Dehydrins Impart Protection against Oxidative Stress in Transgenic Tobacco Plants

Dexmedetomidine affects the NOX4/Nrf2 pathway to improve renal antioxidant capacity

OBJECTIVES

The study aimed to investigate the protective effects of dexmedetomidine (DEX) on renal injury caused by acute stress in rats and explore the protective pathways of DEX on rat kidneys in terms of oxidative stress.

METHODS

An acute restraint stress model was utilized, where rats were restrained for 3 hours after a 15-minute swim. Biochemical tests and histopathological sections were conducted to evaluate renal function, along with the measurement of oxidative stress and related pathway proteins.

KEY FINDINGS

The open-field experiments validated the successful establishment of the acute stress model. Acute stress-induced renal injury led to increased NADPH oxidase 4 (NOX4) protein expression and decreased expression levels of nuclear transcription factor 2 (Nrf2), heme oxygenase-1 (HO-1), and NAD(P)H: quinone oxidoreductase 1 (NQO1). Following DEX treatment, there was a significant reduction in renal NOX4 expression. The DEX-treated group exhibited normalized renal biochemical results and less damage observed in pathological sections compared to the acute stress group.

CONCLUSIONS

The findings suggest that DEX treatment during acute stress can impact the NOX4/Nrf2/HO-1/NQO1 signaling pathway and inhibit oxidative stress, thereby preventing acute stress-induced kidney injury. Additionally, DEX shows promise for clinical applications in stress syndromes.

Prokaryotic expression, purification, and the in vitro and in vivo protection study of dehydrin WDHN2 from Triticum aestivum

Dehydrins proteins accumulate and play important protective roles in most plants during abiotic stresses. The objective of this study was to characterize a YSK2-type dehydrin gene, WDHN2, isolated from Triticum aestivum previously. In this work, wheat dehydrin WDHN2 was expressed in Escherichia coli and purified by immobilized metal affinity chromatography, which exhibited as a single band by sodium dodecyl sulfonate polyacrylamide gel electrophoresis and western blotting. We show that WDHN2 is capable of alleviating lactate dehydrogenase inactivation from heat and desiccation in vitro enzyme activity protection assay. In vivo assay of Escherichia coli viability demonstrates the enhancement of cell survival by the overexpression of WDHN2. The protein aggregation prevention assay explores that WDHN2 has a broad protective effect on the cellular proteome. The results show that WDHN2 is mainly accumulated in the nucleus and cytosol, suggesting that this dehydrin may exert its function in both cellular compartments. Our data suggest that WDHN2 acts as a chaperone molecular in vivo.

Creating Climate-Resilient Crops by Increasing Drought, Heat, and Salt Tolerance

Over the years, the changes in the agriculture industry have been inevitable, considering the need to feed the growing population. As the world population continues to grow, food security has become challenged. Resources such as arable land and freshwater have become scarce due to quick urbanization in developing countries and anthropologic activities; expanding agricultural production areas is not an option. Environmental and climatic factors such as drought, heat, and salt stresses pose serious threats to food production worldwide. Therefore, the need to utilize the remaining arable land and water effectively and efficiently and to maximize the yield to support the increasing food demand has become crucial. It is essential to develop climate-resilient crops that will outperform traditional crops under any abiotic stress conditions such as heat, drought, and salt, as well as these stresses in any combinations. This review provides a glimpse of how plant breeding in agriculture has evolved to overcome the harsh environmental conditions and what the future would be like.

Heterologous overexpression of Tawzy1-2 gene encoding an SK3 dehydrin enhances multiple abiotic stress tolerance in Escherichia coli and Nicotiania benthamiana

MAIN CONCLUSION

The nuclear localized TaWZY1-2 helps plants resist abiotic stress by preserving the cell's ability to remove reactive oxygen species and decrease lipid oxidation under such conditions. In light of the unpredictable environmental conditions in which food crops grow, precise strategies must be developed by crops to effectively cope with abiotic stress and minimize damage over their lifespan. A key component in this endeavor is the group II of late embryogenesis abundant (LEA) proteins, known as dehydrins, which play crucial roles in enhancing the tolerance of plants to abiotic stress. Tawzy1-2 is a dehydrin-encoding gene which is constitutively expressed in various tissues of wheat. However, the biological function of TaWZY1-2 is not yet fully understood. In this study, TaWZY1-2 was isolated and identified in the wheat genome, and its functional role in conferring tolerance to abiotic stresses was detected in both prokaryotic and eukaryotic cells. Results showed that TaWZY1-2 is a nuclear localized hydrophilic protein that accumulates in response to multiple stresses. Escherichia coli cells expressing TaWZY1-2 showed enhanced tolerance to multiple stress conditions. Overexpression of TaWZY1-2 in Nicotiania benthamiana improved growth, germination and survival rate of the transgenic plants exposed to four kinds of abiotic stress conditions. Our results show that Tawzy1-2 transgenic plants exhibit improved capability in clearing reactive oxygen species and reducing lipid degradation, thereby enhancing their resistance to abiotic stress. This demonstrates a significant role of TaWZY1-2 in mitigating abiotic stress-induced damage. Consequently, these findings not only establish a basis for future investigation into the functional mechanism of TaWZY1-2 but also contribute to the expansion of functional diversity within the dehydrin protein family. Moreover, they identify potential candidate genes for crop optimization.

Integrative Physiological and Transcriptome Analysis Reveals the Mechanism of Cd Tolerance in Sinapis alba

Recently, pollution caused by the heavy metal Cd has seriously affected the environment and agricultural crops. While Sinapis alba is known for its edible and medicinal value, its tolerance to Cd and molecular response mechanism remain unknown. This study aimed to analyze the tolerance of S. alba to Cd and investigate its molecular response mechanism through transcriptomic and physiological indicators. To achieve this, S. alba seedlings were treated with different concentrations of CdCl2 (0.25 mmol/L, 0.5 mmol/L, and 1.0 mmol/L) for three days. Based on seedling performance, S. alba exhibited some tolerance to a low concentration of Cd stress (0.25 mmol/L CdCl2) and a strong Cd accumulation ability in its roots. The activities and contents of several antioxidant enzymes generally exhibited an increase under the treatment of 0.25 mmol/L CdCl2 but decreased under the treatment of higher CdCl2 concentrations. In particular, the proline (Pro) content was extremely elevated under the 0.25 and 0.5 mmol/L CdCl2 treatments but sharply declined under the 1.0 mmol/L CdCl2 treatment, suggesting that Pro is involved in the tolerance of S. alba to low concentration of Cd stress. In addition, RNA sequencing was utilized to analyze the gene expression profiles of S. alba exposed to Cd (under the treatment of 0.25 mmol/L CdCl2). The results indicate that roots were more susceptible to disturbance from Cd stress, as evidenced by the detection of 542 differentially expressed genes (DEGs) in roots compared to only 37 DEGs in leaves. GO and KEGG analyses found that the DEGs induced by Cd stress were primarily enriched in metabolic pathways, plant hormone signal transduction, and the biosynthesis of secondary metabolites. The key pathway hub genes were mainly associated with intracellular ion transport and cell wall synthesis. These findings suggest that S. alba is tolerant to a degree of Cd stress, but is also susceptible to the toxic effects of Cd. Furthermore, these results provide a theoretical basis for understanding Cd tolerance in S. alba.

Evaluation of toxicological effects of chemical substances by gut microbiota: The example of adenine damage to the kidney and gut

This study explored the effects of different doses of adenine intake on mice in terms of kidney function, oxidative stress and gut content microbiota to elucidate interactions between adenine-induced kidney function impairment and gut content microbiota disorder. Mice were gavaged with low-dosage adenine suspension (NML), middle-dosage adenine suspension (NMM), high-dosage adenine suspension (NMH) and sterile water (NC). Behaviour, kidney structure and function, colonic structure, oxidative stress and gut content microbiota were detected. Mice in NML, NMM, and NMH groups had significantly lower body weight, anal temperature and food intake, increased water intake, the mice had loose and deformed feces with obvious water stains through the paper. NMM mice presented significantly structural damage to kidney and colonic tissues, considerably higher BUN and Cr, MDA and lower SOD. MDA and SOD levels in NMM and NMH groups were closely associated with Cr and BUN. Moreover, different doses of adenine intake effected the mice gut content microbiota, and enriched the different characteristic bacteria. Characteristic bacteria Lactobacillus and Bifidobacterium presented significant correlations with MDA. Eventually, Lactobacillus and Bifidobacterium mediated oxidative stress pathway involved in the process of adenine-induced kidney injure in mice.

