Non-enzymatic Antioxidant Activity Research Articles

The Role of Pigments and Cryptochrome 1 in the Adaptation of Solanum lycopersicum Photosynthetic Apparatus to High-Intensity Blue Light.

The effects of high-intensity blue light (HIBL, 500/1000 µmol m-2s-1, 450 nm) on Solanum lycopersicum mutants with high pigment (hp) and low pigment (lp) levels and cryptochrome 1 (cry1) deficiency on photosynthesis, chlorophylls, phenols, anthocyanins, nonenzymatic antioxidant activity, carotenoid composition, and the expression of light-dependent genes were investigated. The plants, grown under white light for 42 days, were exposed to HIBL for 72 h. The hp mutant quickly adapted to 500 µmol m-2s-1 HIBL, exhibiting enhanced photosynthesis, increased anthocyanin and carotenoids (beta-carotene, zeaxanthin), and increased expression of key genes involved in pigment biosynthesis (PSY1, PAL1, CHS, ANS) and PSII proteins along with an increase in nonenzymatic antioxidant activity. At 1000 µmol m-2s-1 HIBL, the lp mutant showed the highest photosynthetic activity, enhanced expression of genes associated with PSII external proteins (psbO, psbP, psbQ), and increased in neoxanthin content. This mutant demonstrated greater resistance at the higher HIBL, demonstrating increased stomatal conductance and photosynthesis rate. The cry1 mutant exhibited the highest non-photochemical quenching (NPQ) but had the lowest pigment contents and decreased photosynthetic rate and PSII activity, highlighting the critical role of CRY1 in adaptation to HIBL. The hp and lp mutants use distinct adaptation strategies, which are significantly hindered by the cry1 mutation. The pigment content appears to be crucial for adaptation at moderate HIBL doses, while CRY1 content and stomatal activity become more critical at higher doses.

An assessment of nanotechnology-based interventions for cleaning up toxic heavy metal/metalloid-contaminated agroecosystems: Potentials and issues

Heavy metals (HMs) are among the most dangerous environmental variables for a variety of life forms, including crops. Accumulation of HMs in consumables and their subsequent transmission to the food web are serious concerns for scientific communities and policy makers. The function of essential plant cellular macromolecules is substantially hampered by HMs, which eventually have a detrimental effect on agricultural yield. Among these HMs, three were considered, i.e., arsenic, cadmium, and chromium, in this review, from agro-ecosystem perspective. Compared with conventional plant growth regulators, the use of nanoparticles (NPs) is a relatively recent, successful, and promising method among the many methods employed to address or alleviate the toxicity of HMs. The ability of NPs to reduce HM mobility in soil, reduce HM availability, enhance the ability of the apoplastic barrier to prevent HM translocation inside the plant, strengthen the plant's antioxidant system by significantly enhancing the activities of many enzymatic and nonenzymatic antioxidants, and increase the generation of specialized metabolites together support the effectiveness of NPs as stress relievers. In this review article, to assess the efficacy of various NP types in ameliorating HM toxicity in plants, we adopted a ‘fusion approach’, in which a machine learning-based analysis was used to systematically highlight current research trends based on which an extensive literature survey is planned. A holistic assessment of HMs and NMs was subsequently carried out to highlight the future course of action(s).

How does water stress affect the bioaccumulation of galanthamine and lycorine, growth performance, phenolic content and defense enzyme activities in summer snowflake (Leucojum aestivum L.)?

AbstractLeucojum aestivum L. is an Amaryllidaceae bulbous plant with two alkaloids that have remarkable medicinal potential: galanthamine and lycorine. Although the presence of galanthamine in L. aestivum has commercial value for the pharmaceutical industry and the effect of water stress (WS) applications on secondary metabolite enhancement is well established in a variety of plants, no studies have been carried out to reveal the effectiveness of WS on this beneficial medicinal plant. Objective of the study was to investigate the effects of eight different WS treatments [Control, waterlogging (WL) condition, and drought stress conditions (water deficiency generated by water deficit irrigation-WDI 25%, 50%, and 75%- and polyethylene glycol-PEG 6000 15%, 30%, and 45%-)] on growth parameters, alkaloid levels (galanthamine and lycorine), non-enzymatic antioxidant activities (total phenol-flavonoid content and free radical scavenging activity), and enzymatic antioxidant activities [superoxide dismutase (SOD) and catalase (CAT)] of L. aestivum in a pot experiment. Based on the findings, maximum increases in growth parameters were obtained with PEG-induced WS treatments. Moderate water deficiency (50% WDI) produced the highest levels of galanthamine and lycorine, total phenol-flavonoid content, and antioxidant capacity, along with moderately elevated CAT activity in the bulbs. All WS treatments resulted in increased CAT activity in the bulbs. It was observed that bulbs had higher SOD and CAT activities under WL conditions had lower fresh weights and were close to control in terms of alkaloid levels, total phenol-flavonoid content, and free radical scavenging activity. When all of the outcomes were taken into account, it can be concluded that moderate water-deficit stress (50% WDI) was regarded as the most effective treatment for increasing the pharmaceutical value of L. aestivum. Graphical abstract

