Ascorbate Peroxidase Enzyme Activity Research Articles

Moisture content and mycorrhizal fungi in maternal environment influence performance and composition of Lallemantia species offspring

The availability of soil water content and nutrition in the maternal plant environment plays pivotal roles in shaping the performance, physio-biochemical properties, and chemical composition of the produced seed. This study aimed to investigate the effects of water and arbuscular mycorrhizal fungi (AMF) of maternal plant environment on performance, physio-biochemical properties, and chemical compositions of Lallemantia species offspring. A split-factorial experiment was performed using a randomized complete block design (RCBD) with three replications. The main plot consisted of three drought stress (30%, 60% and 90% of soil available water depletion). The subplots were the factorial combination of arbuscular mycorrhizal fungi (AMF- and AMF+) and Lallemantia species (L. iberica and L. royleana). The offspring of both Lallemantia species experienced a decrease in seed performance, superoxide dismutase, catalase, ascorbate peroxidase enzyme activities, proline, and chemical composition as well as a rise in hydrogen peroxide and lipid peroxidation due to the limited availability of water in the maternal plant environment. On the other hand, providing adequate nutrition in the maternal plant environment resulted in improved germination index, increased starch, and oil content, as well as higher levels of nitrogen and phosphorus in the offspring of both Lallemantia species. Compared to the offspring of L. royleana, the offspring of L. iberica had a higher number of achenes, seeds, seed weight, larger seed size, greater germination index, and higher levels of starch, oil, nitrogen, phosphorus, potassium, and calcium. In contrast, the offspring of L. royleana exhibited higher longevity, enhanced germination under osmotic and salinity stress, increased proline levels, and higher activities of antioxidant enzymes such as superoxide dismutase, catalase, and ascorbic peroxidase as well as sucrose and total soluble sugar. The study concludes that the best seed performance, antioxidant enzyme activities, and carbohydrate levels were observed in the offspring of both Lallemantia species produced under 60% soil available water depletion with AMF inoculation in the maternal plant environment. These findings highlight the significant impact of the soil available water depletion and AMF inoculation on the seed performance, physio-biochemical properties, and chemical composition of the offspring, providing valuable insights for optimizing seed production and performance.

Effects of Mixtures Containing Physcion and Several Fungicides on the Yield of Wheat by Seed Coating and Its Potential Mechanisms

Physcion can induce plant resistance to disease, and is registered to control powdery mildew by spraying in China. Seed coating is a widely applied precision method for pest prevention and control. To explore its potential in disease control and yield increase by seed coating, mixtures containing physcion and commonly used fungicides were designed and applied in a field trial. Greenhouse experiments screened the optimal concentration of physcion for seed coating an found it to be 1:50, with excellent promotion of plant growth and powdery mildew control. In field trials, seeds coated with a combinations of physcion with validamycin and pyrimidine nucleotide (2#) at 1:50 exhibited the highest emergence rate, tillering number, control effect of wheat powdery mildew, enzyme activity of ascorbate peroxidase (APX), glutathione reductase (GR), and peroxidase (POD), photosynthetic pigment content, and yield. These results provide an effective approach to wheat disease control and yield increase in wheat fields, and can lay the basis for reasonable application of physcion in Huang-huai-hai plain in China.

The effect of melatonin on physiological, biochemical, and enzymatic properties and the expression of antioxidant genes under different irrigation regimes in wheat

A split-plot experiment was conducted based on a randomized complete block design with four replications in two years to study the effect of melatonin on the biochemical properties and the gene expression related to antioxidant enzyme activity in bread wheat. Irrigation levels (normal (FC = 80%)), mild stress (FC = 60%), and severe stress (FC = 40%)) were assigned to the main plots, and melatonin foliar applications (zero, 50, 100, 150, and 200 μM) were assigned to Subplots. Results showed that, with the intensification of water stress, the 1000 kernel weight decreased, and the activity of ascorbate peroxidase enzyme and flavonoid content increased. Also, the level of 100 μM melatonin had the highest 1000 kernel weight, flavonoid content, and ascorbate peroxidase enzyme activity. In this study, the highest number of grains per spike, biological yield, grain yield, chlorophyll a, chlorophyll b, carotenoids, and the lowest amount of malondialdehyde recorded for foliar treatment with 50 μM of melatonin under normal irrigation conditions and the highest proline content, total phenol, superoxide dismutase, and catalase were allocated to the 100 μM melatonin foliar treatment under severe water stress conditions. The synergistic effect of water deficit stress and melatonin foliar application increased the activity and expression level of genes related to antioxidant enzymes. So, the content of superoxide dismutase (21.30% and 65.16% respectively) and catalase (50.60% and 54.44% respectively) enzyme activity increased significantly under 100- and 150-mM melatonin foliar application in water severe water stress compared to the corresponding control treatment. Furthermore, mentioned melatonin levels increased the gene expression levels of superoxide dismutase (16.67% and 38.19% respectively), ascorbate peroxides (73.76% and 47.57% respectively), polyphenol oxidase (39.32 and 51.15%) and catalase (39.95% and 50.0% respectively) under an extreme water shortage compared with corresponding control treatment. In general, the application of 100- and 150-mM melatonin induced resistance to water deficit stress in wheat by increasing the expression of antioxidant genes.

