Phytohormones-Assisted Management of Salinity Impacts in Plants

The salinity of soils has been significantly limiting crop production in most arid and semi-arid regions of the world. Plant hormones (phytohormones), small molecules with versatile roles in plants can be a sustainable approach for minimizing the major salinity-impacts in plants. Most phytohormones are reported to regulate various signaling cascades interrelated with plant development and stress-resilience and -coping mechanisms. In addition to regulating photosynthesis and related variables, phytohormones also modulate nutrient homeostasis, source-sink capacity, osmoregulation, and antioxidant defense systems in plants under abiotic stresses including soil salinity. Molecular studies have confirmed the coordination between phytohormones and signaling networks, which in turn also maintains ionic homeostasis and plant-salinity tolerance. This chapter aims to appraise the literature available on the role of 10 well-characterized stress response hormones (abscisic acid, ABA; ethylene; salicylic acid, SA; jasmonic acid, JA; and nitric oxide, NO) and also other growth-promoting hormones (such as auxins, gibberellins, GA; cytokinins, CKs; brassinosteroids, BRs; and strigolactones, SLs) in the management of salinity impacts in plants. The discussion outcomes may help in devising and furthering the strategies aimed at sustainably strengthening plant-salinity tolerance

Electrochemical studies on the performance characteristics of alkaline solid embeddable sensor for concrete environments

In this study, alkaline solid embeddable MnO2 is used as a reference sensor for concrete environments. The performance characteristics are evaluated in a saturated calcium hydroxide solution, a synthetic concrete pore solution and ordinary Portland cement (OPC) extracts which correspond to the concrete environments. The electrochemical stability of the MnO2 electrode is studied in the said concrete environments. The uniformity of the MnO2 sensor is tested in concrete environments. The reversibility of MnO2 sensor in three alkaline solutions is within ±10mV, which is very well within the limit as sensor for concrete. The polarization behaviour of MnO2 electrode in concrete environments is carried out potentiodynamically and impedance behaviour showed the stability of sensor. All the studies revealed that MnO2 as a suitable sensor electrode for concrete structure

Evaluation of embeddable potential sensor for corrosion monitoring in concrete structures

Embeddable potential sensor based on MnO2 was assembled and characterised in concrete. The stability, reversibility, polarisability and impedance characteristics have been studied with respect to known reference. The corrosion performance of reinforced steel with respect to MnO2 sensor was monitored by different electrochemical techniques. Reversibility of MnO2 sensor indicated that difference of ±5mV between the forward and reverse scan indicates the better reversibility characteristics in concrete. The rebar potentials (ER) of steel with respect to MnO2 are −315 and −525mV for passive and active conditions of rebar in concrete. The corrosion current from potentiodynamic polarisation and Rct from a.c. impedance technique clearly differentiated the behaviour of steel embedded in chloride contaminated concrete (active condition) from uncontaminated concrete (passive condition) with respect to MnO2 sensor. All these studies revealed that corrosion monitoring of steel in concrete using embedded MnO2 as a better potential sensor for steel in concrete. In addition it is easy to fabricate for amenable miniaturisation, varied configuration as demanded for corrosion monitoring in concrete structures

Elevation dependent sensitivity of northern hardwoods to Ca addition at Hubbard Brook Experimental Forest, NH, USA

Acidic deposition has caused a depletion of calcium (Ca) in the northeastern forest soils. Wollastonite (Ca silicate) was added to watershed 1 (WS1) at the Hubbard Brook Experimental Forest (HBEF) in 1999 to evaluate its effects on various functions of the HBEF ecosystem. The effects of Ca addition on foliar soluble (extractable in 5% HCIO(4)) ions, chlorophyll, polyamines, and amino acids were studied in three hardwood species, namely sugar maple, yellow birch, and American beech. We further analyzed these effects in relation to elevation at Ca-supplemented WS1 and reference WS3 watersheds. Foliar soluble Ca increased significantly in all species at mid and high elevations at Ca-supplemented WS1. This was accompanied by increases in soluble P. chlorophyll, and two amino acids, glutamate and glycine. A decrease in known metabolic indicators of physiological stress (i.e., the amino acids, arginine and gamma-aminobutyric acid (GABA), and the diamine, putrescine) was also observed. In general, these changes were species-specific and occurred in an elevation dependent manner. Despite an observed increase in Ca at high elevation for all three species, only sugar maple exhibited a decrease in foliar putrescine at this elevation indicating possible remediation from Ca deficiency. At higher elevations of the reference WS3 site, foliar concentrations of Ca and Mg, as well as Ca:Mn ratios were lower, whereas Al, putrescine, spermidine, and GABA were generally higher. Comparison of metabolic data from these three species reinforces the earlier findings that sugar maple is the most sensitive and American beech the least sensitive species to soil Ca limitation. Furthermore, there was an increase in sensitivity with an increase in elevation. Published by Elsevier B.V

