Adaptive mechanisms of plants against salt stress and salt shock

Salinization process occurs when soil is contaminated with salt, which consequently influences plant growth and development leading to reduction in yield of many food crops. Responding to a higher salt concentration than the normal range can result in plant developing complex physiological traits and activation of stress-related genes and metabolic pathways. Many studies have been carried out by different research groups to understand adaptive mechanism in many plant species towards salinity stress. However, different methods of sodium chloride (NaCl) applications definitely give different responses and adaptive mechanisms towards the increase in salinity. Gradual increase in NaCl application causes the plant to have salt stress or osmotic stress, while single step and high concentration of NaCl may result in salt shock or osmotic shock. Osmotic shock can cause cell plasmolysis and leakage of osmolytes in plant. Also, the gene expression pattern is influenced by the type of methods used in increasing the salinity. Therefore, this chapter discusses the adaptive mechanism in plant responding to both types of salinity increment, which include the morphological changes of plant roots and aerial parts, involvement of signalling molecules in stress perception and regulatory networks and production of osmolyte and osmoprotective proteins

Two-component spike nanoparticle vaccine protects macaques from SARS-CoV-2 infection

Brouwer et al. present preclinical evidence in support of a COVID-19 vaccine candidate, designed as a self-assembling two-component protein nanoparticle displaying multiple copies of the SARS-CoV-2 spike protein, which induces strong neutralizing antibody responses and protects from high-dose SARS-CoV-2 challenge.The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic is continuing to disrupt personal lives, global healthcare systems, and economies. Hence, there is an urgent need for a vaccine that prevents viral infection, transmission, and disease. Here, we present a two-component protein-based nanoparticle vaccine that displays multiple copies of the SARS-CoV-2 spike protein. Immunization studies show that this vaccine induces potent neutralizing antibody responses in mice, rabbits, and cynomolgus macaques. The vaccine-induced immunity protects macaques against a high-dose challenge, resulting in strongly reduced viral infection and replication i

Nonlinear Allometric Equation for Crop Response to Soil Salinity

Crop response to soil salinity has been extensively studied, from empirical works to modelling approach, being described by different equations, first as a piecewise linear model. The equation employed can differ with actual response, causing miscalculation in practical situations, particularly at the higher extremes of the curve. The aim of this work is to propose a new equation, which allows determining the full response to salinity of plant species and to provide a verification using different experimental data sets. A new nonlinear equation is exposed supported by the allometric approach, in which the allometric exponent is salinity-dependent and decreases with the increase in relative salinity. A conversion procedure of parameters of the threshold-slope model is presented; also, a simple procedure for estimating the maximum salinity (zero-yield point) when data sets are incomplete is exposed. The equation was tested in a wide range of experimental situations, using data sets from published works, as well as new measurements on seed germination. The statistical indicators of quality (R2, absolute sum of squares and standard deviation of residuals) showed that the equation accurately fits the tested empirical results. The new equation for determining crop response to soil salinity is able to follow the response curve of any crop with remarkable accuracy and flexibility. Remarkable characteristics are: a maximum at minimum salinity, a maximum salinity point can be found (zero-yield) depending on the data sets, and a meaningful inflection point, as well as the two points at which the slope of the curve equals unity, can be found

Physiological and biochemical responses to the exogenous application of proline of tomato plants irrigated with saline water

In scope of crop salinity tolerance, an experiment was carried out in a field using saline water (6.57 dS m−1) and subsurface drip irrigation (SDI) on two tomato cultivars (Solanum lycopersicum, cv. Rio Grande and Heinz-2274) in a salty clay soil. Exogenous application of proline was done by foliar spray at two concentrations: 10 and 20 mg L−1, with a control (saline water without proline), during the flowering stage. Significant higher increases in proline and total soluble protein contents, glutamine synthetase (GS, EC6.3.1.2) activities and decreases in proline oxidase (l-proline: O2 Oxidoreductase, EC1.4.3.1) activities were detected in both tomato cultivars when irrigated with saline water (6.57 dS m−1) and exogenously applied by the lower concentration of proline. Taking in consideration the obtained results, it was concluded that the foliar spray of low concentration of proline can increase the tolerance of both cultivars of tomato to salinity under field conditions

Effect of electromagnetic treatment of saline water on soil and crops

Two experiments were carried out to study the effect of the electromagnetic treatment of saline water on seed germination of corn and the response of soil and potato crop irrigated with such water. The experiments were performed under controlled conditions with different water quality and soil texture. The electromagnetic water treatment was applied using Aqua-4D physical water treatment device. Results showed a significant increase in germination rate of corn seedlings watered with electromagnetic-treated saline water (EC = 4 dS m−1), particularly when water was exposed to electromagnetic fields for 15 min. The experiments carried on potato crop with two soil textures, showed a significant increase in tuber yield when irrigated with electromagnetic treated water. It was also observed a significant decrease of soil salinity (ECe), Na+ and Cl− contents of soils irrigated with electromagnetic treated saline water compared to the soils irrigated with non-treated saline water. In contrast, compared to both treatments (control treatment and saline water treatment), the electromagnetic saline water treatment produced non-significant effect on tuber yield, Mg2+ and HCO3-. However, the electromagnetic treatment of saline water increased significantly K+, N and P adsorption in all tissues of potato and decreased significantly the adverse effects of saline water. Based on our results, electromagnetic treatment of saline water can reduce the negative effect of salinity on corn germination and potato crop and increase yield in about 10% in test conditions. Keywords: Electromagnetic water treatment, Seed germination, Potatoes, Tunisia, Salinit