheat endosperm is discovered in the course of the study. The new genetic material with the improved grain quality indicators is recommended for use in wheat selection.     

Low molecular weight glutenin subunit gene composition at <Emphasis Type="Italic">Glu</Emphasis>-<Emphasis Type="Italic">D3</Emphasis> loci of <Emphasis Type="Italic">Aegilops tauschii</Emphasis> and common wheat and a further view of wheat evolution

Key message

A comprehensive comparison of LMW-GS genes between Ae. tauschii and its progeny common wheat.

Abstract

Low molecular weight glutenin subunits (LMW-GSs) are determinant of wheat flour processing quality. However, the LMW-GS gene composition in Aegilops tauschii, the wheat D genome progenitor, has not been comprehensively elucidated and the impact of allohexaploidization on the Glu-D3 locus remains elusive. In this work, using the LMW-GS gene molecular marker system and the full-length gene-cloning method, LMW-GS genes at the Glu-D3 loci of 218 Ae. tauschii and 173 common wheat (Triticum aestivum L.) were characterized. Each Ae. tauschii contained 11 LMW-GS genes, and the whole collection was divided into 25 haplotypes (AeH01–AeH25). The Glu-D3 locus in common wheat lacked the LMW-GS genes D3-417, D3-507 and D3-552, but shared eight genes of identical open reading frame (ORF) sequences when compared to that of Ae. tauschii. Therefore, the allohexaploidization induces deletions, but exerts no influence on LMW-GS gene coding sequences at the Glu-D3 locus. 92.17% Ae. tauschii had 7-9 LMW-GSs, more than the six subunits in common wheat. The haplotypes AeH16, AeH20 and AeH23 of Ae. tauschii ssp. strangulate distributed in southeastern Caspian Iran were the main putative D genome donor of common wheat. These results facilitate the utilization of the Ae. tauschii glutenin gene resources and the understanding of wheat evolution.

     

Unreduced gamete formation in wheat × <Emphasis Type="Italic">Aegilops</Emphasis> spp. hybrids is genotype specific and prevented by shared homologous subgenomes

Key message

The presence of homologous subgenomes inhibited unreduced gamete formation in wheat × Aegilops interspecific hybrids. Unreduced gamete rates were under the control of the wheat nuclear genome.

Abstract

Production of unreduced gametes is common among interspecific hybrids, and may be affected by parental genotypes and genomic similarity. In the present study, five cultivars of Triticum aestivum and two tetraploid Aegilops species (i.e. Ae. triuncialis and Ae. cylindrica) were reciprocally crossed to produce 20 interspecific hybrid combinations. These hybrids comprised two different types: T. aestivum × Aegilops triuncialis; 2n = ABDU^tC^t (which lack a common subgenome) and T. aestivum × Ae. cylindrica; 2n = ABDD^cC^c (which share a common subgenome). The frequency of unreduced gametes in F₁ hybrids was estimated in sporads from the frequency of dyads, and the frequency of viable pollen, germinated pollen and seed set were recorded. Different meiotic abnormalities recorded in the hybrids included precocious chromosome migration to the poles at metaphase I and II, laggards in anaphase I and II, micronuclei and chromosome stickiness, failure in cell wall formation, premature cytokinesis and microspore fusion. The mean frequency of restitution meiosis was 10.1 %, and the mean frequency of unreduced viable pollen was 4.84 % in T. aestivum × Ae. triuncialis hybrids. By contrast, in T. aestivum × Ae. cylindrica hybrids no meiotic restitution was observed, and a low rate of viable gametes (0.3 %) was recorded. This study present evidence that high levels of homologous pairing between the D and D^c subgenomes may interfere with meiotic restitution and the formation of unreduced gametes. Variation in unreduced gamete production was also observed between T. aestivum × Ae. triuncialis hybrid plants, suggesting genetic control of this trait.

