Stresses, Volume 2, Issue 4 (December 2022) – 12 articles

This study aimed to test the role of hydrogen sulfide (H₂S) in the responses regarding the nitric oxide- (NO) and sulfur (S)-mediated improvement in photosynthesis and growth under cadmium (Cd) stress in mustard (Brassica juncea L. cv. Giriraj), and integrate the mechanisms of S, nitrogen (N), and antioxidant metabolism. The plants grown with Cd (200 mg Cd kg⁻¹ soil) exhibited reduced assimilation of S and N and diminished photosynthetic performance, which was associated with higher Cd accumulation-induced excess reactive oxygen species (ROS) production. The application of 100 μM of sodium nitroprusside (SNP, a NO donor) together with a more prominent concentration of S resulted in increased photosynthetic S- and N-use efficiency, production of non-protein thiols and phytochelatins, efficiency of enzymatic (superoxide dismutase, ascorbate peroxidase, and glutathione reductase), non-enzymatic antioxidants (ascorbate and glutathione) limiting Cd accumulation and, thus, reduced oxidative stress (superoxide radical, hydrogen peroxide, and thiobarbituric acid reactive species content). The benefit of NO together with S was manifested through a modulation in H₂S production. The use of 100 μM of hypotaurine (HT; H₂S scavenger) or 100 μM of cPTIO (2-4-carboxyphenyl-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide) in plants treated with NO plus S reversed the action of NO plus S, with a higher reduction in photosynthesis and growth with the use of HT, suggesting that H₂S plays a significant role in the NO- and S-mediated alleviation of Cd stress. The interplay of NO and ES with H₂S may be used in augmenting the photosynthesis and growth of Cd-grown mustard plants. Full article

Cyanobacteria are oxygen-evolving photoautotrophs with worldwide distribution in every possible habitat, and they account for half of the global primary productivity. Because of their ability to thrive in a hostile environment, cyanobacteria are categorized as “extremophiles”. They have evolved a fascinating repository of distinct secondary metabolites and biomolecules to promote their development and survival in various habitats, including severe conditions. However, developing new proteins/enzymes and metabolites is mostly directed by an appropriate gene regulation system that results in stress adaptations. However, only few proteins have been characterized to date that have the potential to improve resistance against abiotic stresses. As a result, studying environmental stress responses to post-genomic analysis, such as proteome changes using latest structural proteomics and synthetic biology techniques, is critical. In this regard, scientists working on these topics will benefit greatly from the stress of proteomics research. Progress in these disciplines will aid in understanding cyanobacteria’s physiology, biochemical, and metabolic systems. This review summarizes the most recent key findings of cyanobacterial proteome study under various abiotic stresses and the application of secondary metabolites formed during different abiotic conditions. Full article

Bioindication of the environment is one of the actively developing directions of ecology. Information about pollutants and the level of environmental pollution can be obtained as a result of studying the biological reaction of plants to pollution. Ecological palynology is a new direction, when pollen of various woody and herbaceous species is used for bioindication of the level of environmental pollution and the presence of mutagens. The review considers the morphological variability of pollen, its fertility and viability under the influence of pollutants, the possibility of its use as a bioindicator of pollution of urban areas by emissions of vehicle transport and industry. Full article

Global crop yield and food security are being threatened by phytophagous insects. Innovative methods are required to increase agricultural output while reducing reliance on hazardous synthetic insecticides. Using the revolutionary CRISPR-Cas technology to develop insect-resistant plants appears to be highly efficient at lowering production costs and increasing farm profitability. The genomes of both a model insect, Drosophila melanogaster, and major phytophagous insect genera, viz. Spodoptera, Helicoverpa, Nilaparvata, Locusta, Tribolium, Agrotis, etc., were successfully edited by the CRISPR-Cas toolkits. This new method, however, has the ability to alter an insect’s DNA in order to either induce a gene drive or overcome an insect’s tolerance to certain insecticides. The rapid progress in the methodologies of CRISPR technology and their diverse applications show a high promise in the development of insect-resistant plant varieties or other strategies for the sustainable management of insect pests to ensure food security. This paper reviewed and critically discussed the use of CRISPR-Cas genome-editing technology in long-term insect pest management. The emphasis of this review was on the prospective uses of the CRISPR-Cas system for insect stress management in crop production through the creation of genome-edited crop plants or insects. The potential and the difficulties of using CRISPR-Cas technology to reduce pest stress in crop plants were critically examined and discussed. Full article

