APX Activity Research Articles

Differential responses of Hollyhock (Alcea rosea L.) varieties to salt stress in relation to physiological and biochemical parameters

The response of 14 Hollyhock (Alcea rosea L.) varieties to salinity were evaluated in a field experiment over two growing seasons. Carotenoid, Chl a, Chl b, total Chl, proline and MDA content, CAT, APX and GPX activity and petal and seeds yields were determined in order to investigate the mechanism of salt tolerance exhibited by Hollyhock, and too identify salt tolerant varieties. Overall, the photosynthetic pigment content,petal and seed yields were reduced by salt stress. Whereas the proline and MDA content, and the CAT, APX and GPX activities increased as salt levels increased. However, the values of the measured traits were dependent upon the on the level of salt stress, the Varietie and the interaction between the two variables. Based upon the smallest reduction in petal yield, the Masouleh variety was shown to be the most salt tolerant, when grown under severe salt stress. However, based upon the smallest reduction in seed yield, Khorrmabad was the most tolerant variety to severe salt stress. These data suggest that the selection of more salt tolerant Hollyhock genotypes may be possible based upon the wide variation in tolerance to salinity exhibited by the varieties tested.

Populus euphratica PeNADP-ME interacts with PePLDδ to mediate sodium and ROS homeostasis under salinity stress

Populus euphratica phospholipase Dδ (PePLDδ) is transcriptionally regulated and mediates reactive oxygen species (ROS) and ion homeostasis under saline conditions. The purpose of this study is to explore the post-transcriptional regulation of PePLDδ in response to salt environment. P. euphratica PePLDδ was shown to interact with the NADP-dependent malic enzyme (NADP-ME) by screening the yeast two-hybrid libraries. The transcription level of PeNADP-ME increased upon salt exposure to NaCl (200 mM) in leaves and roots of P. euphratica. PeNADP-ME had a similar subcellular location with PePLDδ in the cytoplasm, and the interaction between PeNADP-ME and PePLDδ was further verified by GST pull-down and yeast two-hybrid. To clarify whether PeNADP-ME interacts with PePLDδ to enhance salt tolerance, PePLDδ and PeNADP-ME were overexpressed singly or doubly in Arabidopsis thaliana. Dual overexpression of PeNADP-ME and PePLDδ resulted in an even more pronounced improvement in salt tolerance compared with single transformants overexpressing PeNADP-ME or PePLDδ alone. Greater Na+ limitation and Na+ efflux in roots were observed in doubly overexpressed plants compared with singly overexpressed plants with PeNADP-ME or PePLDδ. Furthermore, NaCl stimulation of SOD, APX, and POD activity and transcription were more remarkable in the doubly overexpressed plants. It is noteworthy that the enzymic activity of NADP-ME and PLD, and total phosphatidic acid (PA) concentrations were significantly higher in the double-overexpressed plants than in the single transformants. We conclude that PeNADP-ME interacts with PePLDδ in Arabidopsis to promote PLD-derived PA signaling, conferring Na+ extrusion and ROS scavenging under salt stress.

Acidic electrolyzed-oxidizing water treatment mitigated the disease progression in Phomopsis longanae Chi-infected longans by modulating ROS and membrane lipid metabolism

Postharvest harmful pathogenic infestation leads to rapid decay in longan fruit. Compared with P. longanae-infected longans, AEOW alleviated fruit disease severity and diminished the O2-. production rate and MDA content. It also increased APX, CAT, and SOD activities, delayed the decrease in the levels of GSH and AsA, as well as the reducing power and DPPH radical scavenging ability, which resulted in a decline in membrane lipid peroxidation in P. longanae-infected longans. Additionally, AEOW reduced LOX, lipase, PI-PLC, PC-PLC, and PLD activities, maintained higher levels of PC, PI, IUFA, USFAs, and U/S, while reducing levels of PA, DAG, SFAs, and CMP. These effects alleviated membrane lipid degradation and peroxidation in P. longanae-infected longans. Consequently, AEOW effectively maintained membrane integrity via improving antioxidant capacity and suppressing membrane lipid peroxidation. This comprehensive coordination of ROS and membrane lipid metabolisms improved fruit resistance and delayed disease development in longans.

