Ascorbate Peroxidase Activity Research Articles

Physiological and antioxidant responses of synthetic hexaploid wheat germplasm under drought

BackgroundAs a result of the world population and climate change impact increases (especially in arid environments), there is a critical need for high-yield, drought-tolerant wheat. Synthetic hexaploid wheat derived lines (SHW-DL), were created artificially by crossing different durum wheat cultivars (AABB) with accessions of Aegilops tauschii (DD), a beneficial source of new genes for common bread wheat (Triticum aestivum L). Here, we studied the response of a panel of 91 SHW-DL for drought tolerance based on physiological, antioxidant enzyme activities, and drought tolerance indices.ResultsA wide range of variation and high values of heritability observed for grain yield, physiological and antioxidant traits indicating that the SHW-DL panel constitutes a valuable gene source for drought tolerance improvement of wheat. Despite decreases in grain yield (YLD), leaf area index (LAI), and relative water content (RWC) an increase in the content of malondialdehyde (MDA) was observed. Moreover, drought streass increased the antioxidant enzyme activities of ascorbate peroxidase (APX), catalase (CAT) and peroxidase (POD), and also photosynthetic pigments, proline (Pro), and MDA content. With higher values of grain yield, physiological and biochemical traits such as photosynthetic pigments, and RWC, and lower content of MDA, and peroxidase (H2O2) activity, SHW-DL performed better compared to common wheat lines under water stress conditions.ConclusionsDifferent responses to water stress within the germplasm and between synthetic and common wheat suggest that selection for adaptive and suitable genotypes is possible for drought tolerance in synthetic wheat germplasm. Genotypes 54, 98, 102, 105, 122, 124, 143, 159, 196, and 198 were identified to be directly used in breeding programs or indirectly by crossing them with other wheat germplasm collections.

Effects of Low-Temperature Stress on Cold Resistance Biochemical Characteristics of Dali and Siqiu Tea Seedlings

Cold stress causes considerable damage to tender tea seedlings. Previous studies have explored changes in the physiological and biochemical factors of tea in response to cold stress; however, the mechanisms of cold resistance in ancient tea tree plants are unclear. The aim of this study was to analyze the effects of 0 °C cold stress for 15 days and 24 °C ambient temperature recovery for 5 days on the physiological and biochemical characteristics of two representative old tea varieties: Dali tea and Siqiu tea. The results revealed significant changes in antioxidant, photosynthetic efficiency, and physiological and biochemical indicators in response to cold stress, with the two species exhibiting different patterns. Cold stress decreased chlorophyll and carotene content, Fv/Fm, Y(II), non-photochemical quenching coefficient, photochemical quenching, and superoxide dismutase (SOD) activity, and increased intercellular CO2 concentration and ascorbate peroxidase activity. Siqiu tea showed a higher increase in soluble sugar content and antioxidant enzyme activity and a lower accumulation of malondialdehyde and minimal fluorescence (F0) than Dali, indicating a greater tolerance to cold stress. Based on partial least-squares discriminant analysis, six key differential physiological indicators of cold resistance—water-soluble sugar, F0, peroxidase, catalase, SOD, and gas conductance—were identified. Our findings provide technical support for identifying ways to protect ancient tea trees from extreme weather conditions.

Proline inhibits postharvest physiological deterioration of cassava by improving antioxidant capacity

Cassava (Manihot esculenta Crantz), a crucial global tuber crop, encounters significant economic losses attributed to postharvest physiological deterioration (PPD). The PPD phenomenon in cassava is closely related to the accumulation of reactive oxygen species (ROS), and amino acids play a pivotal role in regulating signaling pathways and eliminating ROS. In this study, the storage performance of eight cassava varieties were conducted. Cassava cultivar SC5 showed the best storage performance among the eight cassava varieties, but the edible cassava cultivar SC9 performed much worse. Comparative analysis of free amino acids was conducted in eight cassava varieties, revealing changes in proline, aspartic acid, histidine, glutamic acid, threonine, and serine. Exogenous supplementation of these six amino acids was performed to inhibit PPD of SC9. Proline was confirmed as the key amino acid for inhibiting PPD. Treatment with optimal exogenous proline of 5 g/L resulted in a 17.9% decrease in the deterioration rate compared to untreated cassava. Accompanied by a decrease in H2O2 content and an increase in catalase, superoxide dismutase and ascorbate peroxidase activity. Proline treatment proved to be an effective approach to alleviate cell oxidative damage, inhibit PPD in cassava, and prolong shelf life.

