Accumulation of cadmium and zinc in barley regenerants on a provocative soil background with cadmium

Background. An effective way to obtain barley (Hordeum vulgare L.) genotypes stress-tolerant to cadmium, with a low level of toxic ion accumulation in grain, is the selection of cells in selective in vitro systems, based on somaclonal variability, which promotes the formation of specific and nonspecific adaptive mechanisms.Materials and methods. The object of the study was cv. ‘999-93’, developed by selection from a hybrid combination of spring barley (Luly × Conrad) × 2867-80, and its regenerated forms in seed reproductions of the 3–5th generation, induced in the process of cell selection on media with cadmium, aluminum and polyethylene glycol. The plants were grown under normal soil conditions and against a provocative background for cadmium.Results. The contribution of the environment-forming activity in the roots of the studied genotypes to inactivation of toxic ions appeared insignificant. The total removal of cadmium by plants against a provocative background increased 22.5 times, reaching 5.8–10.3 mg/kg of dry phytomass when distributed among organs: roots (91.9–93.4%) > stems (5.9–7.8%) > grain (0.5–0.8%). The amount of toxic metal in grain increased 11 times in the original form and 2.8–6.8 times in regenerants. The negative effect of excess cadmium in the soil on the accumulation of zinc in barley was shown. There was no gradation in the importance of organs for zinc accumulation or any presence of functional barriers preventing this. Regenerants induced on selective media with cadmium had the greatest adaptive advantages to stress: pronounced barrier functions of roots, minimal accumulation of toxic ions in aerial organs, and high seed productivity (they exceeded the original genotype by 35.5%). Adaptive reactions associated with the limitation of cadmium accumulation in plant tissues of regenerants, obtained by in vitro selections with aluminum and an osmotic, were shown to be weak.

Hydropriming with Moringa Leaf Extract Mitigates Salt Stress in Wheat Seedlings

Salinity is the major constraint that decreases the yield and production of crops. Wheat has a significant value in agricultural food commodities. The germination and growth of wheat seedlings are a big challenge in salt-affected soils. The seed priming technique is used to mitigate salt stress and enhance the germination and growth of the crops. Therefore, the current study was conducted to evaluate the hydropriming of natural plant extract (moringa leaf extract) and water on wheat seeds and grown under different saline (0, 0.05, 0.1, 0.15, and 0.2 M NaCl) environments. The germination attributes (germination percentage, germination index, mean germination day, coefficient of variance, vigor index) and seedling growth (fresh weight, dry weight, root length, shoot length) were enhanced in the plants primed by moringa leaf extract. The germination percentage was observed 10% more at 0.2 M NaCl stress in seeds treated with moringa leaf extract than seeds treated with water. The nutrient (K, Ca, Mg, P, S, Fe, B, Mn, Zn, Cu) uptake was also observed more in the shoots and roots of wheat seedlings soaked in moringa leaf extract as compared to soaked in water. Controlled plants showed higher concentrations of toxic ions (Na) and reactive oxygen species (H2O2) in shoots and roots of wheat seedlings. The use of moringa leaf extract for priming wheat seeds will enhance their germination and growth by maintaining efficient nutrient uptake and restricting the toxic ions and reactive oxygen species accumulation.

Salt and Water Stress Responses in Plants

Climate change-driven ecological disturbances have a great impact on freshwater availability which hampers agricultural production. Currently, drought and salinity are the two major abiotic stress factors responsible for the reduction of crop yields worldwide. Increasing soil salt concentration decreases plant water uptake leading to an apparent water limitation and later to the accumulation of toxic ions in various plant organs which negatively affect plant growth. Plants are autotrophic organisms that function with simple inorganic molecules, but the underlying pathways of defense mechanisms are much more complex and harder to unravel. However, the most promising strategy to achieve sustainable agriculture and to meet the future global food demand, is the enhancement of crop stress tolerance through traditional breeding techniques and genetic engineering. Therefore, it is very important to better understand the tolerance mechanisms of the plants, including signaling pathways, biochemical and physiological responses. Although, these mechanisms are based on a well-defined set of basic responses, they can vary among different plant species.

The periodic table of photosynthetic purple non-sulfur bacteria: intact cell-metal ions interactions

Photosynthetic purple non-sulfur bacteria (PNB) have been widely utilized as model organisms to study bacterial photosynthesis. More recently, the remarkable resistance of these microorganisms to several metals ions called particular interest. As a result, several research efforts were directed toward clarifying the interactions of metal ions with PNB. The mechanisms of metal ions active uptake and bioabsorption have been studied in detail, unveiling that PNB enable harvesting and removing various toxic ions, thus fostering applications in environmental remediation. Herein, we present the most important achievements in the understanding of intact cell-metal ions interactions and the approaches utilized to study such processes. Following, the application of PNB-metal ions interactions toward metal removal from contaminated environments is presented. Finally, the possible coupling of PNB with abiotic electrodes to obtain biohybrid electrochemical systems is proposed as a sustainable pathway to tune and enhance metal removal and monitoring. Graphic abstract

Phenotypic Characterization and Determination of Gene expression of Genetically Modified Rice Strains Using CRISPR-CAS9 Technology With Sodium Chloride Effect

This study was conducted with the target of determine the role of OsHKT4 and OsHKT6 genes in rice plants under salt stress and observe its gene expression by GUS technology, as well as studying the Na+ and K+ accumulation in different tissues. The results obtained show that OsHKT4::GUS appeared strong GUS activity, expressed mainly in vascular tissues. In contrast, the GUS activity of the OsHKT6 promoters in NaCl-treated leaves was greater than that in water-treated leaves. Also in wild type plants, increasing the Na+ concentration has the effect of increasing the Na+ content of the tissues generally, the old leaves accumulating more Na+ which reduced the K+ content in roots and old leaves (Na+ levels are higher in the leaf lower parts). These results suggest that OsHKT4 and OsHKT6 genes plays a role in the accumulation of Na+ in old leaves, by adopting the mechanical exclusion of toxic ions in the old leaves of the plant.