Brassinolide as potential rescue agent for Pinellia ternata grown under microplastic condition: Insights into their modulatory role on photosynthesis, redox homeostasis, and AsA-GSH cycling

Microplastic (MP), as a new pollutant, not only affects the growth and development of plants but also may affect the secondary metabolites of plants. The anti-tumor role of Pinellia ternata is related to secondary metabolites. The role of brassinolide (BR) in regulating plant resistance is currently one of the research hotspots. The paper mainly explores the regulation of BR on growth and physiology of Pinellia ternata under MP stress. The experimental design includes two levels of MP (0, 1%) and two levels of BR (0, 0.1 mg/L). MP led to a marked reduction in plant height (15.0%), Fv/Fm (3.2%), SOD and APX activity (15.0%, 5.1%), whereas induced an evident raise in the rate of O2·- production (29.6%) and GSH content (4.4%), as well as flavonoids (6.8%), alkaloids (75%), and β-sitosterol (26.5%) contents. Under MP addition, BR supply significantly increased plant height (15.7%), aboveground and underground biomass (16.1%, 10.3%), carotenoid and GSH content (11.8%, 4.2%), Fv/Fm (2.9%), and activities of SOD, GR, and MDHAR (32.2%, 21.08%, 20.9%). These results indicate that MP suppresses the growth of P. ternata, although it promotes secondary metabolism. BR can alleviate the inhibitory effect of MP on growth by improving photosynthesis, redox homeostasis, and the AsA-GSH cycle.

The regulating mechanism of salt tolerance of black walnut seedlings was revealed by the physiological and biochemical integration analysis

Salt stress is an important abiotic stress that seriously affects plant growth. In order to research the salt tolerance of walnut rootstocks so as to provide scientific basis for screening salt-tolerant walnut rootstocks, two kinds of black walnut seedlings, Juglans microcarpa L. (JM) and Juglans nigra L. (JN), were treated under salt stress with different concentrations of NaCl (0, 50, 100, and 200 mM) and the growth situation of seedlings were observed. The physiological indexes of JM and JN seedlings were also measured in different days after treatment. Our study showed salt stress inhibited seedlings growth and limited biomass accumulation. Walnut mainly increased osmotic adjustment ability by accumulation Pro and SS. Furthermore, with the duration of treatment time increased, SOD and APX activities decreased, TPC and TFC contents increased. Walnut accumulated Na mostly in roots and transported more K and Ca to aboveground parts. The growth and physiological response performance differed between JM and JN, specifically, the differences occurred in the ability to absorb minerals, regulate osmotic stress, and scavenge ROS. Salt tolerance of JM and JN was assessed by principal component analysis (PCA) and resulted in JN > JM. In conclusion, our results indicated that JN has higher salt tolerance than JM, and JN might be used as a potential germplasm resource for the genetic breeding of walnuts.

Assessment of bioactive compounds, antioxidant potential, and enzymatic activity in different guava (Psidium guajava) cultivars

AbstractFresh fruits of five guava (Psidium guajava L.) cultivars were assessed for ascorbic acid (AA) content and enzymatic antioxidants (superoxide dismutase [SOD] and ascorbate peroxidase [APX]) activities, while extracted peel and pulp samples were analyzed for total phenol (TP) and total flavonoids (TFs). The hydrophilic and lipophilic antioxidant activity was evaluated using six different analytical assays. We noticed significant differences in the antioxidant compounds (AA, TP, and TF). SOD and APX activities varied from ∼54 to 71 and ∼41 to 59 U/g FW, respectively. Cv. KG Guava had the highest TP (in both hydrophilic and lipophilic peel and pulp fractions) and TF (in hydrophilic pulp and lipophilic peel and pulp fractions). Therefore, the strongest antioxidant potential was exhibited by KG Guava using most of the assays, which was followed by the cultivars Kimchu and Salithong. The results provide valuable information about antioxidant potential of guava peel and pulp fractions, which is essential for their future application in the food and health industry.

