Towards the Development of Salt-Tolerant Potato

Soil salinity is a major constrain to crop production and climate change accelerates it. It reduces plant water potential, causes ion imbalance, reduce plant growth and productivity, and eventually leads to death of the plant. This is the case in potato. However, potato has coping strategies such as accumulation of proline, an osmoregulator and osmoprotector. In addition, leaching of salts below the root zone is preferred, exogenous application of ascorbic acid and growth hormones are practiced to combat salinity. Breeding and genetic engineering also play key roles in salinity management of potato. Varieties such as: Amisk, BelRus, Bintje, Onaway, Sierra, and Tobique were tolerant in North America, variety Cara in Egypt, Sumi in Korea and varieties Vivaldi and Almera in Mediterranean region. Transgenic lines of Kennebec variety, lines S2 and M48 also proved tolerance due to transcription factor MYB4 encoded by rice Osmyb4 gene.

Sequential Application of Antioxidants Rectifies Ion Imbalance and Strengthens Antioxidant Systems in Salt-Stressed Cucumber

Exogenous antioxidant applications enable salt-stressed plants to successfully cope with different environmental stresses. The objectives of this investigation were to study the effects of sequential treatments of proline (Pro), ascorbic acid (AsA), and/or glutathione (GSH) on 100 mM NaCl-stressed cucumber transplant’s physio-biochemical and growth traits as well as systems of antioxidant defense. Under salinity stress, different treatment of AsA, Pro, or/and GSH improved growth characteristics, stomatal conductance (gs), enhanced the activities of glutathione reductase (GR), superoxide dismutase (SOD), ascorbate peroxidase (APX), and catalase (CAT) as well as increased contents of AsA, Pro, and GSH. However, sequential application of antioxidants (GSH-Pro- AsA) significantly exceeded all individual applications, reducing leaf and root Cd2+ and Na+ contents in comparison to the control. In plants grown under NaCl-salt stress, growth characteristics, photosynthetic efficiency, membrane stability index (MSI), relative water content (RWC), contents of root and leaf K+ and Ca2+, and ratios of K+/Na+ and Ca2+/Na+ were notably reduced, while leaf contents of non-enzymatic and enzymatic antioxidants, as well as root and leaf Cd2+ and Na+ concentrations were remarkably increased. However, AsA, Pro, or/and GSH treatments significantly improved all investigated growth characteristics, photosynthetic efficiency, RWC and MSI, as well as AsA, Pro, and GSH, and enzymatic activity, leaf and root K+ and Ca2+ contents and their ratios to Na+, while significantly reduced leaf and root Cd2+ and Na+ contents.

Application of Crumpled Aluminum Hydroxide Nanostructures for Cancer Treatment

The tumormicroenvironment regulates tumor progression and the spread of cancer in the body. Applications of nanomaterials that can dysregulate tumor-microenvironment are emerging as a promising anti-cancer approaches, which can improve the efficacy of existing cancer treatments. We have reported that agglomerates of radially assembled Al hydroxide crumpled nanosheets with the disordered defective surface structure have a large positive charge and therefore can lead to ion imbalance at the cell perimembranous space through the selective adsorption of extracellular anionic species. This effect was demonstrated in vitro by reduced viability and proliferationof tumor cells, and further validated in a murine melanoma cancer model. Furthermore, crumpled Al hydroxide nanostructures showed a much stronger suppressive effect on tumor growth in combination with a minimally effective dose of doxorubicin. Taken together, the described approach of tumor microenvironment dysregulation through selective adsorption properties of folded crumpled nanostructures opened a new avenue for development of innovative anticancer therapy strategies.

