Comparison between the impact of osmotic and NaCl treatments on the expression of genes coding for ion transporters in Oryza glaberrima Steud.

We analyzed the expression of genes coding for Na+ transporters (OsHKT1.5, OsHKT1.1, OsSOS1, OsSOS2, OsNHX1, OsNHX2), Cl- transporter (OsNRT1, OsCLC, OsCCC1) and gene coding for the transcription factor DREB (OsDREB2) involved in response to desiccation in two cultivars of O. glaberrrima differing in salt-resistance (salt-tolerant cultivar (TOG5307) and salt-sensitive (TOG 5949)) exposed to NaCl, PEG or both agents present simultaneously. Seedlings were grown in iso-osmotic nutrient solution (Ψs = -0.47±0.02 MPa) containing PEG 6,000 12.9% (water stress), NaCl 75 mM (salt stress) and PEG 6.4% + NaCl 37.5 mM (MIX-treatment) during 1 and 7 days. Plants were analyzed for gene expression, mineral nutrients, and photosynthetic-related parameters. Na+ and Cl- accumulations in salt-treated plants were lower in roots and shoots of TOG5307 comparatively to TOG5949 while water content decreased in TOG5307. TOG5307 exhibited tolerance to water stress and maintained higher net photosynthesis and water use efficiency than TOG5949 in response to all treatments, but was less efficient for osmotic adjustment. Dehydration tolerance of TOG5307 involves a higher OsDREB2 expression. TOG5307 also exhibited a higher OsSOS1, OsSOS2, OsNHX1 and OsNHX2 expression than TOG5949 in response to salinity. OsHKT1.5 was slightly induced in the shoot. OsHKT1.1 was recorded in the shoots but remained undetectable in the roots. Chloride and sodium accumulations were strongly reduced in the shoots when PEG was present. Salinity resistance in Oryza glaberrima implies tolerance to dehydration as well as complementary strategies of Na+ exclusion through the SOS system and Na+ tolerance through vacuolar sequestration.

Dynamic change of tea (Camellia sinensis) leaf cuticular wax in white tea processing for contribution to tea flavor formation.

Despite some studies on tea leaf cuticular wax, their component changes during dehydration and withering treatments in tea processing and suspected relation with tea flavor quality formation remain unknown. Here, we showed that tea leaf cuticular wax changed drastically in tea leaf development, dehydration, or withering treatment during tea processing, which affected tea flavor formation. Caffeine was found as a major component of leaf cuticular wax. Caffeine and inositol contents in leaf cuticular wax increased during dehydration and withering treatments. Comparisons showed that tea varieties with higher leaf cuticular wax loading produced more aroma than these with lower cuticular wax loading, supporting a positive correlation between tea leaf cuticular wax loading and degradation with white tea aroma formation. Dehydration or withering treatment of tea leaves also increased caffeine and inositol levels in leaf cuticular wax and triggered cuticular wax degradation into various molecules, that could be related to tea flavor formation. Thus, tea leaf cuticular waxes not only protect tea plants but also contribute to tea flavor formation. The study provides new insight into the dynamic changes of tea leaf cuticular waxes for tea plant protection and tea flavor quality formation in tea processing.

Ascorbic acid addition during dehydration improves garlic shoot tip cryopreservation but does not affect viral load.

Cryopreservation is known be an effective method for virus elimination in garlic. However, oxidative damage during the cryopreservation seriously affects the survival of garlic after cryopreservation. Ascorbic acid (AsA) can reduce oxidative damage and improve regrowth following cryopreservation, and its effect may be influenced by the step during which it is added. In this study, AsA was added at the osmoprotection (O) and dehydration (DE) steps of cryopreservation. By observing the dynamic changes in cell viability and reactive oxygen species (ROS) components with different AsA treatments, AsA has been linked to the reduced accumulation of ROS in the shoot tips. Increased gene expression levels of antioxidant enzymes also explained the ROS scavenging effect of AsA. The correlation analysis between cell viability, ROS, membrane lipid peroxidation-related indicators and antioxidant-related indicators showed that membrane lipid peroxidation caused by excess ROS was the main factor affecting cell viability. Ascorbic acid added during dehydration minimized the accumulation of ROS from dehydration to dilution and alleviated the oxidative damage during cryopreservation. Thus, the survival and regrowth of the garlic was significantly improved after cryopreservation. Dehydration was found to be the suitable step for the addition of AsA during garlic cryopreservation. We further evaluated the virus elimination effect under optimal AsA treatment. However, there was no significant difference in virus content in regenerated plants when compared with the control.