Coating seeds with biopolymers extracted from waste-activated sludge

Seeds can be coated with biopolymers extracted from waste-activated sludge, and the seeds of lettuce and spinach can be coated. When coated with the biopolymers, these seeds exhibited largely improved resistance to high temperature and humidity. The seeds coated or not coated with the biopolymers were aged, and the germination potential, germination ratio, and antioxidant enzyme activity of the coated seeds exhibited markedly greater differences than did those of the uncoated seeds. Moreover, the CAT, POD, and APX activities in the coated lettuce and spinach seeds increased by 56%, 2%, and 17%, respectively (lettuce), as did the activity of 8%, 3%, and 31%, respectively (spinach). In the pot trials, the contents of soluble protein and soluble sugar and the activities of antioxidant enzymes were also enhanced—42% and 56% (lettuce) as well as 34% and 23% (spinach). Thus, biopolymers can contribute to protecting against the aging of some rare seeds.

Bacillus sp. alone or combined with salicylic acid inhibited Trichoderma spp. infection on harvested white Hypsizygus marmoreus.

White Hypsizygus marmoreus is a popular edible mushroom. It is rich in nutrition and flavor but vulnerable to fungal disease, resulting in nutrient loss and aging. In this study, the pathogenic fungus Trichoderma spp. BBP-6 and its antagonist Bacillus sp. 1-23 were isolated and identified. The negative effects caused by this pathogen were judged by detecting a series of changes in the infected white H. marmoreus. The effects of Bacillus sp. 1-23 on Trichoderma spp. BBP-6 and the infected white H. marmoreus were detected. The effect of Bacillus sp. 1-23 treatment combined with salicylic acid (SA) was also considered. The results showed that Trichoderma spp. BBP-6 could affect the activities of antioxidant enzymes PAL, POD, CAT, SOD, GR, PPO, and APX to interfere with the stability of the white H. marmoreus antioxidant enzyme system and cause the mushroom severe browning and nutrition loss, as well as general quality deterioration. Bacillus sp. 1-23 could produce chitinase and chitosanase enzymes to inhibit Trichoderma spp. BBP-6 directly. SA reinforced this inhibitory. Bacillus sp. 1-23 alone or combined with SA could help white H. marmoreus from the Trichoderma spp. BBP-6 infection to effectively maintain nutrients, restore and stabilize the antioxidant system, and reduce the production of malondialdehyde, superoxide anion and hydrogen peroxide. Thus, such treatments could be considered potential methods to alleviate damage from disease and extend the shelf life of white H. marmoreus.

Antioxidant Activity, Inhibition of Intestinal Cancer Cell Growth and Polyphenolic Compounds of the Seagrass Posidonia oceanica's Extracts from Living Plants and Beach Casts.

The aim of the present study was to investigate the use of Posidonia oceanica for making products beneficial for human health. Firstly, we demonstrated that the antioxidant defense (i.e., SOD and APX activity) of P. oceanica's living leaves (LP) has low efficacy, as they partly neutralize the produced H2O2. However, high H2O2 levels led LP to produce, as a response to oxidative stress, high phenolic content, including chicoric acid, p-coumaric acid, caftaric acid, trans-cinnamic and rutin hydrate, as shown by UHPLC-DAD analysis. In addition, LP extracts inhibited intestinal cancer cell proliferation. Moreover, P. oceanica's beach casts consisting of either Wet 'Necromass' (WNP) or Dry 'Necromass' (DNP) were used for preparing extracts. Both DNP and WNP exhibited antioxidant and antiproliferative activities, although lower as compared to those of LP extracts. Although both P. oceanica's meadows and beach casts are considered priority habitats in the Mediterranean Sea due to their high ecological value, legislation framework for beach casts forbidding their removal is still missing. Our results suggested that both LP and DNP could be utilized for the production of high-added value products promoting human health, provided that a sustainability management strategy would be applied for P. oceanica's meadows and beach casts.

The comparison expression of Rare cold inducible 2 (RCI2), some enzymatic antioxidant, and proline in two tolerant and sensitive genotypes chickpea under drought stress