     

Wild relatives of wheat: <Emphasis Type="Italic">Aegilops</Emphasis>–<Emphasis Type="Italic">Triticum</Emphasis> accessions disclose differential antioxidative and physiological responses to water stress

Wild relatives of wheat are an outstanding source of resistance to both abiotic and biotic stresses. In the present study, we evaluated the activity of four antioxidant enzymes—superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX) and guaiacol peroxidase (GPX)—along with photosynthetic pigments and shoot biomass in 12 Aegilops–Triticum accessions with different genomic constitutions and two tolerant and sensitive control varieties under well-watered (WW; 90% FC), moderate (MS; 50% FC) and severe (SS; 25% FC) water stress treatments. The analysis of variance for measured traits indicated highly significant effects of the water stress treatments, accessions, and their interactions. The 12 domesticated and wild relatives of wheat exhibited more variability and greater activity in the expression of antioxidative enzymes than cultivated wheats. While domesticated forms of wheat, T. aestivum (AABBDD) and T. durum (AABB) seem to have a functionally active antioxidant mechanism, other accessions with alien genomes—Ae. umbellulata (UU), Ae. crassa (MMDD), Ae. caudata (CC), Ae. cylindrica (DDCC) and T. boeoticum (A^bA^b)—respond to water stress by increasing enzymatic antioxidants as the dominant mechanism that contributes to the retention of oxidative balance in the cell. Furthermore, abovementioned accessions with alien genomes had higher photosynthetic pigment contents (chlorophyll a, chlorophyll b, total chlorophyll, and carotenoid) under water stress than well-watered conditions. Hence, these accessions could be used in future breeding programs to combine beneficial stress-adaptive characters of alien genomes into synthetic hexaploid wheat varieties in the field, even at limited water supply.     

Intraspecific divergence in wheats of the Emmer group using in situ hybridization with the Spelt-1 family of tandem repeats

Fluorescence in situ hybridization (FISH) was used to study the distribution of Spelt-1 repetitive DNA sequences on chromosomes of 37 accessions representing eight polyploidy wheat species of the Emmer evolutionary lineage: Triticum dicoccoides Körn, T. dicoccum (Schrank) Schuebel, T. durum Desf., T. polonicum L., T. carthlicum Nevski, T. aethiopicum Jakubz., T. aestivum L., and T. spelta L. Substantial polymorphism in the number, distribution, and the sizes of the Spelt-1 loci was revealed. On the chromosomes of the accessions examined, Spelt-1 tandem repeats were found in seven different positions (per haploid chromosome set). These were “potential hybridization sites”, including the subtelomeric regions of either short or long arms of chromosomes 2A and 6B, the short arm of chromosome 1B, and the long arms of chromosomes 2B and 3B. However, in individual genotypes, only from one to three Spelt-1 loci were revealed. Furthermore, no hybridization with Spelt-1 probe was detected on chromosomes from 12 accessions. Thus, the total number of Spelt-1 sites in karyotypes varied from zero to three, with the average number of 1.16. This was substantially lower than in the species of the Timopheevi section and diploid Aegilops speltoides Tausch, a putative donor of the B genome. The decrease of the content of Spelt-1 sequences in the genomes of the Emmer group wheats in comparison with the species of the Timopheevii group and diploid Ae. speltoides was assumed to result from the repetitive sequences reorganization during polyploidization and the repeat elimination during wheat evolution.     

The homologous identification of the stem rust resistance genes <Emphasis Type="Italic">Rpg5</Emphasis>, <Emphasis Type="Italic">Adf3</Emphasis> and <Emphasis Type="Italic">RGA1</Emphasis> in the relatives of barley

The barley genes Rpg5, RGA1 and Adf3, which provide a strong resistance to many pathotypes of stem rust, were cloned a few years ago, but it was still unclear whether their homologues were represented in wheat and in related species. The paper describes the results of a bioinformatic research to determine the homologues of Rpg5, RGA1 and Adf3 in the genomes of Triticum aestivum and several wild grasses, which breeders usually use as sources of stem rust resistance, and which are available in the genome databases. It was found that the Th. elongatum sequence Q9FEC6 and T. aestivum sequence Q43655 were the highly identical homologues of the Adf3 sequence. T. urartu M8A999 sequence and T. aestivum W5FCU1 sequence were found to be the closest homologues of Rpg5 complete protein sequence, but the identity of their kinase domains was not as clear as that of the other domains. The separate Rpg5 kinase part analysis did not provide the strong evidences that its orthologs were present in our corn species. T. urartu M7ZZX9 sequence and T. aestivum W5FFP0 and W5FI33 sequences were shown to be the homologues of RGA1. The analysis of the predicted active sites allowed finding out the difference between sequences of Rpg5, RGA1, Adf3 protein and their homologues.     