Effect of cadmium toxicity on growth, physiochemical parameters and antioxidant system of castor seedlings

The research was aimed to determine the potential impact of cadmium contamination on Ricinus communis. The glucose-6-phosphate dehydrogenase (G6PDH) activity in the root was highest when exposed to 0.2 mM of Cd, with an increase of 15.63 % and 14.48 % at 0 and 24 h, respectively, compared to its control. However, citrate synthase (CS) activity declined in leaves, in contrast, to root, i.e., 12.22 % at 48 h of Cd stress. Isocitrate dehydrogenase (ICDH) activity was maximum in leaves at 0.2 mM of Cd at 0 and 24 h, i.e., 12.36 % and 13.08 % respectively, and later decreased in activity was seen in roots and leaves as the Cd stress increased. Moreover, the level of malate dehydrogenase (MDH) declined in leaves as the Cd level increased, while activity increased in roots at 0.4 mM of Cd i.e., 17.21 %, 17.52 %, and 10.53 % at 0, 24, and 48 h respectively. The important metabolite, glutathione level in the roots of SKP 84 was higher than in the leaf extract. A decline in biomass of up to 28.70 % and 30.91 % and plant length of up to 20.80 % and 26.10 % in shoot and roots, respectively, tolerance index was maximum at 0.2 mM, i.e., 98.62 % was seen. The leaves had 35.40 % catalase (CAT) activity, while the roots had 78.26 % guaiacol peroxidase (GPX) activity at 0.6 mM of Cd. At 0.2 mM of Cd, the maximum activity of ascorbate peroxidase (APX) was observed, with 67.32 % and 62.85 % activity in roots and leaves respectively. However, a reduction in the SOD activity was seen as the Cd stress increased. Increased Cd levels decreased chlorophyll but increased MDA and proline content in leaves at 0.8 mM of Cd, i.e., 82.92 % and 21.7 %, respectively. It indicated that R. communis SKP 84, a fusarium wilt resistance line, is also tolerant to Cd and can be used for phytoremediation in Cd-contaminated areas.

Differential Oxidative Stress Management in Industrial Hemp (IH: Cannabis sativa L.) for Fiber under Saline Regimes.

In the current study, two commercial industrial hemp (IH) fiber varieties (V1: CFX-2 and V2: Henola) were assessed for their ability to regulate salt-induced oxidative stress metabolism. For 30 days, plants were cultivated in greenhouse environments with five different salinity treatments (0, 50, 80, 100, 150, and 200 mM NaCl). Hydrogen peroxide (H2O2), malondialdehyde (MDA), and lipoxygenase (LOX) and antioxidant enzymes (superoxide dismutase (SOD), catalase, guaiacol peroxidase (GPOD), ascorbate peroxidase (APX), glutathione reductase (GR), and glutathione-S-transferase (GST)) were assessed in fully expanded leaves. At 200 and 100 mM NaCl concentrations, respectively, 30 days after saline treatment, plants in V1 and V2 did not survive. At 80 mM NaCl, the leaves of V2 showed higher concentrations of H2O2, MDA, and LOX than those of V1. Higher SOD, CAT, GPOD, APX, GR, and GST activity in the leaves of V1 up to 100 mM NaCl resulted in lower levels of H2O2 and MDA. At 80 mM NaCl, V2 demonstrated the total failure of the antioxidant defense mechanism. These results reveal that V1 demonstrated stronger salt tolerance than V2, in part due to better antioxidant metabolism.