Genome-wide identification of ascorbate peroxidase (APX) gene family and the function of SmAPX2 under high temperature stress in eggplant

Ascorbate peroxidase (APX) plays pivotal roles in regulating diverse biological processes in plants against biotic and abiotic stresses by eliminating hydrogen peroxide (H2O2). However, the function and information of APX gene family members in eggplant's response to high temperature stress remain largely unclear. Herein, we have identified nine APXs in the eggplant genome (SmAPXs), which were classified into three clades and the members of each clade exhibited similar gene structures and motifs. SmAPXs were distributed on seven chromosomes and contained phytohormone responsiveness-, defense and stress-related, and transcription factors binding cis-elements within their promoters. Transcript expressions of some SmAPXs, especially SmAPX2 that localize in cytomembrane and cytoplasm, were up-regulated by high temperature and ABA treatment. SmAPX2 exhibits APX enzyme activity, which enables to catalyze oxidation of ascorbic acid by H2O2in vitro and alleviate the H2O2 accumulation under high temperature stress by SmAPX2 transient expression in vivo. SmAPX2 silencing decreased eggplant's tolerance to high temperature stress, accompanied by transcript expression down-regulation of high temperature defense-related and ABA-response-related genes, reduction of APX enzyme activity, and increase of H2O2 content. These data provide comprehensive overview of SmAPX gene family, and indicate that SmAPX2 positively functions in eggplant response to high temperature stress.

Influence of Water Stress on Expression of the X95950 Gene and Several Cellular Callus Components in Violet-Treated Sunflower Varieties

The research was conducted between 2017 and 2019 at the College of Agricultural Engineering Sciences and Laboratory of Plant Tissue Culture for Postgraduate Studies at the University of Baghdad. One experiment used a totally random design. The experiment examined the effects of PEG (Polyethylene glycol) at concentrations of 0, 2, 4, 6, and 8% on the development of three sunflower types (Ishaqi-1, Aqmar, and AL-Haja) exposed to UV-C rays for 40 minutes as a result of the growing of the juvenile peduncle outside the live body. The aim of the study was to better comprehend the physiological and biochemical changes caused by water stress on the callus of several sunflower varieties. The X95950 gene was amplified using qPCR technology to investigate drought tolerance gene expression and callus cell content of glutathione, ascorbic acid, and APX enzyme as indicators to determine the effect of PEG on callus tissue cells in the nutrient medium. The expression of the X95950 gene was influenced by water stress. It was particularly expressed in Ishaqi-1 at 4 and 8% PEG concentrations, with values of 1.64 and 1.01, respectively. The glutathione content and activity of the enzyme ascorbate peroxidase, which were 56.49 mol-1 and 0.149 mg-1 protein absorption units, differed significantly among the varieties. PEG concentrations significantly influenced glutathione content, with 8% achieving the highest average of 50.07 mol g-1 and 4% achieving the highest averages of ascorbic acid and ascorbate peroxidase enzyme activity of 2.462 mg 100 g-1 and 0.138 mg-1 protein absorption units, respectively. The interaction was considerable, with the maximum average glutathione callus content in the Aqmar variety reaching 69.60 mol g-1 at 6% PEG concentration. At 4% PEG concentration, the Aqmar variety outperformed in terms of APX enzyme efficacy, reaching 0.238 mg-1 absorption units of protein.