Multi-omics insights into the positive role of strigolactone perception in barley drought response

BACKGROUND

Drought is a major environmental stress that affects crop productivity worldwide. Although previous research demonstrated links between strigolactones (SLs) and drought, here we used barley (Hordeum vulgare) SL-insensitive mutant hvd14 (dwarf14) to scrutinize the SL-dependent mechanisms associated with water deficit response.

RESULTS

We have employed a combination of transcriptomics, proteomics, phytohormonomics analyses, and physiological data to unravel differences between wild-type and hvd14 plants under drought. Our research revealed that drought sensitivity of hvd14 is related to weaker induction of abscisic acid-responsive genes/proteins, lower jasmonic acid content, higher reactive oxygen species content, and lower wax biosynthetic and deposition mechanisms than wild-type plants. In addition, we identified a set of transcription factors (TFs) that are exclusively drought-induced in the wild-type barley.

CONCLUSIONS

Critically, we resolved a comprehensive series of interactions between the drought-induced barley transcriptome and proteome responses, allowing us to understand the profound effects of SLs in alleviating water-limiting conditions. Several new avenues have opened for developing barley more resilient to drought through the information provided. Moreover, our study contributes to a better understanding of the complex interplay between genes, proteins, and hormones in response to drought, and underscores the importance of a multidisciplinary approach to studying plant stress response mechanisms.

Plant dehydrins and dehydrin-like proteins: characterization and participation in abiotic stress response

Abiotic stress has a significant impact on plant growth and development. It causes changes in the subcellular organelles, which, due to their stress sensitivity, can be affected. Cellular components involved in the abiotic stress response include dehydrins, widely distributed proteins forming a class II of late embryogenesis abundant protein family with characteristic properties including the presence of evolutionarily conserved sequence motifs (including lysine-rich K-segment, N-terminal Y-segment, and often phosphorylated S motif) and high hydrophilicity and disordered structure in the unbound state. Selected dehydrins and few poorly characterized dehydrin-like proteins participate in cellular stress acclimation and are also shown to interact with organelles. Through their functioning in stabilizing biological membranes and binding reactive oxygen species, dehydrins and dehydrin-like proteins contribute to the protection of fragile organellar structures under adverse conditions. Our review characterizes the participation of plant dehydrins and dehydrin-like proteins (including some organellar proteins) in plant acclimation to diverse abiotic stress conditions and summarizes recent updates on their structure (the identification of dehydrin less conserved motifs), classification (new proposed subclasses), tissue- and developmentally specific accumulation, and key cellular activities (including organellar protection under stress acclimation). Recent findings on the subcellular localization (with emphasis on the mitochondria and plastids) and prospective applications of dehydrins and dehydrin-like proteins in functional studies to alleviate the harmful stress consequences by means of plant genetic engineering and a genome editing strategy are also discussed.

Current advances in the molecular regulation of abiotic stress tolerance in sorghum via transcriptomic, proteomic, and metabolomic approaches

Sorghum (Sorghum bicolor L. Moench), a monocot C4 crop, is an important staple crop for many countries in arid and semi-arid regions worldwide. Because sorghum has outstanding tolerance and adaptability to a variety of abiotic stresses, including drought, salt, and alkaline, and heavy metal stressors, it is valuable research material for better understanding the molecular mechanisms of stress tolerance in crops and for mining new genes for their genetic improvement of abiotic stress tolerance. Here, we compile recent progress achieved using physiological, transcriptome, proteome, and metabolome approaches; discuss the similarities and differences in how sorghum responds to differing stresses; and summarize the candidate genes involved in the process of responding to and regulating abiotic stresses. More importantly, we exemplify the differences between combined stresses and a single stress, emphasizing the necessity to strengthen future studies regarding the molecular responses and mechanisms of combined abiotic stresses, which has greater practical significance for food security. Our review lays a foundation for future functional studies of stress-tolerance-related genes and provides new insights into the molecular breeding of stress-tolerant sorghum genotypes, as well as listing a catalog of candidate genes for improving the stress tolerance for other key monocot crops, such as maize, rice, and sugarcane.

Dehydration response in Stylosanthes scabra: Transcriptional, biochemical, and physiological modulations

Stylosanthes scabra, popularly known as stylo, is native to the Brazilian Caatinga semiarid region and stands out as a drought-tolerant shrub forage crop. This work provides information about the plant response during the first 48 h of water deficit, followed by a rehydration treatment. Besides root transcriptomics data, 13 physiological or biochemical parameters were scrutinized. Additionally, RNA-Seq annotated transcripts not associated with the "Viridiplantae" clade were taxonomically categorized. It was found that S. scabra quickly perceives and recovers from the oscillations of the imposed water regime. Physiologically, mechanisms that minimize evapotranspiration or protect the photosynthetic apparatus stood out. Biochemically, it was found that the root tissue invests in synthesizing compounds that can act as osmolytes (proline and sugars), emphasizing the importance of osmoregulation to water deficit acclimation. Consistently, transcriptome and qPCR analyses showed that a set of enriched biological processes with upregulated (UR) transcripts were involved in protective functions against reactive oxygen species or encoding enzymes of important metabolic pathways, which might contribute to S. scabra response to water deficit. Additionally, several UR kinases and transcription factors were identified. Finally, in an innovative approach, some naturally occurring microbial groups (such as Schizosaccharomyces, Bradyrhizobium, etc.) were identified in the S. scabra roots. This study reveals insights into the physiological, biochemical, and molecular mechanisms underlying the S. scabra response to water deficit and provides candidate genes that may be useful in developing drought-tolerant crop varieties through biotechnological applications.

Increased dehydrin level decreases leaf rolling grade by altering the reactive oxygen species homeostasis and abscisic acid content in maize subjected to osmotic stress

Dehydrins (DHNs) are stress proteins involved in the development of protective reactions in plants against dehydration. The relationship between DHNs and morphological responses such as leaf rolling in plants exposed to water deficit is not well known. In this study, we detected how variations in DHN levels affect the leaf rolling response in maize exposed to osmotic stress in relation to the antioxidant system and ABA level. In this context, we altered the DHN levels in maize seedlings by treatment with bio-regulators (salicylic acid and abscisic acid) under PEG6000-free and PEG6000-induced osmotic stress. When the DHN levels were increased by the bio-regulators (25 µM SA and 100 µM ABA), the relative expression level of the Zea mays dehydrin COR410 gene increased in the seedlings, while reactive oxygen species (ROS) and leaf rolling grade decreased. Moreover, induction of DHNs caused increases in the antioxidant enzyme activity and content of antioxidant substances, and very high amounts of endogenous abscisic acid. When DHN level was suppressed by a bio-regulator (200 µM SA) in the maize seedlings, dehydrin COR410 expression level decreased, while ROS and the leaf rolling grade increased. Moreover, the antioxidant enzyme activity and content of antioxidant substances decreased in the seedlings, while the amount of abscisic acid increased. Taken all together, an increase in DHN level by bio-regulator treatment can stimulate the antioxidant system, enable abscisic acid regulation, and thus reduce leaf rolling through decreased ROS levels. The results also indicated that DHNs may be involved in the signal pathways inducing expression of some genes related to leaf rolling response, possibly by modulating ROS levels, in maize seedlings exposed to osmotic stress.