Chickpeas from a Chilean Region Affected by a Climate-Related Catastrophe: Effects of Water Stress on Grain Yield and Flavonoid Composition.

The Valparaiso region in Chile was decreed a zone affected by catastrophe in 2019 as a consequence of one of the driest seasons of the last 50 years. In this study, three varieties ('Alfa-INIA', 'California-INIA', and one landrace, 'Local Navidad') of kabuli-type chickpea seeds produced in 2018 (control) and 2019 (climate-related catastrophe, hereafter named water stress) were evaluated for their grain yield. Furthermore, the flavonoid profile of both free and esterified phenolic extracts was determined using liquid chromatography-mass spectrometry, and the concentration of the main flavonoid, biochanin A, was determined using liquid chromatography with diode array detection. The grain yield was decreased by up to 25 times in 2019. The concentration of biochanin A was up to 3.2 times higher in samples from the second season (water stress). This study demonstrates that water stress induces biosynthesis of biochanin A. However, positive changes in the biochanin A concentration are overshadowed by negative changes in the grain yield. Therefore, water stress, which may be worsened by climate change in the upcoming years, may jeopardize both the production of chickpeas and the supply of biochanin A, a bioactive compound that can be used to produce dietary supplements and/or nutraceuticals.

Sugar beet extract rich in glycine betaine modulates oxidative defense system and key physiological characteristics of maize under water-deficit stress.

Now-a-days, plant-based extracts, as a cheap source of growth activators, are being widely used to treat plants grown under extreme climatic conditions. So, a trial was conducted to assess the response of two maize (Zea mays L.) varieties, Sadaf (drought tolerant) and Sultan (drought sensitive) to foliar-applied sugar beet extract (SBE) under varying water-deficit conditions. Different SBE (control, 1%, 2%, 3% & 4%) levels were used in this study, and plants were exposed to water-deficit [(75% and 60% of field capacity (FC)] and control (100% FC) conditions. It was observed that root and shoot dry weights (growth), total soluble proteins, RWC-relative water contents, total phenolics, chlorophyll pigments and leaf area per plant decreased under different water stress regimes. While, proline, malondialdehyde (MDA), RMP-relative membrane permeability, H2O2-hydrogen peroxide and the activities of antioxidant enzymes [CAT-catalase, POD-peroxidase and SOD-superoxide dismutase] were found to be improved in water stress affected maize plants. Exogenous application of varying levels of SBE ameliorated the negative effects of water-deficit stress by enhancing the growth attributes, photosynthetic pigments, RWC, proline, glycinebetaine (GB), activities of POD and CAT enzymes and levels of total phenolics, whereas it reduced the lipid peroxidation in both maize varieties under varying water stress levels. It was noted that 3% and 4% levels of SBE were more effective than the other levels used in enhancing the growth as well as other characteristics of the maize varieties. Overall, the sugar beet extract proved to be beneficial for improving growth and metabolism of maize plants exposed to water stress.

Funneliformis mosseae inoculation under water deficit stress improves the yield and phytochemical characteristics of thyme in intercropping with soybean.

Intercropping of medicinal plants/legumes along with bio-fertilizer application is a relatively new sustainable practice for improving the yield and secondary metabolites production. Here, a 2-years field experiment was performed to evaluate the effects of water deficit stress and arbuscular mycorrhizal fungi (AMF) application (as bio-fertilizer) on nutrients concentration, dry matter yield, essential oil quantity and quality of thyme in intercropping with soybean. Three irrigation levels, including (i) irrigation after depletion of 20% (I20) as non-stressed, 50% (I50) as moderate water deficit and 80% (I80) available water as severe water deficit were applied as the main factor. The sub-factor was represented by different cropping patterns including thyme sole culture, replacement intercrop ratio of 50:50 and 66:34 (soybean: thyme) and the third factor was non-usage (control) and usage of AMF. According to our results, the thyme dry yield under moderate and severe water deficit stress decreased by 35 and 44% in the first year, and by 27 and 40% in the second year compared with non-stressed (I20) plants, respectively. Also, the macro- and micro-nutrients of thyme leaves increased significantly in intercropping patterns after application of AMF. The maximum essential oil percentage of thyme was achieved in 50:50 intercropping ratio treated with AMF. Under moderate and severe water deficits, the major constituents of thyme essential oil including thymol, p-cymene and γ-terpinene were increased in intercropping patterns treated with AMF. Generally, AMF application in intercropping ratio of 50:50 may be proposed to farmers as an eco-friendly approach to achieve desirable essential oil quality and quantity in thyme under water deficit stress conditions.

