Background: Soil salinity adversely affects plant growth and development and disturbs intracellular ion homeostasis resulting cellular toxicity. The Salt Overly Sensitive 1 (SOS1) gene encodes a plasma membrane Na⁺/H⁺ antiporter that plays an important role in imparting salt stress tolerance to plants. Here, we report the cloning and characterisation of the SbSOS1 gene from Salicornia brachiata, an extreme halophyte. Results: The SbSOS1 gene is 3774 bp long and encodes a protein of 1159 amino acids. SbSOS1 exhibited a greater level of constitutive expression in roots than in shoots and was further increased by salt stress. Overexpressing the S. brachiata SbSOS1 gene in tobacco conferred high salt tolerance, promoted seed germination and increased root length, shoot length, leaf area, fresh weight, dry weight, relative water content (RWC), chlorophyll, K⁺/Na⁺ ratio, membrane stability index, soluble sugar, proline and amino acid content relative to wild type (WT) plants. Transgenic plants exhibited reductions in electrolyte leakage, reactive oxygen species (ROS) and MDA content in response to salt stress, which probably occurred because of reduced cytosolic Na⁺ content and oxidative damage. At higher salt stress, transgenic tobacco plants exhibited reduced Na⁺ content in root and leaf and higher concentrations in stem and xylem sap relative to WT, which suggests a role of SbSOS1 in Na⁺ loading to xylem from root and leaf tissues. Transgenic lines also showed increased K⁺ and Ca²⁺ content in root tissue compared to WT, which reflect that SbSOS1 indirectly affects the other transporters activity. Conclusions: Overexpression of SbSOS1 in tobacco conferred a high degree of salt tolerance, enhanced plant growth and altered physiological and biochemical parameters in response to salt stress. In addition to Na⁺ efflux outside the plasma membrane, SbSOS1 also helps to maintain variable Na⁺ content in different organs and also affect the other transporters activity indirectly. These results broaden the role of SbSOS1 in planta and suggest that this gene could be used to develop salt-tolerant transgenic crops.

Metabolomics is now considered a wide-ranging, sensitive and practical approach to acquire useful information on the composition of a metabolite pool present in any organism, including plants. Investigating metabolomic regulation in plants is essential to understand their adaptation, acclimation and defense responses to environmental stresses through the production of numerous metabolites. Moreover, metabolomics can be easily applied for the phenotyping of plants; and thus, it has great potential to be used in genome editing programs to develop superior next-generation crops. This review describes the recent analytical tools and techniques available to study plants metabolome, along with their significance of sample preparation using targeted and non-targeted methods. Advanced analytical tools, like gas chromatography-mass spectrometry (GC-MS), liquid chromatography mass-spectroscopy (LC-MS), capillary electrophoresis-mass spectrometry (CE-MS), fourier transform ion cyclotron resonance-mass spectrometry (FTICR-MS) matrix-assisted laser desorption/ionization (MALDI), ion mobility spectrometry (IMS) and nuclear magnetic resonance (NMR) have speed up precise metabolic profiling in plants. Further, we provide a complete overview of bioinformatics tools and plant metabolome database that can be utilized to advance our knowledge to plant biology.

Climate change fuels invasions of plant species and displacement of local plants. Little is known about the ecophysiological adaptation of the invasive species, and their ability to cope with the changing conditions in their new habitat. Halophila stipulacea, a tropical seagrass native to the Gulf of Aqaba (GoA; northern Red Sea), became a Lessepsian migrant spreading within the eastern Mediterranean where it could potentially outcompete local species. We analyzed temperature records in the last 35 years and show that water temperature has increased faster in the eastern Mediterranean Sea compared to GoA, suggesting that H. stipulacea’s invasive success is associated with adaptation to thermal warming. Furthermore, we compared the responses of native (Eilat, Israel) and invasive (Limassol, Cyprus) H. stipulacea plants to current (26°C) and predicted thermal maxima (29 and 32°C) in a controlled experimental microcosm. Morphological and photo-physiological results showed negative effects of heat stress on the native plants while un-affected/or even enhanced performance in their invasive counterparts. Gene expression, studied for the 1^st time in H. stipulacea, pointed to differences in the molecular responses of two populations to thermal stress. Results predict that sea warming will cause vast reductions in H. stipulacea meadows growing in the GoA while it will facilitate H. stipulacea’s spread within the Mediterranean Sea.

Dwindling water resources combined with meeting the demands for food security require maximizing water use efficiency (WUE) both in rainfed and irrigated agriculture. In this regard, deficit irrigation (DI), defined as the administration of water below full crop-water requirements (evapotranspiration), is a valuable practice to contain irrigation water use. In this study, the mechanism of paclobutrazol (Pbz)-mediated improvement in tolerance to water deficit in tomato was thoroughly investigated. Tomato plants were subjected to normal irrigated and deficit irrigated conditions plus Pbz application (0.8 and 1.6 ppm). A comprehensive morpho-physiological, metabolomics and molecular analysis was undertaken. Findings revealed that Pbz application reduced plant height, improved stem diameter and leaf number, altered root architecture, enhanced photosynthetic rates and WUE of tomato plants under deficit irrigation. Pbz differentially induced expression of genes and accumulation of metabolites of the tricarboxylic acid (TCA) cycle, γ-aminobutyric acid (GABA-shunt pathway), glutathione ascorbate (GSH-ASC)-cycle, cell wall and sugar metabolism, abscisic acid (ABA), spermidine (Spd) content and expression of an aquaporin (AP) protein under deficit irrigation. Our results suggest that Pbz application could significantly improve tolerance in tomato plants under limited water availability through selective changes in morpho-physiology and induction of stress-related molecular processes.

The single crystal X-ray structure of the newly synthesized ruthenium (II)-polypyridyl complex, [(bpy)₂Ru(L)](PF₆)₂ (1) (bpy is 2,2′-bipyridyl and L is 2-methyl-2H-1,3,7,8-tetraaza-cyclopenta[l]phenanthren-2-ol revealed a near planar conformation for the fused imidazole moiety, suggesting the complex may be capable of binding to duplex DNA. Binding-induced changes in spectral properties, along with thermal denaturation and viscosity measurement studies confirmed that the complex binds to CT-DNA with a moderately high binding constant value (4.1 × 10⁵ M⁻¹) through intercalation. Photocleavage studies with the pBR322 plasmid DNA were performed following excitation of this complex into the Ru(dπ) → bpy/L(π*)-based MLCT band and have shown that this complex cleaves the circular pBR322 DNA into linear DNA. Inhibitor studies revealed that the hydroxyl radicals were mainly responsible for the DNA photocleavage reaction. Preliminary studies indicate that the –OH functionality in 1 was also found to hydrolyse the phosphodiester linkage of pBR322 in the dark.