Accumulation Of Compatible Solutes Research Articles

Metabolic responses of date palm (Phoenix dactylifera L.) leaves to drought differ in summer and winter climate.

Drought negatively impacts growth and productivity of plants, particularly in arid and semi-arid regions. Although drought events can take place in summer and winter, differences in the impact of drought on physiological processes between seasons are largely unknown. The aim of this study was to elucidate metabolic strategies of date palms in response to drought in summer and winter season. To identify such differences, we exposed date palm seedlings to a drought-recovery regime, both in simulated summer and winter climate. Leaf hydration, carbon discrimination (${\Delta}$13C), and primary and secondary metabolite composition and contents were analyzed. Depending on season, drought differently affected physiological and biochemical traits of the leaves. In summer, drought induced significantly decreased leaf hydration, concentrations of ascorbate, most sugars, primary and secondary organic acids, as well as phenolic compounds, while thiol, amino acid, raffinose and individual fatty acid contents were increased compared with well-watered plants. In winter, drought had no effect on leaf hydration, ascorbate and fatty acids contents, but resulted in increased foliar thiol and amino acid levels as observed in summer. Compared with winter, foliar traits of plants exposed to drought in summer only partly recovered after re-watering. Memory effects on water relations, and primary and secondary metabolites seem to prepare foliar traits of date palms for repeated drought events in summer. Apparently, a well-orchestrated metabolic network, including the anti-oxidative system, compatible solutes accumulation and osmotic adjustment, and maintenance of cell-membrane stability strongly reduces the susceptibility of date palms to drought. These mechanisms of drought compensation may be more frequently required in summer.

Drought Stress Impacts on Plants and Different Approaches to Alleviate Its Adverse Effects.

Drought stress, being the inevitable factor that exists in various environments without recognizing borders and no clear warning thereby hampering plant biomass production, quality, and energy. It is the key important environmental stress that occurs due to temperature dynamics, light intensity, and low rainfall. Despite this, its cumulative, not obvious impact and multidimensional nature severely affects the plant morphological, physiological, biochemical and molecular attributes with adverse impact on photosynthetic capacity. Coping with water scarcity, plants evolve various complex resistance and adaptation mechanisms including physiological and biochemical responses, which differ with species level. The sophisticated adaptation mechanisms and regularity network that improves the water stress tolerance and adaptation in plants are briefly discussed. Growth pattern and structural dynamics, reduction in transpiration loss through altering stomatal conductance and distribution, leaf rolling, root to shoot ratio dynamics, root length increment, accumulation of compatible solutes, enhancement in transpiration efficiency, osmotic and hormonal regulation, and delayed senescence are the strategies that are adopted by plants under water deficit. Approaches for drought stress alleviations are breeding strategies, molecular and genomics perspectives with special emphasis on the omics technology alteration i.e., metabolomics, proteomics, genomics, transcriptomics, glyomics and phenomics that improve the stress tolerance in plants. For drought stress induction, seed priming, growth hormones, osmoprotectants, silicon (Si), selenium (Se) and potassium application are worth using under drought stress conditions in plants. In addition, drought adaptation through microbes, hydrogel, nanoparticles applications and metabolic engineering techniques that regulate the antioxidant enzymes activity for adaptation to drought stress in plants, enhancing plant tolerance through maintenance in cell homeostasis and ameliorates the adverse effects of water stress are of great potential in agriculture.

Polyols-related gene expression is affected by cyclic desiccation in lichen microalgae