Creatinine accelerates APAP-induced liver damage by increasing oxidative stress through ROS/JNK signaling pathway

Serum creatinine is an endogenous biomarker to estimate glomerular filtration rate (GFR) and is commonly used to assess renal function in clinical practice. Acetaminophen (APAP), the most available analgesic and antipyretic medication, is recommended as the drug of choice for pain control in patients with renal diseases. However, an overdose of APAP can lead to severe acute liver injury, which is also the most common cause of acute liver failure in western countries. The role of creatinine in APAP-induced liver injury is unclear and should be further explored. Herein, clinical data on patients with drug-induced liver injury revealed that the creatinine concentration between 82-442 μmol/L for female and 98–442 μmol/L for male is positively correlated with alanine aminotransferase (ALT), aspartate aminotransferase (AST). While there was no correlation between creatinine and ALT and AST when creatinine concentration is over 442 μmol/L. In addition, mice were administrated with creatinine intraperitoneally for 1 week before APAP injection to investigated the pathophysiological role of creatinine in APAP-induced acute liver injury. The results showed that creatinine administration aggravated hepatic necrosis and elevated serum lactate dehydrogenase (LDH) and ALT levels in mice upon APAP injection. The mechanism study demonstrated that creatinine could increase the production of reactive oxygen activation (ROS) and the activation of c-Jun N-terminal kinase (JNK). Furthermore, the liver injury was alleviated and the difference between APAP-treated mice and APAP combined with creatinine-treated mice was blunted after using specific ROS and JNK inhibitors. Significantly, creatinine stimulation aggravates APAP-induced cell death in HepaRG cells with the same mechanism. In summary, this study proposed that creatinine is closely related with liver function of drug-induced liver injury and exacerbates APAP-induced hepatocyte death by promoting ROS production and JNK activation, thus providing new insight into the usage of APAP in patients with kidney problems.

Inhibition of the NLRP3/caspase-1 signaling cascades ameliorates ketamine-induced renal injury and pyroptosis in neonatal rats

Ketamine is a widely-used anesthetic in the field of pediatrics and obstetrics. Multiple studies have revealed that ketamine causes neurotoxicity in developing animals. However, further studies are needed to determine whether clinical doses of ketamine (20 mg/kg) are able to cause kidney damage in developing animals. Herein, we investigated the effects of continuous ketamine exposure on kidney injury and pyroptosis in seven-day-old rats. Serum renal function indicators, renal histopathological analysis, pyroptosis, as well as oxidative stress indicators, were tested. Additionally, the NLRP3 inhibitor MCC950 and the Caspase-1 inhibitor VX765 were used to evaluate the role of the NLRP3/Caspase-1 axis in ketamine-induced kidney injury among developing rats. Our findings indicate that ketamine exposure causes renal histopathological injury, increased the levels of blood urea nitrogen (BUN) and creatinine (Cre), and led to upregulation in the levels of pyroptosis. Furthermore, we found that ketamine induced an increase in levels of reactive oxygen species (ROS) and malonaldehyde (MDA), as well as a decrease in the content of glutathione (GSH) and catalase (CAT) in the kidneys of neonatal rats. Moreover, targeting NLRP3 and caspase-1 with MCC950 or VX765 improved pyroptosis and reduced renal damage after continuous ketamine exposure. In conclusion, this study suggested that continued exposure to ketamine caused kidney damage among neonatal rats and that the NLRP3/Caspase-1 axis-related pyroptosis may be involved in this process.

Effects of Dexmedetomidine Administered Through Different Routes on Kidney Tissue in Rats with Spinal Cord Ischaemia–Reperfusion Injury

Background

Ischaemia–reperfusion (IR) injury, which can be encountered during surgical procedures involving the abdominal aorta, is a complex process that affects distant organs, such as the heart, liver, kidney, and lungs, as well as the lower extremities. In this study, we aimed to contribute to the limited literature by investigating the protective effect of dexmedetomidine, which was administered through different routes, on kidney tissue in rats with spinal cord IR injury.

Methods

A total of 30 rats were randomly divided into five groups: control (C group), IR (IR group), IR-intraperitoneal dexmedetomidine (IRIPD group), IR-intrathecal dexmedetomidine (IRITD group), and IR-intravenous dexmedetomidine (IRIVD group). The spinal cord IR model was established. Dexmedetomidine was administered at doses of 100 µg/kg intraperitoneally, 3 µg/kg intrathecally, and 9 µg/kg intravenously. Histopathologic parameters in kidney tissue samples taken at the end of the reperfusion period and biochemical parameters in serum were evaluated.

Results

When examined histopathologically, tubular dilatation was found to be significantly reduced in the IRIVD, IRITD, and IRIPD groups compared with the IR group (p = 0.012, all). Vascular vacuolization and hypertrophy were significantly decreased in the IRIVD, IRITD, and IRIPD groups compared with the IR group (p = 0.006, all). Tubular cell degeneration and necrosis were significantly reduced in the IRIVD, IRITD, and IRIPD groups compared with the IR group (p = 0.008, p = 0.08, and p = 0.030, respectively). Lymphocyte infiltration was significantly decreased in the IRIVD and IRITD groups compared with the IR group (p = 0.006 and p = 0.06, respectively).

Conclusion

It was observed that dexmedetomidine administered by different routes improved the damage caused by IR in kidney histopathology. We think that the renoprotective effects of dexmedetomidine administered intravenously and intrathecally before IR in rats are greater.

Expression, Purification, and Preliminary Protection Study of Dehydrin PicW1 From the Biomass of Picea wilsonii

Dehydrins (DHNs) belong to group II of late embryogenesis-abundant (LEA) proteins, which are up-regulated in most plants during cold, drought, heat, or salinity stress. Despite the importance of dehydrins for the plants to resist abiotic stresses, it is necessary to obtain plant-derived dehydrins from different biomass. Generally, dehydrin PicW1 from Picea wilsonii is involved in Kn-type dehydrin with five K-segments, which has a variety of biological activities. In this work, Picea wilsonii dehydrin PicW1 was expressed in Escherichia coli and purified by chitin-affinity chromatography and size-exclusion chromatography, which showed as a single band by SDS-PAGE. A cold-sensitive enzyme of lactate dehydrogenase (LDH) is used to explore the protective activities of other proteins. Temperature stress assays showed that PicW1 had an effective protective effect on LDH activity, which was better than that of bovine serum albumin (BSA). This study provides insights into the purification and protective activity of K5 DHNs for the advancement of dehydrin structure and function from biomass.

Effect of Cryopreservation Method Supported with Biochemical Analyses in the Axillary Bud of Jewel Orchid, Ludisia discolor

This study investigated conserving an endangered terrestrial jewel orchid Ludisia discolor, using in vitro grown axillary buds. Excised segments of axillary buds (4-5 mm in length) were precultured on a modified Murashige and Skoog (MS) medium supplemented with 0.2 M sucrose for 24 h and osmoprotected in a loading solution for 20 min. Then, axillary buds were dehydrated in plant vitrification solution 2 (PVS2) for 10 min at 0 °C and incubated in liquid nitrogen for 1 h. Subsequently, axillary buds were rewarmed rapidly by dilution solution and transferred to a growth recovery medium supplemented with 0.05 µM melatonin, which led to an improved survival chance (16.67%) for cryopreserved L. discolor. The osmotic stress and the overproduction of reactive oxygen species (ROS) during cryopreservation stages may result in cryoinjuries and poor survival as increased levels of proline (5.51 µmol/g), catalase (85.64 U/g), peroxidase (565.37 U/g), and ascorbate peroxidase activities (12.19 U/g) were detected after dehydration, preculture, rewarming, and loading stage, respectively. Results obtained from this study indicate that further experimental designs which apply different PVS and exogenous antioxidants are needed for improved survival and regrowth of L. discolor.