Polyvinylpyrrolidone-coated copper nanoparticles dose-dependently conferred tolerance to wheat under salinity and/or drought stress by improving photochemical activity and antioxidant system

Copper (Cu) is one of the essential micronutrients for plants and has been used extensively in agricultural applications from the past to the present. However, excess copper causes toxic effects such as inhibiting photosynthesis, and disrupting biochemical processes in plants. Nanotechnology applications have offered a critical method for minimizing adverse effects and improving the effectiveness of copper nanoparticles. For this purpose, this study investigated the physiological and biochemical effects of polyvinylpyrrolidone (PVP)-coated Cu nanoparticles (PVP–Cu NP, N1, 100 mg L−1; N2, 400 mg L−1) in Triticum aestivum under alone or combined with salt (S, 150 mM NaCl) and/or drought (D, %10 PEG-6000) stress. Salinity and water deprivation caused 51% and 22% growth retardation in wheat seedlings. The combined stress condition (S + D) resulted in an approximately 3-fold reduction in the osmotic potential of the leaves. PVP-Cu NP treatments to plants under stress, especially N1 dose, were effective in restoring growth rate and regulating water relations. All stress treatments limited gas exchange in stomata and suppressed the maximal quantum yield of PSII (Fv/Fm). More than 50% improvement was observed in stomatal permeability and carbon assimilation rate under S + N1 and S + N2 applications. Examination of OJIP transient parameters revealed that N1 treatments protected photochemical reactions by reducing the dissipated energy flux (DIo/RC) in drought and S + D conditions. Exposure to S and/or D stress caused high hydrogen peroxide (H2O2) accumulation and lipid peroxidation in wheat leaves. The results indicated that S + N1 and S + N2 treatments reduced oxidative damage by stimulating the activities of antioxidant enzymes superoxide dismutase (SOD), peroxidase (POX), and ascorbate peroxidase (APX). Although similar effects were observed at D and S + D conditions with 100 mg L−1 PVP-Cu NP treatments (N1), the curative effect of the N2 dose was not observed. In D + N1 and S + D + N1 groups, AsA regeneration and GSH redox status were maintained by triggering APX, GR, and other enzyme activities belonging to the AsA-GSH cycle. In these groups, N2 treatment did not contribute to the availability of enzymatic and non-enzymatic antioxidants. As a result, this study revealed that N1 dose PVP-Cu NP application was successful in providing stress tolerance and limiting copper-induced adverse effects under all stress conditions.

Computational and experimental analysis of foxtail millet under salt stress and selenium supplementation.

Salinity stress is a major threat to crop growth and productivity. Millets are stress-tolerant crops that can withstand the environmental constraints. Foxtail millet is widely recognized as a drought and salinity-tolerant crop owing to its efficient ROS scavenging mechanism. Ascorbate peroxidase (APX) is one of the reactive oxygen species (ROS) scavenging enzymes that leads to hydrogen peroxide (H2O2) detoxification and stabilization of the internal biochemical state of the cell under stress. This inherent capacity of the APX enzyme can further be enhanced by the application of an external mitigant. This study focuses on the impact of salt (NaCl) and selenium (Se) application on the APX enzyme activity of foxtail millet using in silico and in-vitro techniques and mRNA expression studies. The NaCl was applied in the concentrations, i.e., 150mM and 200mM, while the Se was applied in 1μM, 5μM, and 10μM concentrations. The in silico studies involved three-dimensional structure modeling and molecular docking. The in vitro studies comprised the morphological and biochemical parameters, alongside mRNA expression studies in foxtail millet under NaCl stress and Se applications. The in silico studies revealed that the APX enzyme showed better interaction with Se as compared to NaCl, thus suggesting the enzyme-modulating role of Se. The morphological and biochemical analysis indicated that Se alleviated the NaCl (150mM and 200mM) and induced symptoms at 1µM as compared to 5 and 10µM by enhancing the morphological parameters, upregulating the gene expression and enzyme activity of APX, and ultimately reducing the H2O2 content significantly. The transcriptomic studies confirmed the upregulation of chloroplastic APX in response to salt stress and selenium supplementation. Hence, it can be concluded that Se as a mitigant at lower concentrations can alleviate NaCl stress in foxtail millet.

Transcriptomic and genetic approaches reveal that low-light-induced disease susceptibility is related to cellular oxidative stress in tomato.

The impact of low light intensities on plant disease outbreaks represents a major challenge for global crop security, as it frequently results in significant yield losses. However, the underlying mechanisms of the effect of low light on plant defense are still poorly understood. Here, using an RNA-seq approach, we found that the susceptibility of tomato to Pseudomonas syringae pv. tomato DC3000 (Pst DC3000) under low light was associated with the oxidation-reduction process. Low light conditions exacerbated Pst DC3000-induced reactive oxygen species (ROS) accumulation and protein oxidation. Analysis of gene expression and enzyme activity of ascorbate peroxidase 2 (APX2) and other antioxidant enzymes revealed that these defense responses were significantly induced by Pst DC3000 inoculation under normal light, whereas these genes and their associated enzyme activities were not responsive to pathogen inoculation under low light. Additionally, the reduced ascorbate to dehydroascorbate (AsA/DHA) ratio was lower under low light compared with normal light conditions upon Pst DC3000 inoculation. Furthermore, the apx2 mutants generated by a CRISPR-Cas9 gene-editing approach were more susceptible to Pst DC3000 under low light conditions. Notably, this increased susceptibility could be significantly reduced by exogenous AsA treatment. Collectively, our findings suggest that low-light-induced disease susceptibility is associated with increased cellular oxidative stress in tomato plants. This study sheds light on the intricate relationship between light conditions, oxidative stress, and plant defense responses, and may pave the way for improved crop protection strategies in low light environments.

