Dehydrin Gene Research Articles

Comparative expression analysis of dehydrins between two barley varieties, wild barley and Tibetan hulless barley associated with different stress resistance

Drought, salinity and cold are the major environmental factors impacting on survival and productivity of Tibetan hulless barley in Tibetan Plateau of China. Tibetan hulless barley cultivar, Tibetan Heiqingke No. 1, has developed a strong tolerance and adaptation to stresses in relation to the wild barley. The differences of dehydrin gene transcription and translation between Tibetan Heiqingke No. 1 and the wild barley under drought, salinity and low temperature stresses were investigated in the present study to figure out the putative mechanism of stress tolerance of Tibetan Heiqingke No. 1. The leaf relative water contents (RWCs) decreased more slowly in Tibetan hulless barley than the wild barley under osmotic and low temperature conditions. Electrolyte leakage, malondialdehyde and H2O2 contents increased faster in wild barley than those of Tibetan hulless barley, which indicated that cells of wild barley received more damages than Tibetan hulless barley. Furthermore, the expression of several dehydrin genes, belonging to four different classifications respectively, was also investigated. Polyclonal antibodies against dehydrins were obtained from rabbit after prokaryotic expression and purification of TDHN4, a dehydrin protein from Tibetan hulless barley. With these antibodies and dehydrin gene fragments, western blotting analysis and RT-PCR showed that Tibetan Heiqingke No. 1 accumulated higher abundance of dehydrins than stress-sensitive wild barley under all stress conditions.

Expression for Caffeine Biosynthesis and Related Enzymes in Camellia sinensis

Caffeine (1,3,7-trimethylxanthine) is a purine alkaloid that is present in high concentrations in the tea plant Camellia sinensis. Caffeine synthase (CS, EC 2.1.1.160) catalyzes the S-adenosyl-L-methionine-dependent N-3- and N-1-methylation of the purine base to form caffeine, the last step in the purine alkaloid biosynthetic pathway. We studied the expression profile of the tea caffeine synthase (TCS) gene in developing leaves and flowers by means of northern blot analysis, and compared it with those of phenylalanine ammonia lyase (PAL, EC 4.3.1.5), chalcone synthase (CHS, EC 2.3.1.74), and S-adenosyl-L-methionine synthase (SAMS, EC 2.5.1.6). The amount of TCS transcripts was highest in young leaves and declined markedly during leaf development, whereas it remained constant throughout the development of the flower. Environmental stresses other than heavy metal stress and plant hormone treatments had no effect on the expression of TCS genes, unlike the other three genes. Drought stress suppressed TCS gene expression in leaves, and the expression pattern mirrored that of the dehydrin gene. The amounts of TCS transcripts increased slightly on supply of a nitrogen source. We discuss the regulation of TCS gene expression.

Stress Metabolism in Green Coffee Beans (Coffea arabica L.): Expression of Dehydrins and Accumulation of GABA during Drying

In order to produce tradeable standard green coffee, processed beans must be dried. The drying procedure affects the abundance of relevant aroma substances, e.g. carbohydrates. Using molecular tools, the corresponding metabolic basis is analyzed. A decrease in water potential of the still living coffee seeds induces massive drought stress responses. As a marker for these stress reactions, accumulation of a general stress metabolite, GABA (gamma-aminobutyric acid), and associated gene expression of drought stress-associated dehydrins were monitored. The results of this study indicate that metabolism in drying coffee beans is quite complex since several events trigger accumulation of GABA. The first peak of GABA accumulation during drying is correlated with expression of isocitrate lyase and thus with ongoing germination processes in coffee seeds. Two subsequent peaks of GABA accumulation correspond to maxima of dehydrin gene expression and are thought to be induced directly by drought stress in the embryo and endosperm tissue, respectively. Apart from the significance for understanding basic seed physiology, metabolic changes in coffee seeds during processing provide valuable information for understanding the role and effect of the steps of green coffee processing on the quality of the resulting coffee.