Drought Stress Interacts With Powdery Mildew Infection in Tomato

Under field conditions, plants are often exposed to more than one stress factor at the same time, and therefore need to adapt to different combinations of stresses. Crosstalk between responses to abiotic and biotic stresses is known to occur, and the interaction between stress responses can be positive or negative. We studied the interaction of drought stress and powdery mildew (PM) infection in tomatoes using near-isogenic tomato lines (NILs) carrying the Ol-1, ol-2, or Ol-4 gene that confers resistance to tomato PM caused by Oidium neolycopersici. Our study demonstrated that drought-induced growth reduction was not further reduced by powdery mildew infection. Drought stress, however, decreased fungal infection in the susceptible genotype Moneymaker (MM) with fungal biomass tending to decrease further as the drought severity increased. Drought stress did not affect PM resistance levels of resistant NIL carrying ol-2 (a mutant of the tomato susceptibility Mlo gene) and Ol-4 an NLR (nucleotide-binding site-LRR) R gene associated with a fast hypersensitivity response (HR) but tended to slightly decrease disease levels of NIL-Ol-1 (no gene characterized yet, associated with a slow HR following PM infection). At the molecular level, genes involved in abscisic acid (ABA), salicylic acid (SA), and ethylene pathways were highly induced under combined stress indicating the involvement of ABA, SA, and ethylene in the crosstalk between abiotic and biotic stress. Messenger RNA expression of the ABA-responsive dehydrin SlTAS14 was induced under drought and combined stress with the highest induction under combined stress, and resistant NIL lines showed higher expression levels than MM. The expression of SlNCED (involved in ABA synthesis) was also upregulated under drought and highly induced under combined stress. Expression levels of pathogen responsive gene SlPR1 (an indicator of the SA pathway) and SlACS (involved in ethylene synthesis) were highly induced under powdery mildew infection in MM and the Ol-1 and were induced the most under combined stress in these lines. Taken together, these findings indicate that drought stress can interact with and influence PM infection in tomatoes in a resistance type-dependent manner. The role of hormonal signaling pathways in the crosstalk between drought stress and PM infection is further discussed.

A rice R2R3-MYB (OsC1) transcriptional regulator improves oxidative stress tolerance by modulating anthocyanin biosynthesis

The R2R3 type MYB transcription factors participate in controlling flavonoid production in plants, including anthocyanin and proanthocyanin. Black rice with high anthocyanin content is an important candidate for understanding R2R3-MYB-based regulation of the anthocyanin biosynthesis pathway (ABP). This study was undertaken to draw the functional relationship of an R2R3-MYB protein with anthocyanin biosynthesis and oxidative stress tolerance in plants. The expression levels of the late ABP genes in the panicle stage of black rice were in good agreement with the accumulation of anthocyanin, especially cyanidin 3-glucoside. Among all MYB genes present in rice, an R2R3 type (C1) regulates anthocyanin biosynthesis and was studied further. The positive correlation between the expression of ABP genes and OsC1 along with the nuclear localization of OsC1 are in line with its possible involvement as a transcriptional regulator of ABP genes. Interestingly, OsC1 overexpressed in white rice plants triggered anthocyanin production through augmentation of the transcript level of late ABP genes. Moreover, OsC1-transformed plants exhibited a lower amount of reactive oxygen species upon exposure to oxidative stress. The increased anthocyanin content in white rice seedlings resulted in higher photosynthetic efficiency, less membrane damage and consequently lower oxidative stress. The OsC1 transcriptional regulator helps to ameliorate oxidative stresses in plants owing to its anthocyanin modulating ability.

Adaptive defence and sensing responses of host plant roots to fungal pathogen attack revealed by transcriptome and metabolome analyses

Plant root-produced constitutive and inducible defences inhibit pathogenic microorganisms within roots and in the rhizosphere. However, regulatory mechanisms underlying host responses during root-pathogen interactions are largely unexplored. Using the model species Brachypodium distachyon (Bd), we studied transcriptional and metabolic responses altered in Bd roots following challenge with Fusarium graminearum (Fg), a fungal pathogen that causes diseases in diverse organs of cereal crops. Shared gene expression patterns were found between Bd roots and spikes during Fg infection associated with the mycotoxin deoxynivalenol (DON). Overexpression of BdMYB78, an up-regulated transcription factor, significantly increased root resistance during Fg infection. We show that Bd roots recognize encroaching Fg prior to physical contact by altering transcription of genes associated with multiple cellular processes such as reactive oxygen species and cell development. These changes coincide with altered levels of secreted host metabolites detected by an untargeted metabolomic approach. The secretion of Bd metabolites was suppressed by Fg as enhanced levels of defence-associated metabolites were found in roots during pre-contact with a Fg mutant defective in host perception and the ability to cause disease. Our results help to understand root defence strategies employed by plants, with potential implications for improving the resistance of cereal crops to soil pathogens.

ROS-induced oxidative stress in plant cryopreservation: occurrence and alleviation

Reactive oxygen species (ROS)-induced oxidative stress results in low success or even total failure of cryopreservation. Better understanding of how the plant establishes resistance/tolerance to ROS-induced oxidative stress facilitates developments of robust cryopreservation procedures. Cryopreservation provides a safe and efficient strategy for long-term preservation of plant genetic resources. ROS-induced oxidative stress caused damage to cells and reduced the ability of the plant to survive following cryopreservation, eventually resulting in low success or even total failure. This paper provides updated and comprehensive information obtained in the past decade, including the following: (1) ROS generations and adaptive responses of antioxidant systems during cryopreservation; (2) expressions of oxidative stress-associated genes and proteins during cryopreservation; (3) ROS-triggered programmed cell death (PCD) during cryopreservation; and (4) exogenous applications of enzymatic and non-enzymatic antioxidants in improving success of cryopreservation. Prospects for further studies are proposed. The goal of the present study was to facilitate better understanding of the mechanisms by which the plant establishes resistance/tolerance to oxidative stress during cryopreservation and promote further studies toward the developments of robust cryopreservation procedures and wider application of plant cryobiotechnology.

Protective Effects of Low-Dose Alcohol against Acute Stress-Induced Renal Injury in Rats: Involvement of CYP4A/20-HETE and LTB4/BLT1 Pathways

Low-dose alcohol possesses multiple bioactivities. Accordingly, we investigated the protective effect and related molecular mechanism of low-dose alcohol against acute stress- (AS-) induced renal injury. Herein, exhaustive swimming for 15 min combined with restraint stress for 3 h was performed to establish a rat acute stress model, which was verified by an open field test. Evaluation of renal function (blood creatinine and urea nitrogen), urine test (urine leukocyte esterase and urine occult blood), renal histopathology, oxidative stress, inflammation, and apoptosis was performed. The key indicators of the cytochrome P450 (CYP) 4A1/20-hydroxystilbenetetraenoic acid (20-HETE) pathway, cyclooxygenase (COX)/prostaglandin E₂ (PGE₂) pathway, and leukotriene B₄ (LTB₄)/leukotriene B₄ receptor 1 (BLT1) pathway were measured by real-time PCR and ELISA. We found that low-dose alcohol (0.05 g/kg, i.p.) ameliorated AS-induced renal dysfunction and histological damage. Low-dose alcohol also attenuated AS-induced oxidative stress and inflammation, presenting as reduced malondialdehyde and hydrogen peroxide formation, increased superoxide dismutase and glutathione activity, and decreased myeloperoxidase, interleukin-6, interleukin-1β, and monocyte chemoattractant protein-1 levels (P < 0.05). Moreover, low-dose alcohol alleviated AS-induced apoptosis by downregulating Bax and cleaved caspase 3 protein expression and reduced numbers of terminal deoxynucleotidyl transferase-mediated dUTP nick-end label-positive cells (P < 0.01). Correlation analysis indicated that 20-HETE was strongly correlated with oxidative stress, while LTB₄ was strongly correlated with inflammation. Low-dose alcohol inhibited AS-induced increases in CYP4A1, CYP4A2, CYP4A3, CYP4A8, and BLT1 mRNA levels and LTB₄ and 20-HETE content (P < 0.01). Interestingly, low-dose alcohol had no effect on COX1 or COX2 mRNA expression or the concentration of PGE₂. Furthermore, low-dose alcohol reduced calcium-independent phospholipase A₂ mRNA expression, but did not affect secreted phospholipase A₂ or cytosolic phospholipase A₂ mRNA expression. Together, these results indicate that low-dose alcohol ameliorated AS-induced renal injury by inhibiting CYP4A/20-HETE and LTB₄/BLT1 pathways, but not the COX/PGE₂ pathway.