Impact of Pre-Storage Melatonin Application on the Standard, Sensory, and Bioactive Quality of Early Sweet Cherry.

Melatonin (N-acetyl-5-methoxytryptamine) is involved in multiple functions in plants. However, its role in some metabolic pathways and exogenous application's effect on fruits is still unclear. Furthermore, the effects of pre-storage melatonin treatment on sensory traits and consumer acceptance of cherries have yet to be studied. For this reason, the early sweet cherry cultivar 'Samba' harvested at the commercial ripening stage was treated with different melatonin concentrations (0.1, 0.3, and 0.5 mmol L-1) and stored for 21 days under controlled cold temperature and humidity. The standard quality, respiration rate, postharvest aptitude, sensory quality, phenols, and antioxidant systems (non-enzymatic and enzymatic) were analysed at 14 and 21 days of storage. Postharvest treatment with melatonin 0.5 mmol L-1 improved firmness and reduced weight loss and non-commercial fruit percentage while increasing respiration rate, lipophilic antioxidant activity, and ascorbate peroxidase enzyme activity. Furthermore, the treated cherries showed better sensory qualities, such as uniformity of colour and skin colour, as well as being sourer and showing better consumer acceptance and liking after 14 days of storage. Therefore, we conclude that the 0.5 mmol L-1 concentration is effective on the standard, sensory, and bioactive quality of early sweet cherries and can be considered an eco-friendly tool for maintaining the postharvest quality of early cherries.

The effect of foliar application of amino acids on some nutritional properties, antioxidant capacity and some other physiologic parameters of African marigold (Tagetes erecta L.), Taishan ‘Yellow’ and ‘Orange’

African marigold (Tagetes erecta L.) is one of the most well-known ornamental, medicinal and edible flowers in the world. A factorial experiment based on completely randomized design with 20 treatments in 3 replications, 60 plots and 5 plants per plot were conducted in order to investigate the effect of amino acids on growth, nutritional parameters and antioxidant capacity in African marigold. Experimental treatments included two cultivars of African marigold (‘Yellow’ and ‘Orange’) and foliar application of three amino acids (arginine, glutamine and proline) each one at three levels (100, 500 and 1000 μM). Distilled water was used as control. The results showed that the application of amino acids increased plant height, display life, fresh weight and dry matter of flower, leaf total chlorophyll and petal carotenoid compared to the control in both African marigold cultivars. Petal protein content and malondialdehyde (MDA) were not affected by the above treatments, but the use of amino acids, especially arginine and proline, increased proline and calcium, zinc and iron in the petals of both African marigold cultivars. Treatments of 100 μM arginine and 1000 μM proline induced the highest vitamin C in both African marigold cultivars. In ‘Orange’ cultivar, the highest enzyme activity of superoxide dismutase (SOD) and ascorbate peroxidase (APX) belonged to 1000 μM proline and the highest peroxidase (POD) activity belonged to two treatments of 100 μM arginine and 1000 μM proline. In ‘Yellow’ cultivar, all three levels of arginine and proline together with 1000 μM glutamine significantly increased SOD and POD activity compared to other treatments. Also, the highest APX enzyme activity was recorded for 100 μM arginine. The results of the present study showed that external application of amino acids, especially arginine and proline, improved the nutritional properties of both African marigold cultivars by increasing the activity of antioxidants.

Effects of foliage-applied exogenous γ-aminobutyric acid on seedling growth of two rice varieties under salt stress.