Individual or successiveseed priming with nitric oxide and calcium toward enhancing salt tolerance of wheat crop through early ROS detoxification and activation of antioxidant defense

Despite the considerable efforts reported so far to enhance seed priming, novel ideas are still needed to be suggested to this sustainable sector of agri-seed industry. This could be the first study addressing the effect of nitric oxide (NO) under open field conditions. The impacts of seed redox-priming using sodium nitroprusside (SNP) and osmo-priming with calcium chloride (CaCl2), both applied individually or successively, were investigated under salinity stress conditions on wheat plants (Triticum aestivum L.). Various parameters, including water relations, growth, yield, photosynthetic pigments, and antioxidant activities (enzymatic and non-enzymatic), were recorded to assess the outcomes of these priming agents on mitigating the negative impacts of salinity stress on wheat plants. Water consumptive use (ETa) and irrigation water applied (IWA) decreased with seeds priming. Successive priming with SNP + CaCl2 induced the greatest values of crop water productivity (CWP), irrigation water productivity (IWP), seed index, grain yield and grain nitrogen content.Under salinity stress, the dry weight of plants was decreased. However, hydro-priming and successive chemical priming agents using combinations of calcium chloride and sodium nitroprusside (CaCl2 + SNP & SNP + CaCl2) preserved growth under salinity stress.Individual priming with sodium nitroprusside (SNP) and calcium chloride (CaCl2) resulted in the lowest recorded content of sodium in the shoot, with a value of 2 ppm. On the other hand, successive priming using CaCl2 + SNP or SNP + CaCl2 induced the contents of potassium in the shoot, with values of 40 ppm and 39 ppm, respectively. Malondialdehyde decreased in shoot significantly withapplicationof priming agents. Successive priming with CaCl2 + SNP induced the highest proline contents in shoot (6 µg/ g FW). The highest value of phenolics and total antioxidants contents in shoot were recorded under successive priming using CaCl2 + SNP and SNP + CaCl2.Priming agents improved the activities of ascorbate peroxidase and catalase enzymes. The successive priming improved water relations (ETa, IWA, CWP and IWP) and wheat growth and productivity under salinity stress more than individual priming treatments.

Chitosan stabilized lemon essential oil nanoemulsion controls black mold rot and maintains quality of table grapes

Aspergillus carbonarius infection leads to black mold rot in table grapes, causes grape decay, reduces fruit quality and marketability, which produces significant economic losses. This study investigated the antifungal efficacy of chitosan-stabilized lemon essential oil nanoemulsion (LO-CNE) against A. carbonarius and black mold rot of table grapes. LO-CNE was prepared with a mean diameter of 130.01 ± 8.34 nm. LO-CNE exhibited superior antifungal activity, reduced spore germination and germ tube elongation, decreased the antioxidant enzyme activities in A. carbonarius; the minimal inhibitory concentration of LO-CNE was determined to be 30 mg/mL. LO-CNE reduced the occurrence of black mold rot by 63 % and lesion diameter by 56.78 % in table grapes compared to the control. At their peak activity level, the grapes treated with LO-CNE exhibited significantly enhanced antioxidant and defense-related enzyme activities. Specifically, polyphenol oxidase activity increased by 2.27-fold, peroxidase activity by 2.22-fold, superoxide dismutase activity by 0.68-fold, catalase activity by 1.61-fold, phenylalanine ammonia-lyase activity by 3.38-fold, and ascorbate peroxidase activity by 2.36-fold. The LO-CNE application reduced natural decay by 95 %, weight loss by 15 % compared to the control, and effectively maintained the quality parameters of table grapes. Therefore, LO-CNE can be considered an alternative disease-control agent for grape preservation.

Biochar with KMnO4-hematite modification promoted foxtail millet growth by alleviating soil Cd and Zn biotoxicity

The excessive accumulation of Cd and Zn in soil poisons crops and threatens food safety. In this study, KMnO4-hematite modified biochar (MnFeB) was developed and applied to remediate weakly alkaline Cd-Zn contaminated soil, and the heavy metal immobilization effect, plant growth, and metal ion uptake of foxtail millet were studied. MnFeB application reduced the phytotoxicity of soil heavy metals; bioavailable acid-soluble Cd and Zn were reduced by 57.79% and 35.64%, respectively, whereas stable, non-bioavailable, residual Cd and Zn increased by 96.44% and 32.08%, respectively. The chlorophyll and total protein contents and the superoxide dismutase (SOD)activity were enhanced, whereas proline, malondialdehyde, the H2O2 content, glutathione reductase (GR), ascorbate peroxidase (APX) and catalase (CAT) activities were reduced. Accordingly, the expressions of GR, APX, and CAT were downregulated, whereas the expression of MnSOD was upregulated. In addition, MnFeB promoted the net photosynthetic rate and growth of foxtail millet plants. Furthermore, MnFeB reduced the levels of Cd and Zn in the stems, leaves, and grains, decreased the bioconcentration factor of Cd and Zn in shoots, and weakened the translocation of Cd and Zn from roots to shoots. Precipitation, complexation, oxidation-reduction, ion exchange, and π-π stacking interaction were the main Cd and Zn immobilization mechanisms, and MnFeB reduced the soil bacterial community diversity and the relative abundance of Proteobacteria and Planctomycetota. This study provides a feasible and effective remediation material for Cd- and Zn-contaminated soils.