Organ protection by SGLT2 inhibitors: role of metabolic energy and water conservation.

Therapeutic inhibition of the sodium-glucose co-transporter 2 (SGLT2) leads to substantial loss of energy (in the form of glucose) and additional solutes (in the form of Na+ and its accompanying anions) in urine. However, despite the continuously elevated solute excretion, long-term osmotic diuresis does not occur in humans with SGLT2 inhibition. Rather, patients on SGLT2 inhibitor therapy adjust to the reduction in energy availability and conserve water. The metabolic adaptations that are induced by SGLT2 inhibition are similar to those observed in aestivation - an evolutionarily conserved survival strategy that enables physiological adaptation to energy and water shortage. Aestivators exploit amino acids from muscle to produce glucose and fatty acid fuels. This endogenous energy supply chain is coupled with nitrogen transfer for organic osmolyte production, which allows parallel water conservation. Moreover, this process is often accompanied by a reduction in metabolic rate. By comparing aestivation metabolism with the fuel switches that occur during therapeutic SGLT2 inhibition, we suggest that SGLT2 inhibitors induce aestivation-like metabolic patterns, which may contribute to the improvements in cardiac and renal function observed with this class of therapeutics.

Exogenous Melatonin Modulates the Physiological and Biochemical Mechanisms of Drought Tolerance in Tartary Buckwheat (Fagopyrum tataricum (L.) Gaertn).

Tartary buckwheat is one of the nutritious minor cereals and is grown in high-cold mountainous areas of arid and semi-arid zones where drought is a common phenomenon, potentially reducing the growth and yield. Melatonin, which is an amphiphilic low molecular weight compound, has been proven to exert significant effects in plants, under abiotic stresses, but its role in the Tartary buckwheat under drought stress remains unexplored. We evaluated the influence of melatonin supplementation on plant morphology and different physiological activities, to enhance tolerance to posed drought stress by scavenging reactive oxygen species (ROS) and alleviating lipid peroxidation. Drought stress decreased the plant growth and biomass production compared to the control. Drought also decreased Chl a, b, and the Fv/Fm ratio by 54%, 70%, and 8%, respectively, which was associated with the disorganized stomatal properties. Under drought stress, H2O2, O2•-, and malondialdehyde (MDA) contents increased by 2.30, 2.43, and 2.22-folds, respectively, which caused oxidative stress. In contrast, proline and soluble sugar content were increased by 84% and 39%, respectively. However, exogenous melatonin (100 µM) could improve plant growth by preventing ROS-induced oxidative damage by increasing photosynthesis, enzymatic antioxidants (superoxide dismutase, peroxidase, catalase, and ascorbate peroxidase), secondary metabolites like phenylalanine ammonialyase, phenolics, and flavonoids, total antioxidant scavenging (free radical DPPH scavenging), and maintaining relative water content and osmoregulation substances under water stress. Therefore, our study suggested that exogenous melatonin could accelerate drought resistance by enhancing photosynthesis and antioxidant defense in Tartary buckwheat plants.

Maintenance Fluid Therapy with Saline, Dextrose-Supplemented Saline or Lactated Ringer in Childhood: Short-Term Metabolic Effects.