Transcriptomic analysis of cold response in tomato fruits identifies dehydrin as a marker of cold stress

Tomato is sensitive to cold during vegetative growth, fruit set, development, and ripening. We have characterized the effect of cold stress (6xC for up to 48 h) on the transcriptome of Micro-Tom tomato fruits during ripening by subtractive PCR. The cold stress caused modifications in gene expression of housekeeping genes. From a total of 38 genes up-regulated by cold, only one clone - a dehydrin homologue - was related to previously identified cold-stress genes. Phylogenetic analysis showed its clustering with other cold-induced dehydrins, and increased distances from dehydrins activated by abscisic acid. Quantitative expression analysis of tomato dehydrin showed it was activated by cold treatment in leaves and fruits. As dehydrin is a member of the Sl-CBF1 regulon from tomato, we analyzed the cold-responsive transcription factor Sl-CBF1 in mature leaves and ripening fruits stored at 6xC. Leaves of Micro-Tom showed high basal levels of the transcription factor Sl-CBF1, compared to fruits. Cold treatment caused increased levels of Sl-CBF1 expression in leaves but not in fruits of Micro-Tom and Demisem (a commercial cultivar). Tomato dehydrin can be used as a transcriptional marker of cold stress in leaves and ripening fruits. However, our results indicate that the cold response activation of dehydrin gene in tomato fruits is the consequence of an alternative pathway, different from the Sl-CBF1 regulon.

The role of endogenous ABA in cold-induced expression of the TADHN dehydrin gene in wheat seedlings

The effect of fluridone, an efficient inhibitor of ABA synthesis, on expression of the TADHN gene encoding dehydrin was studied in four-day-old wheat (Triticum aestivum L.) seedlings exposed to low temperature (6°C). It was found that complete inhibition of a rapid cold-induced transient ABA formation reduced but did not eliminate cold-induced enhancement of this dehydrin gene transcription. These results argue for an important role of endogenous ABA in the induction of the TADHN gene expression in wheat seedlings under low temperature. Thus, under hypothermia, TADHN gene expression is controlled by both low temperature and endogenous ABA.

Identification of barley mutants in the cultivar ‘Lux’ at the Dhn loci through TILLING

AbstractTILLING is a reverse genetic strategy that allows screening for mutations in genes with known sequences in a plant mutant population. A TILLING population has been developed for the Danish barley variety ‘Lux’ (Hordeum vulgare L.), by using sodium azide to induce mutations. Scoring of four visible phenotypic characters of barley seedling in reference to the parental cultivar ‘Lux’ in the M3 plants showed over 3.5% lethality. A series of pool ratios of mixed DNA from mutant lines were tested and 10‐fold pools appeared to be the practical mixing ratio for the detection of fragments in the 500–700 bp range. Two of the 13 known dehydrin genes, Dhn12 and Dhn13, respectively, were examined and five independent missense mutations were obtained from a population of 9575 barley mutant plants. This corresponds to a mutation density of approximately one mutation every two and half million base pairs for these two genes. The mutant population of approximately 10 000 lines was screened for mutations in two genes in a short time due to high pooling ratio.

Differential expression of a poplar SK2-type dehydrin gene in response to various stresses

Dehydrins are group II, late embryogenesis abundant proteins that act putatively as chaperones in stressed plants. To elucidate the function of dehydrins in poplar, we isolated the SK(2)-type dehydrin gene Podhn from Populus alba x P. tremula var. glandulosa suspension cells and analyzed its expression following treatments of abiotic stress, wounding and plant growth regulator. Sequence homology and phylogenetic analyses indicate Podhn encodes an acidic dehydrin (pI 5.14, 277 amino acids, predicted size 25.6 kDa) containing two lysine-rich "K-segments" and a 7-serine residue "S-segment", both characteristic of SK(2)-type dehydrins. Southern blots show Podhn genes form a small gene family in poplar. Podhn was expressed in all tissues examined under unstressed conditions, but most strongly in cell suspensions (especially in the stationary phase). Drought, salt, cold and exogenous abscisic acid (ABA) treatments enhanced Podhn expression, while wounding and jasmonic acid caused its reduction. Therefore, Podhn might be involved in ABA or stress response.