Microplastic exposure inhibits nitrate uptake and assimilation in wheat plants

Microplastic (MP) contamination in soil severely impairs plant growth. However, mechanisms underlying the effects of MPs on plant nutrient uptake remain largely unknown. In this study, we revealed that NO3− content was significantly decreased in shoots and roots of wheat plants exposed to high concentrations (50–100 mg L−1) of MPs (1 μm and 0.1 μm; type: polystyrene) in the hydroponic solution. Isotope labeling experiments demonstrated that MP exposure led to a significant inhibition of NO3− uptake in wheat roots. Further analysis indicated that the presence of MPs markedly inhibited root growth and caused oxidative damage to the roots. Additionally, superoxide dismutase and peroxidase activities in wheat roots decreased under all MP treatments, whereas catalase and ascorbate peroxidase activities significantly increased under the 100 mg L−1 MP treatment. The transcription levels of most nitrate transporters (NRTs) in roots were significantly downregulated by MP exposure. Furthermore, exposure to MPs distinctly suppressed the activity of nitrate reductase (NR) and nitrite reductase (NiR), as well as the expression levels of their coding genes in wheat shoots. These findings indicate that a decline in root uptake area and root vitality, as well as in the expression of NRTs, NR, and NiR genes caused by MP exposure may have adverse effects on NO3− uptake and assimilation, consequently impairing normal growth of plants.

Maintaining quality of postharvest green pepper fruit using melatonin by regulating membrane lipid metabolism and enhancing antioxidant capacity

Green pepper quality often deteriorates during storage because of membrane lipid damage and oxidative stress. This study investigated the effects of exogenous melatonin (MT) on green pepper storage quality, membrane lipids, and antioxidant metabolism. The results showed that MT increased the activities of superoxide dismutase, catalase, ascorbate peroxidase, peroxidase, monodehydroascorbate reductase, and dehydroascorbate reductase in green peppers compared to the control group. It upregulated expression of multiple enzymes; reduced accumulation of reactive oxygen species such as dehydroascorbic acid, H2O2, and O2.-; and maintained high ascorbic acid, glutathione, coenzyme II, and nicotinamide adenine dinucleotide while reducing oxidized glutathione levels. In addition, MT decreased lipoxygenase and phospholipase D activities, downregulated ReLOX and RePLD expression, and delayed the degradation of phosphatidylcholine, phosphatidylethanolamine, and oleic, linoleic, and linolenic acids in green peppers. These results suggest that MT helps to improve the chilling injury and quality of green peppers and extends shelf life.

Mitigating heat-induced yield loss in peanut: Insights into 24-epibrassinolide-mediated improvement in antioxidant capacity, photosynthesis, and kernel weight

Context or problemAs global temperatures steadily increase, the frequent occurrence of extreme high-temperature events has significantly hampered peanut (Arachis hypogaea L.) production in low-latitude regions. Objective or research questionPreviously, 24-epibrassinolide (EBR) was identified as a substance capable of mitigating abiotic stress damage in plants. However, it remains unclear whether and by what mechanisms EBR can diminish the yield loss caused by heat stress in peanuts. MethodsDuring the flowering phase, two distinct peanut cultivars, Qinghua7 (heat-resistant type) and Shanhua101 (heat-sensitive type) were exposed to a 10-day heat stress treatment (+4.2 ℃). EBR or water was sprayed on the 1st, 3rd, and 5th days of heating, and water-sprayed natural peanuts was used as control, to assess the effect of EBR on antioxidant capacity, photosynthetic performance, and yield in heat-stressed peanuts. ResultsEBR application increased activities of superoxide dismutase, peroxidase, catalase, and ascorbate peroxidase in heat-stressed peanut leaves. Simultaneously, EBR decreased hydrogen peroxide and superoxide anion production, along with a reduction in malondialdehyde content. Additionally, EBR notably alleviated the oxidation damage to chloroplast membranes and grana lamella under heat stress. Thus, an increase in maximum photochemical efficiency, comprehensive performance index, rubisco activity, net photosynthetic rate, and biomass accumulation was observed in heat-stress peanuts. Synergistic enhancement provided by EBR on antioxidant capacity and photosynthetic performance resulted in improved plant growth, kernel weight, and effective pods per plant, led to a reduction in yield loss for heat-stressed cultivars Qinghua7 and Shanhua101 by 26.92 % and 55.18 %, respectively. ConclusionsThe application of EBR enhanced the antioxidant capacity of peanut leaves. This, in turn, mitigated oxidative damage to chloroplast membranes, resulting in improved photosynthetic performance. Ultimately, this intervention led to a reduction in yield loss for heat-stressed peanuts, achieved through an increase in kernel weight. Implications or significanceThe foliar spraying of EBR holds significant promise in crop production, offering a broad application prospect. This practice is beneficial for enhancing the heat resistance of peanuts and potentially other field crops, equipping them to better withstand the increasingly severe climate challenges anticipated in the future.