OsLEA1a overexpression enhances tolerance to diverse abiotic stresses by inhibiting cell membrane damage and enhancing ROS scavenging capacity in transgenic rice

Late embryogenesis abundant (LEA) proteins are involved in diverse abiotic stresses tolerance in many different organisms. Our previous studies have shown that the heterologous expression of OsLEA1a interfered with the resistance of Escherichia coli to abiotic stresses. However, in the present study, based on growth status and physiological indices of rice plant, the overexpression of OsLEA1a in rice conferred increased resistance to abiotic stresses compared with the wild-type (WT) plants. Before applying abiotic stresses, there were no significant differences in physiological indices of rice seedlings. After NaCl, sorbitol, CuSO4 and H2O2 stresses, the transgenic lines had lower relative electrical conductivity, malondialdehyde and lipid peroxidation, greater the contents of proline, soluble sugar and glutathione, and higher the activities of superoxide dismutase, catalase and peroxidase than the WT plants. The results indicate that the OsLEA1a gene is involved in the protective response of plants to various abiotic stresses by inhibiting cell membrane damage and enhancing reactive oxygen species scavenging capacity. It was speculated that post-translational modification causes OsLEA1a functional differences in E. coli and rice. The present study shows that OsLEA1a could be a useful candidate gene for engineering abiotic stress tolerance in cultivated plants.

Accumulation Dynamics of Transcripts and Proteins of Cold-Responsive Genes in Fragaria vesca Genotypes of Differing Cold Tolerance

Identifying and characterizing cold responsive genes in Fragaria vesca associated with or responsible for low temperature tolerance is a vital part of strawberry cultivar development. In this study we have investigated the transcript levels of eight genes, two dehydrin genes, three putative ABA-regulated genes, two cold–inducible CBF genes and the alcohol dehydrogenase gene, extracted from leaf and crown tissues of three F. vesca genotypes that vary in cold tolerance. Transcript levels of the CBF/DREB1 transcription factor FvCBF1E exhibited stronger cold up-regulation in comparison to FvCBF1B.1 in all genotypes. Transcripts of FvADH were highly up-regulated in both crown and leaf tissues from all three genotypes. In the ‘ALTA’ genotype, FvADH transcripts were significantly higher in leaf than crown tissues and more than 10 to 20-fold greater than in the less cold-tolerant ‘NCGR1363’ and ‘FDP817’ genotypes. FvGEM, containing the conserved ABRE promoter element, transcript was found to be cold-regulated in crowns. Direct comparison of the kinetics of transcript and protein accumulation of dehydrins was scrutinized. In all genotypes and organs, the changes of XERO2 transcript levels generally preceded protein changes, while levels of COR47 protein accumulation preceded the increases in COR47 RNA in ‘ALTA’ crowns.

Multiple copies of a novel amphipathic α-helix forming segment in Physcomitrella patens dehydrin play a key role in abiotic stress mitigation

Plants use a diverse set of proteins to mitigate various abiotic stresses. The intrinsically disordered protein dehydrin is an important member of this repertoire of proteins, characterized by a canonical amphipathic K-segment. It can also contain other stress-mitigating noncanonical segments—a likely reflection of the extremely diverse nature of abiotic stress encountered by plants. Among plants, the poikilohydric mosses have no inbuilt mechanism to prevent desiccation and therefore are likely to contain unique noncanonical stress-responsive motifs in their dehydrins. Here we report the recurring occurrence of a novel amphipathic helix-forming segment (D-segment: EGφφD(R/K)AKDAφ, where φ represents a hydrophobic residue) in Physcomitrella patens dehydrin (PpDHNA), a poikilohydric moss. NMR and CD spectroscopic experiments demonstrated the helix-forming tendency of the D-segment, with the shuffled D-segment as control. PpDHNA activity was shown to be size as well as D-segment dependent from in vitro, in vivo, and in planta studies using PpDHNA and various deletion mutants. Bimolecular fluorescence complementation studies showed that D-segment-mediated PpDHNA self-association is a requirement for stress abatement. The D-segment was also found to occur in two rehydrin proteins from Syntrichia ruralis, another poikilohydric plant like P. patens. Multiple occurrences of the D-segment in poikilohydric plant dehydrins/rehydrins, along with the experimental demonstration of the role of D-segment in stress abatement, implies that the D-segment mediates unique resurrection strategies, which may be employed by plant dehydrins that are capable of mitigating extreme stress.

Functional characterization of VviDHN2 and VviDHN4 dehydrin isoforms from Vitis vinifera (L.): An in silico and in vitro approach

Dehydrins, a family of hydrophilic and intrinsically disordered proteins, are a subgroup of late embryogenesis abundant proteins that perform different protective roles in plants. Although the transition from a disordered to an ordered state has been associated with dehydrin function or interactions with specific partner molecules, the question of how the primary and secondary dehydrin protein structure is related to specific functions or target molecule preferences remains unresolved. This work addresses the in silico sequencing analysis and in vitro functional characterization of two dehydrin isoforms, VviDHN2 and VviDHN4, from Vitis vinifera. Conformational changes suggest potential interactions with a broad range of molecules and could point to more than one function. The in silico analysis showed differences in conserved segments, specific amino acid binding sequences, heterogeneity of structural properties and predicted sites accessible for various post-translational modifications between the sequence of both dehydrins. Moreover, in vitro functional analysis revealed that although they both showed slight antifungal activity, only VviDHN4 acts as a molecular shield that protects proteins from freezing and dehydration. VviDHN4 also demonstrated high potential as a chaperone and reactive oxygen species scavenger, in addition to presenting antifreeze activity, all of which confirms its multifunctional nature. Our findings highlight the significant role of Y-segments and the differential and specific amino acid composition of less conserved segments that are rich in polar/charged residues between S- and K-segments, coupled with post-translational modifications, in modulating and switching dehydrin biological function.

Over-Expression of a Melon Y3SK2-Type LEA Gene Confers Drought and Salt Tolerance in Transgenic Tobacco Plants

Climate change, with its attendant negative effects, is expected to hamper agricultural production in the coming years. To counteract these negative effects, breeding of environmentally resilient plants via conventional means and genetic engineering is necessary. Stress defense genes are valuable tools by which this can be achieved. Here we report the successful cloning and functional characterization of a melon Y3SK2-type dehydrin gene, designated as CmLEA-S. We generated CmLEA-S overexpressing transgenic tobacco lines and performed in vitro and in vivo drought and salt stress analyses. Seeds of transgenic tobacco plants grown on 10% polyethylene glycol (PEG) showed significantly higher germination rates relative to wild-type seeds. In the same way, transgenic seeds grown on 150 mM sodium chloride (NaCl) recorded significantly higher germination percentages compared with wild-type plants. The fresh weights and root lengths of young transgenic plants subjected to drought stress were significantly higher than that of wild-type plants. Similarly, the fresh weights and root lengths of transgenic seedlings subjected to salt stress treatments were also significantly higher than wild-type plants. Moreover, transgenic plants subjected to drought and salt stresses in vivo showed fewer signs of wilting and chlorosis, respectively. Biochemical assays revealed that transgenic plants accumulated more proline and less malondialdehyde (MDA) compared with wild-type plants under both drought and salt stress conditions. Finally, the enzymatic activities of ascorbate peroxidase (APX) and catalase (CAT) were enhanced in drought- and salt-stressed transgenic lines. These results suggest that the CmLEA-S gene could be used as a potential candidate gene for crop improvement.