The Genome of Bread Wheat <Emphasis Type="Italic">Triticum aestivum</Emphasis> L.: Unique Structural and Functional Properties

Polyploidy is the major mechanism of speciation in flowering plants. All genomes of ancient species that are the progenitors of extant plant species experienced polyploidization. Three consecutive stages of polyploidization, i.e., ancient polyploidization, tetra-, and hexaploidization, resulted in the emergence of modern allohexaploid bread wheat Triticum aestivum L. with the BBAADD genome. Polyploidization and subsequent stabilization of the polyploid genome of T. aestivum led, on one hand, to cytological diploidization and, on the other hand, to structural and functional asymmetry of its three subgenomes. In recent years, there has been a sharp increase in the data accumulation on the origin and structure of the bread wheat genomes a result of analysis of genomes and transcripomes of natural and synthetic wheats using modern mapping and sequencing methods. This review provides up-to-date information on the peculiarities of the T. aestivum genome reorganization, which affected its structure and functioning.     

Intraspecific divergence in wheats of the Timopheevi group as revealed by in situ hybridization with tandem repeats of the Spelt1 and Spelt52 families

Fluorescent in situ hybridization (FISH) was used to study the distribution of the Spelt1 and Spelt52 repetitive DNA sequences on chromosomes of ten accessions representing three polyploid wheat species of the Timopheevi group: Triticum araraticum (7), T. timopheevii (2), and T. kiharae (1). Sequences of both families were found mostly in the subtelomeric chromosome regions of the G genome. The total number of Spelt1 sites varied from 8 to 14 in the karyotypes of the species under study; their number, location, and size differed among the seven T. araraticum accessions and were the same in the two T. timopheevii accessions and T. kiharae, an amphidiploid T. timopheevii-Aegilops tauschii hybrid. The Spelt52 tandem repeat was detected in the subtelomeric regions of chromosomes 1-4; its sites did not coincide with the Spelt1 sites. The chromosome distribution and signal intensity of the Spelt52 repeats varied in T. araraticum and were the same in T. timopheevii and T. kiharae. The chromosome distributions of the Spelt1 and Spelt52 repeats were compared for the polyploid wheats of the Timopheevi group and diploid Ae. speltoides, a putative donor of the G genome. The comparison revealed a decrease in hybridization level: both the number of sites per genome and the size of sites were lower. The decrease was assumed to result from repeat elimination during polyploidization and subsequent evolution of wheat and from the founder effect, since the origin of Timopheevi wheats might involve the genotype of Ae. speltoides, which is highly polymorphic for the distribution of Spelt1 and Spelt52 sequences and is similar in the chromosome location of the repeats to modern wheat.     

Variation at Two Loci affecting Homoeologous Meiotic Chromosome Pairing in <Emphasis Type="Italic">Triticum aestivum</Emphasis> × <Emphasis Type="Italic">Aegilops mutica</Emphasis> Hybrids

HOMOEOLOGOUS chromosomes of the three genomes of bread wheat (Triticum aestivum 2n=6x=42) are normally prevented from pairing at meiosis by the activity of an allele at the Ph locus on chromosome 5B^L (refs. 1–4). This activity is responsible for the regular bivalent-forming meiotic behaviour and for the stable disomic inheritance of T. aestivum. If allelic variation occurs at the PA locus in nature it is extremely rare, although mutation has been induced and mutant alleles isolated^3,4.     

Evolution of <Emphasis Type="Italic">VRN-1</Emphasis> homoeologous loci in allopolyploids of <Emphasis Type="Italic">Triticum</Emphasis> and their diploid precursors

Background

The key gene in genetic system controlling the duration of the vegetative period in cereals is the VRN1 gene, whose product under the influence of low temperature (vernalization) promotes the transition of the apical meristem cells into a competent state for the development of generative tissues of spike. As early genetic studies shown, the dominant alleles of this gene underlie the spring forms of plants that do not require vernalization for this transition. In wheat allopolyploids various combinations of alleles of the VRN1 homoeologous loci (VRN1 homoeoalleles) provide diversity in such important traits as the time to heading, height of plants and yield. Due to genetical mapping of VRN1 loci it became possible to isolate the dominant VRN1 alleles and to study their molecular structure compared with the recessive alleles defining the winter type of plants. Of special interest is the process of divergence of VRN1 loci in the course of evolution from diploid ancestors to wheat allopolyploids of different levels of ploidy.