The Drought Tolerance Function and Tanscriptional Regulation of GhAPX7 in Gossypium hirsutum.

Drought stress significantly affects the growth, development, and yield of cotton, triggering the response of multiple genes. Among them, ascorbate peroxidase (APX) is one of the important antioxidant enzymes in the metabolism of reactive oxygen species in plants, and APX enhances the ability of plants to resist oxidation, thus increasing plant stress tolerance. Therefore, enhancing the activity of APX in cells is crucial to improving plant stress resistance. Previous studies have isolated differentially expressed proteins under drought stress (GhAPX7) in drought-resistant (KK1543) and drought-sensitive (XLZ26) plants. Thus, this study analyzed the expression patterns of GhAPX7 in different cotton tissues to verify the drought resistance function of GhAPX7 and explore its regulatory pathways. GhAPX7 had the highest expression in cotton leaves, which significantly increased under drought stress, suggesting that GhAPX7 is essential for improving antioxidant capacity and enzyme activities in cotton. GhAPX7 silencing indirectly affects pronounced leaf yellowing and wilting in drought-resistant and drought-sensitive plants under drought stress. Malondialdehyde (MDA) content was significantly increased and chlorophyll and proline content and APX enzyme activity were generally decreased in silenced plants compared to the control. This result indicates that GhAPX7 may improve drought resistance by influencing the contents of MDA, chlorophyll, proline, and APX enzyme activity through increased expression levels. Transcriptome analysis revealed that the drought-related differentially expressed genes between the control and treated groups enriched plant hormone signal transduction, MAPK signaling, and plant-pathogen interaction pathways. Therefore, the decreased expression of GhAPX7 significantly affects the expression levels of genes in these three pathways, reducing drought resistance in plants. This study provides insights into the molecular mechanisms of GhAPX7 and its role in drought resistance and lays a foundation for further research on the molecular mechanisms of response to drought stress in cotton.

Metal Sulfates and Microbial Food Treatment Alleviate the Oxidative Damage Caused by PEG-Induced Osmotic Stress in Cotton Plants

Background: Drought stress restricts cotton production, which causes a considerable loss of cotton yields worldwide. Plant activators improve crop production and ameliorate abiotic stresses. Thus, the effects of plant activators on the genotype of cotton (Gossypium hirsutum L.) Candia, which is resistant to drought, were investigated.Methods: Plants were treated with the plant activators, and then osmotic stress was initiated by 30% PEG 6000 treatment for 13 days. Antioxidant enzyme activities such as superoxide dismutase (SOD), ascorbate peroxidase (APX), and peroxidase (POX) were measured along with growth, relative water content (RWC), osmotic potential, photosynthetic pigments, ion leakage, proline accumulation, malondialdehyde (MDA) content, and reactive oxygen species (ROS).Results: Osmotic stress reduced shoot fresh weight (FW) and osmotic potential but increased root length of Candia. Activator treatment alleviated these effects. Photosynthetic pigment contents and cell membrane permeability were not affected by osmotic stress and activator treatments; proline accumulation and lipid peroxidation levels were enhanced by osmotic stress, but activators alleviated these increments. Activity bands for the isozymes Mn-SOD1, SOD2, and SOD3, as well as the isozyme Fe-SOD, were found in Candia. Osmotic stress elevated APX activity in Candia leaves, while activator treatment decreased it. POX activity was not affected by osmotic stress, but activator treatment decreased POX activity. Osmotic stress-induced accumulation of ROS was lessened by activator treatment.Conclusion: Plant activator treatment reduced the amount of oxidative damage (ROS buildup and lipid peroxidation) caused by drought stress in the Candia genotype.Keywords: Antioxidant system; Cotton; Gossypium hirsutum L.; Osmotic stress; PEG 6000; Plant activators