Oxidative stress level and dehydrin gene expression pattern differentiate two contrasting cucumber F1 hybrids under high fertigation treatment

Two cucumber F1 cultivar hybrids were investigated for stress tolerance markers upon application of different strength of Hoagland fertigation solutions (HG). 'Joker' and 'Oitol' cultivar hybrids were studied, representing typically field grown and greenhouse cultivated genotypes, respectively. At standard fertigation level (0.5 × HG) in controlled environment young 'Joker' plants displayed slower growth than 'Oitol' based on total leaf area. At this basal nutrient concentration leaves of 'Joker' plants had significantly lower antioxidant capacity and higher malondialdehyde (MDA, an indicator of lipid peroxidation) level than 'Oitol'. According to RT-qPCR transcript levels of several antioxidant enzymes' genes (ascorbate peroxidase, glutathione reductase and glutathione peroxidase) were significantly higher in 'Joker' compared to 'Oitol'. At increased HG concentrations (1.0, 1.5, 2.0, and 2.5 × HG) growth didn't change significantly in either hybrid. Osmotic potential declined at higher fertigation levels. Antioxidant capacity increased in both hybrids with strong characteristic differences favouring 'Oitol' plants. Higher MDA content of leaves testified more oxidative burden in 'Joker' plants at all and especially at the more concentrated HG treatments. This trend was also approved by results of bio photon emission imaging, which is a powerful method to quantify stress level in living tissues with autoluminescence detection technology. Gene expression for antioxidant enzymes followed HG concentration-dependent increase in both hybrids, at a substantially higher level in 'Joker'. Expression of the dehydrin gene DHN3 was preferentially induced at elevated fertigation levels in 'Oitol' plants, which could contribute to the lower oxidative stress detected in this hybrid. Results presented in this report demonstrate differences in shoot growth, antioxidant capacity, level of oxidative stress and antioxidant gene expression in two contrasting cucumber hybrids at basal fertigation. Furthermore, excessive HG fertigation was found to increase oxidative stress in a genotype-specific way. This effect may be due to different antioxidant capacity and differential expression of stress protective genes, such as the DHN3 dehydrin.

Coordinated mechanisms of leaves and roots in response to drought stress underlying full-length transcriptome profiling in Vicia sativa L

BACKGROUND

Common vetch (Vicia sativa L.) is an important self-pollinating annual forage legume and is of interest for drought prone regions as a protein source to feed livestock and human consumption. However, the development and production of common vetch are negatively affected by drought stress. Plants have evolved common or distinct metabolic pathways between the aboveground and underground in response to drought stress. Little is known regarding the coordinated response of aboveground and underground tissues of common vetch to drought stress.

RESULTS

Our results showed that a total of 30,427 full-length transcripts were identified in 12 samples, with an average length of 2278.89 bp. Global transcriptional profiles of the above 12 samples were then analysed via Illumina-Seq. A total of 3464 and 3062 differentially expressed genes (DEGs) were identified in the leaves and roots, respectively. Gene Ontology (GO) enrichment analyses identified that the dehydrin genes and Δ¹-pyrroline-5-carboxylate synthase were induced for the biosynthesis of proline and water conservation. The Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis results indicated that the DEGs were significantly enriched in hormone signal transduction, starch and sucrose metabolism, and arginine and proline metabolism, and various drought response candidate genes were also identified. Abscisic acid (ABA; the AREB/ABF-SnRK2 pathway) regulates the activity of AMY3 and BAM1 to induce starch degradation in leaves and increase carbon export to roots, which may be associated with the drought stress responses in common vetch. Among the co-induced transcription factors (TFs), AREB/ABF, bHLH, MYB, WRKY, and AP2/ERF had divergent expression patterns and may be key in the crosstalk between leaves and roots during adaption to drought stress. In transgenic yeast, the overexpression of four TFs increased yeast tolerance to osmotic stresses.

CONCLUSION

The multipronged approach identified in the leaves and roots broadens our understanding of the coordinated mechanisms of drought response in common vetch, and further provides targets to improve drought resistance through genetic engineering.

Dexmedetomidine Protects against Ischemia and Reperfusion-Induced Kidney Injury in Rats

Acute kidney injury (AKI), a clinical syndrome, is a sudden onset of kidney failure that severely affects the kidney tubules. One potential treatment is dexmedetomidine (DEX), a highly selective α ₂-adrenoreceptor agonist that is used as an anesthetic adjuvant. It also has anti-inflammatory, neuroprotective, and sympatholytic qualities. The aim of this study was to establish whether DEX also offers protection against ischemia and reperfusion- (I/R-) induced AKI in rats. An intraperitoneal injection of DEX (25 μg/kg) was administered 30 min prior to the induction of I/R. The results indicate that in the I/R rats, DEX played a protective role by reducing the damage to the tubules and maintaining renal function. Furthermore, in response to I/R, the DEX treatment reduced the mRNA expression of TNF-α, IL-1β, IL-6, and MCP-1 in the kidney tissues and the serum levels of TNF-α, IL-1β, IL-6, and MCP-1. DEX also reduced the levels of oxidative stress and apoptosis in the tubular cells. These results indicate that in response to I/R kidney injury, DEX plays a protective role by inhibiting inflammation and tubular cell apoptosis, reducing the production of reactive oxygen species, and promoting renal function.

Overexpression of Ks-type dehydrins gene OeSRC1 from Olea europaea increases salt and drought tolerance in tobacco plants

Agricultural production is greatly affected by environmental stresses, such as cold, drought and high-salinity. It is possible to produce tolerant genotypes by transferring genes encoding protective proteins or enzymes from other organisms. In this regard, the current study was aimed to clone a novel OeSRC1 gene identified during the transcriptome profiling of olives (Olea europaea L.) and to investigate the function of this gene in tobacco plants. Functional evaluation of OeSRC1 gene in putative transgenic tobacco plants were carried out under drought, cold and salt stress conditions by using molecular and biochemical tools. It was observed that the transgenic tobacco plants exhibited higher seed germination and survival rates, better root and shoot growth under cold, salt and drought stress treatments compared to wild type plants. Our results also demonstrated that, under stress conditions, transgenic plants accumulated more free proline while no significant changes were observed regarding electrolyte leakage. Ascorbate peroxidase activity of OeSRC1-overexpressing plants was higher than those of the WT plants under different stress conditions. The overall results demonstrate the explicit role of OeSRC1 gene in conferring multiple abiotic stress tolerance at the whole-plant level. The multifunctional role of olive OeSRC1 gene looks good to enhance environmental stress tolerance in diverse plants.

Isolation and functional characterization of three abiotic stress-inducible (Apx, Dhn and Hsc70) promoters from pearl millet (Pennisetum glaucum L.)

Pearl millet is a C4 cereal crop that grows in arid and semi-arid climatic conditions with the remarkable abiotic stress tolerance. It contributed to the understanding of stress tolerance not only at the physiological level but also at the genetic level. In the present study, we functionally cloned and characterized three abiotic stress-inducible promoters namely cytoplasmic Apx1 (Ascorbate peroxidase), Dhn (Dehydrin), and Hsc70 (Heat shock cognate) from pearl millet. Sequence analysis revealed that all three promoters have several cis-acting elements specific for temporal and spatial expression. PgApx pro, PgDhn pro and PgHsc70 pro were fused with uidA gene in Gateway-based plant transformation pMDC164 vector and transferred into tobacco through leaf-disc method. While PgApx pro and PgDhn pro were active in seedling stages, PgHsc70 pro was active in stem and root tissues of the T2 transgenic tobacco plants under control conditions. Higher activity was observed under high temperature and drought, and less in salt and cold stress conditions. Further, all three promoters displayed higher GUS gene expression in the stem, moderate expression in roots, and less expression in leaves under similar conditions. While RT-qPCR data showed that PgApx pro and PgDhn pro were expressed highly in high temperature, salt and drought, PgHsc70 pro was fairly expressed during high temperature stress only. Histochemical and RT-qPCR assays showed that all three promoters are inducible under abiotic stress conditions. Thus, these promoters appear to be immediate candidates for developing abiotic stress tolerant crops as these promoter-driven transgenics confer high degree of tolerance in comparison with the wild-type (WT) plants.