Chickpea (Cicer arietinum L.) is a highly valued crop that its growth and productivity are severely affected by drought stress. At the molecular level, chickpea plants activate genes and signaling pathways involved in drought and salt stress tolerance. One such mechanism involves the expression of rare cold inducible 2 (RCI2) proteins. The aim of this study was to examine the significance of RCI2 expression for drought resistance in chickpea. Hence, seeds of drought-tolerant (MCC877) and sensitive (MCC588) genotypes were evaluated in the three level of drought stress. The results indicated that drought stress reduced significantly total chlorophyll, RWC, and increased electro leakage, MDA, and improved activity of CAT, SOD, and APX. The molecular analysis suggested four RCI2 genes including RCI2A, RCI2B, RCI2B-like, and RCI2F in chickpeas. The comparison between two genotypes of chickpeas, one drought-tolerant and the other sensitive to drought, revealed that the tolerant genotype could enhance the stability of the cell membrane and moderate reactive oxygen species (ROS) content. This is achieved by improving the proline content, the activity of antioxidant enzymes, and especially by increasing the expression of RCI2 genes, compared to the sensitive genotypes. The expression RCI2A, RCI2B, RCI2B-like, and RCI2F genes in drought-tolerant genotypes was about 68 %, 48 %, 27 %, and 42 % higher than drought-sensitive after 16 h of severe water limitation. This suggests that the expression of RCI2 genes in chickpeas might enhance the plant's ability to scavenge ROS, thereby conferring tolerance to drought stresses.

Detrimental impacts of concomitant application of cadmium and pesticides are ameliorated by 24-epibrassinolide through alteration in oxidative status and CYP genes expression in Zea mays L.

The ameliorative impact of 24-epibrassinolide (EBL) was assessed under toxicity of cadmium (Cd) and three different pesticides including diazinon (DZ), imidacloprid (IMI), and chlorpyrifos (CPS) in maize plants. Maize seeds were pre-treated with 0.01 μM of EBL and grown in soil contaminated with 100 μM Cd for one month. Then, at five fully expanded leaf stage, plants received DZ, IMI, and CPS pesticides separately by foliar spray and were harvested five days later. The EBL seed primed plants, grown in soil contaminated with Cd and exposed to pesticides, exhibited higher deleterious photosynthesis (Pn) and stomatal conductivity (Gs) compared to un-EBL-treated plants. A considerable decrease was observed in the pesticide's residue and Cd, MDA and H2O2 contents of EBL + Cd + Pesticide treated plants compared to the Cd + Pesticide groups plants. Higher phenol, flavonoid and protein contents, as well as increment in SOD, CAT, POD, APX, PAL, GST, and GR enzymes activity were detected in EBL + Cd + Pesticide groups compared to the plants imposed with Cd + Pesticides. The expression analyses of four CYP family members including CYP71C1, CYP71C3v2, CYP72A5, and CYP81A9 revealed downregulation under Cd and Cd + pesticides treatments, while EBL seed priming highly induced transcript abundance of CYP71C1 (EBL + Cd + IMI); CYP71C3v2 (EBL + Cd + DZ & EBL + Cd + IMI) and CYP81A9 (EBL + Cd + DZ & EBL + Cd + CPS), specifically. The higher mRNA accumulation of CYP72A5 gene was exhibited under all three different EBL + Cd + pesticides treatments. The 24-epibrassinolide alleviates the adverse impacts of Cd and pesticides via the activation of enzymatic and non-enzymatic components to eliminate ROS through the up-regulation of CYP genes. This facilitates conjugation of glutathione to pesticides residue, leading to their rapid transportation into the vacuole or out of the membrane.

Application of green synthesized copper oxide nanoparticles for effective mitigation of Fusarium wilt disease in roots of Cicerarietinum

The study investigated the impact of copper oxide nanoparticles (CuONPs) on Fusarium wilt in chickpea. CuONPs, synthesized using coffee powder, were subjected to washing and sonication using Milli-Q water as the solvent during the purification process. Subsequently the nanoparticles were characterized through UV–vis spectroscopy, DLS, Zeta Potential and FTIR analysis. The NPs exhibited a size range of 85–100 nm with a zeta potential of −25.3 mV. Seven days old chickpea seedlings treated with different concentrations of CuONP (10, 25, 50 ppm) via root immersion showed a significant reduction in Fusarium infection severity. Treatment with 10 and 25 ppm CuONPs led to a remarkable 74.5% and 50% decrease in wilt incidence, along with increased root and shoot length, protein, tannin, phenolics, and flavonoid content in chickpea seedlings, grown in Fusarium infected soil. Enzyme activity (PAL, PPO, NR) was enhanced, while proline, H2O2, and MDA content decreased in 10 and 25 ppm CuONPs treated seedlings. A reduced activity of APX and SOD was also recorded in 10 and 25 ppm CuONPs treated seedlings. Chlorophyll content increased by 50.08% in 10 ppm treated seedlings but decreased with 25 and 50 ppm. The findings emphasize the protective role of copper oxide nanoparticles (CuONPs) at a lower concentration of 10 ppm against Fusarium wilt disease. This protective effect is manifested through the reduction of oxidative stress, decreased wilt incidence, and an increased biomass.

