SOS1 gene family in mangrove (Kandelia obovata): Genome-wide identification, characterization, and expression analyses under salt and copper stress.

BACKGROUND: Salt Overly Sensitive 1 (SOS1), a plasma membrane Na+/H+ exchanger, is essential for plant salt tolerance. Salt damage is a significant abiotic stress that impacts plant species globally. All living organisms require copper (Cu), a necessary micronutrient and a protein cofactor for many biological and physiological processes. High Cu concentrations, however, may result in pollution that inhibits the growth and development of plants. The function and production of mangrove ecosystems are significantly impacted by rising salinity and copper contamination. RESULTS: A genome-wide analysis and bioinformatics techniques were used in this study to identify 20 SOS1 genes in the genome of Kandelia obovata. Most of the SOS1 genes were found on the plasma membrane and dispersed over 11 of the 18 chromosomes. Based on phylogenetic analysis, KoSOS1s can be categorized into four groups, similar to Solanum tuberosum. Kandelia obovata's SOS1 gene family expanded due to tandem and segmental duplication. These SOS1 homologs shared similar protein structures, according to the results of the conserved motif analysis. The coding regions of 20 KoSOS1 genes consist of amino acids ranging from 466 to 1221, while the exons include amino acids ranging from 3 to 23. In addition, we found that the 2.0 kb upstream promoter region of the KoSOS1s gene contains several cis-elements associated with phytohormones and stress responses. According to the expression experiments, seven randomly chosen genes experienced up- and down-regulation of their expression levels in response to copper (CuCl2) and salt stressors. CONCLUSIONS: For the first time, this work systematically identified SOS1 genes in Kandelia obovata. Our investigations also encompassed physicochemical properties, evolution, and expression patterns, thereby furnishing a theoretical framework for subsequent research endeavours aimed at functionally characterizing the Kandelia obovata SOS1 genes throughout the life cycle of plants.

An electrokinetic perspective into the mechanism of divalent and trivalent cation sorption by extracellular polymeric substances of Pseudomonas fluorescens.

Extracellular polymeric substances (EPS) contain a vast number of functional groups which can provide sorption sites for heavy metal cations in solution, however, the mechanisms for the interaction of EPS with various metal cations were not well understood. In this study, the sorption potential of EPS from Pseudomonas fluorescens for different cations was investigated. The changes of electrokinetic properties that occurred on the surface of EPS once they adsorbed these cations were also studied using zeta potential measurements as a function of pH and cation concentration. The adsorption data fitted Freundlich isotherm better than Langmuir and D-R isotherms. The interactions of the cations with EPS were favourable with the separation factor Kr < 1. Under different pH conditions, the zeta potential of EPS in the different cation solution followed the order: Fe(III) (at pH ≤ 5.0) > Al(III) > Cu(II) > Mn(II) > Ni(II)≈Cd(II) > Ca(II) > EPS, while with respect to the initial cation concentration, the zeta potential of EPS was in the order: Fe(III) > Al(III) > Cu(II) > Cd(II) > Ni(II)≈Mn(II)≈Ca(II). The effect of cation sorption on the surface charge of EPS increased with pH as well as cation concentration. The thermodynamic analysis demonstrated that besides the sorption of Fe which was exothermic, all the other cations were adsorbed through an endothermic process. The ΔSads revealed that most of the cations interacted with EPS through the formation of inner-sphere complexes. The ATR-FTIR analyses confirmed that complexation occurred between the cations and functional groups on the surface of EPS. The zeta potential of EPS shifted to positive value direction due to sorption of cations on EPS, indicating that the specific interactions were involved in the sorption process. This study enhances our understanding of EPS aggregation and heavy metal bio-sorption through the electrokinetic mechanism. The results will provide useful references for immobilization of heavy metals and alleviation of Al toxicity in acidic soils.