Overexpression of Saussurea involucrata dehydrin gene SiDHN promotes cold and drought tolerance in transgenic tomato plants

Dehydrins are late embryogenesis abundant proteins that help regulate abiotic stress responses in plants. Overexpression of the Saussurea involucrata dehydrin gene SiDHN has previously been shown to improve water-use efficiency and enhance cold and drought tolerance of transgenic tobacco. To understand the mechanism by which SiDHN exerts its protective function, we transformed the SiDHN gene into tomato plants (Solanum lycopersicum L.) and assessed their response to abiotic stress. We observed that in response to stresses, the SiDHN transgenic tomato plants had increased contents of chlorophyll a and b, carotenoid and relative water content compared with wild-type plants. They also had higher maximal photochemical efficiency of photosystem II and accumulated more proline and soluble sugar. Compared to those wild-type plants, malondialdehyde content and relative electron leakage in transgenic plants were not significantly increased, and H₂O₂ and O₂^- contents in transgenic tomato plants were significantly decreased. We further observed that the production of stress-related antioxidant enzymes, including superoxide dismutase, ascorbate peroxidase, peroxidase, and catalase, as well as pyrroline-5-carboxylate synthetase and lipid transfer protein 1, were up-regulated in the transgenic plants under cold and drought stress. Based on these observations, we conclude that overexpression of SiDHN gene can promote cold and drought tolerance of transgenic tomato plants by inhibiting cell membrane damage, protecting chloroplasts, and enhancing the reactive oxygen species scavenging capacity. The finding can be beneficial for the application of SiDHN gene in improving crop tolerance to abiotic stress and oxidative damage.

Exogenous application of β-sitosterol mediated growth and yield improvement in water-stressed wheat (Triticum aestivum) involves up-regulated antioxidant system

Water stress reduces crop production significantly, and climate change has further aggravated the problem mainly in arid and semi-arid regions. This was the first study on the possible effects of β-sitosterol application in ameliorating the deleterious changes in wheat induced by water stress under field condition and drip irrigation regimes. A field experiment with the split-plot design was conducted, and wheat plants were foliar sprayed with four β-sitosterol (BBS) concentrations (0, 25, 75, and 100 mg L^-1) and two irrigation regimes [50 and 100% of crop evapotranspiration (ET_c)]. Water stress without BBS treatment reduced biological yield, grain yield, harvest index, and photosynthetic efficiency significantly by 28.9%, 42.8%, 19.6%, and 20.5% compared with the well-watered plants, respectively. Proline content increased in water-stressed and BSS-treated plants, owing to a significant role in cellular osmotic adjustment. Application of BSS was effective in reducing the generation of hydrogen peroxide (H₂O₂) and hence the malondialdehyde content significantly in water-stressed and well-watered wheat plants. Application of BSS up-regulated the activity of antioxidant enzymes (SOD, CAT, POD, and APX) significantly and increased the content of tocopherol, ascorbic acid, and carotene thereby reducing the levels of reactive oxygen species. The increased antioxidant system in BSS treated plants was further supported by the expression level of SOD and dehydrin genes in both water-stressed and well-watered plants. In the present study, the application of BBS at 100 mg L^-1 was beneficial and can be recommended for improving the growth and yield of the wheat crop under water stress.

Dehydration Sensitivity at the Early Seedling Establishment Stages of the European Beech (Fagus sylvatica L.)

Shortage of water is a limiting factor for the growth and development of plants, particularly at early developmental stages. We focused on the European beech (Fagus sylvatica L.), which produces seeds and further seedlings in large intervals of up to ten years. To explore the beech seedling establishment process, six stages referring to embryo expansion were studied to determine sensitivity to dehydration. The characterization of the response of elongating embryonic axes and cotyledons included a viability test before and after dehydration and measurement of the amounts of electrolyte leakage, concentration, and arrangement of storage materials, changes in chaperone proteins related to water deficit, and accumulation of hydrogen peroxide and superoxide anion radicals. Elongating embryonic axes and cotyledons differed in water content, dehydration rates, membrane permeability before and after dehydration, protein, and lipid decomposition pattern, and amount of 44-kDa dehydrin and 22-kDa small heat shock protein (sHSP). Protruding embryonic axes were more sensitive to dehydration than cotyledons, although dehydration caused transient reinduction of three dehydrin-like proteins and sHSP synthesis, which accompany desiccation tolerance. Extended deterioration, including overproduction of hydrogen peroxide and depletion of superoxide anion radicals, was reported in dehydrated embryonic axes longer than 10 mm characterized by highly elevated cellular leakage. The apical part elongating embryonic axes consisting of the radicles was the most sensitive part of the seed to dehydration, and the root apical meristem area was the first to become inviable. The effects of severe dehydration involving ROS imbalance and reduced viability in beech seedlings with embryonic axes longer than 10 mm might help to explain the difficulties in beech seedling establishment observed in drought-affected environments. The conversion of environmental drought into climate-originated oxidative stress affecting beech seedling performance is discussed in this report.

Binding of a Vitis riparia dehydrin to DNA

Plants must protect themselves from abiotic stresses such as drought, cold, and high salinity. The common thread of all three stresses is that they cause dehydration, which in turn promotes the formation of reactive oxygen species (ROS). Dehydrin proteins (dehydrins) are a large family of proteins that have been identified in nearly all land plants, and whose presence is correlated with plant protection from abiotic stresses. Several dehydrin studies have shown that some dehydrins localize to the nucleus, as well as the cytoplasm, but a functional role for nuclear dehydrins has not yet been determined. We show here that the Vitis riparia dehydrin VrDHN1 localizes to the nucleus and is able to bind to DNA to protect it from damage caused by hydrogen peroxide, an ROS source. We also show that the binding to DNA is not DNA-sequence specific, suggesting that the protein is able to protect any exposed DNA without interfering with its normal function. NMR studies show that the binding is largely driven by the lysine-rich nature of dehydrins located in the conserved K-segments. Unlike other, previously studied dehydrins, VrDHN1 binding to DNA is not enhanced through the presence of metals. Lastly, we demonstrate that the Y-segment does not bind ATP, as has long been proposed.

Responses of olive plants exposed to different irrigation treatments in combination with heat shock: physiological and molecular mechanisms during exposure and recovery

A water-deficit period, leading to stomatal control and overexpression of protective proteins (sHSP and DHN), contributes to olive´s tolerance to later imposed stress episodes. Aquaporins modulation is important in olive recovery. Olive is traditionally cultivated in dry farming or in high water demanding irrigated orchards. The impact of climate change on these orchards remains to unveil, as heat and drought episodes are increasing in the Mediterranean region. To understand how young plants face such stress episodes, olive plants growing in pots were exposed to well-irrigated and non-irrigated treatments. Subsequently, plants from each treatment were either exposed to 40 °C for 2 h or remained under control temperature. After treatments, all plants were allowed to grow under well-irrigated conditions (recovery). Leaves were compared for photosynthesis, relative water content, mineral status, pigments, carbohydrates, cell membrane permeability, lipid peroxidation and expression of the protective proteins' dehydrin (OeDHN1), heat-shock proteins (OeHSP18.3), and aquaporins (OePIP1.1 and OePIP2.1). Non-irrigation, whilst increasing carbohydrates, reduced some photosynthetic parameters to values below the ones of the well-irrigated plants. However, when both groups of plants were exposed to heat, well-irrigated plants suffered more drastic decreases of net CO₂ assimilation rate and chlorophyll b than non-irrigated plants. Overall, OeDHN1 and OeHSP18.3 expression, which was increased in non-irrigated treatment, was potentiated by heat, possibly to counteract the increase of lipid peroxidation and loss of membrane integrity. Plants recovered similarly from both irrigation and temperature treatments, and recovery was associated with increased aquaporin expression in plants exposed to one type of stress (drought or heat). These data represent an important contribution for further understanding how dry-farming olive will cope with drought and heat episodes.