Characterization of a Midwinter-Expressed Dehydrin (DHN) Gene from Apple Trees (Malus domestica)

To gain a better understanding of the proteins associated with cold acclimation and winter dormancy in apple trees (Malus domestica), we studied the expression of a dehydrin gene encoding one of the important proteins involved in these processes. A novel gene, designated mddhn, was obtained from M. domestica cv. “Golden Delicious”. The full-length complementary DNA (cDNA) consists of 993 nucleotides with an open reading frame of 687 bp. The deduced amino acid sequence of 229 residues shows similarity to members of the dehydrin (DHN) family. The putative DHN presents a structure typical of DHN proteins that are composed of two consensus Y-segments, a stretch of serine residues, and four lysine-rich repeats (Y2SK4). This apple DHN shows the greatest similarity to members of both the YnKn and YnSKn classes of DHNs from peach and almond: 57% to peach (Y2SK3) and almond (Y2SK3 and Y2K4) and a lower percentage (35%) to peach (Y2K9). When we analyzed the available expressed sequence tag databases for additional apple DHNs, we identified a DHN of the class Y2SK4 with a deduced amino acid sequence with 79–98% identity among the cultivars “Royal Gala”, “Goldrush”, and the M9 rootstock that showed high identity to our DHN from “Golden Delicious” (92–98%). The transcripts of mddhn are highly expressed in bark and bud tissues when the plant is dormant and cold hardy in midwinter, but are not expressed in early spring when cold hardiness is lost and the buds are growing.

Dehydrin genes and their expression in recalcitrant oak (Quercus robur) embryos

In this work, three dehydrin genes, QrDhn1, QrDhn2, QrDhn3, were isolated from recalcitrant oak (Quercus robur). Their expression pattern was analyzed in both zygotic and somatic embryos as well as in vegetative tissues exposed to different kinds of abiotic stresses including desiccation, osmotic stress, and chilling. The QrDhn1 gene encoding for Y(n)SK(n) type dehydrin was expressed during later stages of zygotic embryo development but in somatic embryos only when exposed to osmotic or desiccation stress. In contrast, the other two oak dehydrin genes encoding for putative K(n) type dehydrins were expressed only in somatic embryos (both not-treated and osmotically stressed) and leaves of oak seedlings exposed to desiccation. Behavior of these genes suggests that different dehydrins are involved in processes of seed maturation and response to altered osmotic (water status) conditions in somatic embryos. Revealing further members of dehydrin gene family in recalcitrant oak might contribute to clarify non-orthodox seed behavior as well as identify mechanisms contributing to desiccation tolerance in plants.

The dual effects of salicylic acid on dehydrin accumulation in water-stressed barley seedlings

Dehydrins are a group of plant proteins that usually accumulate in response to environmental stresses. They are proposed to play specific protective roles in plant cells. Present study showed that the accumulation of dehydrins in water-stressed barley (Hordeum vulgare L.) seedlings was influenced by their treatment with salicylic acid (SA). The level of dehydrin proteins was increased by 0.20 mM SA, but decreased by 0.50 mM SA treatment. Both mRNA expression and protein accumulation of a typical barley dehydrin, DHN5, were enhanced by SA treatment when SA concentrations were lower than 0.25 mM. However, the higher SA concentrations significantly decreased the protein level of DHN5 despite of a stable mRNA level. Our results also showed that low SA concentrations (less than 0.25 mM) decreased the electrolyte leakage and malondialdehyde (MDA) and H2O2 contents in water-stressed barley seedlings. But high SA concentrations (more than 0.25 mM) enhanced H2O2 accumulation, tended to cause more electrolyte leakage, and increase MDA content. These data indicated that SA could up-regulate the dehydrin gene expression and protein accumulation. Since the protective role of dehydrins in plant cells, such effect could be an important reason for the SA-mediated alleviation on water stress injury. But excessive SA could suppress the accumulation of dehydrin proteins and aggravate the oxidative damage.

Comparative expression and transcript initiation of three peach dehydrin genes

Dehydrin genes encode proteins with demonstrated cryoprotective and antifreeze activity, and they respond to a variety of abiotic stress conditions that have dehydration as a common component. Two dehydrins from peach (Prunus persica L. [Batsch.]) have been previously characterized; here, we describe the characterization of a third dehydrin from peach bark, PpDhn3, isolated by its response to low temperature. The expression of all three dehydrin genes was profiled by semi-quantitative reverse transcription PCR, and transcript initiation was mapped for all three genes using the RNA ligase-mediated 5' rapid amplification of cDNA ends technique. PpDhn3 transcripts from bark collected in December or July, as well as transcripts from developing fruit, initiated at a single site. Although most of the PpDhn1 transcripts initiated at a similar position, those from young fruit initiated much further upstream of the consensus TATA box. Bark and fruit transcripts encoding PpDhn2 initiated ca. 30 bases downstream of a consensus TATA box; however, transcripts from ripe fruit initiated further upstream. Ripe fruit transcripts of PpDhn2 contain a 5' leader intron which is predicted to add some 34 amino acids to the N-terminal methionine of the cognate protein when properly processed. Secondary structure prediction of sequences surrounding the TATA box suggests that conformational transitions associated with decreasing temperature contribute to the regulation of expression of the cold-responsive dehydrin genes. Taken together these results reveal new, unexpected levels of gene regulation contributing to the overall expression pattern of peach dehydrins.