Intergenerational priming by Trichoderma alleviates drought stress in barley

The escalating global climate anomalies and disruption of ecological equilibrium pose profound threats to agroecosystems and crop productivity. Drought stress, a prominent consequence of climate change, exert detrimental effects on plant physiology, thereby reducing crop yield. This study explores the implementation of Trichoderma-mediated defence priming in barley under drought stress. Through a comprehensive evaluation of encompassing morphological, stomatal, biochemical, and yield parameters, Trichoderma- primed barley is compared with non-primed barley under drought stress conditions. Our results revealed that Trichoderma-primed barley exhibits heightened tolerance to drought stress in comparison to non-primed barley. The improved stomatal characteristics indicate that Trichoderma priming enables the plant to better adapt to drought conditions. Biochemical analysis showed enhanced photosynthetic pigments and reduced MDA in primed barley under drought, suggesting that primed barley experiences less oxidative stress compared to non-primed barley. Additionally, Trichoderma-primed plants displayed heightened levels of both non-enzymatic and enzymatic antioxidant activities, aiding in ROS detoxification. Stress responses are activated upon encountering a triggering stimulus (drought stress), but not after Trichoderma priming. This means there was no wasteful diversion of resources towards resistance mechanisms in the absence of stressful situations, leading to enhanced yield for primed barley compared to non-primed barley under stressful conditions. Furthermore, our investigation into the heritability of priming effects in the succeeding generation demonstrates that the progeny of primed barley retains enhanced protection akin to their primed parents. In contrast the progeny of non-primed barley exhibits greater vulnerability under water-deficit conditions. The expression of the epigenetic regulator gene HvDME was more enhanced in primed barley and its subsequent generations than in non-primed barley. This research emphasizes the potential of Trichoderma priming as a cost-effective strategy to enhance barley production amidst climate change challenges. The priming defense approach offers an intelligent plant health management solution devoid of adverse environmental or yield-related implications. This discovery holds significant promise, particularly in regions with limited water resources where crops are highly susceptible to drought stress. The findings contribute to the advancement of sustainable and climate-resilient agriculture, offering insights for practitioners and policymakers aiming to address the adverse impacts of climate change on crop production.

Glycine Betaine Mitigates Heavy Metal Toxicity in Beta vulgaris (L.): An Antioxidant-Driven Approach

Plants are often exposed to non-ideal conditions during their growth. The toxicity of heavy metals as abiotic stressors is a significant concern due to their harmful effects on plants. Glycine betaine (GB) is a potent compatible solute that helps plants resist abiotic stresses and plays a crucial role in alleviating them. This study aimed to determine the effective role of glycine betaine (0.5 and 1 mM) as a foliar treatment in sugar beet plants to cope with the toxicity of cadmium (50 mg/kg soil) and lead (100 mg/kg soil). The application of lead (Pb) and cadmium (Cd) in cultivation soil noticeably suppressed morphological growth attributes, such as chlorophylls, carotenoids, sugars, and proteins. At the same time, the aforementioned levels of heavy metals significantly increased the levels of non-enzymatic antioxidants (phenolics and proline) and enzymatic antioxidants (peroxidase, superoxide dismutase, polyphenol oxidase, and catalase) in the root and shoot tissues of sugar beet plants. In contrast, the use of glycine betaine as foliar treatment at 0.5 and 1 mM alleviated the adverse impacts of cadmium and lead by promoting the aforementioned attributes. Furthermore, the application of 1 mM GB was more effective in increasing the contents of phenolics in root by approximately 16% and 29%, phenolics in shoot by about 25% and 10%, peroxidase activity by about 82% and 116%, superoxide dismutase activity by about 56% and 47%, polyphenol oxidase activity by about 9% and 36%, catalase activity by about 19% and 25%, in cadmium- and lead-stressed plants, respectively. Additionally, it reduced the levels of proline in sugar beet tissues. Overall, the application of glycine betaine has the efficacy to counteract the adverse impacts of cadmium and lead toxicity on sugar beet plants by enhancing the metabolic indices as well as the non-enzymatic and enzymatic antioxidant activities.