Seed Treatment with Cold Plasma and Electromagnetic Field: Changes in Antioxidant Capacity of Seedlings in Different Picea abies (L.) H. Karst Half-Sib Families.

In the context of climate change, methods to improve the resistance of coniferous trees to biotic and abiotic stress are in great demand. The common plant response to exposure to vastly different stressors is the generation of reactive oxygen species (ROS) followed by activation of the defensive antioxidant system. We aimed to evaluate whether seed treatment with physical stressors can activate the activity of antioxidant enzymes and radical scavenging activity in young Picea abies (L.) H. Karst seedlings. For this, we applied seed treatment with cold plasma (CP) and electromagnetic field (EMF) and compared the response in ten different half-sib families of Norway spruce. The impact of the treatments with CP (1 min-CP1; 2 min-CP2) and EMF (2 min) on one-year-old and two-year-old P. abies seedlings was determined by the emergence rate, parameters of growth, and spectrophotometric assessment of antioxidant capacity (enzyme activity; DPPH and ABTS scavenging) in needles. The results indicated that the impact of seed treatment is strongly dependent on the genetic family. In the 577 half-sib family, the activity of antioxidant enzymes catalase (CAT), ascorbate peroxidase (APX), peroxidase (POX), and glutathione reductase (GR) increased after EMF-treatment in one-year-old seedlings, while similar effects in 477 half-sib family were induced by CP2 treatment. In two-year-old seedlings, CP1-treatment increased CAT, APX, POX, GR, SOD, DPPH, and ABTS activity in the 457 half-sib family. However, no significant impact of the treatment with CP1 was determined in one-year-old seedlings in this family. The application of novel technologies and the consideration of the combinatory impact of genetic and physical factors could have the potential to improve the accumulation of compounds that play an essential role in the defense mechanisms of P. abies. Nevertheless, for different resistance and responses to stressors of plants, their genetic properties play an essential role. A comprehensive analysis of interactions among the stress factors (CP and EMF), genetic properties, and changes induced in the antioxidant system can be of importance both for the practical application of seed treatment in forestry and for understanding fundamental adaptation mechanisms in conifers.

The Influence of Varying Wavelengths of LED Light on the Development, Physiology Response, and Metabolism Activities of Micropropagated Dendrobium Hybrid ‘Shuijing’ Plantlets

Dendrobium hybrids have a significant role in the present floral sector. The aim of this research was to evaluate how various light qualities affect the physiological and biochemical traits of Dendrobium ‘Shuijing’. In order to determine the optimal light quality for in vitro cultivation of Dendrobium plantlets, we examined the correlations between growth, antioxidant capacity, and nutrient and chlorophyll levels, as well as chlorophyll fluorescence. The growth rate was compared by using different light qualities emitted by the LED light source. These included red light (R), blue light (B), and three ratios: 8R:2B, 7R:3B, and equal proportions of both colors, known as white, fluorescent light (CK). The combination of 7R:3B resulted in noticeable enhancements in leaf count, root length, root activity, fresh and dry weight measurements, antioxidant capability, as well as chlorophyll content and fluorescence. Specifically, the mixture of red and blue LED lights at a ratio of 7R:3B led to increased leaf number, root length, root activity, fresh and dry weight measurements, antioxidant ability, and chlorophyll content with improved fluorescence. In order to explore the effect of light quality on the growth and development of Dendrobium, the chlorophyll content and chlorophyll fluorescence parameters of plants under all light quality conditions were analyzed by using a linear regression model with other physiological and biochemical indexes. A significant correlation between non-photochemical quenching (NPQ) and leaf length was also observed. The content of chlorophyll b showed significant correlations with both root number and leaf number. Furthermore, chlorophyll a, along with its ratio to chlorophyll b, significantly correlated with root length. Chlorophyll b and the relative electron transport rate of PSII (ETRII) significantly correlated with root activity and the free proline content (FPC) and catalase (CAT) activity. The photochemical quenching coefficient (qP) significantly correlated with total soluble sugars content (SSC) and peroxidase (POD) activity. The correlation between the quantum yield of PSII (Fv/Fm ratio) and superoxide dismutase (SOD) activity was found to be significant. Similarly, the effective quantum yield of PSII photochemistry (ΦPSII) showed significant correlations with fresh weight, dry weight, soluble protein content (SPC), and ascorbate peroxidase (APX) activity. Through a principal component analysis (PCA), it was observed that plants cultivated under the 7R:3B light treatment achieved significantly better comprehensive scores compared to those grown under different light treatments. In conclusion, growth achieved under an LED emitting a ratio of 7R:3B light yielded the most robust Dendrobium hybrid plantlets within a controlled environment.

