The accumulation of salt in arable lands is a source of significant abiotic stress, contributing to a 10% decline in the world’s total arable lands and threatening food productivity and the sustainability of agriculture. About 76 million hectares of productive land are estimated to have been affected by human-induced salinization such as extreme salt deposits in soil, which are mainly caused by the actions of humans. For instance, continued irrigation and the frequent use of chemical fertilizers need to be understood. To ensure food availability, it is essential to improve upon traditional farming methods using current technologies to facilitate the reclamation of saline-affected arable lands to achieve high and sustainable food production. This review details current innovative strategies such as the modification of metabolic pathways, manipulation of antioxidant pathways, genetic engineering, RNA interference technology, engineered nanoparticles, arbuscular mycorrhizal fungi (AMF), organic amendments, and trace elements for improving saline marginal lands. These strategies were identified to have contributed to the improvement of plants salinity tolerance in diverse ways. For instance, the accumulation of plant metabolites such as amino acids, sugars, polyols, organic acids, saponins, anthocyanins, polyphenols, and tannins detoxify plants and play crucial roles in mitigating the detrimental effects of oxidative damage posed by salinity stress. Multiple plant miRNAs encoding the up- and down-regulation of single- and multi-ion transporters have been engineered in plant species to enhance salt tolerance. Nanomaterials and plant root system colonized by arbuscular mycorrhizal increase water uptake, photosynthetic efficiency, and biomass allocation in plants exposed to saline stress by excluding 65 percent of the Na⁺ uptake and enhancing K⁺ uptake by 84.21 percent. Organic amendments and trace elements reduced salinity concentrations by 22 percent and improved growth by up to 84 percent in maize subjected to salinity stress. This study also discusses how researchers can use these strategies to improve plants growth, development, and survival in saline soil conditions to enhance the productivity and sustainability of agriculture. The strategies discussed in this study have also proven to be promising approaches for developing salinity stress tolerance strategies for plants to increase agricultural productivity and sustainability.

From the moment of planting, plants are susceptible to damage by various types of pathogens, including viruses. The traditional approach in the fight against viral, fungal, and bacterial infections involves the use of pesticides as well as the selection of varieties that are resistant to pathogens. In addition to fundamental aspects, the mechanism of RNA interference, due to the ability to eliminate foreign nucleic acids, is applicable to increase plant resistance to various types of biotic stresses. This approach involves the use of endogenous and exogenous short interfering RNAs. The phenomenon of “superinfection” was discovered in 1929. It assumes the resistance of a plant affected by a weakened form of the virus to reinfection with the most pathogenic strain of the same virus. In this article, the reinoculation process is referred to as superinoculation. Superinoculation involves reinoculating a plant with a wild-type virus after infection of plants with a mutant form of the virus that does not contain pathological activity, which triggers a phytoimmunity response to the subsequent invasion of the wild-type. When reinoculating tobacco plants (Nicotiana benthamiana Domin) with a wild-type virus, which were previously infected with a mutant form of Tomato Bushy Stunt Virus defective in the suppressor protein, the plants showed the recovery phenotype represented by the elimination of genomic RNA Tomato Bushy Stunt Virus and its viral suppressor protein in plant tissues.

The accumulation of proline, an important osmoprotective and antioxidant compound, is a key defense mechanism induced in plants in response to stress factors, including salinity, and is likely dependent on abscisic acid (ABA). However, in barley grown for 8 days under salinity conditions (125 mM NaCl), proline accumulation was not accompanied by changes in ABA content. Co-application of 0.5 mM molybdenum (Mo) significantly reduced NaCl-induced oxidative stress, as measured by H₂O₂, O₂⁻, MDA, and chlorophyll content, and increased the activity of Mo-containing aldehyde oxidase (AO), an enzyme involved in de novo ABA synthesis. As a result, elevated ABA levels were observed, but proline content under salinity conditions was similar in Mo-treated and non-Mo-treated plants. In contrast, exposing plants to 0.5 mM tungsten (W), an antagonist of Mo, inhibited AO activity without significantly altering ABA content, while proline and oxidative stress marker levels increased dramatically under both non-saline and saline conditions. The observed changes in proline content are mainly due to modulation of the rate of synthesis and, to a lesser extent, the rate of degradation, as revealed by transcript abundance of P5CS1 and PDH, which encode D1-pyrroline-5-carboxylate synthetase and proline dehydrogenase, respectively. The results indicate that in barley grown under salinity conditions, proline accumulation is ABA-independent but depends on the level of oxidative stress modulated by Mo and W ions.

Modern studies in the field of plant molecular biology pay considerable attention to the mechanisms of regulation of the antioxidant system. In this work we study the effect of heavy metals molybdenum and tungsten on the modulation of molybdenum-containing hydroxylases (Mo-hydroxylases) and the functioning of the antioxidant system of plants using the model organism Nicotiana benthamiana. The aim of the study is to analyse the effects of molybdenum and tungsten on the activity of antioxidant enzymes (SOD, CAT) as well as the Mo-enzymes aldehyde oxidase (AO) and xanthine dehydrogenase (XDH). The methods used include native gel electrophoresis and spectrophotometry. The main results show that molybdenum application promotes the activation of plant antioxidant system by increasing the production of reactive oxygen species (ROS) and superoxide dismutase (SOD) enzyme activities, while catalase activity changed insignificantly. Also, AO activity increased, whereas XDH activity was almost unchanged. On the contrary, tungsten application reduced the activity of these antioxidant defence mechanisms and inhibited Mo-hydroxylases. The practical significance of the work lies in the possibility of developing biotechnological approaches to increase plant resistance to abiotic stresses by regulating the activity of Mo-hydroxylases. The obtained data can be used in crop production and agriculture to improve stress tolerance of agricultural crops.

Crops of food value are often exposed to viral pathogens. Therefore, crops can noticeably decrease or die completely. For example, in 2021, the tomato brown wrinkle virus was detected in Kazakhstan, the main hosts of which are tomatoes and peppers. At the same time, in farms where the pathogen was detected, yield loss ranged from 30 to 70%. Therefore, it is important to develop methods aimed at increasing plant stress tolerance to viral infection. The scientific novelty of this manuscript is that previously the simultaneous effect of viral pathogens and heavy metals on plants has not been studied. Antioxidant enzymes play an important role in regulating the concentration of reactive oxygen species in plant cells. The enzyme catalase catalyzes the conversion of hydrogen peroxide into water and molecular oxygen, thereby neutralizing superoxide radicals. Thus, antioxidant enzymes prevent tissue damage and necrosis. Molybdenum enzymes can produce reactive oxygen species when exposed to adverse conditions, such as pathogen infestation or drought. Molybdenum is an integral part of the Moco cofactor within molybdoenzymes, but tungsten has the ability to substitute for molybdenum, resulting in a reversible loss of enzyme function. Consequently, tungsten acts as a stressor for plants. Inoculation of plants with tomato bush stunt virus of the wild type leads to their death. At the same time, when infected with TBSV 157, RMJ1 and RMJ2 mutants, the plants recovered after some time. Plants are expected to be more viable when the subject is exposed to heavy metal solutions and inoculated with viruses.