The activity of superoxide dismutases (SODs) at the early stages of wheat deetiolation

One stone two birds: Endophytes alleviating trace elements accumulation and suppressing soilborne pathogen by stimulating plant growth, photosynthetic potential and defense related gene expression

In the present investigation, we utilized zinc nanoparticles (Zn-NPs) and bacterial endophytes to address the dual challenge of heavy metal (HM) toxicity in soil and Rhizoctonia solani causing root rot disease of tomato. The biocontrol potential of Bacillus subtilis and Bacillus amyloliquefaciens was harnessed, resulting in profound inhibition of R. solani mycelial growth and efficient detoxification of HM through strong production of various hydrolytic enzymes and metabolites. Surprisingly, Zn-NPs exhibited notable efficacy in suppressing mycelial growth and enhancing the seed germination (%) while Gas chromatography-mass spectrometry (GC-MS) analysis unveiled key volatile compounds (VOCs) crucial for the inhibition of pathogen. Greenhouse trials underscored significant reduction in the disease severity (%) and augmented biomass in biocontrol-mediated plants by improving photosynthesis-related attributes. Interestingly, Zn-NPs and biocontrol treatments enhanced the antioxidant enzymes and mitigate oxidative stress indicator by increasing H2O2 concentration. Field experiments corroborated these findings, with biocontrol-treated plants, particularly those receiving consortia-mediated treatments, displayed significant reduction in disease severity (%) and enhanced the fruit yield under field conditions. Root analysis confirmed the effective detoxification of HM, highlighting the eco-friendly potential of these endophytes and Zn-NPs as fungicide alternative for sustainable production that foster soil structure, biodiversity and promote plant health.

The influence of Au-based nanoparticles on some physiological, biochemical and molecular characteristics of wheat plants during low temperature hardening

One of the most significant problems of the 21st century is the anthropogenic strain on the environment. The development of nanotechnology makes it possible to produce a variety of nanomaterials widely used in people's daily lives. However, nanomaterials can accumulate in ecosystems and spread through food chains. The environmental risks of nanoparticle proliferation are unclear. At the same time, certain nanoparticles act as adaptogens, improving plant tolerance to unfavorable stress factors. It is quite realistic to choose such experimental conditions, under which the effect on plant stress tolerance will be obvious and the accumulation of nanoparticles in tissues will be minimal. In this case, the main relevant factors are the type of nanoparticles, their concentration and their way of penetration into plants. We chose to study gold nanoparticles (Au-NPs), widely used in biomedical research. The concentration of Au-NPs was 20 μg/mL, which is considered safe for living organisms. The influence of Au-NPs on some physiological, biochemical and molecular characteristics of wheat plants during low temperature hardening was examined. The study of the photosynthetic apparatus and antioxidant system was the primary focus. The stimulating effect of Au-NPs on cold tolerance of wheat plants was shown. The results expand our knowledge of the processes by which nanoparticles impact plants and the potential applications of nanoparticles as adaptogens in science and agriculture.

Fungal Elicitation Enhances Vincristine and Vinblastine Yield in the Embryogenic Tissues of Catharanthus roseus

Fungal elicitation could improve the secondary metabolite contents of in vitro cultures. Herein, we report the effect of Fusarium oxysporum on vinblastine and vincristine alkaloid yields in Catharanthus roseus embryos. The study revealed increased yields of vinblastine and vincristine in Catharanthus tissues. Different concentrations, i.e., 0.05% (T1), 0.15% (T2), 0.25% (T3), and 0.35% (T4), of an F. oxysporum extract were applied to a solid MS medium in addition to a control (T0). Embryogenic calli were formed from the hypocotyl explants of germinating seedlings, and the tissues were exposed to Fusarium extract elicitation. The administration of the F. oxysporum extract improved the growth of the callus biomass, which later differentiated into embryos, and the maximum induction of somatic embryos was noted T2 concentration (102.69/callus mass). A biochemical analysis revealed extra accumulations of sugar, protein, and proline in the fungus-elicitated cultivating tissues. The somatic embryos germinated into plantlets on full-strength MS medium supplemented with 2.24 µM of BA. The germination rate of the embryos and the shoot and root lengths of the embryos were high at low doses of the Fusarium treatment. The yields of vinblastine and vincristine were measured in different treated tissues via high-pressure thin-layer chromatography (HPTLC). The yield of vinblastine was high in mature (45-day old) embryos (1.229 µg g-1 dry weight), which were further enriched (1.267 µg g-1 dry weight) via the F. oxysporum-elicitated treatment, especially at the T2 concentration. Compared to vinblastine, the vincristine content was low, with a maximum of 0.307 µg g-1 dry weight following the addition of the F. oxysporum treatment. The highest and increased yields of vinblastine and vincristine, 7.88 and 15.50%, were noted in F. oxysporum-amended tissues. The maturated and germinating somatic embryos had high levels of SOD activity, and upon the addition of the fungal extracts, the enzyme's activity was further elevated, indicating that the tissues experienced cellular stress which yielded increased levels of vinblastine and vincristine following the T2/T1 treatments. The improvement in the yields of these alkaloids could augment cancer healthcare treatments, making them easy, accessible, and inexpensive.