Contrasting Effects of Wild Arachis Dehydrin Under Abiotic and Biotic Stresses

Plant dehydrins (DNHs) belong to the LEA (Late Embryogenesis Abundant) protein family and are involved in responses to multiple abiotic stresses. DHNs are classified into five subclasses according to the organization of three conserved motifs (K-; Y-; and S-segments). In the present study, the DHN protein family was characterized by molecular phylogeny, exon/intron organization, protein structure, and tissue-specificity expression in eight Fabaceae species. We identified 20 DHN genes, encompassing three (YnSKn, SKn, and Kn) subclasses sharing similar gene organization and protein structure. Two additional low conserved DHN Φ-segments specific to the legume SKn-type of proteins were also found. The in silico expression patterns of DHN genes in four legume species (Arachis duranensis, A. ipaënsis, Glycine max, and Medicago truncatula) revealed that their tissue-specific regulation is associated with the presence or absence of the Y-segment. Indeed, DHN genes containing a Y-segment are mainly expressed in seeds, whereas those without the Y-segment are ubiquitously expressed. Further qRT-PCR analysis revealed that, amongst stress responsive dehydrins, a SKn-type DHN gene from A. duranensis (AdDHN1) showed opposite response to biotic and abiotic stress with a positive regulation under water deficit and negative regulation upon nematode infection. Furthermore, transgenic Arabidopsis lines overexpressing (OE) AdDHN1 displayed improved tolerance to multiple abiotic stresses (freezing and drought) but increased susceptibility to the biotrophic root-knot nematode (RKN) Meloidogyne incognita. This contradictory role of AdDHN1 in responses to abiotic and biotic stresses was further investigated by qRT-PCR analysis of transgenic plants using a set of stress-responsive genes involved in the abscisic acid (ABA) and jasmonic acid (JA) signaling pathways and suggested an involvement of DHN overexpression in these stress-signaling pathways.

Dexmedetomidine Ameliorates Acute Stress-Induced Kidney Injury by Attenuating Oxidative Stress and Apoptosis through Inhibition of the ROS/JNK Signaling Pathway

Acute stress induces tissue damage through excessive oxidative stress. Dexmedetomidine (DEX) reportedly has an antioxidant effect. However, protective roles and related potential molecular mechanisms of DEX against kidney injury induced by acute stress are unknown. Herein, rats were forced to swim 15 min followed by restraint stress for 3 h with/without DEX (30 μg/kg). Successful model establishment was validated by an open-field test. Assessment of renal function (creatinine, urea nitrogen), histopathology, oxidative stress (malondialdehyde, glutathione, and superoxide dismutase), and apoptosis (transferase-mediated dUTP nick end labeling) was performed. Localization of apoptosis was determined by immunohistochemistry of cleaved caspase 3 protein. In addition, key proteins of the death receptor-mediated pathway, mitochondrial pathway, endoplasmic reticulum stress (ERS) pathway, and ROS/JNK signaling pathway were measured by Western blot. We found that DEX significantly improved renal dysfunction, ameliorated kidney injury, reduced oxidative stress, and alleviated apoptosis. DEX also inhibited the release of norepinephrine (NE), decreased the production of reactive oxygen species (ROS), and inhibited JNK phosphorylation. Additionally, DEX downregulated the expression of Bax, cytochrome C, cleaved caspase 9, and cleaved caspase 3 proteins in mitochondria-dependent pathways. In summary, DEX protects against acute stress-induced kidney injury in rats by reducing oxidative stress and apoptosis via inhibition of the ROS/JNK pathway.

Oxidative damage and antioxidative indicators in 48 h germinated rice embryos during the vitrification-cryopreservation procedure

Cu/Zn SOD and other genes may be critical indicators of a stress response to reactive oxygen species (ROS) accumulation in 48 h germinated rice embryos subjected to vitrification cryopreservation. In the current study, reactive oxygen species (ROS) accumulation was investigated in 48 h germinated rice embryos during the vitrification-cryopreservation process. We found that vitrification-cryopreservation significantly affected ROS levels, especially superoxide anion levels, in 48 h germinated rice embryos. Malonaldehyde content in the apical meristems of germinated embryos was significantly positively correlated with the rate of superoxide anion generation and the highest levels of malonaldehyde content were reached after vitrification treatment. Cell viability in 48 h germinated embryos was significantly negatively correlated with the rate of superoxide anion generation, malonaldehyde content, and electrolyte leakage. Spatial and temporal patterns in ROS accumulation in these embryos existed during the vitrification procedure. Among the vitrification-cryopreservation treatments we assessed, the preculture treatment was found to stimulate superoxide anion generation and to activate the response system in the apical meristems of germinated embryos. Loading treatments motivated the catalase and ascorbate peroxidase activities. During the vitrification-dehydration treatment, oxidative stress reached the highest levels causing an antioxidative response. This response involved antioxidant enzymes promoting detoxification of ROS. Based on a comprehensive correlation analysis involving ROS accumulation, cell viability, the activities of antioxidant enzymes, and gene expression profiles, Cu/Zn SOD, CAT1, APX7, GR2, GR3, MDHAR1, and DHAR1 may be critical indicators of oxidative stress affected by the vitrification-cryopreservation treatments. The investigation of these antioxidative responses in 48 h germinated rice embryos may, therefore, provide useful information with respect to plant vitrification-cryopreservation.

Molecular Cloning and Functional Characterization of the Dehydrin (IpDHN) Gene From Ipomoea pes-caprae

Dehydrin (DHN) genes can be rapidly induced to offset water deficit stresses in plants. Here, we reported on a dehydrin gene (IpDHN) related to salt tolerance isolated from Ipomoea pes-caprae L. (Convolvulaceae). The IpDHN protein shares a relatively high homology with Arabidopsis dehydrin ERD14 (At1g76180). IpDHN was shown to have a cytoplasmic localization pattern. Quantitative RT-PCR analyses indicated that IpDHN was differentially expressed in most organs of I. pes-caprae plants, and its expression level increased after salt, osmotic stress, oxidative stress, cold stress and ABA treatments. Analysis of the 974-bp promoter of IpDHN identified distinct cis-acting regulatory elements, including an MYB binding site (MBS), ABRE (ABA responding)-elements, Skn-1 motif, and TC-rich repeats. The induced expression of IpDHN in Escherichia coli indicated that IpDHN might be involved in salt, drought, osmotic, and oxidative stresses. We also generated transgenic Arabidopsis lines that over-expressed IpDHN. The transgenic Arabidopsis plants showed a significant enhancement in tolerance to salt/drought stresses, as well as less accumulation of hydrogen peroxide (H₂O₂) and the superoxide radical (O₂ ^-), accompanied by increasing activity of the antioxidant enzyme system in vivo. Under osmotic stresses, the overexpression of IpDHN in Arabidopsis can elevate the expression of ROS-related and stress-responsive genes and can improve the ROS-scavenging ability. Our results indicated that IpDHN is involved in cellular responses to salt and drought through a series of pleiotropic effects that are likely involved in ROS scavenging and therefore influence the physiological processes of microorganisms and plants exposed to many abiotic stresses.

PtrA/NINV, an alkaline/neutral invertase gene of Poncirus trifoliata, confers enhanced tolerance to multiple abiotic stresses by modulating ROS levels and maintaining photosynthetic efficiency

BACKGROUND

Alkaline/neutral invertase (A/N-INV), an enzyme that hydrolyzes sucrose irreversibly into glucose and fructose, is essential for normal plant growth,development, and stress tolerance. However, the physiological and/or molecular mechanism underpinning the role of A/N-INV in abiotic stress tolerance is poorly understood.

RESULTS

In this report, an A/N-INV gene (PtrA/NINV) was isolated from Poncirus trifoliata, a cold-hardy relative of citrus, and functionally characterized. PtrA/NINV expression levels were induced by cold, salt, dehydration, sucrose, and ABA, but decreased by glucose. PtrA/NINV was found to localize in both chloroplasts and mitochondria. Overexpression of PtrA/NINV conferred enhanced tolerance to multiple stresses, including cold, high salinity, and drought, as supported by lower levels of reactive oxygen species (ROS), reduced oxidative damages, decreased water loss rate, and increased photosynthesis efficiency, relative to wild-type (WT). The transgenic plants exhibited higher A/N-INV activity and greater reducing sugar content under normal and stress conditions.

CONCLUSIONS

PtrA/NINV is an important gene implicated in sucrose decomposition, and plays a positive role in abiotic stress tolerance by promoting osmotic adjustment, ROS detoxification and photosynthesis efficiency. Thus, PtrA/NINV has great potential to be used in transgenic breeding for improvement of stress tolerance.