Exogenous γ-aminobutyric acid (GABA) has been used and regarded as a potential enhancer for plant resistance against various biotic or abiotic attackers in the crop production, especially as a promising alleviator against salt stress. In order to determine whether GABA is truly effective in promoting rice resistance under a certain level of salt stress or not and to evaluate its effect on the growth and some physiological responses of two Japonica rice varieties under salt stress. 3-leaf rice seedlings germinated from seeds were cultivated in a separate hydroponic cup with a nutrient solution that was salinized with 0, 25, 50, or 75 mmol K+ of NaCl. A 4 mmol L-1 GABA solution or water were sprayed onto leaves once a day for 8 days prior to an assessment of the seedling growth, the growth indices, root activities and three antioxidant enzyme activities in leaves were measured. Data analyses indicated that as the salt concentration increased, the plant height and the leaf area of both rice varieties decreased, while the dead leaf rate, weight ratio of the dry- and fresh-roots, superoxide dismutase (SOD) and peroxidase (POD) activities increased. Under the same saline conditions, the root activities and the leaf ascorbate peroxidase (APX) activity were enhanced at a low NaCl concentration but reduced when the salt concentration was high. A foliar application of GABA daily on both rice varieties for over a week under 3 different salinized treatments as compared with the corresponding treatments sprayed with water resulted in an enhanced effect on plant height increment by 1.7-32.4%, a reduction of dead leaf rate by 1.6-36.4%, a decline of root dry weight by 9.3-30.9% respectively, and an increment in root activities by 8.1-114.5%, and POD, SOD and APX enzyme activities increased by 5.0-33.3%, 4.1-18.5%, and 7.2-64.4% respectively. However, two rice varieties showed a significant difference in response to various salinized levels. Overall results of this study demonstrate that the application of exogenous GABA on the leaves of rice seedlings under salt stress has improved rice salt tolerance, which should provide a sufficient information for ultimately making it possible to grow rice in salinized soil.

Antioxidant enzymes activity and gene expression in wheat-stripe rust interaction at seedling stage

The current study was designed to determine the activity of antioxidant enzymes: superoxide dismutase (SOD), ascorbate peroxidase (APX), glutathione peroxidase GPX and catalase (CAT) and the expression of their genes in 10 wheat isogenic differential lines showing compatible and incompatible interactions with Puccinia striiformis. The enzyme activity was determined at 24 h after inoculation (24hai), 48 h after inoculation (48hai), and 72 h after inoculation (72hai). However, enzyme gene expression was determined only at 72hai. To fulfill the objectives, 12-day-old wheat seedlings of isogenic differential lines were inoculated with stripe rust race (race 574232). The results of the study showed that enzyme activity and gene expression was significantly high in incompatible interaction as compared to compatible interaction. The enzyme activity of SOD was high at 24hai in resistant isogenic differential lines. High enzyme activity (97.54 ± 4.84) was recorded in was recorded Yr5/6* Avocet S. Enzyme activities of CAT and APX were higher at 72hai in resistant isogenic differential lines. CAT, APX genes were significantly upregulated and while gene expression of SOD was low at 72hai.The results indicate a unique pattern of enzyme activity and gene expression of the antioxidant enzymes in the compatible and incompatible interaction is playing a crucial role in the plant defense system.

PHYSIOLOGICAL AND BIOCHEMICAL ANALYSIS OF ASA-GSH ANTIOXIDANT SYSTEM OF SEA-ISLAND COTTON IN RESPONSE TO VERTICILLIUM DAHLIAE