Drought priming reduces Calligonum mongolicum sensitivity to recurrent droughts via coordinated regulation of osmolytes, antioxidants, and hormones.

Pre-exposure of plants to abiotic stressors may induce stress memory and improve tolerance to subsequent stresses. Here, 3-month-old Calligonum mongolicum seedlings were exposed to drought (60 days) with (primed) or without (unprimed) early drought exposure of 50 days, to determine whether this enhances seedling resistance and investigate possible underlying mechanisms. Compared to unprimed, primed seedlings had higher biomass, shoot relative water content (15% and 22%), chlorophyll a, chlorophyll b, and carotenoids. They also had more superoxide anions (O2 -• ) and H2 O2 scavenging mechanisms through higher activity of SOD, CAT, APX, and dehydroascorbate reductase in assimilating shoots and roots, resulting in less ROS and oxidative stress damage. Plants also had higher ABA and JA but lower SA, likely reflecting an adaptive response to subsequent stress. Primed seedlings accumulated more IAA and brassinosteroids, which may account for their better growth. Accumulation of glycine betaine, pro, and total amino acids in assimilating shoots and roots of primed seedlings led to reduced osmotic stress. Drivers of responses of non-primed and primed seedlings to drought varied. Responses of primed seedlings were primarily characterized by more photosynthetic pigments, increased oxidative scavenging of O2 -• and H2 O2 , more phytohormones and osmolytes. Early drought priming of drought stress memory in C. mongolicum seedlings may provide a useful management approach to improve seedling establishment in vegetation restoration programs.

The germination response of Zea mays L. to osmotic potentials across optimal temperatures via halo-thermal time model

The maize (Zea mays L.) is a monocot that is a member of the Poaceae family and a valuable feed for livestock, human food, and raw material for various industries. The halothermal time model determines how plants respond to salt (NaCl) stress under sub-optimal conditions. This model examines the relation between NaClb (g), GR, GP, salinity and temperature stress on germination of seeds dynamics in various crops. Five constant temperatures i.e. 20, 25, 30, 35, and 40 °C and five ψ levels (NaCl concentrations converted to ψ − 0, − 0.2, − 0.4, − 0.6, and − 0.8 MPa) were used in this experiment. In light of the results, the maximum halo-thermal time constant value was recorded at 35 °C temperature, while maximum germination percentage was detected at 30 °C in the controlled condition. Moreover, the lowermost value was recorded at 20 °C at − 0.8 MPa osmotic potential. The highest CAT, APX, and GPX activities were recorded at 15 °C at − 0.8 MPa, while the lowest values were observed for 0 MPa at 30 °C temperature. In conclusion, by employing the halo thermal time model, the germination of maize variety (var.30W52) was accurately predicted for the first time under varying levels of temperature and osmotic potentials.

Effect of trehalose treatment on growth, hydrogen peroxide, and antioxidant enzymes of Tomato (Solanum lycopersicum L.) plants under drought stress

The study was to determine the effect of trehalose treatment on growth, hydrogen peroxide and antioxidant enzymes in tomato plants growing under drought stress. In an experiment, the seeds were transferred to plastic pots, and the pots were divided into four groups. , the first and second groups without treatment 90%, 20% WHC (Water Holding Capacity)), while the third and fourth groups, 90%, 20% WHC In the presence of 25 mM trehalose (Tre). On day 30, plants were harvested, growth parameters, hydrogen peroxide (H2O2) and enzymes measured. Drought stress caused significant growth inhibition including fresh and dry weight, root length and shoot height. There was an increase in hydrogen peroxide and also an increase in the activity of some enzymatic antioxidants (SOD, CAT, and PPO) and a decrease of others (APx, GR, and GHPx) in the roots and stems of drought-stressed plants. Treatment with 25 mM trehalose significantly improved growth parameters compared to drought-stressed plants, and the results in this study showed a decrease in the activity of hydrogen peroxide (H2O2) and an increase in the activities of SOD, CAT, APx, GSHPx, GPx and PPO in the treated plants.