Maintenance with isotonic fluids is recommended in children with gastroenteritis and failure of oral rehydration therapy. However, little is known on the short-term effects of the commonly prescribed intravenous solutions on metabolic balance in children. The aim of this study is to report on our experience with normal saline, dextrose-supplemented saline and lactated Ringer solution. METHODS: A retrospective analysis from the charts of all previously apparently healthy children with acute gastroenteritis, mild to moderate dehydration and failure of oral rehydration, evaluated between January 2016 and December 2019 at our institution, was performed. Subjects prescribed the above-mentioned maintenance intravenous fluids and with blood testing immediately before starting fluid therapy and 4-6 h later, were eligible. The changes in bicarbonate, ionized sodium, potassium, chloride, anion gap and glucose were investigated. Kruskal-Wallis test with the post-hoc Dunn's comparison and the Fisher exact test were applied. RESULTS: A total of 134 out of 732 children affected by acute gastroenteritis were included (56 patients were prescribed normal saline, 48 dextrose-supplemented normal saline and 30 lactated Ringer solution). The effect of the three solutions on sodium and potassium was similar. As compared to non-supplemented normal saline (+0.4 (-1.9 - +2.2) mmol/L), dextrose-supplemented normal saline (+1.5 (+0.1 - +4.2) mmol/L) and lactated Ringer (+2.6 (+0.4 - +4.1) mmol/L) solution had a positive effect on plasma bicarbonate. Finally, the influence of dextrose-supplemented saline on blood glucose was different (+1.1 (+0.3 - +2.2) mmol/L) compared to that observed in cases hydrated with non-supplemented saline (-0.4 (-1.2 - +0.3) mmol/L) or lactated Ringer solution (-0.4 (-1.2 - +0.1) mmol/L). CONCLUSIONS: This study points out that maintenance intravenous therapies using normal saline, dextrose-supplemented saline or lactated Ringer solution have different effects on metabolic balance. A personalized fluid therapy that takes into account the clinical and biochemical variables is advised.

Variation in Terpene Profiles of Thymus vulgaris in Water Deficit Stress Response.

Thyme (Thymus spp.) volatiles predominantly consisting of monoterpenes and sesquiterpenes, serve as antimicrobial, antiseptic and antioxidant in phytomedicine. They also play a key role in plants as secondary metabolites via their potential role against herbivores, attracting pollinators and abiotic stress tolerance. Plant volatiles are affected by different environmental factors including drought. Here, the effect of prolonged water deficit stress on volatile composition was studied on the sensitive and tolerant thyme plant cultivars (T. vulgaris Var. Wagner and T. vulgaris Var. Varico3, respectively). Volatile sampling along with morpho-physiological parameters such as soil moisture, water potential, shoot dry weight, photosynthetic rate and water content measurements were performed on one-month-old plants subsequent to water withholding at 4-day intervals until the plants wilted. The tolerant and sensitive plants had clearly different responses at physiological and volatile levels. The most stress-induced changes on the plants' physiological traits occurred in the photosynthetic rates, where the tolerant plants maintained their photosynthesis similar to the control ones until the 8th day of the drought stress period. While the analysis of the volatile compounds (VOCs) of the sensitive thyme plants displayed the same pattern for almost all of them, in the tolerant plants, the comparison of the pattern of changes in the tolerant plants revealed that the changes could be classified into three separate groups. Our experimental and theoretical studies totally revealed that the most determinant compounds involved in drought stress adaptation included α-phellandrene, O-cymene, γ-terpinene and ß-caryophyelene. Overall, it can be concluded that in the sensitive plants trade-off between growth and defense, the tolerant ones simultaneously activate their stress response mechanism and continue their growth.

Antifreeze protein complements cryoprotective dehydration in the freeze-avoiding springtail Megaphorura arctica.

The springtail, Megaphorura arctica, is freeze-avoiding and survives sub-zero temperatures by cryoprotective dehydration. At the onset of dehydration there is some supercooling of body fluids, and the danger of inoculative freezing, which would be lethal. To see if the springtails are protected by antifreeze proteins in this pre-equilibrium phase, we examined extracts from cold-acclimated M. arctica and recorded over 3 °C of freezing point depression. Proteins responsible for this antifreeze activity were isolated by ice affinity. They comprise isoforms ranging from 6.5 to 16.9 kDa, with an amino acid composition dominated by glycine (>35 mol%). Tryptic peptide sequences were used to identify the mRNA sequence coding for the smallest isoform. This antifreeze protein sequence has high similarity to one characterized in Hypogastrura harveyi, from a different springtail order. If these two antifreeze proteins are true homologs, we suggest their origin dates back to the Permian glaciations some 300 million years ago.

miR167 limits anther growth to potentiate anther dehiscence.

