Evidence for Ovarian and Testicular Toxicities of Cadmium and Detoxification by Natural Substances

Cadmium (Cd) is an environmental toxicant, capable of reducing mitochondrial ATP production and promoting the formation of reactive oxygen species (ROS) with resultant oxidative stress conditions. The ovary and testis are the primary gonads in which female gametes (oocytes) and male gametes (spermatozoa), estrogen and testosterone are produced. These organs are particularly susceptible to Cd cytotoxicity due to their high metabolic activities and high energy demands. In this review, epidemiological and experimental studies examining Cd toxicities in gonads are highlighted together with studies using zinc (Zn), selenium (Se), and natural substances to reduce the effects of Cd on follicular genesis and spermatogenesis. Higher blood concentrations of Cd ([Cd]b) were associated with longer time-to-pregnancy in a prospective cohort study. Cd excretion rate (ECd) as low as 0.8 μg/g creatinine was associated with reduced spermatozoa vitality, while Zn and Se may protect against spermatozoa quality decline accompanying Cd exposure. ECd > 0.68 µg/g creatinine were associated with an increased risk of premature ovarian failure by 2.5-fold, while [Cd]b ≥ 0.34 µg/L were associated with a 2.5-fold increase in the risk of infertility in women. Of concern, urinary excretion of Cd at 0.68 and 0.8 μg/g creatinine found to be associated with fecundity are respectively 13% and 15% of the conventional threshold limit for Cd-induced kidney tubular effects of 5.24 μg/g creatinine. These findings suggest that toxicity of Cd in primary reproductive organs occurs at relatively low body burden, thereby arguing for minimization of exposure and environmental pollution by Cd and its transfer to the food web.

Glomus mosseae and Pseudomonas fluorescens Application Sustains Yield and Promote Tolerance to Water Stress in Helianthus annuus L.

The inoculation of sunflower (Helianthus annuus L.) plants with arbuscular mycorrhizal fungi (AMF) and plant growth-promoting rhizobacteria (PGPR) can significantly enhance its growth and yield in a sustainable manner. Drought tolerance is mediated by a combination of direct AMF and PGPR benefits that boost the plant’s natural ability to cope with stress, whereas drought mitigation is mediated by indirect AMF and PGPR benefits and increased water uptake. An experiment was carried out to demonstrate the interactive effects of AMF (Glomus mosseae) alone or in association with PGPR (Pseudomonas fluorescens) under water-stressed conditions in order to assess their biofertilizer efficiency. Accordingly, various morphological and biochemical parameters were studied, and the results suggested that all the co-inoculation treatments displayed beneficial effects. Still, the combination of G. mosseae + P. fluorescens showed the maximum increment in all the parameters considered, i.e., plant height and weight, leaves length and width, number of leaves per plant, specific leaf weight, relative leaf water content (RLWC), photosynthetic efficiency, seed length, width, and area, seed yield per plant, number of seeds per flower, days to 50% flowering, days to maturity, flower and head diameter, harvest index, oil content, fatty acid composition (palmitic acid, oleic acid, stearic acid, and linoleic acid), and total yield. The improvement in different parameters may be attributed to the increased availability of nutrients due to the symbiotic association of AMF and PGPR with plant roots along with enhanced root structures for more water absorption under stressed conditions. Therefore, the results suggested that they offer a promising bio-control strategy for crop protection as biofertilizers combined in one formulation.

Morphological and Physiological Response of Different Lettuce Genotypes to Salt Stress

Salt stress (SS) refers to excessive soluble salt concentrations in the plant root zone. SS also causes cellular water deficits, ion toxicity, and oxidative stress in plants, all of which can cause growth inhibition, molecular damage, and even plant mortality. Lettuce (Lactuca sativa L.) has a threshold electrical conductivity of 1.3–2.0 dS/m. Thus, this research focused on physiological, morphological, and biochemical attributes in multiple lettuce genotypes under SS compared to plants grown under control conditions. The experiment was arranged in a randomized complete block design with four replications. One month after planting, the salt treatment was applied at the rate of 100 millimoles (mM). The 0 mM salt in water treatment was considered the control. A significant effect of SS on different morphological and physiological traits was observed in one-month-old lettuce plants. PI 212099, Buttercrunch-1, and PI 171676 were highly salt-tolerant. Genotypes with high salt tolerance usually had poor growth potential under control conditions. This suggests that the morphological and physiological response of 38 lettuce cultivars towards SS is genotype dependent. Identifying SS’s physiological, morphological, and biochemical attributes in lettuce may help plant-breeders develop salt-tolerant lettuce genotypes.