The accumulation of compatible solutes, as sugar and polyols, as a response to stress is a widely biochemical adaptation. However, the signaling process involved in this regulation remains unclear. Lichens and their microalgae have to cope with a variety of stresses associated with sudden changes in water content during daily cycles of desiccation-rehydration (D/R). In this way, we hypothesized: (1) the differences in desiccation tolerance among lichen-forming microalgae could be associated with species-specific differences in their polyol metabolism and (2) the nitric oxide (NO), as a signaling molecule, could assist the regulation of the expression of polyol-related genes in these organisms. Therefore, we carried out a comparative analysis of the transcriptional expression of key genes involved in the synthesis of polyols and metabolite levels, along with the cellular concentration of NO in isolated lichen microalgae during consecutive daily cycles of D/R and correlated the results with the polyol profile and NO measurements. Two microalgae were employed, Trebouxia sp. TR9 (TR9) and Coccomyxa simplex (Csol), obtained from lichens subjected to different water availability in their natural habitat. Our results revealed that, in both microalgae, the expression of myo-inositol and raffinose-related genes is modulated by cyclic D/R. Although, genes seem more prone to be transcriptionally upregulated by cyclic D/R in Csol than in TR9, indicating a more inducible defensive response in Csol in contrast with a constitutive defense system in TR9. Correlation analysis provided evidences that NO may act as a signaling molecule, through the modulation of polyol biosynthetic pathway and may be related to a primed memory state, by assisting in the rapidly and more precise metabolic response to subsequent D/R cycles.

Water-deficit stress - Induced physio-biochemical changes in cotton (Gossypium hirsutum L.) Cultivars

Water stress is a serious global issue regarding growth of agricultural crops and sustainable food production for the large population. In the present situation due to low rainfall and unavailability of advanced irrigation methods, water deficit stress is the most limiting factor decreasing crop production in many regions of the world. In this study, to assess the drought tolerance mechanism in cotton cultivars was monitored by drought induced physio-biochemical changes. To assess the tolerance in cotton cultivars, a field experiment was conducted in split plot design in which the main plot consists of irrigated and complete rainfed conditions as a stress and cotton cultivars arranged in the main plot as a subplot. The overall comparative analysis revealed that hybrid was superior over their parents under well-watered as well as in water deficit conditions in terms of chlorophyll content, wax content, accumulation of compatible solutes, photosynthesis rate, stomatal conductance, transpiration rate and yield parameters. The findings from the results indicate that under water deficit conditions plants having a different adaptive mechanisms for coping with the stress situation. So, some of the adaptive mechanisms such as accumulation of sugars, polyphenols, amino acids, non-enzymatic antioxidants, and wax deposition helps to maintain osmotic balance, to protect cellular macromolecules, to detoxify the cells, and to scavenge free radicals under water deficit condition.

Comparison of Growth and Ion Absorption with Compatible Solute Accumulation of Three Wild Vigna Species under Salt Stress

Comparison of Growth and Ion Absorption with Compatible Solute Accumulation of Three Wild <i>Vigna</i> Species under Salt Stress

Osmotic Adaptation and Compatible Solute Biosynthesis of Phototrophic Bacteria as Revealed from Genome Analyses.

Osmotic adaptation and accumulation of compatible solutes is a key process for life at high osmotic pressure and elevated salt concentrations. Most important solutes that can protect cell structures and metabolic processes at high salt concentrations are glycine betaine and ectoine. The genome analysis of more than 130 phototrophic bacteria shows that biosynthesis of glycine betaine is common among marine and halophilic phototrophic Proteobacteria and their chemotrophic relatives, as well as in representatives of Pirellulaceae and Actinobacteria, but are also found in halophilic Cyanobacteria and Chloroherpeton thalassium. This ability correlates well with the successful toleration of extreme salt concentrations. Freshwater bacteria in general lack the possibilities to synthesize and often also to take up these compounds. The biosynthesis of ectoine is found in the phylogenetic lines of phototrophic Alpha- and Gammaproteobacteria, most prominent in the Halorhodospira species and a number of Rhodobacteraceae. It is also common among Streptomycetes and Bacilli. The phylogeny of glycine-sarcosine methyltransferase (GMT) and diaminobutyrate-pyruvate aminotransferase (EctB) sequences correlate well with otherwise established phylogenetic groups. Most significantly, GMT sequences of cyanobacteria form two major phylogenetic branches and the branch of Halorhodospira species is distinct from all other Ectothiorhodospiraceae. A variety of transport systems for osmolytes are present in the studied bacteria.

Transcriptomic Analysis Reveals Common Adaptation Mechanisms Under Different Stresses for Moderately Piezophilic Bacteria.

