Search

Soil salinity is a major environmental constraint affecting the sustainability and profitability of agricultural production systems. Salinity stress tolerance has been present in wild crop relatives but then lost, or significantly weakened, during their domestication. Given the genetic and physiological complexity of salinity tolerance traits, agronomical solutions may be a suitable alternative to crop breeding for improved salinity stress tolerance. One of them is optimizing fertilization practices to assist plants in dealing with elevated salt levels in the soil. In this review, we analyse the causal relationship between the availability of boron (an essential metalloid micronutrient) and plant's adaptive responses to salinity stress at the whole-plant, cellular, and molecular levels, and a possibility of using boron for salt stress mitigation. The topics covered include the impact of salinity and the role of boron in cell wall remodelling, plasma membrane integrity, hormonal signalling, and operation of various membrane transporters mediating plant ionic and water homeostasis. Of specific interest is the role of boron in the regulation of H+-ATPase activity whose operation is essential for the control of a broad range of voltage-gated ion channels. The complex relationship between boron availability and expression patterns and the operation of aquaporins is also discussed.

Soil salinity is a major environmental hurdle for agricultural production, inhibiting crop growth reducing yield, and resulting in huge economic costs every year. Boron (B) is an essential micronutrient for plants that play a critical role in cell wall composition, membrane structure, and a broad range of metabolic activities. A few studies reported the beneficial effects of B on salinity tolerance in plants; however, the mechanistic basis of this process remains highly elusive. This study aimed to explore the mechanistic basis of the role of B for salt-grown plants including pea (Pisum sativum), Arabidopsis (Arabidopsis thaliana), and barley (Hordeum vulgare) with contrasting salinity stress tolerance, using a range of electrophysiological, molecular, and phenotyping techniques. In the salt-sensitive pea plants (Chapters 3-4), the detrimental effects of salinity on pea seedlings were reduced by the presence of appropriate B due to stimulation of H+-ATPase and the prevention of NaCl-induced K+ loss in the root, the higher shoot K retention, and Ca2+ influx functions as the signal response. Subsequently, we found B also exhibited an effect on halotropism besides root growth stimulation in model plant Arabidopsis (Chapter 5). The ameliorative effect of B on the Arabidopsis under salt stress exhibits a time- and dosedependent pattern based on H+-ATPase stimulation and a subsequent K+ retention, involving auxin- and RALF-FERONIA- pathways. In Chapter 6, B availability resulted in better salt tolerance in barley, which was achieved by improved photosynthetic performance, a more optimal K+/Na+ ratio and reduced Na+ and Cl− accumulation, higher K+ retention resulting from stimulation of H+-ATPase and a consequent plasma membrane (PM) hyperpolarization. The better performance of salt-tolerant TX9425 compared with salt-sensitive Gairdner response to salinity could be attributed to its superior capacity in the sequestration shoot Na+ and root K+ retention as well as

Soil salinity is a major environmental constraint affecting the sustainability and profitability of agricultural production systems. Salinity stress tolerance has been present in wild crop relatives but then lost, or significantly weakened, during their domestication. Given the genetic and physiological complexity of salinity tolerance traits, agronomical solutions may be a suitable alternative to crop breeding for improved salinity stress tolerance. One of them is optimizing fertilization practices to assist plants in dealing with elevated salt levels in the soil. In this review, we analyse the causal relationship between the availability of boron (an essential metalloid micronutrient) and plant's adaptive responses to salinity stress at the whole-plant, cellular, and molecular levels, and a possibility of using boron for salt stress mitigation. The topics covered include the impact of salinity and the role of boron in cell wall remodelling, plasma membrane integrity, hormonal signalling, and operation of various membrane transporters mediating plant ionic and water homeostasis. Of specific interest is the role of boron in the regulation of H+-ATPase activity whose operation is essential for the control of a broad range of voltage-gated ion channels. The complex relationship between boron availability and expression patterns and the operation of aquaporins is also discussed.