Effect of bud burst forcing on transcript expression of selected genes in needles of Norway spruce during autumn

Expression of selected genes in needles of Norway spruce (Picea abies [L.] Karst) was investigated by following their transcription levels during late autumn. Transcription was assessed in mature needles which likely serve as sensor of environmental cues that enable trees in the temperate and boreal regions to change between stages of growth, frost tolerance and bud dormancy. Samples were collected from grafts kept under outdoor conditions and after bud burst forcing in greenhouse at 20 degrees C (12 h darkness) for one week. Transcription was assayed with real-time RT-PCR. During the sampling period, chilling requirement was partially fulfilled, and time to bud burst after forcing was decreased. Of the 27 transcripts studied, expression of 16 was significantly affected either by forcing, sampling time, or interaction between them. PaSAP, PaACP, PaSGS3, PaWRKY, PaDIR9, PaCCCH and dehydrin genes responded drastically to forcing temperatures at all sampling points, showing no correlation with readiness for bud burst. Expression patterns of some vernalization pathway gene homologs PaVIN3, and also of PaMDC, PaLOV1 and PaDAL3 had a clear opposite trends between forcing and outdoor conditions, which could imply their role in chilling accumulation and bud burst regulation/cold acclimation. These genes could constitute putative candidates for further detailed study, whose regulation in needles may be involved in preparation towards bud burst and chilling accumulation sensing.

Search for nucleotide diversity patterns of local adaptation in dehydrins and other cold-related candidate genes in Scots pine (Pinus sylvestris L.)

Nucleotide variation at several cold candidate genes including seven members of the dehydrin gene family was surveyed in haplotypes of Scots pine (Pinus sylvestris) sampled in populations showing divergence for cold tolerance in Europe. Patterns of nucleotide diversity, linkage disequilibrium, and frequency spectrum of alleles were compared between north and south populations to search for signs of directional selection potentially underlying adaptation to cold. Significant differentiation between populations in allelic frequency or haplotype structure was detected at dhn1, dhn3, and abaH loci. Allelic dimorphism with no evidence of haplotype clustering by geographical distribution was found at dhn9. An excess of fixed non-synonymous mutations as compared to the outgroup P. pinaster pine species was found at dhn1. Differences in nucleotide polymorphisms were found between the members of the Kn class of dehydrin upregulated during cold acclimation (average πsil = 0.004) as compared to the SKn class (average πsil = 0.024). The multilocus nucleotide diversity at silent sites (θW = 0.009) was moderate compared to other conifer species, but higher than previous estimates for Scots pine. There was an excess of rare and high frequency derived variants as revealed by significantly negative multilocus value of Tajima’s D (D = −0.72, P < 0.01) and negative mean value of Fay and Wu H statistics (H = −0.50). The level of linkage disequilibrium decayed rapidly with an average expected r2 of 0.2 at about 200 bp. Overall, there was a positive correlation between polymorphism and divergence at ten loci when outgroup sequence was available. The discovered polymorphism will be used for further evaluation of the adaptive role of genes through association mapping studies.

Characterisation of two cold induced dehydrin genes from Cichorium intybus L.

Two dehydrin genes were identified from a Cichorium intybus EST database. They were among the most abundant sequences obtained from 10 cDNA libraries constructed from chicory roots grown under field conditions. The full length cDNA sequences, designated CiDHN1 and CiDHN2, were 1,176 and 1,055 bp long and encoded predicted polypeptides of 262 and 261 amino acids, respectively. The deduced CiDHN1 protein contains a S-segment and four lysine-rich consensus motifs (K-segments) which represent a typical SK(4) structure of dehydrins. The CiDHN2 sequence contains two Y motifs and two K-segments classifying CiDHN2 as Y(2)K(2)-type dehydrin. Southern-blotting analysis suggested that CiDHN1 and CiDHN2 are single copy genes. Northern-blotting analysis revealed that both CiDHN genes are expressed in roots and leaves, with seasonal variations in transcript accumulation. The effect of cold on the CiDHN1 and CiDHN2 transcript level was demonstrated. CiDHN1 and CiDHN2 promoter analysis revealed the presence of low temperature-responsive and ABA-responsive elements.