Physiological and transcriptomic analysis of Hordeum jubatum seedlings in response to salt, alkali and drought stresses under uniform water potential

The early seedling stage is highly susceptible to various abiotic stresses. Hordeum jubatum is an ornamental plant with excellent abiotic stress tolerance, and widely distributed in the northeast of China. However, the mechanism of its physiological and transcriptional resistance under different abiotic stresses is still unclear. The results showed that the leaves of H. jubatum adapted to saline-alkali and drought environments by increasing the density of wax and glandular hairs, reducing the stomatal length, width and opening, and the leaf cells completely ruptured and a large number of organelles disintegrated under alkali stress. With the increasing stress concentration, the chlorophyll content and dry weight reduced under the three stresses, which was related to the broken chloroplasts of such conditions. In addition, the balance of Na+ and K+ was disturbed, and the increase of APX and SOD activity was the strategy to maintain the balance of reactive oxygen species and weaken the degree of membrane lipid peroxidation under three stresses. And alkali stress had the most significant effect on above changes. Moreover, Transcriptional sequencing revealed the alkali stress group had the highest number of differential expressed genes (DEGs) compared to the CK among three stresses, and a significant down-regulation of DEGs related to membrane systems under three stresses. In addition, alkali stress resulted in large number of up-regulation of DEGs associated with light repair processes and down-regulation of DEGs in ribosomal pathway with R proteins involving in regulating leaf phenotype and ultrastructure, which also echoed the overall physiological findings. Together, the adaptation mechanisms of three stresses were different in H. jubatum seedlings with higher tolerance of salt stress, and extremely sensibility to alkali stress.

Effect of irrigation on wild and inbred maize with relation to the antioxidant status of pollens, flag leaves, and developing grains.

The investigation was carried out to evaluate the net effect of limited irrigation on the antioxidant status of pollens, flag leaves, and developing grains of wild and inbred maize lines. Teosinte pollens showed the highest activities of superoxide dismutase (SOD), catalase (CAT), glutathione reductase (GR), glutathione-s-transferase (GST), and peroxidase (POX) under stressful conditions while LM 11 showed a significant decrease in APX, CAT, GR, and GST activities. Limited irrigations increased the contents of superoxide and malondialdehyde (MDA) to maximum levels in LM 11 leaves. The pollens, leaves, and developing grains of teosinte had the highest content of total phenols. Proline was maximum in the developing grains of teosinte and CML 32 while lowest in those of LM 11. Principal component analysis showed that LM 11 genotype and the respective antioxidant enzymes were in completely opposite quadrants. Chord analysis showed that CAT activity and total phenol content in pollens, leaves, and developing grains contributed towards most of the variations observed in teosinte and might be responsible for managing the yield attributes of genotype during stress conditions. The pollens and leaves of teosinte, with significant SOD activity, further helped in optimizing plant yield, under stressful conditions. CML 32 occupied intermediate position owing to the unaffected activities of most of the antioxidant enzymes and high content of antioxidants in its tissues. It may be concluded that the overall antioxidant status of tissues decides the tolerance behavior of plants.

Differential responses of Brassica napus cultivars to dual effects of magnesium oxide nanoparticles.