Drought is a serious challenge that causes significant crop loss worldwide. The developmental processes of plants are regulated by phytohormones and signaling molecules that crosstalk together in signaling cascades. We suppose that nitric oxide (NO) is a secondary messenger of the JAs signaling pathway, as 10⁻⁷ M methyl jasmonate (MeJA) pretreatment regulates NO accumulation in wheat plants under drought stress, modulated by 12% polyethylene glycol (PEG), and in control plants. This study aimed to compare 2 × 10⁻⁴ M nitric oxide donor sodium nitroprusside (SNP) and MeJA pretreatments in regulating growth and water balance parameters at the vulnerable initial first-leaf stage of wheat growth. The application of 12% PEG decreased transpiration intensity twofold, relative water content (RWC) by 7–9%, and osmotic potential of cell sap by 33–40% compared with those of control plants. Under drought, MeJA- and SNP-pretreated plants decreased transpiration intensity by 20–25%, RWC by 3–4%, and osmotic potential of cell sap by 16–21% compared with those of control plants, and enhanced the proline content by 25–55% compared with MeJA- and SNP-untreated plants. Our results suggest that pretreatment with MeJA as well as SNP could mitigate drought stress in wheat plants. Similarities in MeJA- and SNP-induced shifts in plant water balance suggested that NO is a mediator of MeJA-induced regulation of wheat water content during water deficit. Full article

It is necessary to identify the appropriate traits that influence yield in a given environment as part of a breeding programme. The objective of this study was to identify the morphological traits that contribute to maize grain weight (GWt) under abiotic stress conditions. Three drought-tolerant maize varieties were grown under no-stress (NHWS), heat-stress (HS), and combined heat- and water-stress (CHWS) conditions. Data from 19 morphological traits were analysed. The correlation results revealed that eight traits consistently produced a significant positive relationship with GWt under the three growth conditions. The path coefficient analysis revealed that in the NHWS, HS, and CHWS conditions, five traits consistently had a positive direct effect on the GWt. Given the magnitude of the positive direct effects, increasing dry biomass yield, harvest index, and grain number in the NHWS; grain number, harvest index, and ear width in the HS; and harvest index, days till silk appearance, leaf chlorophyll content, and grain number in the CHWS will increase GWt. Under various abiotic stress conditions, maize phenotypic expression varied. Therefore, the identified traits that contributed positively to GWt under various stress conditions should be considered when developing a maize improvement programme in a stress-prone environment. Full article

Heavy metal tolerance and accumulation potential are the two characteristics most important for plant use in phytoremediation technologies. Therefore, the aim of the present study was to characterize the tolerance of Hylotelephium maximum from coastal drift line vegetation against the biogenous heavy metals Cu, Zn, and Mn and its metal accumulation potential in controlled conditions. Plants were propagated vegetatively and cultivated in an automated greenhouse in a vegetative state (Experiment 1; Cu, Zn, and Mn) and in flowering-inducing conditions (Experiment 2; Mn gradient). In Experiment 1, total shoot biomass was negatively affected only by Mn at 1.0 g L⁻¹, but root growth was significantly inhibited by all metals at this concentration. Plants accumulated 250 mg kg⁻¹ Cu, 3200 mg kg⁻¹ Zn, and >11,000 mg kg Mn⁻¹ in their leaves. In Experiment 2, only new shoot growth was significantly suppressed at 0.5 g L⁻¹ Mn. At the highest concentrations, shoot biomass progressively declined at the level of inhibition of flower and stem growth. Visual toxicity symptoms of Mn appeared 2 weeks after full treatment on leaves of 2.0 g L⁻¹ treated plants as black dots along the main veins and spread over the leaf surface with time. The maximum Mn accumulation capacity was reached in leaves (15,000 mg kg⁻¹), together with a high translocation factor and bioconcentration factor. The obtained results suggest that the particular accession of H. maximum has very good potential for practical phytoremediation purposes. Full article

Trees in urban areas provide important ecosystem services and are an essential element of urban green space. The constant increase in artificial light from anthropogenic activities around the world creates photopollution that affects the phenology and physiology of plants. Here we conducted a field study to investigate the anthropogenic impacts on six urban trees (Saraca asoca, Terminalia catappa, Bauhinia variegata, Holoptelea integrifolia, Ficus benjamina and Thevetia peruviana) using chlorophyll fluorescence analysis. OJIP curve, maximum quantum yield of primary photochemistry (ΦPo), quantum yield of electron transport (ΦEo), probability that an absorbed photon will be dissipated (ΦDo), photosynthetic performance index (PIcsm) and reaction center photochemistry were assessed. According to the results, various parameters of chlorophyll fluorescence showed significant and important effects on different tree species. T. peruviana and F. benjamina were found to be tolerant to street lighting, while on the other hand, S. asoca, T. catappa, B. variegata and H. integrifolia were found to be sensitive to artificial light induced by street lamps. This study clearly indicates that chlorophyll fluorescence analysis is a potent method for screening the tolerance of tree species to photopollution induced by artificial lights. Full article