Differential expression of dehydrin genes in hull-less barley (Hordeum vulgare ssp. vulgare) depending on duration of dehydration stress

Dehydrins (DHN) are water-soluble lipid-associating proteins that accumulate during low-temperature and water-stress conditions, and are thought to play a protective role in freezing and drought tolerance in plants. The synthesis of the dehydrins, representing a link between environment and nuclear activity through dehydrin genes (Dhn) expression, was known to be a common response to drought in plants. The association of mRNA accumulations of Dhn genes (Dhn6, Dhn11 and Dhn13) with phenotypically diverse drought-tolerant genotypes was investigated in hull-less barley (Hordeum vulgare subsp. vulgare). Notably, differences between genotypes were observed, mainly in Dhn6 and Dhn13 gene, depending on the duration of the dehydration stress. Compared with drought-sensitive genotypes, the relative expression levels of Dhn6 gene were significantly higher in drought-tolerant lines subjected to 8 h water deficit. By control with continuative ascending accumulations in sensitive plants during drought, the highest transcript level of Dhn13 was observed in tolerant genotypes after 8 h of dehydration, and tended to descend the same levels as sensitive lines subjected to 12 h of dehydration. Based on decreased accumulations of Dhn11 during drought stress, it was concluded that Dhn11 was not up-regulated by water stress between genotypes. The observed differences in the present study may indicate an association of physiological response to water stress with differential accumulations of Dhn genes between drought-contrasting genotypes. The authors suggest different DHNs may play variable functional roles in structural protection in plants subjected to progressive water stress, associated with drought-contrasting genotypes. Key words: Dhydrin genes, quantitative reverse transcription polymerase chain reaction, water deficit, Tibetan hull-less barley

Dehydrin gene expression provides an indicator of low temperature and drought stress: transcriptome-based analysis of Barley (Hordeum vulgare L.)

Low temperature and drought have major influences on plant growth and productivity. To identify barley genes involved in responses to these stresses and to specifically test the hypothesis that the dehydrin (Dhn) multigene family can serve as an indicator of the entire transcriptome response, we investigated the response of barley cv. Morex to: (1) gradual drought over 21 days and (2) low temperature including chilling, freeze-thaw cycles, and deacclimation over 33 days. We found 4,153 genes that responded to at least one component of these two stress regimes, about one fourth of all genes called "present" under any condition. About 44% (1,822 of 4,153) responded specifically to drought, whereas only 3.8% (158 of 4,153) were chilling specific and 2.8% (119 of 4,153) freeze-thaw specific, with 34.1% responsive to freeze-thaw and drought. The intersection between chilling and drought (31.9%) was somewhat smaller than the intersection between freeze-thaw and drought, implying an element of osmotic stress response to freeze-thaw. About 82.4% of the responsive genes were similar to Arabidopsis genes. The expression of 13 barley Dhn genes mirrored the global clustering of all transcripts, with specific combinations of Dhn genes providing an excellent indicator of each stress response. Data from these studies provide a robust reference data set for abiotic stress.

Isolation of a novel dehydrin gene from Codonopsis lanceolata and analysis of its response to abiotic stresses

Dehydrins (DHNs) compose a family of intrinsically unstructured proteins that have high water solubility and accumulate during late seed development at low temperature or in water-deficit conditions. They are believed to play a protective role in freezing and drought-tolerance in plants. A full-length cDNA encoding DHN (designated as ClDhn) was isolated from an oriental medicinal plant Codonopsis lanceolata, which has been used widely in Asia for its anticancer and anti-inflammatory properties. The full-length cDNA of ClDhn was 813 bp and contained a 477 bp open reading frame (ORF) encoding a polypeptide of 159 amino acids. Deduced ClDhn protein had high similarities with other plant DHNs. RT-PCR analysis showed that different abiotic stresses such as salt, wounding, chilling and light, triggered a significant induction of ClDhn at different time points within 4-48 hrs post-treatment. This study revealed that ClDhn assisted C. lanceolata in becoming resistant to dehydration.