Piezophiles, by the commonly accepted definition, grow faster under high hydrostatic pressure (HHP) than under ambient pressure and are believed to exist only in pressurized environments where life has adapted to HHP during evolution. However, recent findings suggest that piezophiles have developed a common adaptation strategy to cope with multiple types of stresses including HHP. These results raise a question on the ecological niches of piezophiles: are piezophiles restricted to habitats with HHP? In this study, we observed that the bacterial strains Sporosarcina psychrophila DSM 6497 and Lysinibacillus sphaericus LMG 22257, which were isolated from surface environments and then transferred under ambient pressure for half a century, possess moderately piezophilic characteristics with optimal growth pressures of 7 and 20MPa, respectively. Their tolerance to HHP was further enhanced by MgCl2 supplementation under the highest tested pressure of 50MPa. Transcriptomic analysis was performed to compare gene expression with and without MgCl2 supplementation under 50MPa for S. psychrophila DSM 6497. Among 4390 genes or transcripts obtained, 915 differentially expressed genes (DEGs) were identified. These DEGs are primarily associated with the antioxidant defense system, intracellular compatible solute accumulation, and membrane lipid biosynthesis, which have been reported to be essential for cells to cope with HHP. These findings indicate no in situ pressure barrier for piezophile isolation, and cells may adopt a common adaptation strategy to cope with different stresses.

Large Diversity in Nitrogen- and Sulfur-Containing Compatible Solute Profiles in Polar and Temperate Diatoms.

Intense bottom-ice algal blooms, often dominated by diatoms, are an important source of food for grazers, organic matter for export during sea ice melt, and dissolved organic carbon. Sea-ice diatoms have a number of adaptations, including accumulation of compatible solutes, that allows them to inhabit this highly variable environment characterized by extremes in temperature, salinity, and light. In addition to protecting them from extreme conditions, these compounds present a labile, nutrient-rich source of organic matter, and include precursors to climate active compounds (e.g., dimethyl sulfide [DMS]), which are likely regulated with environmental change. Here, intracellular concentrations of 45 metabolites were quantified in three sea-ice diatom species and were compared to two temperate diatom species, with a focus on compatible solutes and free amino acid pools. There was a large diversity of metabolite concentrations between diatoms with no clear pattern identifiable for sea-ice species. Concentrations of some compatible solutes (isethionic acid, homarine) approached 1 M in the sea-ice diatoms, Fragilariopsis cylindrus and Navicula cf. perminuta, but not in the larger sea-ice diatom, Nitzschia lecointei or in the temperate diatom species. The differential use of compatible solutes in sea-ice diatoms suggests different adaptive strategies and highlights which small organic compounds may be important in polar biogeochemical cycles.

Deciphering the Role of Trehalose in Tripartite Symbiosis Among Rhizobia, Arbuscular Mycorrhizal Fungi, and Legumes for Enhancing Abiotic Stress Tolerance in Crop Plants.

Drought is a critical factor limiting the productivity of legumes worldwide. Legumes can enter into a unique tripartite symbiotic relationship with root-nodulating bacteria of genera Rhizobium, Bradyrhizobium, or Sinorhizobium and colonization by arbuscular mycorrhizal fungi (AMF). Rhizobial symbiosis provides nitrogen necessary for growth. AMF symbiosis enhances uptake of diffusion-limited nutrients such as P, Zn, Cu, etc., and also water from the soil via plant-associated fungal hyphae. Rhizobial and AMF symbioses can act synergistically in promoting plant growth and fitness, resulting in overall yield benefits under drought stress. One of the approaches that rhizobia use to survive under stress is the accumulation of compatible solutes, or osmolytes, such as trehalose. Trehalose is a non-reducing disaccharide and an osmolyte reported to accumulate in a range of organisms. High accumulation of trehalose in bacteroids during nodulation protects cells and proteins from osmotic shock, desiccation, and heat under drought stress. Manipulation of trehalose cell concentrations has been directly correlated with stress response in plants and other organisms, including AMF. However, the role of this compound in the tripartite symbiotic relationship is not fully explored. This review describes the biological importance and the role of trehalose in the tripartite symbiosis between plants, rhizobia, and AMF. In particular, we review the physiological functions and the molecular investigations of trehalose carried out using omics-based approaches. This review will pave the way for future studies investigating possible metabolic engineering of this biomolecule for enhancing abiotic stress tolerance in plants.

