Plant Peroxidases Research Articles

Maize Endophytic Plant Growth-Promoting Bacteria Peribacillus simplex Can Alleviate Plant Saline and Alkaline Stress.

Soil salinization is currently one of the main abiotic stresses that restrict plant growth. Plant endophytic bacteria can alleviate abiotic stress. The aim of the current study was to isolate, characterize, and assess the plant growth-promoting and saline and alkaline stress-alleviating traits of Peribacillus simplex M1 (P. simplex M1) isolates from maize. One endophytic bacterial isolate, named P. simplex M1, was selected from the roots of maize grown in saline-alkali soil. The P. simplex M1 genome sequence analysis of the bacteria with a length of 5.8 Mbp includes about 700 genes that promote growth and 16 antioxidant activity genes that alleviate saline and alkaline stress. P. simplex M1 can grow below 400 mM NaHCO3 on the LB culture medium; The isolate displayed multiple plant growth-stimulating features, such as nitrogen fixation, produced indole-3-acetic acid (IAA), and siderophore production. This isolate had a positive effect on the resistance to salt of maize in addition to the growth. P. simplex M1 significantly promoted seed germination by enhancing seed vigor in maize whether under normal growth or NaHCO3 stress conditions. The seeds with NaHCO3 treatment exhibited higher reactive oxygen species (ROS) levels than the maize in P. simplex M1 inoculant on maize. P. simplex M1 can colonize the roots of maize. The P. simplex M1 inoculant plant increased chlorophyll in leaves, stimulated root and leaf growth, increased the number of lateral roots and root dry weight, increased the length and width of the blades, and dry weight of the blades. The application of inoculants can significantly reduce the content of malondialdehyde (MDA) and increase the activity of plant antioxidant enzymes (Catalase (CAT), Superoxide Dismutase (SOD), and Peroxidase (POD)), which may thereby improve maize resistance to saline and alkaline stress. Conclusion: P. simplex M1 isolate belongs to plant growth-promoting bacteria by having high nitrogen concentration, indoleacetic acid (IAA), and siderophore, and reducing the content of ROS through the antioxidant system to alleviate salt alkali stress. This study presents the potential application of P. simplex M1 as a biological inoculant to promote plant growth and mitigate the saline and alkaline effects of maize and other crops.

Study of the Effects of Bioactive Compounds of Cyanobacterium Desmonostoc alborizicum on Pathogenic Fungi of Wheat

Wheat, as one of the most economically important crops, constitutes a major part of the human diet. One of the major challenges in wheat preservation is combating various pests, including fungi, through different pesticides. Due to the toxicity caused in agricultural fields by chemical pesticides, there is a growing inclination towards using biopesticides instead. These biopesticides not only possess antimicrobial properties but also aid in the growth and development of crops. In this context, the bioactive compounds present in cyanobacteria are considered as potential biopesticide candidates. Therefore, the aim of this study is to observe the antifungal effect of bioactive compounds from the cyanobacterium Desmonostoc alborizicum on pathogenic fungi affecting wheat. For this purpose, after culturing the cyanobacterial strain Desmonostoc alborizicum for 14 days, the cyanobacterial extract was applied to wheat plants infected with the fungi Alternaria alternata, Fusarium oxysporum, Aspergillus terreus, and Phytophthora nicotiana var. The activity of antioxidant enzymes and MTT assay on 4T1 cells were then evaluated. The results showed that Aspergillus terreus exhibited the highest resistance, while Fusarium oxysporum showed the highest sensitivity to the cyanobacterial extract of Desmonostoc alborizicum. The activity of the enzymes guaiacol peroxidase, superoxide dismutase, catalase, and glutathione peroxidase in infected plants treated with the cyanobacterial extract significantly decreased (p<0.05), indicating effective stress control and enhanced immune response in these treatments. Therefore, the results of this study suggest that the use of Desmonostoc alborizicum extract can be effective as an antifungal agent in protecting wheat and other agricultural crops.