The response of high and low polyamine-producing cell lines to aluminum and calcium stress

The diamine putrescine (Put) has been shown to accumulate in tree leaves in response to high Al and low Ca in the soil, leading to the suggestion that this response may provide a physiological advantage to leaf cells under conditions of Al stress. The increase in Put is reversed by Ca supplementation in the soil. Using two cell lines of poplar (Populus nigra x maximowiczii), one with constitutively high Put (resulting from transgenic expression of a mouse ornithine decarboxylase called HP cells) and the other with low Put (control cells), we investigated the effects of reduced Ca (0.2-0.8 mM vs. 4 mM) and treatment with 0.1 mM Al on several biochemical parameters of cells. We found that in the presence of reduced Ca concentration, the HP cells were at a disadvantage as compared to control cells in that they showed greater reduction in mitochondrial activity and a reduction in the yield of cell mass. Upon addition of Al to the medium, the HP cells, however, showed a reversal of low-Ca effects. We conclude that due to increased ROS production in the HP cells, their tolerance to low Ca is compromised. Contrary to the expectation of deleterious effects, the HP cells showed an apparent advantage in the presence of Al in the medium, which could have come from reduced uptake of Al, enhanced extrusion of Al following its accumulation, and perhaps a reduction in Put catabolism as a result of a reduction in its biosynthesis. (C) 2010 Elsevier Masson SAS. All rights reserved

Current strategies and prospects in algae for remediation and biofuels: an overview

Phycoremediation is an environmentally sustainable method that utilizes macro and microalgae to remediate polluted land and water. Phycoremediation consists of two elements: the microbial niche around the algae and the second by the algae itself, which absorb and degrade the toxic pollutants into less or non-toxic components. The advanced gene cloning technology on algae could improve gene efficiency and produce the active xenobiotic degrading enzyme. As a result, remedial rates have improved, allowing large areas of contaminated sites to be addressed in the process of large-scale application. Many organizations worldwide are already focusing on this bioremediation element, special attention on algae to replace the costly physical or chemical remediation methods. Thus, this review reported the Scenedesmus sp. algae used in the polluted tannery site, and the maximum removal was observed in Pb: 75-98% and Zn: 65-98%. Scenedesmus obliquus illustrated the significant Fe3+ (100%) removal applied in the polluted soil. Moreover, since nuclear and chloroplast transformations are important in commercial applications, C. reinhardtii remains the most effective transgenic algae applied for pollutant deduction. It was discovered that Chlorella, Chlamydomonas, and Scenedesmus sp. had the highest pollutant removal efficacy in medicine polluted sites. Furthermore, Kirchneriella sp. and Enteromorpha clathrate were observed to have the largest algal oil yield than other algal species.National Natural Science Foundation of China (NSFC) 51876083; 51776088. Priority Academic Program Development of Jiangsu High Education Institutions; High-tech Research Key laboratory of Zhenjiang SS2018002info:eu-repo/semantics/publishedVersio

NMR-D study of the local spin dynamics and magnetic anisotropy in different nearly monodispersed ferrite nanoparticles

We present a systematic experimental comparison of the superparamagnetic relaxation time constants obtained by means of dynamic magnetic measurements and 1 H-NMR relaxometry, on ferrite-based nanosystems with different composition, various core sizes and dispersed in different solvents. The application of a heuristic model for the relaxivity allowed a comparison between the reversal time of magnetization as seen by NMR and the results from the AC susceptibility experiments, and an estimation of fundamental microscopic properties. A good agreement between the NMR and AC results was found when fitting the AC data to a Vogel\u2013Fulcher law. Key parameters obtained from the model have been exploited to evaluate the impact of the contribution from magnetic anisotropy to the relaxivity curves and estimate the minimum approach distance of the bulk solven