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Abstract\nNOVELTY STATEMENTMethylene blue, a cationic dye as a pollutant is discharged from industrial effluent into aquatic bodies. The dye is biomagnified through the food chain and is detrimental to the sustainability of aquatic flora. Despite of number of physico-chemical techniques of dye removal, the use of aquatic flora for bio-adsorption is encouraged. Thus, we used Salvinia molesta D. Mitch in bio-reduction of methylene blue on concentrations of 0, 10, 20, and 30 mg L−1 through 5 days with biosorption kinetics. The dye removal was concentration-dependent, maximized at 2 days with 30 mg L−1 which altered the relative growth rate (44%) of plants. Biosorption recorded 71% capacity at optimum pH (8.0), 24 h reducing major bond energies of amide, hydroxyl groups, etc. Bioaccumulation of dye changed potassium content (446%) under maximum dye concentration modifying tissues for dye sequestration. Reactive oxygen species were altered on dye reduction by oxidase (33%) with redox homeostasis by enzymes. Plants altered the metabolism with over accumulation of polyamines (51%), abscisic acids (448%), and phosphoenolpyruvate carboxylase (83%) on dye reduction. Thus, this study is rationalized with a sustainable approach where aquatic ecosystems can be decontaminated from dye toxicity with the exercise of bioresources like Salvinia molesta D. Mitch as herein.Azo dyes as industrial effluents are more hazardous with their high solubility in water causing inhibition of life processes in aquatic ecosystem. Methylene blue as a dye, in the aquatic environment deteriorates the ecosystem by increasing a chemical oxygen demand, impairing light harnessing mechanism, inhibiting growth of microflora, recalcitrance, bioaccumulation, mutagenicity of the whole environment. Aquatic weed like Salvinia molesta D. Mitch is evident as an effective bio-adsorbent, bio-decolorization, finally dye removing material to reduce water pollution as an alternative strategy for environmental remediation. [ABSTRACT FROM AUTHOR]

We examined the efficacy of 2,4-dichlorophenoxy acetic acid (2,4-D; 500 µM) in enhancing the potential of Salvinia species for tolerance to aluminum (Al) toxicity (240 and 480 µM, seven days). Salvinia showed better efficacy in removal of toxicity of Al by sorption mechanism with changes of bond energy shifting on cell wall residues and surface structure. Plants recorded tolerance to Al concentration (480 µM) when pretreated with 2,4-D through adjustment of relative water content, proline content, osmotic potential, and improved the pigment fluorescence for energy utilization under Al stress. Photosynthetic activities with regards to NADP-malic enzyme and malic dehydrogenase and sugar metabolism with wall and cytosolic invertase activities were strongly correlated with compatible solutes. A less membrane peroxidation and protein carbonylation had reduced ionic loss over the membrane that was studied with reduced electrolyte leakage with 2,4-D pretreated plants. Membrane stabilization was also recorded with higher ratio of K+ to Na+, thereby suggesting roles of 2,4-D in ionic balance. Better sustenance of enzymatic antioxidation with peroxidase and glutathione metabolism reduced reactive oxygen species accumulation and save the plant for oxidative damages. Moreover, gene polymorphism for antioxidant, induced by 2,4-D varied through Al concentrations would suggest an improved biomarker for tolerance. Collectively, analysis and discussion of plant's responses assumed that auxin herbicide could be a potential phytoprotectant for Salvinia as well as improving the stability to Al toxicity and its bioremediation efficacy. In previous reports, aquatic weeds, particularly, from pteridophytic flora have been exercised, however, in less frequent. Aluminum (Al) toxicity, being a major problem, specifically with respect to cultivated crops like rice and vegetables, is a serious issue in alkaline soil. In context to growth of Salvinia in the areas of low lands where few important crops like rice are frequently cultivated. Therefore, Al toxicity with regards to rice cultivation in low land conditions, which is habitat for Salvinia, could be interesting. Thus, decontamination of low land for salinity with aquatic environment can be remediated with biological materials where Salvinia would be a choice. This would be something new in studies for the aquatic weeds over the existing database. Moreover, 2,4-dichlorophenoxy acetic acid (2,4-D) being a common herbicide in agricultural field that becomes more problematic with metal toxicity is another focus for physiological responses with Salvinia. The adoption and sustainability of Salvinia against 2,4-D may highlight insights for physiological activities would be the biomarker for herbicide toxicity. [ABSTRACT FROM AUTHOR]

Waterlogging or flooding in agricultural soil constructs a complex abiotic stress-web in crop plants throughout the lowland agricultural system. In rice, a staple grain crop in the world, submergence creates a long-term and recurrent problem for crops withstanding and their succeeding productivity. Therefore, to restore a satisfactory yield instead of a failure of crop in such submerged areas, the analysis of plants' responses is important. Such analysis will facilitate research about the entity components of plants responses to anoxia or submergence. For example, the development of cellular and molecular cascade in gene expression of ROS signaling and its subsequent responses may lead to either tolerance or susceptibility in plants. Interplay of plant growth regulators [e.g., ethylene (ET), abscisic acid (ABA), gibberellic acid (GA) etc.] is the well-recognized residues in the coordination of signaling, its transmission through cellular network, and finally, modulation of gene expression are the keys to such tolerance. Nucleotide elements that are specifically sensitive to ethylene have been rescued from land-races of aus-type group of rice ( Oryza sativa ) and those are considered as the prime determinants for tolerance against anoxia. In this comprehensive text, we tried to accommodate and revise the fundamental and pivotal mechanisms of submergence stress at different angles of physiological and cellular responses of plants. These have also been reviewed for modern state of art techniques deciphering the molecular rejoinders like microRNA, protein-protein interaction, feedback regulation of expression, sugar sensing, amplification of elicitor's responses and others. Finally, strategies including physiological selection, metabolic engineering, marker assisted selection, genetical manipulation, interspecific hybridization are involved in developing stress resilience and plants' architecture to support sustainable agriculture under lowland systems., (© 2021 The Author(s). Published by BRI.)