Improved salt tolerance by α-tocopherol in soybean involves up-regulation of ascorbate-glutathione cycle and secondary metabolites

The effects of α-tocopherol on growth, photosynthesis, oxidative parameters, and tolerance mechanisms in soybean under increased salinity were studied. Salinity stress reduced shoot length, dry weight, chlorophyll and carotenoids, photosynthesis, and PSII activity; however, α-tocopherol mitigated the decline considerably. Salinity stress caused accumulation of superoxide (O2-) hydrogen peroxide (H2O2), thereby increased lipid peroxidation and decreased membrane stability index. Application of α-tocopherol ameliorated oxidative damage by reducing lipid peroxidation and downregulating lipoxygenase activity. The up-regulation of antioxidant and glyoxylase systems protected soybean from the damaging effects of ROS and methylglyoxal. Moreover the content of ascorbate, reduced glutathione and α-tocopherol increased significantly. The activity of γ-glutamyl kinase also increased due to application of α-tocopherol and accumulation of Na+ was significantly declined with enhancement in K+ uptake. Therefore results of present study revealed the beneficial effect of foliar application of α-tocopherol under salinity stress in soybean

Insights into Cadmium-Induced Morphophysiological Disorders in Althea rosea Cavan and Its Phytoremediation through the Exogeneous Citric Acid

Cadmium (Cd) is taken in plants from soil and then travels through the food cycle, posing a major threat to all the units of the ecosystem. A pot experiment was conducted to understand the influence of citric acid (CA) on Cadmium (Cd) phytoextraction ability of hollyhock (Althea rosea Cavan.). A. rosea plants were exposed to Cd concentrations (100 and 200 mg·kg−1), either in simultaneous administration or without adding CA (5 mM·kg−1 dry weight). The results revealed that exposing A. rosea to different levels of Cd stress, i.e., 100 and 200 mg·kg−1, significantly decreased (p < 0.05) plant growth and biochemical attributes, such as root length (RL), shoot length (SL), fresh biomass (FW), dry biomass (DW), relative water content (RWC), and chlorophyll and carotenoid contents. Meanwhile, a net increase in MDA and REL indicated Cd-induced oxidative stress in plants. However, the application of citric acid (CA) as an organic chelator helped the plants to alleviate the phytotoxic effects of Cd stress on A. rosea, which is shown in terms of enhancing plant growth and biomass; that is, the root length (27.3% and 21.12%), shoot length (32.11% and 23.02%), fresh weight (39.66% and 29.8%), and dry weight (29.8% and 57.33%) under 100 and 200 mg·kg−1 of Cd stress, respectively, were observed. CA application also helped to alleviate the level of chlorophyll and carotenoid contents; foster high level of antioxidants, such as SOD, POD, CAT, and APX; and lower concentration of MDA and EL. In addition to enhancing plant-growth attributes, the application of CA also managed to increase the phytoextraction potential of the plants by enhancing the concentration of Cd in roots and shoots tissues. This is also demonstrated by rising levels of bioaccumulation (BAC) and translocation factors (TFs). These findings showed that CA application could be a practical strategy to apply to ornamental plants, such as A. rosea seedlings, cultivated in Cd-contaminated locations, opening ways to cope with Cd stress and enhanced phytoextraction

Correction: Alnusairi et al. Exogenous Nitric Oxide Reinforces Photosynthetic Efficiency, Osmolyte, Mineral Uptake, Antioxidant, Expression of Stress-Responsive Genes and Ameliorates the Effects of Salinity Stress in Wheat. Plants 2021, 10, 1693

In the original publication [...