Magnesium oxide nanoparticles (MgO NPs) have great potential to enhance the crop productivity and sustainability of agriculture. Still, a thorough understanding is lacking about its essentiality or toxicity and precise dose for the safe cultivation of oilseed crops. Thus, we assessed the dual effects of MgO NPs (control, 5, 10, 20, 40, 80, and 200mg/L) on the seed germination, growth performance, photosynthesis, total soluble protein, total carbohydrates, oxidative stress markers (hydrogen peroxide as H2O2 and superoxide anion as O2•‒), lipid peroxidation as MDA, and antioxidant defence machinery (SOD, CAT, APX, and GR activities, and GSH levels) of seven different oilseeds (Brassica napus L.) cultivars (ZY 758, ZD 649, ZD 635, ZD 619, GY 605, ZD 622, and ZD 630). Our findings revealed that low doses of MgO NPs (mainly at 10mg/L) markedly boosted the seed germination, plant growth (shoot and root lengths) (15‒22%), and biomass (fresh and dry) (11‒19%) by improving the levels of photosynthetic pigments (14‒27%), net photosynthetic rate, stomatal conductance, photosynthetic efficiency (Fv/Fm), total soluble protein and total carbohydrates (16‒36%), antioxidant defence, and reducing the oxidative stress in B. napus tissues. Among all B. napus cultivars, these beneficial effects of MgO NPs were pronounced in ZD 635. ile, elevated levels of MgO NPs (particularly at 200mg/L) induced oxidative stress, impairedantioxidant scavenging potential, photosynthetic inhibition, protein oxidation, and carbohydrate degradation and lead to inhibit the plant growth attributes. These inhibitory effects were more pronounced in ZD 622. Collectively, low-dose MgO NPs reinforced the Mg contents, protected the plant growth, photosynthesis, total soluble carbohydrates, enzyme activities, and minimized the oxidative stress. While, the excessive MgO NP levels impaired the above-reported traits. Overall, ZD 622 was highly susceptible to MgO NP toxicity and ZD 635 was found most tolerant to MgO NP toxicity.

Alleviation of chilling injury in cold-stored Chinese olive (Canarium album Lour.) fruit by γ-aminobutyric acid treatment in relation to ROS metabolism

Chinese olives are susceptible to chilling injury (CI) during refrigeration. Exploring economical and convenient approaches to suppress CI development is important for preserving fruit quality and prolonging postharvest shelf-life of Chinese olives. In this study, the effects of 1.0 mM γ-aminobutyric acid (GABA) treatment on CI development and ROS metabolism in cold-stored Chinese olives at 2 °C for 100 d were evaluated. The results demonstrated that, compared to control Chinese olives, GABA treatment observably alleviated CI development, remarkably suppressed the increased CI index, O2−. production rate, and MDA amount, but retained higher SOD, CAT and APX activities, higher values of GSH and AsA, higher abilities of scavenging DPPH radical, and higher reducing power. On the last day of storage (day 100), CI index, O2−. production rate, and MDA content in control Chinese olives were 2.06-, 1.28, 1.48-fold higher compared with those of GABA-treated fruits. In contract, SOD, CAT and APX activities in GABA-treated fruits were 1.54-, 3.24, 1.57-fold higher than in that of control Chinese olives. The GSH and AsA contents, DPPH scavenging ability and reducing power were 64.7%, 128.4%, 51.8% and 35.0% higher in GABA-treated olives, as compared to control fruits. Together, these findings indicate that 1.0 mM GABA shows a potential application in improving antioxidant capacity and alleviating CI development of Chinese olives during cold storage.

Salt-excluder rootstock improves physio-biochemical responses of grafted grapevine plants subjected to salinity stress

This study tests the hypothesis that a more salt-excluder rootstock can attenuate salt stress in grapevine plants by enhancing photosynthesis and providing ionic and oxidative protection. Plants of ‘BRS Vitória’ variety, grafted with the rootstocks IAC 313 (salt-excluder) and SO4, were subjected to salinity by adding NaCl (0, 50, and 100 mM) for 30 days. Plants with SO4 showed more severe salt toxicity symptoms in leaves and lower chlorophyll content under salinity. Conversely, plants with IAC 313 showed improved photosynthesis and stomatal conductance, along with higher carboxylation efficiency under salt compared to SO4. Under salinity, plants with SO4 showed higher losses of K+ in stems, roots, and petioles, as well as increased accumulation of Na+ in these organs, relative to IAC 313. Furthermore, plants with IAC 313 had lower leaf Na+ content under salinity and reduced leaf Cl− content at 50 mM NaCl, a response associated with a higher Na+ allocation in petioles of IAC 313. At 50 mM, IAC 313 exhibited better photochemical activity, as indicated by electron transport rate and non-photochemical quenching. However, at 100 mM, both rootstocks showed similar trends, suggesting that the photosynthetic restriction was primarily due to stomatal disturbances. Plants with IAC 313 showed better APX activity and ascorbate balance under salinity. IAC 313 showed more salt-resistance traits than SO4, although the growth was similarly affected in both rootstocks. This response could be due to the reduced time of salt treatment (30 days). In summary, our data indicate that IAC 313 rootstock possesses better salt tolerance traits than SO4.