Calcium chloride treatment delays the quality deterioration of king oyster mushroom (Pleurotus eryngii) through positive regulation of antioxidants by PeCaMK1

Calcium (Ca2+) signaling plays a crucial role in the growth, development, and stress responses of mushrooms. However, its specific mechanisms in regulating postharvest quality are not fully understood. This study aimed to investigate the underlying mechanism of CaCl2 treatment on the quality of postharvest Pleurotus eryngii and provide theoretical support for the development of future preservation technology. The study found calcium chloride (CaCl2) treatment to be effective in delaying the browning of P. eryngii, reducing weight loss, and mitigating cell membrane damage. The antioxidant levels, and Ca2+ fluorescence signal was measured, to further examine the physiological effects of CaCl2 treatment. The study found that CaCl2 treatment stimulated the activities of catalase (CAT), superoxide dismutase (SOD), ascorbate peroxidase (APX), and peroxidase (POD), ultimately reducing reactive oxygen species (ROS) accumulation. CaCl2 also increased cytolytic Ca2+ levels and the expression levels of Ca2+ signaling genes. The overexpression and silencing transformants were constructed to further analyze the role of PeCaMK1, a gene encoding calcium/calmodulin-dependent protein kinase in Ca2+ signaling. The overexpression of PeCaMK1 increased Ca2+ levels, stimulated the activities of antioxidant enzymes, and inhibited ROS accumulation. The reduced expression of PeCaMK1 by RNAi-mediated gene silencing increased ROS level, demonstrating that PeCaMK1 positively regulated the antioxidant effect in response to Ca2+ signaling. In summary, the results suggested that exogenous CaCl2 treatment transmitted Ca2+ signaling through PeCaMK1 to enhance antioxidant activity, reduce ROS accumulation, and ultimately delay the quality deterioration of P. eryngii.

The photosynthetic performance and photoprotective role of carotenoids response to light stress in intertidal red algae Neoporphyra haitanensis.

Neoporphyra haitanensis, a red alga harvested for food, thrives in the intertidal zone amid dynamic and harsh environments. High irradiance represents a major stressor in this habitat, posing a threat to the alga's photosynthetic apparatus. Interestingly, N. haitanensis has adapted to excessive light despite the absence of a crucial xanthophyll cycle-dependent photoprotection pathway. Thus, it is valuable to investigate the mechanisms by which N. haitanensis copes with excessive light and to understand the photoprotective roles of carotenoids. Under high light intensities and prolonged irradiation time, N. haitanensis displayed reduction in photosynthetic efficiency and phycobiliproteins levels, as well as different responses in carotenoids. The decreased carotene contents suggested their involvement in the synthesis of xanthophylls, as evidenced by the up-regulation of lycopene-β-cyclase (lcyb) and zeaxanthin epoxidase (zep) genes. Downstream xanthophylls such as lutein, zeaxanthin, and antheraxanthin increased proportionally to light stress, potentially participating in scavenging reactive oxygen species (ROS). When accompanied by the enhanced activity of ascorbate peroxidase (APX), these factors resulted in a reduction in ROS production. The responses of intermediates α-cryptoxanthin and β-cryptoxanthin were felt somewhere between carotenes and zeaxanthin/lutein. Furthermore, these changes were ameliorated when the organism was placed in darkness. In summary, down-regulation of the organism's photosynthetic capacity, coupled with heightened xanthophylls and APX activity, activates photoinhibition quenching (qI) and antioxidant activity, helping N. haitanensis to protect the organism from the damaging effects of excessive light exposure. These findings provide insights into how red algae adapt to intertidal lifestyles.