Exogenous Nitric Oxide Reinforces Photosynthetic Efficiency, Osmolyte, Mineral Uptake, Antioxidant, Expression of Stress-Responsive Genes and Ameliorates the Effects of Salinity Stress in Wheat

Salinity stress is one of the major environmental constraints responsible for a reduction in agricultural productivity. This study investigated the effect of exogenously applied nitric oxide (NO) (50 μM and 100 μM) in protecting wheat plants from NaCl-induced oxidative damage by modulating protective mechanisms, including osmolyte accumulation and the antioxidant system. Exogenously sourced NO proved effective in ameliorating the deleterious effects of salinity on the growth parameters studied. NO was beneficial in improving the photosynthetic efficiency, stomatal conductance, and chlorophyll content in normal and NaCl-treated wheat plants. Moreover, NO-treated plants maintained a greater accumulation of proline and soluble sugars, leading to higher relative water content maintenance. Exogenous-sourced NO at both concentrations up-regulated the antioxidant system for averting the NaCl-mediated oxidative damage on membranes. The activity of antioxidant enzymes increased the protection of membrane structural and functional integrity and photosynthetic efficiency. NO application imparted a marked effect on uptake of key mineral elements such as nitrogen (N), potassium (K), and calcium (Ca) with a concomitant reduction in the deleterious ions such as Na+. Greater K and reduced Na uptake in NO-treated plants lead to a considerable decline in the Na/K ratio. Enhancing of salt tolerance by NO was concomitant with an obvious down-regulation in the relative expression of SOS1, NHX1, AQP, and OSM-34, while D2-protein was up-regulated

Exogenous Myo-Inositol Alleviates Salt Stress by Enhancing Antioxidants and Membrane Stability via the Upregulation of Stress Responsive Genes in <i>Chenopodium quinoa</i> L.

Myo-inositol has gained a central position in plants due to its vital role in physiology and biochemistry. This experimental work assessed the effects of salinity stress and foliar application of myo-inositol (MYO) on growth, chlorophyll content, photosynthesis, antioxidant system, osmolyte accumulation, and gene expression in quinoa (Chenopodium quinoa L. var. Giza1). Our results show that salinity stress significantly decreased growth parameters such as plant height, fresh and dry weights of shoot and root, leaf area, number of leaves, chlorophyll content, net photosynthesis, stomatal conductance, transpiration, and Fv/Fm, with a more pronounced effect at higher NaCl concentrations. However, the exogenous application of MYO increased the growth and photosynthesis traits and alleviated the stress to a considerable extent. Salinity also significantly reduced the water potential and water use efficiency in plants under saline regime; however, exogenous application of myo-inositol coped with this issue. MYO significantly reduced the accumulation of hydrogen peroxide, superoxide, reduced lipid peroxidation, and electrolyte leakage concomitant with an increase in the membrane stability index. Exogenous application of MYO up-regulated the antioxidant enzymes’ activities and the contents of ascorbate and glutathione, contributing to membrane stability and reduced oxidative damage. The damaging effects of salinity stress on quinoa were further mitigated by increased accumulation of osmolytes such as proline, glycine betaine, free amino acids, and soluble sugars in MYO-treated seedlings. The expression pattern of OSM34, NHX1, SOS1A, SOS1B, BADH, TIP2, NSY, and SDR genes increased significantly due to the application of MYO under both stressed and non-stressed conditions. Our results support the conclusion that exogenous MYO alleviates salt stress by involving antioxidants, enhancing plant growth attributes and membrane stability, and reducing oxidative damage to plants

Implementation of Floating Treatment Wetlands for Textile Wastewater Management: A Review

The textile industry is one of the most chemically intensive industries, and its wastewater is comprised of harmful dyes, pigments, dissolved/suspended solids, and heavy metals. The treatment of textile wastewater has become a necessary task before discharge into the environment. The textile effluent can be treated by conventional methods, however, the limitations of these techniques are high cost, incomplete removal, and production of concentrated sludge. This review illustrates recent knowledge about the application of floating treatment wetlands (FTWs) for remediation of textile wastewater. The FTWs system is a potential alternative technology for textile wastewater treatment. FTWs efficiently removed the dyes, pigments, organic matter, nutrients, heavy metals, and other pollutants from the textile effluent. Plants and bacteria are essential components of FTWs, which contribute to the pollutant removal process through their physical effects and metabolic process. Plants species with extensive roots structure and large biomass are recommended for vegetation on floating mats. The pollutant removal efficiency can be enhanced by the right selection of plants, managing plant coverage, improving aeration, and inoculation by specific bacterial strains. The proper installation and maintenance practices can further enhance the efficiency, sustainability, and aesthetic value of the FTWs. Further research is suggested to develop guidelines for the selection of right plants and bacterial strains for the efficient remediation of textile effluent by FTWs at large scales