Overexpression of OsTIP1;2 confers arsenite tolerance in rice and reduces root-to-shoot translocation of arsenic

Tonoplast Intrinsic Proteins (TIPs) are vital in transporting water and solutes across vacuolar membrane. The role of TIPs in the arsenic stress response is largely undefined. Rice shows sensitivity to the arsenite [As[III]] stress and its accumulation at high concentrations in grains poses severe health hazards. In this study, functional characterization of OsTIP1;2 from Oryza sativa indica cultivar Pusa Basmati-1 (PB-1) was done under the As[III] stress. Overexpression of OsTIP1;2 in PB-1 rice conferred tolerance to As[III] treatment measured in terms of enhanced shoot growth, biomass, and shoot/root ratio of overexpression (OE) lines compared to the wild-type (WT) plants. Moreover, seed priming with the IRW100 yeast cells (deficient in vacuolar membrane As[III] transporter YCF1) expressing OsTIP1;2 further increased As[III] stress tolerance of both WT and OE plants. The dithizone assay showed that WT plants accumulated high arsenic in shoots, while OE lines accumulated more arsenic in roots than shoots thereby limiting the translocation of arsenic to shoot. The activity of enzymatic and non-enzymatic antioxidants also increased in the OE lines on exposure to As[III]. The tissue-specific localization showed OsTIP1;2 promoter activity in root and root hairs, indicating its possible root-specific function. After As[III] treatment in hydroponic medium, the arsenic translocation factor (TF) for WT was around 0.8, while that of OE lines was around 0.2. Moreover, the arsenic content in the grains of OE lines reduced significantly compared to WT plants.

Oxalic acid alleviates chilling injury and positively influences post-harvest parameters of sweet bell pepper by affecting glycine betaine accumulation, cells respiration rate and NADPH oxidase enzyme activity during cold storage

Bell pepper as tropical crop and warm-season vegetable is sensitive to cold storage under temperatures below 7.5 °C. The purposes of the current study were to investigate the influence of pre-harvest treatment of oxalic acid (OA 0, 1, 5, 10, and 15 mM) on some of most important morphological, physiological and bio-chemical characteristics of red bell pepper cv. "2090 Westland" at post-harvest stage, and assessment of mechanisms and enzymatic pathways of crop response to OA treatments. OA treatments greatly reduced the chilling index, and the positive effects of treatments enhanced by increasing the concentration of OA. The energy level (ATP content) of pepper fruits decreased with extending storage duration, but OA treatment maintained the ATP content of fruits. On 24 d of storage, the highest and lowest activity rate of NADPH oxidase enzyme was recorded in control and 10 mM-treated fruits. Extending storage duration led to a significant increase in cells respiration rate, but this increase was more pronounced in control. Oxalic acid as low-risk and environmentally friendly compound could be an appropriate choice to apply as pre-harvest treatment in order to extend shelf-life of bell pepper fruits during cold storage under 4 ºC. The most important mechanisms reaction of OA are enhancing of enzymatic and non-enzymatic antioxidant activities, increasing the accumulation rate of osmoprotectants and regulation of energy metabolism of cells. Pre-harvest treatment of OA 10 mM could be introduced as efficient technique to overcome adverse effects of chilling stress on post-harvest characteristics of bell pepper.

Early vigour: A key to drought tolerance in cassava based on physiological and biochemical traits including inherent non-enzymatic antioxidant activity

An experiment was conducted with drought-tolerant and susceptible genotypes to find out the key traits that determine drought tolerance in cassava. The drought-tolerant clone 8S501 and the two susceptible clones H-97 and CR43-11 were planted in the field in a Randomized Block Design and the drought stress was imposed when the plants were three months old. The observations were measured at the beginning of the stress period (0-stress), 30 and 75 days of stress. The repeated measures ANOVA stated that there were significant differences among the genotypes, stress duration and their interaction for the majority of the traits. Growth, development and tuber yield of cassava was not significantly affected up to 30 days of drought stress. There was a greater decline in LA, TBM, CGR, RGR and NAR between 30 and 75 days of drought stress suggesting that measures are to be taken if drought stress prolongs for more than 30 days to realize optimum growth and yield of cassava. There was no increment in TY and PSR after 30 days of stress. A greater reduction was observed from 30 to 75 days of stress in leaf TC and CP content. There was a considerable increase in proline and total phenols content in the leaf from 30 to 75 days of stress. The inherent free radical scavenging activity measured as DPPH, FRAP and ABTS assays also demonstrated a notable increase in antioxidant activity at 75 days of drought stress. The early vigour in terms of initial high leafiness, leaf area, tuber yield, proportion of storage roots and total biomass in the first three months after planting facilitated the clone 8S501 to effectively tolerate the drought stress conditions.