Arbuscular mycorrhizal fungi mediated salt tolerance by regulating antioxidant enzyme system, photosynthetic pathways and ionic equilibrium in pea (Pisum sativumL.).

Arbuscular mycorrhizal (AM) fungi play an important role in improving the plant tolerance to salt stress. In the present study, we investigated the influence of AM fungi inoculation on various physiological, biochemical and nutritional aspects of pea grown under salt stress. The AM fungi inoculation successfully reduced the negative effects of salinity by improving the antioxidant enzyme system, a greater accumulation of compatible organic solutes, a higher content of photosynthetic pigment and a balanced uptake of nutrients, which resulted in higher growth and yield. Seed yield was found to be significantly higher by ~ 24, 40 and 54% in T2 (Rhizoglomusintraradices), T3 (Funneliformis mosseae and R. intraradices) and T4 (Rhizoglomus fasciculatum and Gigaspora sp.), respectively, as compared to nonmycorrhizal plants. Overall, a mixed application of Rfasciculatum and Gigaspora sp. was superior to other mycorrhizal treatments, which can be attributed to specific compatibility relationships or functional complementarity that exists between symbionts.

Different Gene Expression Response of Polish and Australian Raphidiopsis raciborskii Strains to the Chill/Light Stress

R. raciborskii is known for growing under wide ranges of temperature and light. In temperate regions, however, low temperature and high light may serve as a stressful condition for invading tropical populations. The genetic basis of R. raciborskii’s adaptation to this combination of stresses are unknown. In this study, the growth rate and the expression of genes that may be crucial in the response to the chill/light stress of two R. raciborskii strains (differing in their climatic origin and toxicity) exposed to low temperature and high light were examined. Results showed that AMU-DH-30, a non CYN (cylindrospermopsin) producing strain isolated from the temperate region, exhibited under stress the upregulation of genes involved in the protein translation (rbp1, nusG, hflX), membrane fluidity (desA), photosynthetic activity (ccr2 and ftsH), and the accumulation of compatible solutes (asd). In contrast, a CYN producing Australian strain CS-505 was not able to adapt quickly and to continue growth during stress conditions. Intriguingly, CS-505 and AMU-DH-30 had a similar ability to resume growth when the stress conditions subsided. Moreover, in strain CS-505 the cyrB gene was significantly upregulated under the stress conditions. The presented results shed new light on the possible mechanisms involved in the response of R.raciborskii to chill/light stress.

Foliar spray of salicylic acid induces physiological and biochemical changes in purslane (Portulaca oleracea L.) under drought stress

Purslane (Portulaca oleracea L.) is a plant with a long history in cooking and folk medicine that has been distributed worldwide. In the present study, purslane was used as a model plant to investigate the effect of foliar application of salicylic acid (SA) on plant tolerance to drought stress. The effects of SA foliar spray (0, 0.5 and 1 mM) on physiological and biochemical responses of purslane seedlings under drought stress (90, 60 and 30% field capacity) were investigated. The results showed that drought stress decreased the contents of photosynthetic pigments, parameters of gas exchanges, proline, soluble sugars, total phenolic, flavonoids, growth, and biomass production. However, SA improved photosynthetic pigments, gas exchanges, compatible solutes and secondary metabolites and thereby increased purslane growth and biomass production. Drought stress also induced oxidative stress (H2O2 and MDA) in purslane seedlings; however, SA reduced the drought-induced oxidative stress by regulating the activity of antioxidant enzymes. Drought stress increased the content of palmitic and arachidonic acid and decreased unsaturated fatty acids (oleic, linoleic and linolenic acid), stearic and behenic acid in the leaves of purslane. However, SA improved the fatty acids content under drought stress. These results indicate that foliar application of SA improved the adaptation and tolerance of the purslane plant to drought stress by improving gas exchange, increasing the accumulation of secondary metabolites and compatible solutes, improving the antioxidant defence system and regulating the fatty acids profile of membrane lipid.