Identification of Plant Peroxidases Catalyzing the Degradation of Fluorinated Aromatics Using a Peroxidase Library Approach

ABSTRACTIn this work, the degradation of mono‐ and polyfluorinated phenolic compounds was demonstrated by a series of crude plant peroxidases, including horseradish root (HRP) and six members of the Cucurbita genus. Highly active samples were identified using a library screening approach in which more than 50 crude plant samples were initially evaluated for defluorination activity toward 4‐fluorophenol. The highest concentrations were observed in the HRP, pumpkin skin (PKS), and butternut squash skin (BNS), which consistently gave the highest intrinsic rates of decomposition for all the substrates tested. Although HRP exhibited a significant decrease in activity with increased fluorination of the phenolic substrate, PKS showed only minor reductions. Furthermore, in silico studies indicated that the active site of HRP poorly accommodates the steric bulk of additional fluorines, causing the substrate to dock farther from the catalytic heme and thus slowing the catalysis rate. We propose that the PKS active site might be larger, allowing closer access to the perfluorinated substrate, and therefore maintaining higher activity compared to the HRP enzyme. However, detailed kinetic characterization studies of the peroxidases are recommended. Conclusively, the high catalytic activity of PKS and its high yield per gram of tissue make it an excellent candidate for developing environmentally friendly biocatalytic methods for degrading fluorinated aromatics. Finally, the success of the library approach in identifying highly active samples for polyfluorinated aromatic compound (PFAC) degradation suggests the method may find utility in the quest for other advanced catalysts for PFAS degradation.

Evaluation of Bacillus velezensis F9 for Cucumber Growth Promotion and Suppression of Fusarium wilt Disease.

Cucumber wilt, caused by Fusarium oxysporum f. sp. cucumerinum (FOC), is a soilborne disease that poses a significant threat to cucumber production, resulting in substantial yield losses. This study aimed to evaluate the biocontrol and growth-promoting effects of Bacillus velezensis, a highly active bacterial strain. In vitro assays revealed that B. velezensis F9 exhibited broad-spectrum antifungal activity against eight plant pathogenic fungi, with inhibition ratio ranging from 62.66% to 88.18%. Additionally, the strain displayed the ability to produce IAA (5.97 ± 1.75 µg/mL), fix nitrogen, produce siderophores, and form biofilms. In vitro growth promotion assays demonstrated that different concentrations of B. velezensis F9 significantly promoted cucumber seedling growth. Furthermore, two pot experiments revealed that the strain exhibited biocontrol efficacy against cucumber wilt, with disease control rates ranging from 42.86% to 67.78%. Notably, the strain significantly increased the plant height, fresh weight, and dry weight, with increases ranging from 20.67% to 60.04%, 40.27% to 75.51%, and 22.07% to 52.54%, respectively. Two field trials confirmed the efficacy of B. velezensis F9 in controlling cucumber wilt, with disease control rates of 44.95% and 33.99%, respectively. The strain effectively alleviated the dwarfing and wilting symptoms caused by the pathogen. Compared with the FOC treatment, the F9 + FOC treatment significantly increased the plant height, fresh weight, and dry weight, with increases of 43.85% and 56.28%, 49.49% and 23.70%, and 36.25% and 73.63%, respectively. Enzyme activity assays indicated that inoculation significantly increased SOD activity in cucumber leaves and neutral phosphatase, sucrase, and urease activity in rhizosphere soil. Correlation analysis revealed a negative correlation between the disease index and plant height, fresh weight, dry weight, and peroxidase activity, with correlation coefficients of -0.53, -0.60, -0.38, and -0.45, respectively. These findings suggest that plant height, fresh weight, and dry weight are significantly negatively correlated with the cucumber disease index, highlighting their importance as indicators for evaluating the biocontrol efficacy of B. velezensis F9. In conclusion, B. velezensis F9 is a highly effective plant growth-promoting rhizobacterium with excellent biocontrol potential, showcasing promising applications in agricultural production.

Role of defense inducers in modulating biochemical responses to Alternaria leaf blight

Alternaria leaf blight of sunflower has been considered as a potentially destructive disease. Due to cons of using chemical pesticides, the present investigation was undertaken to know the effect of three plant defence inducers viz., salicylic acid, monopotassium phosphate and sodium propionate for the eco-friendly management of Alternaria leaf blight disease. Seed treatment with salicylic acid at 100 ppm followed by foliar spray of salicylic acid at 100 ppm recorded highest secondary metabolites such as flavonoids (68.71 mg g FW) and phenols (73.53 mg g FW) -1 -1 -1 when compared to phenolics (45.07 mg g FW) and flavonoids (51.43 mg g FW) in control plants -1 . Seed treatment with salicylic acid at 100 ppm followed by foliar spray of salicylic acid at 100 ppm showed increased defense enzymes such as superoxide dismutase (40.45 mg/50 per cent inhibition) and peroxidase (16.86 mg min mg protein) when compared to superoxide dismutase -1 -1 (54.36 mg/50 per cent inhibition) and peroxidase (9.63 mg min mg protein) in control plants. This study -1 -1 demonstrated that seed treatment followed by foliar spray with salicylic acid can be used effectively for the management of Alternaria blight in fields as it exhibited more defense enzyme activity and secondary metabolites.. KEYWORDS :Alternaria, defense enzymes, secondary metabolites, seed treatment

Silencing of GhSINAT5 Reduces Drought Resistance and Salt Tolerance in Cotton.