Enhancement of sweetpotato tolerance to chromium stress through melatonin and glutathione: Insights into photosynthetic efficiency, oxidative defense, and growth parameters

Melatonin (MT) and reduced glutathione (GSH) roles in mitigating chromium (Cr) toxicity in sweetpotato were explored. Plants, pre-treated with varying MT and GSH doses, were exposed to Cr (40 μM). Cr severely hampered growth by disrupting leaf photosynthesis, root system, and oxidative processes and increased Cr absorption. However, the exogenous application of 1 μM of MT and 2 mM of GSH substantially improved growth parameters by enhancing chlorophyll content, gas exchange (Pn, Tr, Gs, and Ci), and chlorophyll fluorescence (Fv/Fm, ETR, qP, and Y(II)). Furthermore, malondialdehyde (MDA), hydrogen peroxide (H2O2), superoxide ion (O2•−), electrolyte leakage (EL), and Cr uptake by roots (21.6 and 27.3%) and its translocation to shoots were markedly reduced by MT and GSH application, protecting the cell membrane from oxidative damage of Cr-toxicity. Microscopic analysis demonstrated that MT and GSH maintained chloroplast structure and integrity of mesophyll cells; they also enhanced stomatal length, width, and density, strengthening the photosynthetic system and plant growth and biomass. MT and GSH improved osmo-protectants (proline and soluble sugars), gene expression, and enzymatic and non-enzymatic antioxidant activities, mitigating osmotic stress and strengthening plant defenses under Cr stress. Importantly, the efficiency of GSH pre-treatment in reducing Cr-toxicity surpassed that of MT. The findings indicate that MT and GSH alleviate Cr detrimental effects by enhancing photosynthetic organ stability, component accumulation, and resistance to oxidative stress. This study is a valuable resource for plants confronting Cr stress in contaminated soils, but further field validation and detailed molecular exploration are necessary.

Trichoderma Inoculation Alleviates Cd and Pb-Induced Toxicity and Improves Growth and Physiology of Vigna radiata (L.).

Heavy metals (HMs) pose a serious threat to agricultural productivity. Therefore, there is a need to find sustainable approaches to combat HM stressors in agriculture. In this study, we isolated Trichoderma sp. TF-13 from metal-polluted rhizospheric soil, which has the ability to resist 1600 and 1200 μg mL-1 cadmium (Cd) and lead (Pb), respectively. Owing to its remarkable metal tolerance, this fungal strain was applied for bioremediation of HMs in Vigna radiata (L.). Strain TF-13 produced siderophore, salicylic acid (SA; 43.4 μg mL-1) and 2,3-DHBA (21.0 μg mL-1), indole-3-acetic acid, ammonia, and ACC deaminase under HM stressed conditions. Increasing concentrations of tested HM ions caused severe reduction in overall growth of plants; however, Trichoderma sp. TF-13 inoculation significantly (p ≤ 0.05) increased the growth and physiological traits of HM-treated V. radiata. Interestingly, Trichoderma sp. TF-13 improved germination rate (10%), root length (26%), root biomass (32%), and vigor index (12%) of V. radiata grown under 25 μg Cd kg-1 soil. Additionally, Trichoderma inoculation showed a significant (p ≤ 0.05) increase in total chlorophyll, chl a, chl b, carotenoid content, root nitrogen (N), and root phosphorus (P) of 100 μg Cd kg-1 soil-treated plants over uninoculated treatment. Furthermore, enzymatic and nonenzymatic antioxidant activities of Trichoderma inoculated in metal-treated plants were improved. For instance, strain TF-13 increased proline (37%), lipid peroxidation (56%), catalase (35%), peroxidase (42%), superoxide dismutase (27%), and glutathione reductase (39%) activities in 100 μg Pb kg-1 soil-treated plants. The uptake of Pb and Cd in root/shoot tissues was decreased by 34/39 and 47/38% in fungal-inoculated and 25 μg kg-1 soil-treated plants. Thus, this study demonstrates that stabilizing metal mobility in the rhizosphere through Trichoderma inoculation significantly reduced the detrimental effects of Cd and Pb toxicity in V. radiata and also enhanced development under HM stress conditions.