Sea-Island cotton (Gossypium barbadense) is a high-quality long-fiber cotton species and is mainly planted in southern region of Xinjiang. The primary disease is Verticillium wilt, which is caused by Verticillium dahlia affecting G. barbadense growth and development. That leads to reduction in quality and yield of the fibers and thus to the huge economic loss. AsA-GSH antioxidant system has been extensively studied and is seen as having a crucial function in plant’s response to biotic and abiotic stresses. The goal of this study is to look into the resistant mechanism of AsA-GSH antioxidant system in Gossypiumbarbadense in response to V. dahliae. The two varieties, wilt-susceptible XH17 and wilt-resistant XH24, were incubated by V991 strain of V. dahliae and the treated leaves were collected for the physiological and biochemical analysis of AsA-GSH antioxidant system. The leaves were collected at day 0, 2, 6 and 9 after fungal inoculation and the functions of related enzymes of AsA-GSH antioxidant system including Superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), and glutathione re-oxidase (GR), as well as the physiological indexes of malondialdehyde (MDA) and proline were measured. The mRNA and protein expression levels of the genes of APX, dehydroascorbate reductase (DHAR), monodehydroascorbate reductase (MDHAR), SOD, CAT, and GR, that constitute AsA-GSH antioxidant system, were analyzed by the transcriptomic and proteomic data. The enzyme activities of CAT, SOD, GR, and APX were found to be increased significantly after V. dahliae treatment in both XH24 and XH17. Interestingly, SOD and APX activities maintained at relative high values in wilt-resistant XH24 but a decrease in values was observed during the late stage of V. dahliae treatment in case of wilt-susceptible XH17. High proline accumulation and low MDA content were observed in wilt-resistant XH24. The results of AsA-GSH antioxidant system genes shows that four APX members of GbAPX1A, GbAPX1D, GbAPX10D, and GbAPX12A, one DHAR member GbDHAR2D, four MDHAR members of GbMDHAR1A, GbMDHAR1D, GbMDHAR3A, and GbMDHAR3D, two GR members of GbGR2A and GbGR2D, two CAT members of GbCAT1A and GbCAT1D, and six SOD members of GbCSD4A, GbCSD5A, GbCSD4D, GbCSD5D, GbMSD1D and GbMSD1A were all expressed induced accumulations significantly after V. dahliae treatment, implying their important potential functions for G. barbadense to resist V. dahliae. Generally, the protein expression and mRNA expression indicated a similar profile, while some unique expressions of these AsA-GSH antioxidant system genes were also been discovered. There were ten APX members of GbAPX1D, GbAPX2A, GbAPX2D, GbAPX3A, GbAPX3D, GbAPX6A, GbAPX6D, GbAPX8A, GbAPX12A, and GbAPX3D; all six DHAR members with the exception of GbDHAR2D; three GR members locating in A sub-genome containing GbGR 1A, GbGR 2A, and GbGR 3A; six MDAHR members including GbMDAHR1A, GbMDAHR1D, GbMDAHR3A, GbMDAHR3D, GbMDAHR4A, and GbMDAHR4D; two CAT members of GbCAT1A and GbCAT4D; as well as eight SOD members of GbCSD1A, GbCSD4A, GbCSD4D, GbCSD2A, GbMSD2D, GbMSD2D, GbMSD1A and GbMSD1D, to indicate steady high expressions. These results indicated that there exist some close link and consistency between the mRNA and protein expressions, and that the preferentially expressed proteins of AsA-GSH antioxidant system might perform important functions as enzymes to catalyze the oxidation/reduction reactions and thus to maintain the redox balance and integrity of the cells in the process of G. barbadense plants to resist V. dahliae.

Interaction of TiO2 nanoparticles with the C. vulgaris: oxidative stress, lipid peroxidation and lipid amount.

Nanoparticles are widely used in many industries such as food and cosmetics. With increasing use, its spread to environmental environments is also increasing. Microalgae have an important place in the uptake of nanoparticles into the food chain. In this study, the effect of TiO2 nanoparticle on antioxidant enzyme activity, malondialdehyde, hydrogen peroxide, chlorophyll-a and total lipid amount in C. vulgaris microalgae has been investigated. As a result of the dose study, while the superoxide dismutase and ascorbate peroxidase enzyme activities decreased, the amount of MDA, H2O2 and chlorophyll-a increased. Depending on the times at different light:dark ratios, both an increase and a decrease occurred in the SOD, APX enzyme activity and the amount of MDA, H2O2. There was an increase in the amount of chlorophyll-a. In the time study, while the SOD and APX enzyme activities increased, the amount of MDA and H2O2 decreased. The amount of chlorophyll-a increased. In the total lipid study, the total lipid amount in the group with nano TiO2 increased compared to the control group. At the same time, C18:2 T (linoleic acid) has been found as fatty acid methyl ester in both groups.

Genome-Wide Identification of C2H2 ZFPs and Functional Analysis of BRZAT12 under Low-Temperature Stress in Winter Rapeseed (Brassica rapa).

Zinc-finger protein (ZFP) transcription factors are among the largest families of transcription factors in plants. They participate in various biological processes such as apoptosis, autophagy, and stemness maintenance and play important roles in regulating plant growth and development and the response to stress. To elucidate the functions of ZFP genes in the low-temperature response of winter (Brassica rapa L.) B. rapa, this study identified 141 members of the C2H2 ZFP gene family from B. rapa, which are heterogeneously distributed on 10 chromosomes and have multiple cis-acting elements related to hormone regulation and abiotic stress of adversity. Most of the genes in this family contain only one CDS, and genes distributed in the same evolutionary branch share mostly the same motifs and are highly conserved in the evolution of cruciferous species. The genes were significantly upregulated in the roots and growth cones of ‘Longyou-7’, indicating that they play a role in the stress-response process of winter B. rapa. The expression level of the Bra002528 gene was higher in the strongly cold-resistant varieties than in the weakly cold-resistant varieties after low-temperature stress. The survival rate and BrZAT12 gene expression of trans-BrZAT12 Arabidopsis thaliana (Arabidopsis) were significantly higher than those of the wild-type plants at low temperature, and the enzyme activities in vivo were higher than those of the wild-type plants, indicating that the BrZAT12 gene could improve the cold resistance of winter B. rapa. BrZAT12 expression and superoxide dismutase and ascorbate peroxidase enzyme activities were upregulated in winter B. rapa after exogenous ABA treatment. BrZAT12 expression and enzyme activities decreased after the PD98059 treatment, and BrZAT12 expression and enzyme activities were higher than in the PD98059 treatment but lower than in the control after both treatments together. It is speculated that BrZAT12 plays a role in the ABA signaling process in which MAPKK is involved. This study provides a theoretical basis for the resolution of cold-resistance mechanisms in strong winter B. rapa.