Synergistic staphylocidal interaction of benzoic acid derivatives (benzoic acid, 4-hydroxybenzoic acid and β-resorcylic acid) and capric acid: mechanism and verification study using artificial skin

Objectives The present study was designed to investigate a synergistic staphylocidal interaction of antimicrobials. Methods The widely used preservative benzoic acid (BzA) and its derivatives [4-hydroxybenzoic acid (HA) and β-resorcylic acid (β-RA)] combined with capric acid (CPA) were investigated. Results β-RA was identified as the most effective antimicrobial exhibiting synergistic action with CPA against both Staphylococcus aureus and MRSA. For example, a complete reduction of bacteria (>7.3 log reduction) was obtained within 5 min after treatment with 5.0 mM β-RA (0.079%) plus 0.20 mM CPA (0.004%), while treatment with each material individually showed low bactericidal effects (<1.5 log reduction). Flow cytometry analysis identified membrane disruption related to the synergistic mechanisms, including the following: (i) membrane disruption by CPA (69.2% of cells were damaged by 0.20 mM CPA treatment); (ii) antimicrobial entry through the damaged membrane; and (iii) cytoplasmic ion imbalance resulting in cell death. We verified that the synergistic combination was also effective against MRSA on artificial skin (99.989% elimination after 5 min). Conclusions We used only consumer-preferred natural-borne antimicrobials and a very small amount of material was needed based on the synergistic effects. Therefore, these antimicrobials can be widely used as alternative anti-MRSA compounds in healthcare products, cosmetics, pharmaceutical products, foods and for environmental hygiene.

Accumulation of Phenylpropanoids in Tartary Buckwheat (Fagopyrum tataricum) under Salt Stress

Salinity stress affects plants by reducing the water potential and causing ion imbalance or disturbances in ion homeostasis and toxicity. Salinity stress frequently causes both osmotic and ionic stress in plants, resulting in the increase or decrease of certain secondary metabolites in plants. In this study, the effect of NaCl treatment on the nutritional quality of tartary buckwheat plants was studied by conducting an HPLC analysis of phenylpropanoid and anthocyanin content. It was observed that there was no significant change of color in tartary buckwheat during salt treatment. The accumulation of most phenylpropanoid compounds increased slightly in response to the NaCl concentration. The total phenylpropanoid content in tartary buckwheat was the highest at 100 mM NaCl treatment. Seven-day-old wheat plantlets treated with 100 mM NaCl for 2, 4, 6, and 8 days showed the highest accumulation of total phenylpropanoids at day 8 after treatment, while the content of most phenylpropanoids was higher than that in the control during this period. Although the development of tartary buckwheat slightly decreased with NaCl treatment and the accumulation of anthocyanin compounds did not change in plants with a diffident NaCl concentration and time treatment, the results suggest that the salinity treatment of tartary buckwheat causes antioxidant activity improvement by inducing an accumulation of flavonoid and phenolic compounds. However, since the anthocyanin content did not increase, the antioxidant effect of the treatment is not expected to be significant.

Adaptation of Plants to Salt Stress: Characterization of Na+ and K+ Transporters and Role of CBL Gene Family in Regulating Salt Stress Response

Salinity is one of the most serious factors limiting the productivity of agricultural crops, with adverse effects on germination, plant vigor, and crop yield. This salinity may be natural or induced by agricultural activities such as irrigation or the use of certain types of fertilizer. The most detrimental effect of salinity stress is the accumulation of Na+ and Cl− ions in tissues of plants exposed to soils with high NaCl concentrations. The entry of both Na+ and Cl− into the cells causes severe ion imbalance, and excess uptake might cause significant physiological disorder(s). High Na+ concentration inhibits the uptake of K+, which is an element for plant growth and development that results in lower productivity and may even lead to death. The genetic analyses revealed K+ and Na+ transport systems such as SOS1, which belong to the CBL gene family and play a key role in the transport of Na+ from the roots to the aerial parts in the Arabidopsis plant. In this review, we mainly discuss the roles of alkaline cations K+ and Na+, Ion homeostasis-transport determinants, and their regulation. Moreover, we tried to give a synthetic overview of soil salinity, its effects on plants, and tolerance mechanisms to withstand stress.