Screening and characterization of bioactive compounds from two epiphytic microlichen and evaluation of their in vitro antioxidant activity

BackgroundLichens in symbiosis produce a wide range of primary and secondary fine compounds in extreme environmental conditions that have a broad range of biological properties as well as antioxidant potential and can be used in future pharmaceuticals as a natural source of antioxidant molecules.ResultsThe two microlichen species collected are identified based on morphological and molecular techniques; further studies are carried out by analyzing phytochemicals (FTIR, GC MS), and antioxidant assays are evaluated. The non-enzymatic antioxidant activity is evaluated by DPPH and FRAP assays. The methanol extract of both lichens showed virtuous DPPH scavenge with IC50 of P. nitida (125.76 ± 0.023 µg/ml) and G. scripta IC50 (176.90 ± 0.058 µg/ml). FRAP activity was prominent in the methalonic extract. The enzymatic antioxidant activity is observed by SOD and catalase activity. The cytosolic (Cu–Zn-SOD and Fe-SOD) and mitochondrial SOD (Mn-SOD) are detected in lichens, though P. nitida shows mitochondrial Mn-SOD and cytosolic Cu–Zn-SOD and Fe-SOD, whereas G. scripta has a single cytosolic Cu–Zn-SOD; however, two isoforms of catalase were reported. GC–MS analysis screened bioactive metabolites such as phenols, Quinons, heterocyclic compounds, benzofurans, fatty acids, pyrans, carboxylic acid, aliphatic aldehydes, organic alcohol, fluorinated aliphatic substances, ketones, terpenes and fatty alcohols in P. nitida, whereas, in G. scripta screened fatty acids, alcohols, hydrocarbons, carbonyl compounds, polyols, terpenes, glycosides, phenols, and sugar alcohols detected in the chromatogram peak. FTIR analysis revealed functional groups like Alcohols, Amines, Amides, Alkanes, Aldehydes, Carboxylic acid, Alkynes, Esters, Ketones, Anhydrides, Acid chlorides, Alkenes, Aromatic compounds, Nitro compounds, Alkyl and Aryl Halides in both lichens.ConclusionsThe results obtained in the present study proved that P. nitida and G. scripta have promising antioxidant activity owing to the presence of polyphenols and terpenes, as evidenced by DPPH and FRAP assay along with enzymatic analysis (SOD and CAT). Thus both the lichens may be used as natural sources of new bioactive molecules having pharmaceutical interest.

Morpho-physiological and metabolites alteration in the susceptible and tolerant genotypes of sesame under waterlogging stress and post-waterlogging recovery

Among the oil-seed crops, Sesamum indicum L. is an important nutritionally rich crop, well adapted to grow in semi-arid regions. Waterlogging stress adversely affects the growth of sesame by limiting diffused oxygen availability in soil and generating hypoxic, subsequently anoxic conditions. The present study aimed to screen the 1,006 accessions for waterlogging stress response at the seedling stage to identify the most tolerant and susceptible genotype. The investigation revealed that, 48 h of stress are detrimental and 10 days post-waterlogging impede crop survival. The screened accessions were narrowed down by 8 to detect the morphological alterations, and the morphological characteristics such as shoot height, root length, SPAD, branches per plant and relative water content r) were significantly higher in check and EC377024. Enzymatic (SOD, CAT and APX) and non-enzymatic (TFC, TPC, DPPH, FRAP, TAA, MDA and proline) antioxidant activity was notably higher in check and EC377024 and lower in IC129289. DAB and NBT assay confirmed lower damages from free radicals in EC377024 compared to IC129289. Moreover, contrasting gene expression profiling of free radicals (POD and RBOHC), carbohydrate metabolism (SuSy2 and StSy1), phosphate group gene (PSRG), and plant hormone (ERF RAP 2–7, ACC) confirmed the tolerance in EC377024 under waterlogging stress conditions. Besides, metabolomics study in EC377024 at control and 48 h of waterlogging stress indicate the significant accumulated metabolites in fatty acid (decanoate), carbohydrate, amino acid, Shikimate, MEP (5-enolpyruvoyl-shikimate-3-phosphate) Krebs cycle and Xanthophyll pathways. This comprehensive combination of morpho-physiological, biochemical, molecular and metabolomic characterizations highlight the stress responsive mechanisms between the tolerant (EC377024) and susceptible (IC129289) genotypes.