Soil salinity is a major environmental constraint affecting agricultural production systems. Boron (B) is an essential micronutrient for plants. This work was aimed to reveal the mechanistic basis of amelioration of detrimental effects of salinity on plant performance by boron. Barley (Hordeum vulgare) plants were exposed to different boron (H3BO3, from 0 to 1 mM) and salt (NaCl, 0 and 100 mM) treatments demonstrating salt-tolerant phenotype in the presence of B. This was manifested by the significant increase in leaf and root fresh weight, enhanced CO2 assimilation, intercellular CO2 concentration, and stomatal conductance. A significant reduction in root and shoot Na content combined with higher amounts of K+ in the presence of B provided more optimal tissue K+/Na+ ratios. At the cellular level, B-treated roots showed stronger stimulation of H+-ATPase by NaCl (using net H+ flux as a proxy) and could maintain more negative membrane potential. This enhanced cytosolic potassium retention (by reducing GORK-mediated K+ loss) and provided a driving force for the operation of SOS1 Na+/H+ exchanger explaining whole-plant ionomics data. Boron also affected the sensitivity of K+- and Ca2+- permeable ion channels to reactive oxygen species. Significantly less root K+ loss but more root Ca2+ uptake was observed for +B plants in response to H2O2, indicating the desensitization of K+- permeable channels and the cell type-specific Ca2+- permeable transporters to H2O2, and the role of B in their regulation. Overall, B availability resulted in better salt tolerance in barley, which could be a suitable alternative to crop breeding aimed at enhancing salt tolerance., Soil salinity is a major environmental constraint affecting agricultural production systems. Boron (B) is an essential micronutrient for plants. This work was aimed to reveal the mechanistic basis of amelioration of detrimental effects of salinity on plant performance by boron. Barley (Hordeum vulgare) plants were exposed to different boron (H3BO3, from 0 to 1 mM) and salt (NaCl, 0 and 100 mM) treatments demonstrating salt-tolerant phenotype in the presence of B. This was manifested by the significant increase in leaf and root fresh weight, enhanced CO2 assimilation, intercellular CO2 concentration, and stomatal conductance. A significant reduction in root and shoot Na content combined with higher amounts of K+ in the presence of B provided more optimal tissue K+/Na+ ratios. At the cellular level, B-treated roots showed stronger stimulation of H+-ATPase by NaCl (using net H+ flux as a proxy) and could maintain more negative membrane potential. This enhanced cytosolic potassium retention (by reducing GORK-mediated K+ loss) and provided a driving force for the operation of SOS1 Na+/H+ exchanger explaining whole-plant ionomics data. Boron also affected the sensitivity of K+- and Ca2+- permeable ion channels to reactive oxygen species. Significantly less root K+ loss but more root Ca2+ uptake was observed for +B plants in response to H2O2, indicating the desensitization of K+- permeable channels and the cell type-specific Ca2+- permeable transporters to H2O2, and the role of B in their regulation. Overall, B availability resulted in better salt tolerance in barley, which could be a suitable alternative to crop breeding aimed at enhancing salt tolerance.