In flowering plants, anther dehiscence and pollen release are essential for sexual reproduction. Anthers dehisce after cell wall degradation weakens stomium cell junctions in each anther locule, and desiccation creates mechanical forces that open the locules. Either effect or both together may break stomium cell junctions. The microRNA miR167 negatively regulates ARF6 and ARF8, which encode auxin response transcription factors. Arabidopsis mARF6 or mARF8 plants with mutated miR167 target sites have defective anther dehiscence and ovule development. Null mir167a mutations recapitulated mARF6 and mARF8 anther and ovule phenotypes, indicating that MIR167a is the main miR167 precursor gene that delimits ARF6 and ARF8 expression in these organs. Anthers of mir167a or mARF6/8 plants overexpressed genes encoding cell wall loosening functions associated with cell expansion, and grew larger than wild-type anthers did starting at flower stage 11. Experimental desiccation enabled dehiscence of miR167-deficient anthers, indicating competence to dehisce. Conversely, high humidity conditions delayed anther dehiscence in wild-type flowers. These results support a model in which miR167-mediated anther growth arrest permits anther dehiscence. Without miR167 regulation, excess anther growth delays dehiscence by prolonging desiccation.

Unigene-based RNA-seq provides insights on drought stress responses in Marsdenia tenacissima.

Marsdenia tenacissima is a well-known anti-cancer medicinal plant used in traditional Chinese medicine, which often grows on the karst landform and the water conservation capacity of land is very poorly and drought occurrences frequently. We found M. tenacissima has strong drought resistance because of continuousdrought16 d, the leaves of M. tenacissima were fully curly and dying. But the leaves were fully almost recovering after re-watering 24h. The activity of SOD and POD were almost doubled under drought stress. The content of osmotic regulating substance proline and soluble sugar were three times than control group. But after re-watering, these indexes were declined rapidly. Three cDNA libraries of control, drought stress, and re-watering treatments were constructed. There were 43,129,228, 47,116,844, and 42,815,454 clean reads with Q20 values of 98.06, 98.04, and 97.88respectively.SRA accession number of raw data was PRJNA498187 on NCBI. A total of 8672, 6043, and 6537 differentially expressed genes (DEGs) were identified in control vs drought stress, control vs re-watering, and drought stress vs re-watering, respectively. In addition, 1039, 1016, and 980 transcription factors (TFs) were identified, respectively. Among them, 363, 267, and 299 TFs were identified as DEGs in drought stress, re-watering, and drought stress and re-watering, respectively. These differentially expressed TFs mainly belonged to the bHLH, bZIP, C2H2, ERF, MYB, MYB-related, and NAC families. A comparative analysis found that 1174 genes were up-regulated and 2344 were down-regulated under drought stress and this pattern was the opposite to that found after re-watering. Among the up-regulated genes, 64 genes were homologous to known functional genes that directly protect plants against drought stress. Furthermore, 44 protein kinases and 38 TFs with opposite expression patterns under drought stress and re-watering were identified, which are possibly candidate regulators for drought stress resistance in M. tenacissima. Our study is the first to characterize the M. tenacissima transcriptome in response to drought stress, and will serve as a useful resource for future studies on the functions of candidate protein kinases and TFs involved in M. tenacissima drought stress resistance.

How to change the ratio of unsaturated (omega 3, 6, 7 and 9) to saturated fatty acids in Oenothera biennis L. oil under water deficit stress, fertilizers and geographical zones.

The 2015-2020 dietary guidelines for Americans advise substituting total unsaturated fatty acids (∑UFA) for total saturated fatty acids (∑SFA). Thus, field experiments were carried out to verify the influence of irrigation regime (well-irrigated and water deficit) and fertilizers (chemical and biological) on the ratio of ∑UFA to ∑SFA of evening primrose seed oil. Therefore, two experiments were conducted at the experimental stations (arid and semi-arid) of Iran in 2014 and 2015. Experiments were conducted in a split factorial layout within a randomized complete block design with three replications. Water deficit significantly reduced UFA (omega 3, 6, 7 and 9), ∑UFA and ratio of ∑UFA to ∑SFA (especially in the arid region), but it increased SFA and ∑SFA (especially in the arid region). In fact, fatty acid quality (increased ratio of ∑UFA to ∑SFA) of evening primrose seed oil was significantly increased in well-irrigated compared to water deficit stress (especially in the semi-arid region). Bio-fertilizers (Azospirillum lipoferum and Glomus mosseae) and chemical fertilizers (urea + triple superphosphate) increased the ratio of ∑UFA to ∑SFA of evening primrose seed oil (especially in the semi-arid region), but fatty acid quality of evening primrose oil was significantly increased in bio-fertilizers compared to the chemical fertilizers (especially in the arid region).