Impact of Gamma Irradiation on Biochemical and Physiological Characteristics of Black Rice

Rice (Oryza sativa L.) is a fruit caryopsis, well known for its high calorific value and presence of high antioxidant phytochemicals such as flavonoids and anthocyanins. Further exposure of crops to different doses of physical mutagens is useful to give insight into development of quality traits for plant breeding. So, the objective of the present study was to analyse the effects of gamma irradiation on black rice seeds that were exposed to different radiation doses and to evaluate the irradiation effect on physiological and biochemical characteristics of plants. Variations were observed among different doses from non-enzymatic antioxidant activities that showed the increasing flavonoids, phenolics and carotenoids accumulation from low to high doses. A high dose irradiation releases, high amount of H2O2 as compare to O2- indicating the involvement of enzymatic antioxidants as a defence mechanism. An inverse relation was shown between peroxidase and catalase enzyme and concentration of Superoxide dismutase also increased with increasing doses. To know the level of stress on cellular metabolism, total proline and malon dialdehyde accumulation was estimated and both showed positive results for increasing doses. In case of measurement of photosynthetic parameters, chlorophyll concentration increased from 50 Gy to 100 Gy and decreased from 150 Gy to 200 Gy due to peroxidation of membrane. Significant effect was not observed in the concentration of soluble sugar among various doses. Thus, the present study, was useful to isolating effective dose (50Gy, 100 Gy) that may contribute towards advancement of qualitative traits for future breeding purposes.

The antimicrobial activity of Hypericum perforatum L. flower extract against food pathogens and its non-enzymatic antioxidant activity

Foodborne pathogens pose a significant hazard to food safety. Most cases of foodborne illnesses are caused by bacterial pathogens that have infiltrated the food chain at some point, from farm to kitchen. According to the World Health Organization (WHO), approximately one-third of individuals in developed countries are affected by foodborne pathogens each year. Although there are studies on Hypericum perforatum L. in the literature, research in Turkey remains limited. Therefore, the aim is to contribute to the literature by studying H. perforatum samples from the Yaraş region of Muğla province in Turkey. This study specifically aims to investigate the antimicrobial activities against foodborne pathogens and the antioxidant activity of H. perforatum in Muğla. The in vitro antimicrobial activities of flower components from plants grown in Mugla were evaluated using the disc diffusion method and broth dilution test. Additionally, the extracts underwent ABTS (2,2'-azinobis-(3-ethyl benzothiazoline-6-sulfonic acid)) free-radical testing to evaluate their antioxidant activity. The extract exhibited a maximum inhibition zone of 16 mm against Staphylococcus aureus and Listeria monocytogenes. Notably, S. aureus and L. monocytogenes demonstrated the lowest sensitivity to H. perforatum methanol extract (1625 µg/mL). The methanol extract displayed moderate antioxidant activity, with a 53% ABTS radical scavenging capacity. Consequently, the extracts of H. perforatum exhibited both antimicrobial and antioxidant potential.

Mitigating Salinity Stress in Quinoa (Chenopodium quinoa Willd.) with Biochar and Superabsorber Polymer Amendments.

In agriculture, soil amendments are applied to improve soil quality by increasing the water retention capacity and regulating the pH and ion exchange. Our study was carried out to investigate the impact of a commercial biochar (Bc) and a superabsorbent polymer (SAP) on the physiological and biochemical processes and the growth performance of Chenopodium quinoa (variety ICBA-5) when exposed to high salinity. Plants were grown for 25 days under controlled greenhouse conditions in pots filled with a soil mixture with or without 3% Bc or 0.2% SAP by volume before the initiation of 27 days of growth in hypersaline conditions, following the addition of 300 mM NaCl. Without the Bc or soil amendments, multiple negative effects of hypersalinity were detected on photosynthetic CO2 assimilation (Anet minus 70%) and on the production of fresh matter from the whole plant, leaves, stems and roots (respectively, 55, 46, 64 and 66%). Moreover, increased generation of reactive oxygen species (ROS) was indicated by higher levels of MDA (plus 142%), antioxidant activities and high proline levels (plus 311%). In the pots treated with 300 mM NaCl, the amendments Bc or SAP improved the plant growth parameters, including fresh matter production (by 10 and 17%), an increased chlorophyll content by 9 and 13% and Anet in plants (by 98 and 115%). Both amendments (Bc and SAP) resulted in significant salinity mitigation effects, decreasing proline and malondialdehyde (MDA) levels whilst increasing both the activity of enzymatic antioxidants and non-enzymatic antioxidants that reduce the levels of ROS. This study confirms how soil amendments can help to improve plant performance and expand the productive range into saline areas.