Results

Molecular analysis of VRN1 loci allowed to establish that various dominant alleles of these loci appeared as a result of mutations in two main regulatory regions: the promoter and the first intron. In the diploid ancestors of wheat, especially, in those of A- genome (T. boeoticum, T. urartu), the dominant VRN1 alleles are rare in accordance with a limited distribution of spring forms in these species. In the first allotetraploid wheat species including T. dicoccoides, T. araraticum (T. timopheevii), the spring forms were associated with a new dominant alleles, mainly, within the VRN-A1 locus. The process of accumulation of new dominant alleles at all VRN1 loci was significantly accelerated in cultivated wheat species, especially in common, hexaploid wheat T. aestivum, as a result of artificial selection of spring forms adapted to different climatic conditions and containing various combinations of VRN1 homoeoalleles.

Conclusions

This mini-review summarizes data on the molecular structure and distribution of various VRN1 homoeoalleles in wheat allopolyploids and their diploid predecessors.

     

Genetic mapping of a novel recessive allele for non-glaucousness in wild diploid wheat <Emphasis Type="Italic">Aegilops tauschii</Emphasis>: implications for the evolution of common wheat

Cuticular wax on the aerial surface of plants has a protective function against many environmental stresses. The bluish–whitish appearance of wheat leaves and stems is called glaucousness. Most modern cultivars of polyploid wheat species exhibit the glaucous phenotype, while in a wild wheat progenitor, Ae. tauschii, both glaucous and non-glaucous accessions exist. Iw2, a wax inhibitor locus on the short arm of chromosome 2D, is the main contributor to this phenotypic variation in Ae. tauschii, and the glaucous/non-glaucous phenotype of Ae. tauschii is usually inherited by synthetic hexaploid wheat. However, a few synthetic lines show the glaucous phenotype although the parental Ae. tauschii accessions are non-glaucous. Molecular marker genotypes indicate that the exceptional non-glaucous Ae. tauschii accessions share the same genotype in the Iw2 chromosomal region as glaucous accessions, suggesting that these accessions have a different causal locus for their phenotype. This locus was assigned to the long arm of chromosome 3D using an F₂ mapping population and designated W4, a novel glaucous locus in Ae. tauschii. The dominant W4 allele confers glaucousness, consistent with phenotypic observation of Ae. tauschii accessions and the derived synthetic lines. These results implied that glaucous accessions of Ae. tauschii with the W2W2iw2iw2W4W4 genotype could have been the D-genome donor of common wheat.     

Sequence divergence between spelt and common wheat

Key message

Sequence comparison between spelt and common wheat reveals that the former has huge potential in enriching the genetic variation of the latter.

Abstract

Genetic variation is the foundation of crop improvement. By comparing genome sequences of a Triticum spelta accession and one of its derived hexaploid lines with the sequences of the international reference genotype Chinese Spring, we detected variants more than tenfold higher than those present among common wheat (T. aestivum L) genotypes. Furthermore, different from the typical ‘V-shaped’ pattern of variant distribution often observed along wheat chromosomes, the sequence variation detected in this study was more evenly distributed along the 3B chromosome. This was also the case between T. spelta and the wild emmer genome. Genetic analysis showed that T. spelta and common wheat formed discrete groups. These results showed that, although it is believed that the spelt and common wheat are evolutionarily closely related and belong to the same species, a significant sequence divergence exists between them. Thus, the values of T. spelta in enriching the genetic variation of common wheat can be huge.

     

A moso bamboo (<Emphasis Type="Italic">Phyllostachys edulis</Emphasis>) miniature inverted-repeat transposable element (MITE): the possible role of a suppressor

Transposable elements (transposons) are fragments of DNA sequences which can move within host genome. Miniature inverted-repeat transposable elements (MITEs) are widespread and high-copy transposable elements in eukaryotic genomes. Tourist-like MITEs are especially abundant in plant kingdom. Earlier genome-wide analysis has shown that MITEs are widely distributed in the moso bamboo genome and preferentially inserted into gene regions. In the present study, in order to examine the potential influence of MITEs on the moso bamboo gene expressions, a highly conserved Tourist-like MITE family, which distributed near genes, was selected as research focus and named PhTst-3 (Phyllostachys edulis Tourist-like element 3). The MITEs’ insertion sites were tested in moso bamboo half-sib seedlings by real-time fluorescence quantitative PCR. Amplification polymorphisms were found in a copy of PhTst-3 (PhTst-3-55) which was located in the intron of PH01002699G0010. This inserted PhTst-3-55 had a significant impact on the gene expression revealed by the real-time fluorescence quantitative PCR. The gene expression levels were four times higher in the absence of PhTst-3-55 than those in the presence of it. This finding suggests that the PhTst-3 located in the intron is involved in the regulation of the gene. In order to examine the impact of PhTst-3-55 on the near genes, the PhTst-3-55 was inserted into a promoter analysis vector, pxk7S2D, between the two promoter sequences. The Agrobacterium-mediated transient expression showed that PhTst-3-55 insertion decreases the expression level of upstream GUS gene and downstream GFP gene. So, PhTst-3-55 can have a silencing role by bidirectionally inhibiting gene expression.     