Soil salinity is a major environmental constraint affecting agricultural production systems. Boron (B) is an essential micronutrient for plants. This work was aimed to reveal the mechanistic basis of amelioration of detrimental effects of salinity on plant performance by boron. Barley (Hordeum vulgare) plants were exposed to different boron (H3BO3, from 0 to 1 mM) and salt (NaCl, 0 and 100 mM) treatments demonstrating salt-tolerant phenotype in the presence of B. This was manifested by the significant increase in leaf and root fresh weight, enhanced CO2 assimilation, intercellular CO2 concentration, and stomatal conductance. A significant reduction in root and shoot Na content combined with higher amounts of K+ in the presence of B provided more optimal tissue K+/Na+ ratios. At the cellular level, B-treated roots showed stronger stimulation of H+-ATPase by NaCl (using net H+ flux as a proxy) and could maintain more negative membrane potential. This enhanced cytosolic potassium retention (by reducing GORK-mediated K+ loss) and provided a driving force for the operation of SOS1 Na+/H+ exchanger explaining whole-plant ionomics data. Boron also affected the sensitivity of K+- and Ca2+- permeable ion channels to reactive oxygen species. Significantly less root K+ loss but more root Ca2+ uptake was observed for +B plants in response to H2O2, indicating the desensitization of K+- permeable channels and the cell type-specific Ca2+- permeable transporters to H2O2, and the role of B in their regulation. Overall, B availability resulted in better salt tolerance in barley, which could be a suitable alternative to crop breeding aimed at enhancing salt tolerance., Soil salinity is a major environmental constraint affecting agricultural production systems. Boron (B) is an essential micronutrient for plants. This work was aimed to reveal the mechanistic basis of amelioration of detrimental effects of salinity on plant performance by boron. Barley (Hordeum vulgare) plants were exposed to different boron (H3BO3, from 0 to 1 mM) and salt (NaCl, 0 and 100 mM) treatments demonstrating salt-tolerant phenotype in the presence of B. This was manifested by the significant increase in leaf and root fresh weight, enhanced CO2 assimilation, intercellular CO2 concentration, and stomatal conductance. A significant reduction in root and shoot Na content combined with higher amounts of K+ in the presence of B provided more optimal tissue K+/Na+ ratios. At the cellular level, B-treated roots showed stronger stimulation of H+-ATPase by NaCl (using net H+ flux as a proxy) and could maintain more negative membrane potential. This enhanced cytosolic potassium retention (by reducing GORK-mediated K+ loss) and provided a driving force for the operation of SOS1 Na+/H+ exchanger explaining whole-plant ionomics data. Boron also affected the sensitivity of K+- and Ca2+- permeable ion channels to reactive oxygen species. Significantly less root K+ loss but more root Ca2+ uptake was observed for +B plants in response to H2O2, indicating the desensitization of K+- permeable channels and the cell type-specific Ca2+- permeable transporters to H2O2, and the role of B in their regulation. Overall, B availability resulted in better salt tolerance in barley, which could be a suitable alternative to crop breeding aimed at enhancing salt tolerance.

Wide bandgap oxide semiconductors constitute a unique class of materials that combine properties of electrical conductivity and optical transparency. They are being widely used as key materials in optoelectronic device applications, including flat-panel displays, solar cells, OLED, and emerging flexible and transparent electronics. In this article, an up-to-date review on both the fundamental understanding of materials physics of oxide semiconductors, and recent research progress on design of new materials and high-performing thin film transistor (TFT) devices in the context of fundamental understanding is presented. In particular, an in depth overview is first provided on current understanding of the electronic structures, defect and doping chemistry, optical and transport properties of oxide semiconductors, which provide essential guiding principles for new material design and device optimization. With these principles, recent advances in design of p-type oxide semiconductors, new approaches for achieving cost-effective transparent (flexible) electrodes, and the creation of high mobility 2D electron gas (2DEG) at oxide surfaces and interfaces with a wealth of fascinating physical properties of great potential for novel device design are then reviewed. Finally, recent progress and perspective of oxide TFT based on new oxide semiconductors, 2DEG, and low-temperature solution processed oxide semiconductor for flexible electronics will be reviewed.

This work reports a fundamental study on the relationship of the electronic structure, catalytic activity and surface reconstruction process of Fe doped NiS2 (FexNi1-xS2) for the oxygen evolution reaction (OER). A combined photoemission and X-ray absorption spectroscopic study reveals that Fe doping introduces more occupied Fe 3d6 states at the top of the valence band and thereby induces a metallic phase. Meanwhile, Fe doping also significantly increases the OER activity and results in much better stability with the optimum found for Fe0.1Ni0.9S2. More importantly, we performed detailed characterization to track the evolution of the structure and composition of the catalysts after different cycles of OER testing. Our results further confirmed that the catalysts gradually transform into amorphous (oxy)hydroxides which are the actual active species for the OER. However, a fast phase transformation in NiS2 is accompanied by a decrease of OER activity, because of the formation of a thick insulating NiOOH layer limiting electron transfer. On the other hand, Fe doping retards the process of transformation, because of a shorter Fe-S bond length (2.259 Å) than Ni-S (2.400 Å), explaining the better electrochemical stability of Fe0.1Ni0.9S2. These results suggest that the formation of a thin surface layer of NiFe (oxy)hydroxide as an active OER catalyst and the remaining Fe0.1Ni0.9S2 as a conductive core for fast electron transfer is the base for the high OER activity of FexNi1-xS2. Our work provides important insight and design principle for metal chalcogenides as highly active OER catalysts.