Molecular and Biochemical Analysis of Duplicated Cytosolic CuZn Superoxide Dismutases of Rice and in silico Analysis in Plants

Superoxide dismutases (SODs, EC 1.15.1.1) are ubiquitous antioxidant metalloenzymes important for oxidative stress tolerance and cellular redox environment. Multiple factors have contributed toward the origin and diversity of SOD isoforms among different organisms. In plants, the genome duplication events, responsible for the generation of multiple gene copies/gene families, have also contributed toward the SOD diversity. However, the importance of such molecular events on the characteristics of SODs has not been studied well. This study investigated the effects of divergence on important characteristics of two block-duplicated rice cytosolic CuZn SODs (OsCSD1, OsCSD4), along with in silico assessment of similar events in other plants. The analysis revealed heterogeneity in gene length, regulatory regions, untranslated regions (UTRs), and coding regions of two OsCSDs. An inconsistency in the database-predicted OsCSD1 gene structure was also identified and validated experimentally. Transcript analysis showed differences in the basal levels and stress responsiveness of OsCSD1 and OsCSD4, and indicated the presence of two transcription start sites in the OsCSD1. At the amino acid level, the two OsCSDs showed differences at 18 sites; however, both exist as a homodimer, displaying typical CuZn SOD characteristics, and enhancing the oxidative stress tolerance of Escherichia coli cells. However, OsCSD4 showed higher specific activity as well as stability. The comparison of the two OsCSDs with reported thermostable CSDs from other plants identified regions likely to be associated with stability, while the homology modeling and superposition highlighted structural differences. The two OsCSDs displayed heteromeric interaction capability and forms an enzymatically active heterodimer (OsCSD1:OsCSD4) on co-expression, which may have significance as both are cytosolic. In silico analysis of 74 plant genomes revealed the prevalence of block duplications for multiple CSD copies (mostly cytosolic). The divergence and clustering analysis of CSDs suggested the possibility of an ancestral duplication event in monocots. Conserved SOD features indicating retention of SOD function among CSD duplicates were evident in few monocots and dicots. In most other species, the CSD copies lacked critical features and may not harbor SOD function; however, other feature-associated functions or novel functions might be present. These aspects of divergent CSD copies encoding co-localized CSDs may have implications in plant SOD functions in the cytosol and other organelles.

Dynamics of Etiolation Monitored by Seedling Morphology, Carotenoid Composition, Antioxidant Level, and Photoactivity of Protochlorophyllide in Arabidopsis thaliana

Although etiolated Arabidopsis thaliana seedlings are widely used as a model to study the de-etiolation process, the etiolation itself at the molecular level still needs elucidation. Here, we monitored the etiolation dynamics for wild type A. thaliana seedlings and lutein-deficient (lut2) mutant between 2 and 12 days of their growth in the absence of light. We analyzed the shape of the apex, the growth rate, the carotenoids and protochlorophyllide (Pchlide) accumulation, and the light-dependent protochlorophyllide oxidoreductase (LPOR) transcripts. Differences concerning the apical hook curvature and cotyledon opening among seedlings of the same age were observed, mostly after day 6 of the culture. We categorized the observed apex shapes and presented quantitatively how distribution among the categories changed during 12 days of seedling growth. The Pchlide₆₅₄/Pchlide₆₃₃ ratio, corresponding to the amount of the photoactive Pchlide, was the highest in the youngest seedlings, and decreased with their age. LPORA, LPORB, and LPORC transcripts were detected in etiolated seedlings, and their content decreased during seedling growth. Expression of SAG12 or SAG13 senescence markers, depletion in antioxidants, and excess ion leakage were not observed during the etiolation. Lack of lutein in the lut2 mutant resulted in slow Pchlide accumulation and affected other xanthophyll composition.