Influence of sodium chloride on growth and metabolic reprogramming in nonprimed and haloprimed seedlings of blackgram (Vigna mungo L.).

Salinity hinders agricultural productivity worldwide by distressing plant metabolism. Growth of blackgram (Vigna mungo L. var. Sulata), an adverse climate-resistant pulse, is arrested under salinity. Present research integrates study of physio-biochemical parameters and non-targeted metabolomics approach to explore the alterations in metabolic pathway during adaptive responses of nonprimed and haloprimed blackgram seedlings grown hydroponically under NaCl stress. Salinity provoked accumulation of peroxides, compatible solutes and phenolics which increased free radical scavenging activities of nonprimed seedlings under salinity. Pre-germination seed halopriming abrogated NaCl-mediated adversities in haloprimed plantlets favouring better growth. Thus, farmers may adopt seed halopriming technique to improve blackgram productivity in saline-prone fields. Additionally, metabolomics study uncovered numerous metabolites amongst which 35 compounds altered significantly under salinity. The candidate metabolites were aspartic acid, L-glutamic acid, L-proline, L-asparagine, DL-isoleucine, L-homoserine, citrulline, L-ornithine, D-altrose, D-allose, N-acetyl-D-mannosamine, fructose, tagatose, sucrose, D-glucose, maltose, glycerol-1-phosphate, D-sorbitol, benzoic acid, shikimic acid, 4-hydroxycinnamic acid, arbutin, succinic acid, pipecolic acid, fumaric acid, nicotinic acid, L-pyroglutamic acid, oxalic acid, glyceric acid, maleamic acid, adenine, guanosine, lauric acid, stearic acid and porphine. Comparing metabolic responses of nonprimed and haloprimed seedlings, it was clear that efficient alteration in carbohydrate metabolism, phenolics accumulation, amino acid, organic acid and nucleic acid metabolism were the key places of metabolic reprogramming for tolerating salinity. Overall, we report, for the first time, 35 contributory candidate compounds that constituted core fundamental metabolome invoking salinity tolerance in nonprimed and haloprimed blackgram. These metabolites may be targeted by biotechnologists to produce high vigour salt-tolerant transgenic blackgram via genetic engineering.

Evaluation of usage and time of glycine amino acid application on growth and vegetative organs yield and antioxidant activity of Hyssop (Hyssopus officinalis L .) under different irrigation conditions

IntroductionHyssop (Hyssopus officinalis L.) belongs to the family of Lamiaceae. woody, perennial, shrubs with short, four-stalks, with a height of 50 to 70 centimeters. Its small and reciprocal leaves, the sharp, perfect, very aromatic, and its beautiful flowers, dark blue to purple, white. This herb has a powerful, cough- Soothing, expectorant effect, more or less diuretic and stomach tonic. Drought stress, while decreasing green growth and yield, causes changes in antioxidant activity in this plant. In nature, different environmental stresses threaten the survival, yield and growth of plants. Drought stress is one of the most important environmental stresses limiting the production of plants around the world, especially in arid and semi-arid regions. Drought stress generally destroys and breaks down chloroplates and decreases chlorophyll content and decreases the amount of enzymes activity in the Calvin cycle during photosynthesis and ultimately reduces the growth and yield of the crop. The accumulation of compatible solutes is one of the effective mechanisms for modulating the stresses of dehydration or salinity. This regulation is performed by the production of more organic materials such as protein, soluble sugars, and amino acids such as glycine, proline, alanine and valine in the air and root organs. Glycine is one of the important amino acids in the environmental stresses and chemical formula is NH2-CH2-COOH. This research were investigate the effects of foliar application of glycine amino acid and its application time on growth and yield and antioxidant compounds of Hyssop under different irrigation conditions.Materials and methodsThe experiment was conducted as split plot factorial in a randomized complete block design with three replications of Yazd agricultural and natural resources research farm in 2016-2017. Irrigation at 25, 50, 75% of the available soil water from the soil, order to control, medium stress, severe stress as the main factor and foliar application treatments in two levels of distilled water (control) and glycine amino acid (2.5 per thousand) and two levels of foliar application (vegetative and just flowering, flowering) were considered as subplots. The measured traits included plant height, lateral branch number, leaf number, fresh and dry weight yield, total phenolic compounds flavonoid and anthocyanin levels. SAS software was used to analyze the data. Mean comparison was performed by LSD at the probability level of 5%.Results and discussionDifferent irrigation treatments reduced the number of lateral branches, number of leaf, fresh and dry weight yields, total phenol, but the anthocyanin content increased. No significant differences were observed between foliar application time treatments. Interaction effects showed that the combination of control irrigation and foliar application of glycine increased the height and number of lateral branches. Also this material in combination with irrigation mild and severe stress treatments levels increased leaf number, fresh and dry weight yield of plant compared to control. Conclusion The results of this present study indicated that the external application of glycine amino acid in addition to reducing the damage caused by water stress in the plant, also has increased the plant's ability to improve grow and enhance yield.