Role of compost in assisted phytostabilization via three naturally occurring species on mine-contaminated soil and health risk alleviation for livestock

Phytostabilization emerges as an efficient and enduring remediation technique for heavy metal-contaminated mine soils using plants acclimatized to such circumstances. In this research, the synergistic effects of Marrubium cuneatum, Verbascum speciosum, and Stipa arabica species, alongside municipal solid waste compost (MSWC) amendment at 0, 1, 3, and 5 % rates, were assessed for a six-month pot experiment aimed at remediating naturally polluted soil containing lead (Pb) and cadmium (Cd) and mitigating the health risks associated with these metal exposures for grazing ruminants. Applying compost improved the aboveground biomass of M. cuneatum and V. speciosum and S. arabica by 13, 19, and 18 %, respectively. Also, soil dehydrogenase and urease enzyme activities were enhanced up to 131 and 34 %. Upon MSWC application, all three species uptake Cd and Pb at a significantly lower rate, except in the V. speciosum shoot at 3 and 5 % doses, and bioaccumulation factors were markedly diminished. Compost notably augmented the antioxidant system, leading to a reduction in malondialdehyde content of V. speciosum, M. cuneatum, and S. arabica by 35, 29, and 23 %, respectively, and an elevation in chlorophyll level. Superoxide dismutase, catalase, glutathione peroxidase, and ascorbate peroxidase activities either increased or displayed no significant differences. Risk assessment revealed that MSWC substantially decreased the daily intake of Pb and Cd and their accumulation in animal organs, thereby eliminating limits on meat consumption. Findings affirm the combined efficacy of MSWC and the study species in stabilizing contaminated Pb and Cd soils, diminishing risks to animal feed security and human health.

Dodatek nano selena zmanjšuje od vročine povzročene oksidativne poškodbe v sejankah dateljeve palme s spremembami v rastlinskih hormonih in antioksidativni obrambi

Crops are destroyed by extreme heat, which also limits their growth and yield. The present study sought to determine whether selenium (0, 15, or 30 mg l-1) impacted ‘Barhee’ date palm seedling’s development under heat stress (in the field and canopy temperature). The growth parameters, chlorophyll and relative water content, ascorbic acid, catalase activity, and phytohormones in seedlings were reduced under heat stress. At the same time, ascorbate peroxidase activity, proline, phenols, malondialdehyde, hydrogen peroxide, and abscisic acid in seedlings increased. Enhancing growth features, chlorophyll content, relative water content, ascorbic acid, catalase activity, plant hormones, proline, phenols, and ascorbate peroxidase activity with exogenous nano-Selenium (15 mg l-1) reduced the negative impacts of heat stress. Date palm seedlings can be protected from high temperatures by using nano-selenium. Selenium reverses heat-induced oxidative damage by enhancing the antioxidative mechanism, improving reactive oxygen species scavenging, lowering lipid peroxidation, and modulating plant hormone levels.

Effects of electron beam irradiation on the postharvest quality characteristics of winter jujube (Zizyphus jujuba mill. cv. Dalidongzao)

Winter jujube was irradiated with 0.5 kGy electron beam (EB) and stored at 0 °C for 60 days. The quality of winter jujube was analyzed every 10 days to explore the effect of EB on antioxidant activity of winter jujube. Results indicated that 0.5 kGy EB reduced the decay rate of winter jujube (25.95% the 60th day), maintained the hardness and cell membrane integrity, delayed the changes of total soluble solids (TSS) and ascorbic acid (AA) contents, moreover maintained high contents of total phenols (TPC) and flavonoids. Furthermore, the activities of superoxide dismutase (SOD), peroxidase (POD), catalase (CAT) and ascorbate peroxidase (APX) increased, and the free radical scavenging ability of 2,2-diphenyl-1-picrylhydrazyl (DPPH) radicals and 2,2-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid (ABTS) cation radicals and the ferric ion reducing antioxidant power (FRAP) increased. Research demonstrated the potential of EB in the preservation of winter jujube and provided important information for the application of irradiation technology.