Influence of phosphorus on the uptake and biotransformation of arsenic in Porphyra haitanensis at environmental relevant concentrations

Edible seaweeds are rich in essential vitamins and minerals, which made them a popular food worldwide. Porphyra haitanensis is one of the most commonly consumed seaweeds with the known ability to accumulate a high level of total arsenic (As). A large number of articles have shown arsenic and phosphorus (P) interactions in microalgae due to the plant's inability to differentiate arsenate from phosphate. However, very limited information is available for edible seaweed at environmentally relevant concentrations. In this study, P. haitanensis was treated with arsenic as As^V (As1: 0.06 μM, As2: 0.4 μM, As3: 1.2 μM) and phosphorous (P1: 3.2 μM, P2: 13 μM) in a filtered seawater matrix under laboratory condition for six days. A better growth rate was found in seaweeds grown in P2 treatments. Moreover, superoxide dismutase (SOD) activity and malondialdehyde (MDA) content measurements revealed that a higher P concentration prevent seaweeds from lipid peroxidation and oxidative stress. Transcriptome studies indicated the As replacement to P has the ability to target seaweed cell membrane composition, transmembrane transport, DNA and ATP binding. The inorganic As (iAs) had a concentration of 0.54 to 4.45 mg/kg in P. haitanensis on Day 6 with As1, As2, and As3 treatments under low P regime (P1), which exceeds the limits of iAs concentration (0.1-0.5 mg/kg) in National Food Safety Standard-Limits of Pollutants in Food (GB 2762-2017). High P regime (P2) not only reduced the total As but also iAs effectively, even in the highest As treatment (As3), the iAs concentration was less than 0.5 mg/kg on Day 6. These findings provide a good insight for seafood safety guarantees and are important for the management of coastal artificial seaweed farming.

Overexpression of an aquaporin protein from Aspergillus glaucus confers salt tolerance in transgenic soybean

Salt stress is an important abiotic factor that causes severe losses in soybean yield and quality. Therefore, breeding salt-tolerant soybean germplasm resources via genetic engineering has gained importance. Aspergillus glaucus, a halophilic fungus that exhibits significant tolerance to salt, carries the gene AgGlpF. In this study, we used the soybean cotyledonary node transformation method to transfer the AgGlpF gene into the genome of the soybean variety Williams 82 to generate salt-tolerant transgenic soybean varieties. The results of PCR, Southern blot, ddPCR, and RT-PCR indicated that AgGlpF was successfully integrated into the soybean genome and stably expressed. When subjected to salt stress conditions via treatment with 250 mM NaCl for 3 d, the transgenic soybean plants showed significant tolerance compared with wild-type plants, which exhibited withering symptoms and leaf abscission after 9 d. The results of this study indicated that the transfer of AgGlpF into the genome of soybean plants produced transgenic soybean with significantly improved salt stress tolerance.

Insights Into Manganese Solubilizing Bacillus spp. for Improving Plant Growth and Manganese Uptake in Maize