Impact of high salinity and the compatible solute glycine betaine on gene expression of Bacillus subtilis

The Gram-positive bacterium Bacillus subtilis is frequently exposed to hyperosmotic conditions. In addition to the induction of genes involved in the accumulation of compatible solutes, high salinity exerts widespread effects on B. subtilis physiology, including changes in cell wall metabolism, induction of an iron limitation response, reduced motility and suppression of sporulation. We performed a combined whole-transcriptome and proteome analysis of B. subtilis 168 cells continuously cultivated at low or high (1.2 M NaCl) salinity. Our study revealed significant changes in the expression of more than one-fourth of the protein-coding genes and of numerous non-coding RNAs. New aspects in understanding the impact of high salinity on B. subtilis include a sustained low-level induction of the SigB-dependent general stress response and strong repression of biofilm formation under high-salinity conditions. The accumulation of compatible solutes such as glycine betaine aids the cells to cope with water stress by maintaining physiologically adequate levels of turgor and also affects multiple cellular processes through interactions with cellular components. Therefore, we additionally analysed the global effects of glycine betaine on the transcriptome and proteome of B. subtilis and revealed that it influences gene expression not only under high-salinity, but also under standard growth conditions.

Nitric Oxide Stimulates Antioxidant System and Osmotic Adjustment in Soybean Under Drought Stress

The target of the present study was to determine the effect of nitric oxide (NO) on drought stress amelioration in soybean plant. Plants were treated with different polyethylene glycol (PEG) concentrations (0, 5, 10, and 15%) without or with NO (100 μM). Based on our results, drought stress significantly decreased growth in soybean plants. Increase in hydrogen peroxide, malondialdehyde, and aldehyde content indicated drought-induced oxidative stress in soybean plants. Drought stress enhanced the activities of catalase, ascorbate peroxidase, accumulation of proline and glycine betaine, and lipoxygenase activity as well as total phenol and tocopherol content. NO had a beneficial effect on drought tolerance and promoted growth in soybean plants. NO treatment maintained soybean against drought-induced oxidative hurt, thereby improving the antioxidant defense mechanism (enzymatic and non-enzymatic antioxidants). NO application caused osmotic adjustment by up-regulation accumulation of compatible solutes in stressed plants. Enhanced plant growth was linked with induction of phenylalanine ammonia-lyase and tyrosine ammonia-lyase activity and decrease in electrolyte leakage by NO application. Our results revealed that NO had ability to alleviate the destructive effects in soybean plants under drought stress.

Foliar Pre-Treatment with Abscisic Acid Enhances Olive Tree Drought Adaptability.