COVID-19 Mortality in Patients with a Ward-Based Ceiling of Care

Objectives: COVID-19 patients thought unlikely to benefit from organ support, thereby having a ward-based ceiling of care (WBCoC), represent a distinct subgroup. There are no associated studies in mortality. We sought to identify clinical risk factors for inpatient COVID-19 mortality. Design and setting: this was a retrospective observational study of patients admitted to Northumbria Healthcare NHS Foundation Trust. Clinical variables were associated with inpatient mortality via logistic regression. Participants: all patients admitted with COVID-19 infection and who had a WBCoC at point of admission were included (n = 114). Main outcome measures: the outcome measure was inpatient death.

Paenibacillus polymyxa A26 and Its Surfactant-Deficient Mutant Degradation of Polycyclic Aromatic Hydrocarbons

We compared the ability of two bacterial strains, Paenibacillus polymyxa A26 and P. polymyxa A26Sfp, for biodegradation of naphthalene (NAP). The studies were performed under simulated laboratory conditions, in liquid medium and soil with different carbon sources, pH and salt contents. Changes in the luminescence inhibition of Aliivibrio fischeri, as an indicator of the baseline toxicity, were observed in degradation mixtures during 7 days of incubation. While both strains expressed the best growth and NAP degradation ability in the minimal salt medium containing sucrose and 5% NaCl at pH 7 and 8, the mutant strain remained effective even under extreme conditions. A26Sfp was found to be an efficient and potentially industrially important polycyclic aromatic hydrocarbon degradation strain. Its extracellular polysaccharide production is 30%, and glucan production is twice that of the wild type A 26. The surface tension reduction ability was ascertained as 25–30% increased emulsification ability.

Antioxidant Enzyme Activities as Biomarkers of Cu and Pb Stress in Centella asiatica

The present study investigated the antioxidant enzyme activities (AEA) of ascorbate peroxidase (APX), catalase (CAT), guaiacol peroxidase (GPX), and superoxide dismutase (SOD) as biomarkers of Cu and Pb stress by using Centella asiatica grown in an experimental hydroponic condition. The results showed (i) higher accumulations of Cu and Pb in the roots of C. asiatica than those in the leaves, (ii) synergistic effects of Cu and Pb stress at higher metal-level exposures, and (iii) Cu and Pb stress triggered the increment of APX, CAT, GPX, and SOD levels in both the leaves and roots of C. asiatica. The increment of four AEA indicated that C. asiatica underwent oxidative stress caused by the production of reactive oxygen species when the plant was exposed to Cu and Pb. In order to prevent damages caused by Cu and Pb stress, the AEA system was heightened in C. asiatica, in which APX, CAT, GPX, and SOD can be used as biomarkers of Pb and Cu stress in the plant.

Utilization of Tomato Landraces to Improve Seedling Performance under Salt Stress

Salt stress is considered as one of the most frequent factors limiting plant growth and productivity of crops worldwide. The aim of the study was to evaluate physiological and biochemical responses of nine diverse tomato genotypes exposed to salt stress. In this regard, four-week-old seedlings of one modern variety, five landraces, the salt-sensitive accession of ‘Ailsa Craig’, the salt-tolerant wild accession of S. pimpinellifolium ‘LA1579’, as well as the vitamin C-rich S. pennellii introgression line ‘IL12-4’, were exposed to moderate salt stress (200 mM NaCl) for 10 days. At the end of the stress treatment, agronomical traits and stress indices were evaluated, while gas exchange-related parameters, root electrolyte leakage, malondialdehyde content and ascorbic acid were also determined. All parameters were significantly affected by salt stress, but to a different extent, verifying the diverse degree of tolerance within the selected genotypes, and further highlighting the different stress-induced mechanisms. The landrace originated from ‘Santorini’ island, as well as the modern variety, which originated from traditional cultivars, demonstrated a better performance and adaptivity under moderate salt stress, accompanied by reduced lipid peroxidation and enhanced ascorbic acid content, indicating that they could be potential promising genetic material for breeding programs or as grafting rootstocks/scions.