Manganese (Mn) is an essential micronutrient for plant growth that is involved in the structure of photosynthetic proteins and enzymes. Mn deficiency is widespread mainly in dry, calcareous, and sandy soil, which leads to a significant decrease in crop yield. Mn-reducing bacteria promote the solubilization of Mn minerals, thus increasing Mn availability in soil. The present study aimed to assess the Mn solubilizing ability and plant growth-promoting potential of Bacillus spp. strains for maize plants with insoluble Mn compounds. Several Mn-solubilizing bacterial (MSB) strains were isolated from the maize rhizosphere using nutrient agar media amended with 50 mM MnO₂. These strains were screened based on qualitative and quantitative solubilization of Mn, phosphorus, potassium, and zinc and production of ammonia. The majority of MSB strains were positive for catalase, protease, amylase, and oxidase activity, while more than 60% of tested strains were positive for lipase activity, and the production of indole-3-acetic acid and siderophores. Forty-five percent of the tested strains also showed solubilization of potassium. All the MSB strains were evaluated for their ability to promote plant growth and Mn uptake in the presence of MnO₂ under axenic sand culture conditions. The results revealed that inoculation with MSB strains under sand culture significantly improved the growth of maize seedlings except for strains ASH7, ASH10, and ASH12. Comparatively, strains ASH6, ASH11, ASH19, ASH20, and ASH22 demonstrated a better increase in plant growth, fresh and dry biomass, and Mn uptake in roots and shoots than the other strains tested. All of these strains were identified as Bacillus spp. through 16S rRNA partial gene sequencing. Maize inoculation with these selected identified MSB strains also resulted in an increase in maize growth and nutrient uptake in maize roots and shoots under soil culture conditions in the presence of native soil Mn. The current study highlights the importance of MSB strain inoculation which could be a potential bioinoculants to promote plant growth under Mn deficiency.

Role of mitochondrial alternative oxidase in the regulation of cellular homeostasis during development of photosynthetic function in greening leaves

Here, recent publications on the role of mitochondrial non-phosphorylating pathways (NPhPs) in the electron transport chain during the de-etiolation of wheat leaves are reviewed. Among NPhPs, the alternative oxidase (AOX) pathway is the most effective pathway in maintaining cellular redox and energy balance, especially under stress conditions, including light stress. AOX is considered to dissipate excess reductants produced in the chloroplasts, and thereby prevent photooxidation. However, when etiolated wheat plants were exposed to a physiologically relevant light level, AOX was rapidly induced and increased, although the etioplasts did not produce excess reductants and have their own strong photoprotective mechanisms. The present study provides further insights into the role of AOX in greening cells and highlights the importance of AOX in the integration of cellular signalling pathways.

Ectopic expression of a poplar gene NAC13 confers enhanced tolerance to salinity stress in transgenic Nicotiana tabacum

NACs are one of the major transcription factor families in plants which play an important role in plant growth and development, as well as in adverse stress responses. In this study, we cloned a salt-inducible NAC transcription factor gene (NAC13) from a poplar variety 84K, followed by transforming it into both Nicotiana tabacum and Arabidopsis thaliana. Stable expression analysis of 35S::NAC13-GFP fusion protein in Arabidopsis indicated that NAC13 protein was localized to the nucleus. We also obtained five transgenic tobacco lines. Evidence from morphological and physiological characterization and salt treatment analyses indicated that in the transgenic tobacco the salt tolerance was enhanced, suggesting that NAC13 gene may function as a positive regulator in tobacco responses to salt stress.

Adjustment of Photosynthetic and Antioxidant Activities to Water Deficit Is Crucial in the Drought Tolerance of Lolium multiflorum/Festuca arundinacea Introgression Forms

Lolium multiflorum/Festuca arundinacea introgression forms have been proved several times to be good models to identify key components of grass metabolism involved in the mechanisms of tolerance to water deficit. Here, for the first time, a relationship between photosynthetic and antioxidant capacities with respect to drought tolerance of these forms was analyzed in detail. Two closely related L. multiflorum/F. arundinacea introgression forms distinct in their ability to re-grow after cessation of prolonged water deficit in the field were selected and subjected to short-term drought in pots to dissect precisely mechanisms of drought tolerance in this group of plants. The studies revealed that the form with higher drought tolerance was characterized by earlier and higher accumulation of abscisic acid, more stable cellular membranes, and more balanced reactive oxygen species metabolism associated with a higher capacity of the antioxidant system under drought conditions. On the other hand, both introgression forms revealed the same levels of stomatal conductance, CO₂ assimilation, and consequently, intrinsic water use efficiency under drought and recovery conditions. However, simultaneous higher adjustment of the Calvin cycle to water deficit and reduced CO₂ availability, with respect to the accumulation and activity of plastid fructose-1,6-bisphosphate aldolase, were clearly visible in the form with higher drought tolerance.