Water is the most widely limiting factor for plants distribution, survival and agricultural productivity, their responses to drought and recovery being critical for their success and productivity. Olea europaea L. is a well-adapted species to cyclic drought events, still at considerable expense of carbon reserves and CO2 supply. To study the role of abscisic acid (ABA) as a promoter of drought adaptability, young potted olive trees subjected to three drought-recovery cycles were pre-treated with ABA. The results demonstrated that ABA pre-treatment allowed the delay of the drought effects on stomatal conductance (gs) and net photosynthesis (An), and under severe drought, permitted the reduction of the non-stomatal limitations to An and the relative water content decline, the accumulation of compatible solutes and avoid the decline of photosynthetic pigments, soluble proteins and total thiols concentrations and the accumulation of ROS. Upon rewatering, ABA-sprayed plants showed an early recovery of An. The plant ionome was also changed by the addition of ABA, with special influence on root K, N and B concentrations. The improved physiological and biochemical functions of the ABA-treated plants attenuated the drought-induced decline in biomass accumulation and potentiated root growth and whole-plant water use efficiency after successive drought-rewatering cycles. These changes are likely to be of real adaptive significance, with important implications for olive tree growth and productivity.

Comparative effects of nitric oxide and salicylic acid on salinity tolerance in saffron (Crocus sativus)

Salinity is a major environmental stress worldwide that adversely affects plant’s growth and metabolism. Various studies have demonstrated the positive effect of growth regulators on improving stress tolerance of plants. In this study, Crocus sativus as a profitable herb and expensive spice was subjected to nitric oxide and salicylic acid treatments to improve its sustainability under salinity stress. Based on our results treating Crocus sativus corms with nitric oxide caused more growth under salinity stress, also nitric oxide was able to reduce stress effects by compatible solutes accumulation, inducing antioxidative enzyme activities and increasing the biosynthesis of secondary metabolites. However, salicylic acid treatment did not improve plant growth under salinity.

Unveiling salinity effects on photo-bioelectrocatalysis through combination of bioinformatics and electrochemistry

Little is known about the adaptation strategies utilized by photosynthetic microorganisms to cope with salinity changes happening in the environment, and the effects on microbial electrochemical technologies. Herein, bioinformatics analysis revealed a metabolism shift in Rhodobacter capsulatus resulting from salt stress, with changes in gene expression allowing accumulation of compatible solutes to balance osmotic pressure, together with the up-regulation of the nitrogen fixation cycle, an electron sink of the photosynthetic electron transfer chain. Using the transcriptome evidence of hindered electron transfer in the photosynthetic electron transport chain induced by adaption to salinity, increased understanding of photo-bioelectrocatalysis under salt stress is achieved. Accumulation of glycine-betaine allows immediate tuning of salinity tolerance but does not provide cell stabilization, with a 40 ± 20% loss of photo-bioelectrocatalysis in a 60 min time scale. Conversely, exposure to or inducing the expression of the Rhodobacter capsulatus gene transfer agent tunes salinity tolerance and increases cell stability. This work provides a proof of concept for the combination of bioinformatics and electrochemical tools to investigate microbial electrochemical systems, opening exciting future research opportunities.

Important roles of glycinebetaine in stabilizing the structure and function of the photosystem II complex under abiotic stresses.

The molecular and physiological mechanisms of glycinebetaine stabilizing photosystem II complex under abiotic stresses are discussed, helping to address food shortage problems threatening the survival of growing population. In the backdrop of climate change, the frequency, dimensions and duration of extreme events have increased sharply, which may have unintended consequences for agricultural. The acclimation of plants to a constantly changing environment involves the accumulation of compatible solutes. Various compatible solutes enable plants to tolerate abiotic stresses, and glycinebetaine (GB) is one of the most-studied. The biosynthesis and accumulation of GB appear in numerous plant species, especially under environmental stresses. The exogenous application of GB and GB-accumulating transgenic plants have been proven to further promote plant development under stresses. Early research on GB focused on the maintenance of osmotic potential in plants. Subsequent experimental evidence demonstrated that it also protects proteins including the photosystem II complex (PSII) from denaturation and deactivation. As reviewed here, multiple experimental evidences have indicated considerable progress in the roles of GB in stabilizing PSII under abiotic stresses. Based on these advances, we've concluded two effects of GB on PSII: (1) it stabilizes the structure of PSII by protecting extrinsic proteins from dissociation or by promoting protein synthesize; (2) it enhances the oxygen-evolving activity of PSII or promotes the repair of the photosynthetic damage of PSII.