The SEVEN IN ABSENTIA (SINA) E3 ubiquitin ligase is widely involved in drought and salt stress in plants. However, the biological function of the SINA proteins in cotton is still unknown. This study aimed to reveal the function of GhSINAT5 through biochemical, genetic and molecular approaches. GhSINAT5 is expressed in several tissues of cotton plants, including roots, stems, leaves and cotyledons, and its expression levels are significantly affected by polyethylene glycol, abscisic acid and sodium chloride. When GhSINAT5 was silenced in cotton plants, drought and salinity stress occurred, and the length, area and volume of the roots significantly decreased. Under drought stress, the levels of proline, superoxide dismutase, peroxidase and catalase in the GhSINAT5-silenced cotton plants were significantly lower than those in the non-silenced control plants, whereas the levels of hydrogen peroxide and malondialdehyde were greater. Moreover, the expression of stress-related genes in silenced plants under drought stress suggested that GhSINAT5 may play a positive role in the plant response to drought and salt stress by regulating these stress response-related genes. These findings not only deepen our understanding of the mechanisms of drought resistance in cotton but also provide potential targets for future improvements in crop stress resistance through genetic engineering.

Enhancing tomato plant immune responses to Fusarium wilt disease by red seaweed Jania sp.

The novelty of this study lies in demonstrating a new approach to control wilt diseases using Jania ethyl acetate extract. In the current investigation, the potential impacts of Jania sp. ethyl acetate extract (JE) on Tomato Fusarium oxysporum wilt (FOW) have been studied. The in vitro antifungal potential of JE against F. oxysporum (FO) was examined. GC–MS investigation of the JE revealed that, the compounds possessing fungicidal action were Phenol,2-methoxy-4-(2-propenyl)-,acetate, Eugenol, Caryophyllene oxide, Isoespintanol, Cadinene, Caryophylla-4(12),8(13)-dien-5à-ol and Copaen. Jania sp. ethyl acetate extract exhibited strong antifungal potential against FO, achieving a 20 mmzone of inhibition. In the experiment, two different methods were applied: soil irrigation (SI) and foliar application (FS) of JE. The results showed that both treatments reduced disease index present DIP by 20.83% and 33.33% respectively. The findings indicated that during FOW, proline, phenolics, and the antioxidant enzymes activity increased, while growth and photosynthetic pigments decreased. The morphological features, photosynthetic pigments, total phenol content, and antioxidant enzyme activity of infected plants improved when JE was applied through soil or foliar methods. It is interesting to note that the application of JE had a substantially less negative effect on the isozymes peroxidase and polyphenol oxidase in tomato plants, compared to FOW. These reactions differed depending on whether JE was applied foliarly or via the soil. Finally, the use of Jania sp. could be utilized commercially as an ecologically acceptable method to protect tomato plants against FOW.

Molecular Insights into the Defense of Dioscorea opposita Cultivar Tiegun Callus Against Pathogenic and Endophytic Fungal Infection Through Transcriptome Analysis.