Effects of polar compounds in fried palm oil on liver lipid metabolism in C57 mice

Polar components (PCs) are produced during the frying of oil, affecting the quality of edible oil and posing a hazard to human health. In this study, C57 mice were fed a high-fat (HF) diet containing purified PCs for nine weeks. Their effects on lipid metabolism and liver function in animals were analyzed. Our results indicated that the contents of total PCs and saturated fatty acid increased from 6.07 ± 0.6% and 58.27 ± 0.35% to 19.17 ± 1.8% and 69.91 ± 0.51%, respectively (P < 0.01). PC intake resulted an 18.56% higher liver index in mice than that in the HF group. The PC group had the highest malondialdehyde (MDA) content (1.94 ± 0.11 nmol/mg protein) and the liver nonalcoholic fatty liver disease (NAFLD) activity score (NAS) was 4, which already showed NAFLD characteristics. In addition, the expression levels of lipid metabolism-related genes, including sterol regulatory element binding protein-1c (SREBP-1c), fatty acid synthetase (FAS), peroxisome proliferator-activated receptor-alpha, and peroxisome acyl-CoA oxidase 1, indicated that PC increased hepatic lipid accumulation by upregulating the transcriptional level of fat synthesis genes and further leads to liver damage by affecting mitochondrial function. Our results provided important information about the effects of PCs produced in the frying process of PO on animal health, which is critical for assessing the biosafety of fried products. PRACTICAL APPLICATION: The research will help promote the industrial upgrading of fried foods and help consumers build healthy lifestyles.

The effect of heavy metal contamination on humans and animals in the vicinity of a zinc smelting facility

A diagnosis of heavy metal poisoning in sheep living on pastures in the vicinity of a smelting facility in the Wumeng mountain area of China was based on laboratory tests and clinical symptoms. Furthermore, heavy metal contamination in the food chain was found to have a deleterious effect on the health of local residents. The levels of copper(Cu), zinc(Zn), cadmium (Cd), and lead (Pb) in irrigation water, soil, forages, and animal tissues were measured in samples taken from the vicinity of a smelting facility and control samples. Heavy metal contents in food (corn, rice, and wheat), as well as in human tissues (blood and hair) obtained from local residents were also determined. Hematological values were also determined in human and animal samples. The content of Cu, Zn, Cd, and Pb in irrigation water, soils, and forages were markedly higher in affected areas than in samples from healthy pastures. Concentrations of Cd and Pb were 177.82 and 16.61 times greater in forages than controls, respectively, and 68.71 and 15.66 times greater in soils than controls, respectively. The heavy metal content in food (corn, rice, and wheat) from affected areas was markedly higher than in the control samples. Cd and Pb content in the tissues of affected sheep were markedly higher than in control animals (P < 0.01), while concentrations of Cd and Pb in blood and hair samples from local residents were markedly higher than in control samples (P < 0.01). The occurrence of anemia in affected humans and animals followed a hypochromic and microcytic pattern. The intake of Cd and Pb was estimated according to herbage ingestion rates. It was found that the levels of Cd and Pb which accumulated in sheep through the ingestion of vegetation growing in the sites closest to the smelter were approximately 3.36 and 38.47 mg/kg body wt./day, respectively. Such levels surpassed the fatal dosages for sheep of 1.13 mg Cd/kg body wt/day and 4.42 mg Pb/kg body wt./day. The serum total antioxidant capacity in affected humans and animals was significantly lower than in the controls (P < 0.01). Serum protein parameters in affected humans and animals were significantly reduced (P < 0.01); therefore, it was concluded that heavy metal contamination caused harm to sheep, and also posed a significant risk to humans living in the vicinity of the zinc smelting facility.