Chilling induces unidirectional solute leak through the locust gut epithelia

Chill-susceptible insects, like the migratory locust, often die when exposed to low temperatures from an accumulation of tissue damage that is unrelated to freezing (chilling injuries). Chilling injury is consistently associated with ion imbalance across the gut epithelia. It has recently been suggested that this imbalance is at least partly caused by a cold-induced disruption of epithelial barrier function. Here, we aim to test this hypothesis in the migratory locust (L. migratoria). First, chill tolerance was quantified by exposing locusts to −2°C for various durations and monitored for chill coma recovery time and survival 24h post-cold exposure. Longer exposure times significantly increased recovery time and caused injury and death. Ion-selective microelectrodes were also used to determine the presence of cold-induced ion imbalance. We found a significant increase and decrease of hemolymph K+ and Na+ concentrations over time, respectively. Next, barrier failure along the gut was tested by monitoring the movement of an epithelial barrier marker (FITC-dextran) across the gut epithelia during exposure to −2°C. We found minimal marker movement across the epithelia in the serosal to mucosal direction, suggesting that locust gut barrier function remains generally conserved during chilling. However, when tested in the mucosal to serosal direction, we saw significant increases of FITC-dextran with chilling. This instead suggests that while cold-induced barrier disruption is present, it is likely unidirectional. It is important to note that these data reveal only the phenomenon itself. The location of this leak as well as the underlying mechanisms remain unclear and require further investigation.Summary statementIn this study, we provide the first evidence for the presence of cold-induced paracellular leak along the gut of the migratory locust, and that this leak is strongest in the mucosal to serosal direction.

Enhanced Activity by NKCC1 and Slc26a6 Mediates Acidic pH and Cl− Movement after Cardioplegia-Induced Arrest of db/db Diabetic Heart

Diabetic heart dysfunctions during cardiac surgeries have revealed several clinical problems associated with ion imbalance. However, the mechanism of ion imbalance mediated by cardioplegia and a diabetic heart is largely unclear. We hypothesized that ion transporters might be regulated differently in the diabetic heart and that the differentially regulated ion transporters may involve in ion imbalance of the diabetic heart after cardioplegic arrest. In this study, we modified the Langendorff-free cardioplegia method and identified the involved ion transporters after cardioplegia-induced arrest between wild type and db/db heart. Enhanced expression of Na+-K+-2Cl− cotransporter 1 (NKCC1) was observed in the db/db heart compared to the wild type heart. Enhanced NKCC1 activity was observed in the left ventricle of db/db mice compared to that of wild type after cardioplegia-induced arrest. The expression and activity of Slc26a6, a dominant Cl−/HCO3− exchanger in cardiac tissues, were enhanced in left ventricle strips of db/db mice compared to that of wild type. The Cl− transporting activity in left ventricle strips of db/db mice was dramatically increased as compared to that of wild type. Interestingly, expression of Slc26a6, as well as carbonic anhydrase IV as a supportive enzyme of Slc26a6, was increased in db/db cardiac strips compared to wild type cardiac strips. Thus, the enhanced Cl− transporting activity and expression by NKCC1 and Slc26a6 in db/db cardiac tissues after cardioplegia-induced arrest provide greater insight into enhanced acidosis and Cl− movement-mediated db/db heart dysfunction. Thus, we suggested that enhanced Cl− influx and HCO3− efflux through NKCC1 and Slc26a6 offer more acidic circumstances in the diabetic heart after cardioplegic arrest. These transporters should be considered as potential therapeutic targets to develop the next generation of cardioplegia solution for protection against ischemia-reperfusion injury in diabetic hearts.

Role of Silicon in Mediating Salt Tolerance in Plants: A Review

Salt stress is a major threat for plant growth worldwide. The regulatory mechanisms of silicon in alleviating salt stress have been widely studied using physiological, molecular genetics, and genomic approaches. Recently, progresses have been made in elucidating the alleviative effects of silicon in salt-induced osmotic stress, Na toxicity, and oxidative stress. In this review, we highlight recent development on the impact of silicon application on salt stress responses. Emphasis will be given to the following aspects. (1) Silicon transporters have been experimentally identified in different plant species and their structure feature could be an important molecular basis for silicon permeability. (2) Silicon could mediate salt-induced ion imbalance by (i) regulating Na+ uptake, transport, and distribution and (ii) regulating polyamine levels. (3) Si-mediated upregulation of aquaporin gene expression and osmotic adjustment play important roles in alleviating salinity-induced osmotic stress. (4) Silicon application direct/indirectly mitigates oxidative stress via regulating the antioxidant defense and polyamine metabolism. (5) Omics studies reveal that silicon could regulate plants’ response to salt stress by modulating the expression of various genes including transcription factors and hormone-related genes. Finally, research areas that require further investigation to provide a deeper understanding of the role of silicon in plants are highlighted.