The effect of humic acid on rapeseed (Brassica napus L.) plant growth, heavy metal uptake, phytoremediation parameters (BCF, TF and TI), and antioxidant activity in heavy metal polluted soil

The aim of this study was to investigate the effects of humic acid (HA) applications on rapeseed (Brassica napus L.) growth, heavy metal uptake, bioconcentration factor (BCF), translocation factor (TF), tolerance index (TI), catalase (CAT), ascorbate peroxidase (APX) enzyme activities and hydrogen peroxide (H2O2) content in polluted soil with lead (Pb), chromium (Cr), cadmium (Cd), and zinc (Zn). Three doses of HA (Control, HA1:500 mg kg-1, HA2:1000 mg kg-1, HA3:2000 mg kg-1) were applied in pots. HA1, HA2, and HA3 applications increased plant growth parameters compared to polluted soil. Compared to the control, HA applications in polluted soil increased the Pb, Cr, Cd, and Zn concentrations in the plant. However, HA applications in polluted soil significantly decreased the heavy metal content in roots and shoots of the plant compared to polluted soil. BCF in both roots and shoots of the plants were greater than 1 for Pb, Cr, Cd, and Zn. However, specifically HA2 application decreased the shoot and root BCF values in polluted soil. TF was smaller than 1 in Pb, Cr, Cd, and Zn in polluted soil. On the other hand, HA applications for Cd increased TF values. Shoot TI decreased 17.37 %, and root TI decreased 9.09% in polluted soil. CAT and APX enzyme activities and H2O2 increased significantly in polluted soil. However, HA applications decreased CAT and APX enzyme activities and H2O2 content in rapeseed. It is concluded that HA application in Pb, Cr, Cd, and Zn polluted soil has a remedial effect on the development of rapeseed by reducing heavy metal content and oxidative stress.

Salicylic acid enhances tolerance of Valeriana officinalis L. to bentazon herbicide

Salicylic acid is an important phytohormone, with regulation role in responses of plants to biotic and abiotic stress, especially detoxification of herbicides. For this purpose, the effect of three rates of salicylic acid (SA) (zero, 0.5, and 1 mM) and six doses of bentazon (zero, 50%, 75%, 100%, 125%, and 150% of recommended dose) on physiological response of valerian (Valeriana officinalis L.) were evaluated in the completely randomized factorial design with three replicates. The results showed that application of bentazon, especially at high levels (125% and 150% of recommended dose, in the absence of SA, exacerbated the rate of phytotoxicity damage, malondialdehyde (MDA) content, catalase (CAT), gaiacol peroxidase (GPX), and ascorbate peroxidase (APX) activity. Exogenous application of SA positively impacted bentazon- and unbentazon-exposed (control) plants, even under elevated concentration of herbicide (50% higher than recommended dose). Highest protection of the bentazon-exposed plants was observed at 0.5 and 1 mM level of SA, respectively. Combination of exogenous application (pre-treatment) of SA and bentazon herbicide reduced MDA content compared with ones were exclusively bentazon-exposed. In addition, exogenous application of SA enhanced antioxidant enzyme system, and increased APX and GPX enzyme activity. Results of present research indicated that external application of SA could be able to increase tolerance to oxidative stress generated in bentazon-exposued plants of valerian by reducing phytotoxicity and mutating antioxidant enzymatic system and antioxidant metabolites content.