The Biochemical Properties of Manganese in Plants

Manganese (Mn) is an essential micronutrient with many functional roles in plant metabolism. Manganese acts as an activator and co-factor of hundreds of metalloenzymes in plants. Because of its ability to readily change oxidation state in biological systems, Mn plays and important role in a broad range of enzyme-catalyzed reactions, including redox reactions, phosphorylation, decarboxylation, and hydrolysis. Manganese(II) is the prevalent oxidation state of Mn in plants and exhibits fast ligand exchange kinetics, which means that Mn can often be substituted by other metal ions, such as Mg(II), which has similar ion characteristics and requirements to the ligand environment of the metal binding sites. Knowledge of the molecular mechanisms catalyzed by Mn and regulation of Mn insertion into the active site of Mn-dependent enzymes, in the presence of other metals, is gradually evolving. This review presents an overview of the chemistry and biochemistry of Mn in plants, including an updated list of known Mn-dependent enzymes, together with enzymes where Mn has been shown to exchange with other metal ions. Furthermore, the current knowledge of the structure and functional role of the three most well characterized Mn-containing metalloenzymes in plants; the oxygen evolving complex of photosystem II, Mn superoxide dismutase, and oxalate oxidase is summarized.

Regulation of physiological processes in winter wheat by growth regulators in conditions of powdery mildew infection

An important way of regulating the key units of metabolism in the plant organism under the action of stressors is the use of biologically active substances with regulating properties – plant growth regulators. They affect endogenous regulatory systems, altering key metabolic pathways and thus increasing the plant's sustainability and productive potential in adverse environmental conditions. The aim of the research was to establish the possibility of regulation of physiological processes in winter wheat varieties by exogenous treatment of plants with growth regulators of synthetic (salicylic acid) and natural (Emistim C and Biolan) origin to increase their resistance to the phytopathogen Erysiphe graminis DC f. sp. tritici Em. Marchal , the causative agent of powdery mildew. The intensity of the physiological processes in plants was evaluated by the dynamics of the activity of antioxidant enzymes – ascorbate peroxidase and catalase, the release of ethylene and the integrity of the cell membranes. The objects were selected varieties of soft winter wheat, which were grown in controlled growing conditions against the background of infection by powdery mildew. The treatment of plants was carried out using aqueous salicylic acid solutions in the concentration of 10–5 M (experimentally established by us), Emistim C and Biolan (manufacturer Agrobiotech) in the concentration specified by the manufacturer at the rate of 20 mL/ha, when the development of the disease reached 5% of the total natural background of the infection in the plants during the stages of heading-beginning of flowering. Infection of winter wheat with powdery mildew leads to disruption of cell membrane integrity, increased activity of catalase and ascorbate peroxidase in leaves of the susceptible winter wheat variety. The intensification of ethylene release by leaves of the resistant variety was observed, which was caused by the hypersensitive reaction of the hormone to the effect of stress. The use of plant treatment by growth regulators contributes to maintaining the integrity of membrane structures, adaptive changes in the activity of antioxidant enzymes and regulation of the synthesis of the stress hormone ethylene in both winter wheat varieties under stress. Such changes in the physiological processes induced by plant growth regulators are accompanied by the preservation of the grain productivity of winter wheat and the increase of their resistance to the development of the disease.

Genetic diversity of submergence stress response in cytoplasms of the Triticum-Aegilops complex

Genetic diversity in cytoplasmic and nuclear genomes and their interaction affecting adaptive traits is an attractive research subject in plants. We addressed submergence stress response of wheat that has become increasingly important but remained largely uninvestigated. Our primary aim was to disclose cytoplasmic diversity using nucleus-cytoplasm (NC) hybrids possessing a series of heterologous cytoplasms in a common nuclear background. Effects of submergence on seedling emergence and growth from imbibed seeds were studied and compared with euplasmic lines. Marked phenotypic variabilities were observed among both lines, demonstrating divergent cytoplasmic and nuclear effects on submergence response. NC hybrids with cytoplasm of Aegilops mutica showed a less inhibition, indicative of their positive contribution to submergence tolerance, whereas cytoplasms of Aegilops umbellulata and related species caused a greater inhibition. Superoxide dismutase (SOD) activity showed a marked increase accompanied by retardation of seedling growth in a susceptible NC hybrid. The observation suggested that the elevated SOD activity was resulted from a high level of reactive oxygen species accumulated and remained in susceptible seedlings. Taken together, our results point to the usefulness of NC hybrids in further studies needed to clarify molecular mechanisms underlying the nucleus-cytoplasm interaction regulating submergence stress response in wheat.