Effect of a single dose of mannitol on hydration status and electrolyte concentrations in patients with tick-borne encephalitis.

OBJECTIVE: This study was performed to assess the effect of a single dose of 15% mannitol on the hydration status and electrolyte balance in patients with tick-borne encephalitis (TBE). METHODS: Forty-one patients with TBE were treated with 0.25 g/kg of 15% mannitol. The electrolyte concentrations (Na, K, and Cl), creatinine concentration, and hydration status were measured before and after mannitol infusion. RESULTS: After mannitol administration, 7 patients had hyponatremia, 3 had hypokalemia, 1 had hyperkalemia, and 17 had hypochloremia. The total body water volume (TBW) changed by 0.44% ± 0.55%, the external body water volume (EBW) changed by 0.12% ± 0.15%, and the internal body water volume (IBW) changed by 0.19% ± 0.40%. The mean ECW/ICW ratio was 0.7694 ± 0.07 before treatment and 0.7699 ± 0.07 after treatment. Age was correlated with the TBW change in men (R = 0.42, p < 0.05) and with the potassium change in women (R = 0.66, p < 0.05). CONCLUSIONS: Patients with TBE should receive mannitol two to four times daily depending on the clinical manifestation. Administration of a single dose of mannitol (0.25 g/kg) requires at least 300 mL of fluid supplementation. Bioimpedance might be useful for individual evaluation of dehydration. Additionally, patients require monitoring for potential hyponatremia. Older men may be more prone to dehydration after receiving mannitol.

The drought-tolerant Solanum pennellii regulates leaf water loss and induces genes involved in amino acid and ethylene/jasmonate metabolism under dehydration.

Breeding for drought-tolerant crops is a pressing issue due to the increasing frequency and duration of droughts caused by climate change. Although important sources of variation for drought tolerance exist in wild relatives, the mechanisms and the key genes controlling tolerance in tomato are little known. The aim of this study is to determine the drought response of the tomato wild relative Solanum pennellii (Sp) compared with the cultivated tomato Solanum lycopersicum (Sl). The paper investigates the physiological and molecular responses in leaves of Sp and Sl plants without stress and moderate drought stress. Significant physiological differences between species were found, with Sp leaves showing greater ability to avoid water loss and oxidative damage. Leaf transcriptomic analysis carried out when leaves did not as yet show visual dehydration symptoms revealed important constitutive expression differences between Sp and Sl species. Genes linked to different physiological and metabolic processes were induced by drought in Sp, especially those involved in N assimilation, GOGAT/GS cycle and GABA-shunt. Up-regulation in Sp of genes linked to JA/ET biosynthesis and signaling pathways was also observed. In sum, genes involved in the amino acid metabolism together with genes linked to ET/JA seem to be key actors in the drought tolerance of the wild tomato species.

Cloning and expression profiling of the PacSnRK2 and PacPP2C gene families during fruit development, ABA treatment, and dehydration stress in sweet cherry.

Plant SNF1-related protein kinase 2 (SnRK2) and protein phosphatase 2C (PP2C) family members are core components of the ABA signal transduction pathway. SnRK2 and PP2C proteins have been suggested to play crucial roles in fruit ripening and improving plant tolerance to drought stress, but supporting genetic information has been lacking in sweet cherry (Prunus avium L.). Here, we cloned six full-length SnRK2 genes and three full-length PP2C genes from sweet cherry cv. Hong Deng. Quantitative PCR analysis revealed that PacSnRK2.2, PacSnRK2.3, PacSnRK2.6, and PacPP2C1-3 were negatively regulated in fruits in response to exogenous ABA treatment, PacSnRK2.4 and PacSnRK2.5 were upregulated, and PacSnRK2.1 expression was not affected. The ABA treatment also significantly promoted the accumulation of anthocyanins in sweet cherry fruit. The expression of all PacSnRK2 and PacPP2C genes was induced by dehydration stress, which also promoted the accumulation of drought stress signaling molecules in the sweet cherry fruits, including ABA, soluble sugars, and anthocyanin. Furthermore, a yeast two-hybrid analysis demonstrated that PacPP2C1 interacts with all six PacSnRK2s, while PacPP2C3 does not interact with PacSnRK2.5. PacPP2C2 does not interact with PacSnRK2.1 or PacSnRK2.4. These results indicate that PacSnRK2s and PacPP2Cs may play a variety of roles in the sweet cherry ABA signaling pathway and the fruit response to drought stress.