Drought and Elevated CO2 Impacts Photosynthesis and Biochemicals of Basil (Ocimum basilicum L.)

Drought-induced reduction in crop growth and productivity can be compensated by increasing atmospheric carbon dioxide (CO2), a significant contributor to climate change. Drought stress (DS) affects crops worldwide due to dwindling water resources and irregular rainfall patterns. The experiment was set up under a randomized complete block design within a three-by-two factorial arrangement. Six SPAR chambers represent three blocks (10 replications each), where each chamber has 30 pots in three rows. Each chamber was maintained with 30/22 (day/night) °C temperature, with either ambient (aCO2; 420 ppm) or elevated CO2 (eCO2; 720 ppm) concentrations. This experiment was designed to address the impact of DS on the physiological and biochemical attributes and study how the eCO2 helps alleviate the adversity of DS in basil. The study demonstrated that DS + eCO2 application highly accelerated the decrease in all forms of carotene and xanthophylls. eCO2 positively influenced and increased anthocyanin (Antho) and chlorophyll (LChl). eCO2 supplementation increased LChl content in basil under DS. Furthermore, DS significantly impeded the photosynthetic system in plants by decreasing CO2 availability and causing stomatal closure. Although eCO2 did not increase net photosynthesis (Pn) activity, it decreased stomatal conductance (gs) and leaf transpiration rate (E) under DS, showing that eCO2 can improve plant water use efficiency by lowering E and gs. Peroxidase and ascorbate activity were higher due to the eCO2 supply to acclimate the basil under the DS condition. This study suggests that the combination of eCO2 during DS positively impacts basil’s photosynthetic parameters and biochemical traits than aCO2.

Prospect and Challenges for Sustainable Management of Climate Change-Associated Stresses to Soil and Plant Health by Beneficial Rhizobacteria

Climate change imposes biotic and abiotic stresses on soil and plant health all across the planet. Beneficial rhizobacterial genera, such as Bacillus, Pseudomonas, Paraburkholderia, Rhizobium, Serratia, and others, are gaining popularity due to their ability to provide simultaneous nutrition and protection of plants in adverse climatic conditions. Plant growth-promoting rhizobacteria are known to boost soil and plant health through a variety of direct and indirect mechanisms. However, various issues limit the wider commercialization of bacterial biostimulants, such as variable performance in different environmental conditions, poor shelf-life, application challenges, and our poor understanding on complex mechanisms of their interactions with plants and environment. This study focused on detecting the most recent findings on the improvement of plant and soil health under a stressful environment by the application of beneficial rhizobacteria. For a critical and systematic review story, we conducted a non-exhaustive but rigorous literature survey to assemble the most relevant literature (sorting of a total of 236 out of 300 articles produced from the search). In addition, a critical discussion deciphering the major challenges for the commercialization of these bioagents as biofertilizer, biostimulants, and biopesticides was undertaken to unlock the prospective research avenues and wider application of these natural resources. The advancement of biotechnological tools may help to enhance the sustainable use of bacterial biostimulants in agriculture. The perspective of biostimulants is also systematically evaluated for a better understanding of the molecular crosstalk between plants and beneficial bacteria in the changing climate towards sustainable soil and plant health.

Coordinated Role of Nitric Oxide, Ethylene, Nitrogen, and Sulfur in Plant Salt Stress Tolerance

Salt stress significantly contributes to major losses in agricultural productivity worldwide. The sustainable approach for salinity-accrued toxicity has been explored. The use of plant growth regulators/phytohormones, mineral nutrients and other signaling molecules is one of the major approaches for reversing salt-induced toxicity in plants. Application of the signaling molecules such as nitric oxide (NO) and ethylene (ETH) and major mineral nutrient such as nitrogen (N) and sulfur (S) play significant roles in combatting the major consequences of salt stress impacts in plants. However, the literature available on gaseous signaling molecules (NO/ETH) or/and mineral nutrients (N/S) stands alone, and major insights into the role of NO or/and ETH along with N and S in plant-tolerance to salt remained unclear. Thus, this review aimed to (a) briefly overview salt stress and highlight salt-induced toxicity, (b) appraise the literature reporting potential mechanisms underlying the role of gaseous signaling molecules and mineral nutrient in salt stress tolerance, and (c) discuss NO and ETH along with N and S in relation to salt stress tolerance. In addition, significant issues that have still to be investigated in this context have been mentioned.