Molecular analysis of the phylogenetic relationships among the diploid <Emphasis Type="Italic">Aegilops</Emphasis> species of the section <Emphasis Type="Italic">Sitopsis</Emphasis>

RAPD analysis was used to study the intraspecific variation and phylogenetic relationships of Sgenome diploid Aegilops species regarded as potential donors of the B genome of cultivated wheat. In total, 21 DNA specimens from six S-genome diploid species were examined. On a dendrogram, Ae. speltoides and Ae. aucheri formed the most isolated cluster. Among the other species, Ae. searsii was the most distant while Ae. longissima and Ae. sharonensis were the closest species. The maximum difference between individual accessions within one species was approximately the same (0.18–0.22) in Ae. bicornis, Ae. longissima, Ae. sharonensis, and Ae. searsii. The difference between the clusters of questionable species Ae. speltoides and Ae. aucheri corresponded to the intraspecific level; the difference between closely related Ae. longissima and Ae. sharonensis corresponded to the interspecific level.     

Identification of <Emphasis Type="Italic">Pm58</Emphasis> from <Emphasis Type="Italic">Aegilops tauschii</Emphasis>

Key message

A novel powdery mildew-resistance gene, designated Pm58, was introgressed directly from Aegilops tauschii to hexaploid wheat, mapped to chromosome 2DS, and confirmed to be effective under field conditions. Selectable KASP? markers were developed for MAS.

Abstract

Powdery mildew caused by Blumeria graminis (DC.) f. sp. tritici (Bgt) remains a significant threat to wheat (Triticum aestivum L.) production. The rapid breakdown of race-specific resistance to Bgt reinforces the need to identify novel sources of resistance. The d-genome species, Aegilops tauschii, is an excellent source of disease resistance that is transferrable to T. aestivum. The powdery mildew-resistant Ae. tauschii accession TA1662 (2n?=?2x?=?DD) was crossed directly with the susceptible hard white wheat line KS05HW14 (2n?=?6x?=?AABBDD) followed by backcrossing to develop a population of 96 BC₂F₄ introgression lines (ILs). Genotyping-by-sequencing was used to develop a genome-wide genetic map that was anchored to the Ae. tauschii reference genome. A detached-leaf Bgt assay was used to screen BC₂F_4:6 ILs, and resistance was found to segregate as a single locus (χ?=?2.0, P value?=?0.157). The resistance gene, referred to as Pm58, mapped to chromosome 2DS. Pm58 was evaluated under field conditions in replicated trials in 2015 and 2016. In both years, a single QTL spanning the Pm58 locus was identified that reduced powdery mildew severity and explained 21% of field variation (P value?<?0.01). KASP? assays were developed from closely linked GBS-SNP markers, a refined genetic map was developed, and four markers that cosegregate with Pm58 were identified. This novel source of powdery mildew-resistance and closely linked genetic markers will support efforts to develop wheat varieties with powdery mildew resistance.

     

Structure of the <Emphasis Type="Italic">TADHN</Emphasis> gene for dehydrin-like protein of soft wheat and activation of its expression by ABA and 24-epibrassinolide

The structure of the cloned fragment of wheat (Triticum aestivum L.) TADHN gene encoding dehydrin-like protein was examined. A comparative analysis of nucleotide and deduced amino acid sequences revealed a high homology of this fragment with sequences of the barley dhn8 gene and wheat wcor gene family. In deduced amino acid sequence of the TADHN fragment, a 15-residue region EKKGFLEKIKEKLPG was found, which corresponded to a highly conserved K-segment of dehydrins. Wheat seedling treatment with 3.7 μM ABA and 0.4 μM 24-epibrassinolide exerted similar stimulatory effects on expression of the TADHN gene, which indicates the involvement of dehydrins in the protective action of these phytohormones in wheat plants.