Silicon improves seed germination and alleviates drought stress in lentil crops by regulating osmolytes, hydrolytic enzymes and antioxidant defense system.

Silicon (Si) has been widely reported to have beneficial effect on mitigating drought stress in plants. However, the effect of Si on seed germination under drought conditions is still poorly understood. This research was carried out to ascertain the role of Si to abate polyethylene glycol-6000 mediated drought stress on seed germination and seedling growth of lentil. Results showed that drought stress significantly decreased the seed germination traits and increased the concentration of osmolytes (proline, glycine betaine and soluble sugars), reactive oxygen species (hydrogen peroxide and superoxide anion) and lipid peroxides in lentil seedlings. The activities of hydrolytic enzymes and antioxidant enzymes increased significantly under osmotic stress. The application of Si significantly enhanced the plants ability to withstand drought stress conditions through increased Si content, improved antioxidants, hydrolytic enzymes activity, decreased concentration of osmolytes and reactive oxygen species. Multivariate data analysis showed statistically significant correlations among the drought-tolerance traits, whereas cluster analysis categorised the genotypes into distinct groups based on their drought-tolerance levels and improvements in expression of traits due to Si application. Thus, these results showed that Si supplementation of lentil was effective in alleviating the detrimental effects of drought stress on seed germination and increased seedling vigour.

Genome-wide identification of the potato WRKY transcription factor family.

WRKY transcription factors play pivotal roles in regulation of stress responses. This study identified 79 WRKY genes in potato (Solanum tuberosum). Based on multiple sequence alignment and phylogenetic relationships, WRKY genes were classified into three major groups. The majority of WRKY genes belonged to Group II (52 StWRKYs), Group III had 14 and Group I consisted of 13. The phylogenetic tree further classified Group II into five sub-groups. All StWRKY genes except StWRKY79 were mapped on potato chromosomes, with eight tandem duplication gene pairs and seven segmental duplication gene pairs found from StWRKY family genes. The expression analysis of 22 StWRKYs showed their differential expression levels under various stress conditions. Cis-element prediction showed that a large number of elements related to drought, heat and salicylic acid were present in the promotor regions of StWRKY genes. The expression analysis indicated that seven StWRKYs seemed to respond to stress (heat, drought and salinity) and salicylic acid treatment. These genes are candidates for abiotic stress signaling for further research.

Regulation and physiological role of silicon in alleviating drought stress of mango.

Improvement of drought stress of mango plants requires intensive research that focuses on physiological processes. In three successive seasons (2014, 2015and 2016) field experiments with four different strains of mango were subjected to two water regimes. The growth and physiological parameters of possible relevance for drought stress tolerances in mango were investigated. Yield and its components were also evaluated. The data showed that all growth and physiological parameters were increased under K2SiO3 (Si) supplement and were followed by the interaction treatment (Si treatment and its combination with drought stress) compared to that of the controlled condition. Drought stress decreased the concentration of auxins (IAA), gibberellins (GA) and cytokinins (CK) in the three mango cultivars leaves, whereas, it increased the concentration of abscisic acid (ABA). On the contrary, IAA, GA, and CK (promoters) endogenous levels were improved by supplementing Si, in contrary ABA was decreased. Drought stress increased the activity of peroxidase (POX), catalase (CAT), and superoxide dismutase (SOD) in the leaves of all mango cultivars grown during three experimental seasons. However, Si supplementation reduced the levels of all these antioxidative enzymes, especially the concentration of SOD when compared to that of control leaves. Fruit quality was improved in three successive seasons when Si was applied. Our results clearly show that the increment in drought tolerance was associated with an increase in antioxidative enzyme activity, allowing mango plants to cope better with drought stress. Si possesses an efficient system for scavenging reactive oxygen species, which protects the plant against destructive oxidative reactions, thereby improving the ability of the mango trees to withstand environmental stress in arid regions.