Biological Control of Root-Knot Nematode Meloidogyne incognita in Psoralea corylifolia Plant by Enhancing the Biocontrol Efficacy of Trichoderma harzianum Using Press Mud

Meloidogyne incognita is a plant pathogen causing root-knot disease and loss of crop yield. The present study aimed to use Trichoderma harzianum as a biocontrol agent against plant-parasitic nematodes and used press mud, which is a solid waste by-product of sugarcane, as a biocontrol agent and biofertilizer. Therefore, the combined application of T. harzianum and press mud may enhance nematode control and plant growth. Elemental analysis of press mud using scanning electron microscopy (SEM) integrated with an Energy Dispersive X-ray (EDX) analyzer revealed the presence of different elements such as C, O, Mg, Si, P, K, Ca, Cu and Zn. In addition, a greenhouse study was conducted to investigate the combined effects of press mud and T. harzianum on M. incognita reproduction and growth and the biochemical features of Psoralea corylifolia. The results showed that plant length, dry biomass, leaf area, the number of seeds per plant, chlorophyll a, chl b, carotenoid content, nitrate reductase, carbonic anhydrase, and nitrogen content were significantly increased (P ≤ 0.05) in the T2 plants (plants were treated with 100 g of press mud + 50 mL T. harzianum before one week of M. incognita inoculation), over inoculated plants (IC). Antioxidant enzyme activity of ascorbate peroxidase (APX), catalase (CAT), peroxidase (POD), and superoxide dismutase (SOD) in the foliage of P. corylifolia was significantly increased when plants were treated with press mud + T. harzianum. A significant reduction in the number of egg masses, nematode population, and root-knot index (RKI) was found in plants with T2 plants. These results suggest that the combined application of T. harzianum and press mud has the potential to control the M. incognita infection and can be used as an environmentally safe alternative to chemical nematicides and also help in the removal of sugarcane waste that causes environmental pollution.

Measurement of Ascorbate Peroxidase Activity in Sorghum.

The ascorbate peroxidase (APX) is a widely distributed antioxidant enzyme. It differs from catalase and other peroxidases in that it scavenges/reduces reactive oxygen species (ROS) such as hydrogen peroxide (H 2 O 2 ) to water using reduced ascorbate as the electron donor. It is advantageous over other similar antioxidant enzymes in scavenging ROS since ascorbate may react with superoxide, singlet oxygen, and hydroxyl radical, in addition to reacting with H 2 O 2 . The estimation of its activity is helpful to analyze the level of oxidative stress in living systems under stressful conditions. The present protocol was performed to analyze the impact of heavy metal chromium (Cr) toxicity on sorghum plants in the form of APX enzyme activity under the application of glycine betaine (GB) and arbuscular mycorrhizal fungi (AMF) as stress ameliorators. Plant defense strategies against heavy metals toxicity involve the utilization of APX and the instigation of AMF symbiotic system, as well as their possible collaboration with one another or with the plant antioxidant system; this has been examined and discussed in literature. In this protocol, an increased APX activity was observed on underlying functions and detoxification capabilities of GB and AMF that are typically used by plants to enhance tolerance to Cr toxicity. Graphical abstract: Flow chart of standardized or calibrated enzyme assay with leaf samples of sorghum.

Effect of powdery mildew on antioxidant enzymes of wheat grain

AbstractPowdery mildew caused by Blumeria graminis f. sp. tritici (Bgt) is a severe leaf disease in wheat (Triticum aestivum). To elucidate the effect of powdery mildew on cell redox homeostasis in grains, three wheat cultivars with different resistance, Xi'nong 979 (susceptible), Zhengmai 379 (moderately susceptible), and Zhengmai 103 (resistant), were inoculated with Bgt in the field, and the changes in gene transcription and activity of the antioxidant enzymes in developing grains were analysed. The results showed that the gene expression patterns and enzyme activity changes of guaiacol peroxidase (POD), catalase (CAT), dehydroascorbate reductase (DHAR), glutathione reductase (GR), and 1‐Cys peroxiredoxin (1‐Cys Prx) were similar under powdery mildew conditions. They increased significantly at 10–20 days after anthesis (DAA) in susceptible cultivars and at 20–30 DAA in the resistant cultivar. However, they showed a significant decrease in susceptible cultivars at 20–30 DAA. The gene expression and enzyme activity of ascorbate peroxidase (APX) and monodehydroascorbate reductase (MDHAR) increased continuously during grain development, especially in susceptible cultivars. The results demonstrated that the antioxidant systems were induced under mild powdery mildew conditions, which was conducive to the synchronous regulation of reactive oxygen species (ROS). However, under severe powdery mildew conditions, the antioxidant systems were inhibited and the regulation of ROS was restricted, resulting in the breakdown of cell redox homeostasis. It is speculated that powdery mildew infection can inhibit the activity of some metabolic proteins (transcription factors or enzymes), change the carbon and nitrogen metabolism of grain cells, and further change the quality of wheat grains.