The influence of elevated CO2 concentrations and UVB radiation in antioxidant activity of selected Chenopodium quinoa varieties

Ecosystems have been affected by climate change. Both agriculture and environmental changes are correlated with various features since climate change is the main cause of abiotic and biotic stress, which affects crop plants. Climate change and its severe impact on plant productivity showed great intensity due to the effects of abiotic stress. In the present investigation, we selected two quinoa varieties to study the response to future climatic factors such as eCO2, enhanced UVB radiation, and UVB+eCO2 combined effects in open-top chambers in the hot climate of the UAE. The treatments were administered for 90 days in the hot UAE weather conditions and the experiment was carried out in a transparent OTC facility. The response of the studied quinoa varieties was measured by analyzing their non-enzymatic antioxidant and antioxidant enzyme activities. Our findings showed that quinoa varieties are suitable as industrial crops for their levels of antioxidants under stimulating climatic conditions because the quantity and quality of their yield have not been affected. Based on the results obtained in the present investigation, further study is warranted for screening more varieties with the addition of climate change factors such as temperature and humidity to find more tolerant varieties of quinoa suitable for future climatic conditions.

Bamboo leaf extract treatment alleviates the surface browning of fresh-cut apple by regulating membrane lipid metabolism and antioxidant properties.

The effect of bamboo leaf extract (BLE) on controlling the browning of fresh-cut apple stored at 4 °C was investigated. Browning index, H2 O2 content, O2 - production rate, malondialdehyde (MDA) contents, total phenolic content (TPC) and soluble quinone content (SQC), the activities of polyphenol oxidase (PPO), peroxidase (POD), lipoxygenase (LOX), superoxide dismutase (SOD), catalase (CAT) and ascorbate peroxidase (APX), DPPH (2,2-diphenyl-2-picryl-hydrazyl) and ABTS [2,2-azinobis(3-ethylbenzothiazoline- 6-sulfonic acid)] radical scavenging activities, and the expression of genes related to browning were all investigated. BLE effectively alleviated the surface browning of fresh-cut apple, accompanied by a reduction in SQC, LOX activity, H2 O2 , O2 - production rate and MDA accumulation. Furthermore, BLE treatment enhanced the TPC, enzymatic (SOD, CAT, APX and POD) and non-enzymatic antioxidant activities. Principal component analysis and Pearson correlation analysis found the browning inhibition by BLE is not through the reduction of phenolic substrates and PPO activity. BLE controls the browning of fresh-cut apple by increasing the antioxidant capacity to scavenge ROS, which could alleviate oxidative damage and maintain the membrane integrity. © 2023 Society of Chemical Industry.

Rice tonoplast intrinsic protein member OsTIP1;2 confers tolerance to arsenite stress

The International Agency for Research on Cancer categorizes arsenic (As) as a group I carcinogen. Arsenic exposure significantly reduces growth, development, metabolism, and crop yield. Tonoplast intrinsic proteins (TIPs) belong to the major intrinsic protein (MIP) superfamily and transport various substrates, including metals/metalloids. Our study aimed to characterize rice OsTIP1;2 in As[III] stress response. The gene expression analysis showed that the OsTIP1;2 expression was enhanced in roots on exposure to As[III] treatment. The heterologous expression of OsTIP1;2 in S. cerevisiae mutant lacking YCF1 (ycf1∆) complemented the As[III] transport function of the YCF1 transporter but not for boron (B) and arsenate As[V], indicating its substrate selective nature. The ycf1∆ mutant expressing OsTIP1;2 accumulated more As than the wild type (W303–1A) and ycf1∆ mutant strain carrying the pYES2.1 vector. OsTIP1;2 activity was partially inhibited in the presence of the aquaporin (AQP) inhibitors. The subcellular localization studies confirmed that OsTIP1;2 is localized to the tonoplast. The transient overexpression of OsTIP1;2 in Nicotiana benthamiana leaves resulted in increased activities of enzymatic and non-enzymatic antioxidants, suggesting a potential role in mitigating oxidative stress induced by As[III]. The transgenic N. tabacum overexpressing OsTIP1;2 displayed an As[III]-tolerant phenotype, with increased fresh weight and root length than the wild-type (WT) and empty vector (EV line). The As translocation factor (TF) for WT and EV was around 0.8, while that of OE lines was around 0.4. Moreover, the OE line bioconcentration factor (BCF) was more than 1. Notably, the reduced TF and increased BCF in the OE line imply the potential of OsTIP1;2 for phytostabilization.