The coronavirus disease 2019 (COVID-19) pandemic has claimed many lives since it was first reported in late December 2019. However, there is still no drug proven to be effective against the virus. In this study, a candidate host–pathogen–interactive (HPI) genome-wide genetic and epigenetic network (HPI-GWGEN) was constructed via big data mining. The reverse engineering method was applied to investigate the pathogenesis of SARS-CoV-2 infection by pruning the false positives in candidate HPI-GWGEN through the HPI RNA-seq time profile data. Subsequently, using the principal network projection (PNP) method and the annotations of the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway, we identified the significant biomarkers usable as drug targets for destroying favorable environments for the replication of SARS-CoV-2 or enhancing the defense of host cells against it. To discover multiple-molecule drugs that target the significant biomarkers (as drug targets), a deep neural network (DNN)-based drug–target interaction (DTI) model was trained by DTI databases to predict candidate molecular drugs for these drug targets. Using the DNN-based DTI model, we predicted the candidate drugs targeting the significant biomarkers (drug targets). After screening candidate drugs with drug design specifications, we finally proposed the combination of bosutinib, erlotinib, and 17-beta-estradiol as a multiple-molecule drug for the treatment of the amplification stage of SARS-CoV-2 infection and the combination of erlotinib, 17-beta-estradiol, and sertraline as a multiple-molecule drug for the treatment of saturation stage of mild-to-moderate SARS-CoV-2 infection. Full article

Maize is one of the globally most important cereal crops used for food, feed and fuel. It requires optimum soil nutrients such as Nitrogen (N), Phosphorus (P), and Potassium (K) for proper growth and development as well as for tolerance to biotic and other abiotic stresses. Yield potentials are not met under suboptimal soil fertility. One of the innovations that can reduce environmental impacts of continuous fertilization and lower the cost of maize production under low soil nutrient conditions is the development and use of tolerant cultivars. This paper provides spotlights on the following: (1) morphology and physiology of root and shoot systems; (2) genetics and genomics; and (3) transcriptome, proteome, and metabolome profiles, to elucidate maize tolerance to low amounts of soil nutrients, N, P, and K. Maize cultivars having deeper rooting structure, more lateral roots, dense roots, and high root exudates are more tolerant to N, P, and K limited conditions. Cultivars that are tolerant to N, P, and K stress (low) have high nutrient use efficiency, good photosynthetic and translocation activity that support high aboveground shoot weight under suboptimal N, P, and K conditions. Maize tolerance to N, P, and K stress (low) is quantitative, and mainly controlled by additive genes. Maize cultivar development and dissemination programs can exploit the mechanisms highlighted in this review. Full article

Ehretia microphylla of the Boraginaceae family has been extensively used as a folklore remedy for the treatment of a wide range of ailments such as cough, cancer, allergies, and gastrointestinal and venereal disorders. Extensive literature review reports have revealed these findings due to the presence of numerous phytomolecules. To validate traditional claims for cytotoxic activity of E. microphylla, the present study was undertaken. Dried leaves of the plant were powdered and defatted with petroleum ether followed by hot continuous extraction with chloroform. The chloroform extract was subjected to in vitro cytotoxic screening against a panel of human cancer cell lines such as HCT-116 (colon), MCF-7 (breast), PC-3 (prostate), A-549 (lung), HL-60 (leukemia) and MiaPaCa-2 (pancreatic) at 50 µM using SRB assay. The extract exhibited noteworthy cytotoxicity activity against breast and lung cancer. It exhibited 85.55% and 77.93% inhibition against MCF-7 and A-549 cancer cell lines, respectively. The mechanism behind cell death was determined using the DAPI staining method, which induces alteration in nuclear morphology in MCF-7 cell lines evidenced through DAPI staining. Phytochemical screening of E. microphylla extract showed the presence of saponins, steroids, lipids, tannins and triterpenoids. The chemoprofile of the chloroform extract of E. microphylla leaves was established using an n-hexane:ethyl acetate solvent system in a ratio of 6:4. The developed chromatogram showed five spots both in visible and UV light at 254 nm. The information provided in the present study will enable further studies on the isolation and characterization of bioactive compounds/fractions by following bioactivity-guided fractionation, and thus, the plant has the potential to reduce proliferation and may induce cell death via apoptosis in breast cancer cells. Full article

Honeybees, Apis mellifera, usually live in large colonies consisting of thousands of individuals. Within the colony, workers interact with their social environment frequently. The large workforce, division of labour, and other features may promote the ecological success of honeybees. For decades, artificial mini colonies in cages within the laboratory have become the gold standard, especially in experiments related to toxicology, effects of pesticides and pathogens. Experiments using caged bees and full-sized colonies yielded contradictory results. Here, the effect of cage experiments on the stress level of individual bees is analysed. Two different stress response were targeted, the heat shock response and the mobilization of energetic resources. While no differences were found for varying group sizes of bees, very strong effects emerged by comparing caged workers with bees from natural colonies. Caged workers showed increased levels of hsp expression and reduced haemolymph titres for trehalose, the energy storage sugar. These results reveal that the lack of the social environment (e.g., lack of queen, lack of sufficient group size) induce stress in caged bees, which might act synergistically when bees are challenged by additional stressors (e.g., pesticides, pathogens) resulting in higher mortality than observed under field conditions. Full article