Expression of dehydrin 5 during the development of frost tolerance in barley ( Hordeum vulgare)

The Dhn5 gene is the major cold-inducible dehydrin gene in barley. This study deals with the relationship between Dhn5 gene expression and its protein product accumulation, and the development of frost tolerance (FT) upon cold acclimation (CA) in 10 barley cultivars of different growth habits and geographical origins. The activation of Dhn5 gene expression was determined by quantitative reverse transcription-polymerase chain reaction (qRT-PCR), the accumulation of DHN5 protein was evaluated by protein gel blot analysis using a specific anti-dehydrin antibody, and the acquired level of FT was determined by a direct frost test. During the first 2 weeks of CA, there was a rapid increase in Dhn5 gene expression, DHN5 protein accumulation and FT in all cultivars examined. After 2 weeks of CA, differences in DHN5 accumulation and in FT measured as lethal temperature (LT(50)) were observed between the cultivars belonging to different growth habits. Specifically, intermediate (I) and winter (W) cultivars showed a higher level of DHN5 accumulation and FT than the spring (S) cultivars, which exhibited a lower level of accumulated DHN5 and FT. (Intermediate cultivars do not have vernalization requirement, but they are able to induce a relatively high level of FT upon CA.) In contrast, no differences between the cultivars belonging to different growth habits in Dhn5 mRNA accumulation were found. After 3 weeks of CA, the differences in accumulated DHN5 and FT between the individual growth habits became evident due to different developmental regulation of FT. The amount of accumulated DHN5 corresponded well with the level of FT of individual cultivars. We conclude that the amount of accumulated DHN5 after a certain period of CA differed according to the growth habits of cultivars and can be used as a marker for determination of FT in barley.

Combinatorial interactions of multiple cis‐elements regulating the induction of the Arabidopsis XERO2 dehydrin gene by abscisic acid and cold

Multiple combinations of mutations in the promoter of the XERO2 dehydrin gene were used to identify elements involved in ABA and cold induction. Mutating one of the three ACGT elements (ACGT1) increases expression in the absence of cold or ABA. An AT-rich element is a novel partner (coupling element) of ACGT-containing ABA-responsive cis-elements. A 12-bp palindrome also acts as a coupling element for ABA induction and includes one of the three dehydration-responsive element/C-repeat (DRE/CRT) elements and two overlapping motifs (TGTCG and TCGGC) previously shown to be statistically enriched in ABA-dependent and 'VP1 or ABA'-dependent activated genes (Plant Physiol. 2005; 139:437). At least two of the DRE/CRT elements are required for significant cold induction. During cold induction the AT-rich element also functions as a coupling element and ACGT1 is involved in repressing this induction. Two of the ACGT and DRE/CRT elements overlap, and mutating a single base in the ACGT of either of the two GCCGACGT sequences while retaining a DRE element reduced both ABA and cold induction. Changing the spatial relationships between the elements by deletion, inversion or insertion of DNA sequences reduced both cold and ABA induction. Overexpression of CBF1, -2 or -3 induced XERO2 expression in untreated plants. The ABI5 transcription factor may have a role in ABA-induced XERO2 expression, whereas ABI3 and ABI4 do not. The GCA2 gene was essential for both cold and ABA induction. A combination of the same overlapping and shared elements is used in the regulation of transcription by ABA and cold.

Expression and function of two dehydrins under environmental stresses in Brassica juncea L.

Dehydrins are capable of conferring abiotic stress tolerance in plants. Few dehydrins have been characterized at the molecular and transgenic level in Brassica juncea. In the present study, two SK2-type B. juncea dehydrin genes, BjDHN2 and BjDHN3, showed improved stress tolerance to salt and freezing stress in transgenic yeast. Semiquantitative reverse transcription polymerase chain reaction (RT-PCR) revealed that BjDHN2 and BjDHN3 were up-regulated by low temperature, drought, and salt stress, as well as exogenous abscisic acid (ABA) in B. juncea. Transgenic studies also showed that BjDHN2 and BjDHN3 increased tolerance to cold and salt stress in tobacco. These results indicate that the BjDHN2 and BjDHN3 genes exert a protective role on membranes and play a role in abiotic stresses.