Beneficial Interactive Effects Provided by an Arbuscular Mycorrhizal Fungi and Yeast on the Growth of Oenothera picensis Established on Cu Mine Tailings

Phytoremediation, an environmentally friendly and sustainable approach for addressing Cu-contaminated environments, remains underutilized in mine tailings. Arbuscular mycorrhizal fungi (AMF) play a vital role in reducing Cu levels in plants through various mechanisms, including glomalin stabilization, immobilization within fungal structures, and enhancing plant tolerance to oxidative stress. Yeasts also contribute to plant growth and metal tolerance by producing phytohormones, solubilizing phosphates, generating exopolysaccharides, and facilitating AMF colonization. This study aimed to assess the impact of AMF and yeast inoculation on the growth and antioxidant response of Oenothera picensis plants growing in Cu mine tailings amended with compost. Plants were either non-inoculated (NY) or inoculated with Meyerozyma guilliermondii (MG), Rhodotorula mucilaginosa (RM), or a combination of both (MIX). Plants were also inoculated with Claroideoglomus claroideum (CC), while others remained non-AMF inoculated (NM). The results indicated significantly higher shoot biomass in the MG-NM treatment, showing a 3.4-fold increase compared to the NY-NM treatment. The MG-CC treatment exhibited the most substantial increase in root biomass, reaching 5-fold that in the NY-NM treatment. Co-inoculation of AMF and yeast influenced antioxidant activity, particularly catalase and ascorbate peroxidase. Furthermore, AMF and yeast inoculation individually led to a 2-fold decrease in total phenols in the roots. Yeast inoculation notably reduced non-enzymatic antioxidant activity in the ABTS and CUPRAC assays. Both AMF and yeast inoculation promoted the production of photosynthetic pigments, further emphasizing their importance in phytoremediation programs for mine tailings.

Silicon dioxide nanoparticles enhance plant growth, photosynthetic performance, and antioxidants defence machinery through suppressing chromium uptake in Brassica napus L.

Chromium (Cr) is a highly toxic heavy metal that is extensively released into the soil and drastically reduces plant yield. Silicon nanoparticles (Si NPs) were chosen to mitigate Cr toxicity due to their ability to interact with heavy metals and reduce their uptake. This manuscript explores the mechanisms of Cr-induced toxicity and the potential of Si NPs to mitigate Cr toxicity by regulating photosynthesis, oxidative stress, and antioxidant defence, along with the role of transcription factors and heavy metal transporter genes in rapeseed (Brassica napus L.). Rapeseed plants were grown hydroponically and subjected to hexavalent Cr stress (50 and 100 μM) in the form of K2Cr2O7 solution. Si NPs were foliar sprayed at concentrations of 50, 100 and 150 μM. The findings showed that 100 μM Si NPs under 100 μM Cr stress significantly increased the leaf Si content by 169% while reducing Cr uptake by 92% and 76% in roots and leaves, respectively. The presence of Si NPs inside the plant leaf cells was confirmed by using energy-dispersive spectroscopy, inductively coupled plasma‒mass spectrometry, and confocal laser scanning microscopy. The study's findings showed that Cr had adverse effects on plant growth, photosynthetic gas exchange attributes, leaf mesophyll ultrastructure, PSII performance and the activity of enzymatic and nonenzymatic antioxidants. However, Si NPs minimized Cr-induced toxicity by reducing total Cr accumulation and decreasing oxidative damage, as evidenced by reduced ROS production (such as H2O2 and MDA) and increased enzymatic and nonenzymatic antioxidant activities in plants. Interestingly, Si NPs under Cr stress effectively increased the NPQ, ETR and QY of PSII, indicating a robust protective response of PSII against stress. Furthermore, the enhancement of Cr tolerance facilitated by Si NPs was linked to the upregulation of genes associated with antioxidant enzymes and transcription factors, alongside the concurrent reduction in metal transporter activity.