Dioscorea opposita cultivar Tiegun is an economically important crop with high nutritional and medicinal value. Plants can activate complex and diverse defense mechanisms after infection by pathogenic fungi. Moreover, endophytic fungi can also trigger the plant immune system to resist pathogen invasion. However, the study of the effects of endophytic fungi on plant infection lags far behind that of pathogenic fungi, and the underlying mechanism is not fully understood. Here, the black spot pathogen Alternaria alternata and the endophytic fungus Penicillium halotolerans of Tiegun were identified and used to infect calli. The results showed that A. alternata could cause more severe membrane lipid peroxidation, whereas P. halotolerans could rapidly increase the activity of the plant antioxidant enzymes superoxide dismutase, peroxidase, and catalase; thus, the degree of damage to the callus caused by P. halotolerans was weaker than that caused by A. alternata. RNA sequencing analysis revealed that various plant defense pathways, such as phenylpropanoid biosynthesis, flavonoid biosynthesis, plant hormone signal transduction, and the mitogen-activated protein kinase signaling pathway, play important roles in triggering the plant immune response during fungal infection. Furthermore, the tryptophan metabolism, betalain biosynthesis, fatty acid degradation, flavonoid biosynthesis, tyrosine metabolism, and isoquinoline alkaloid biosynthesis pathways may accelerate the infection of pathogenic fungi, and the ribosome biogenesis pathway in eukaryotes may retard the damage caused by endophytic fungi. This study lays a foundation for exploring the infection mechanism of yam pathogens and endophytic fungi and provides insight for effective fungal disease control in agriculture.

A meta-analysis of elevated O3 effects on herbaceous plants antioxidant oxidase activity.

Increases in near-surface ozone (O3) concentrations is a global environmental problem. High-concentration O3 induces stress in plants, which can lead to visible damage to plants, reduced photosynthesis, accelerated aging, inhibited growth, and can even plant death. However, its impact has not been comprehensively evaluated because of the response differences between individual plant species, environmental O3 concentration, and duration of O3 stress in plants. We used a meta-analysis approach based on 31 studies 343 observations) to examine the effects of elevated O3 on malondialdehyde (MDA), superoxide dismutase (SOD), and peroxidase (POD) activities in herbaceous plants. Globally, important as they constitute the majority of the world's food crops. We partitioned the variation in effect size found in the meta-analysis according to the presence of plant species (ornamental herb, rice, and wheat), O3 concentration, and duration of O3 stress in plants. Our results showed that the effects of elevated O3 on plant membrane lipid peroxidation depending on plant species, O3 concentration, and duration of O3 stress in plants. The wheat SOD and POD activity was significantly lower compared to the herbs and rice (P<0.01). The SOD activity of all herbaceous plants increased by 34.6%, 10.5%, and 26.3% for exposure times to elevated O3 environments of 1-12, 13-30, and 31-60 days, respectively. When the exposure time was more than 60 days, SOD activity did not increase but significantly decreased by 12.1%. However, the POD activity of herbaceous plants increased by 30.4%, 57.3%, 21.9% and 5.81%, respectively, when exposure time of herbaceous plants in elevated O3 environment was 1-12, 13-30, 31-60 and more than 60 days. Our meta-analysis revealed that (1) rice is more resistant to elevated O3 than wheat and ornamental herbs likely because of the higher activity of antioxidant components (e.g., POD) in the symplasts, (2) exposure to elevated O3 concentrations for >60 days, may result in antioxidant SOD lose its regulatory ability, and the antioxidant component POD in the symplast is mainly used to resist O3 damage, and (3) the important factors affected the activity of SOD and POD in plants were not consistent: the duration of O3 stress in plants was more important than plant species and O3 concentration for SOD activity. However, for POD activity, plant species was the most important factor.

Removal of Phenols fromSynthetic Wastewater byHorseradish Peroxidase(HRP)

Plant peroxidase has a solid potential to remove phenol from wastewater. However, large-scale use of these enzymes for phenol removal requires a source of cheap, abundant, and easily accessible peroxidase-containing material. In this study, the horseradish peroxidase(HRP)removes the phenolic compound from the phenolic environment. The enzymatic method was used to show a reduction of toxicity between the treated and untreated phenolic solution. The HRP, with the addition of hydrogen peroxide (H2O2), reacted with the phenolic compound and produced a treated solution containing about 20% of phenol compared to the initial acidic solution. The concentration of the treated solution was then determined using UV-Vis and FTIR spectroscopy. The effects of treating the acidic solution with HRPenzyme and H2O2were studied. The HRPenzyme decreases the amount of phenol present in an acidic solution by 80 %. The most effective concentrations for treating the acidic solution were HRPat 1.0 M and 1.0 M of H2O2at neutral pH.

Overexpression of VaBAM3 from Vitis amurensis enhances seedling cold tolerance by promoting soluble sugar accumulation and reactive oxygen scavenging.

The VaBAM3 cloned from Vitis amurensis can enhance the cold tolerance of overexpressed plants, but VaBAM3 knock out by CRISPR/Cas9 system weakened grape callus cold tolerance. In grape production, extreme cold conditions can seriously threaten plant survival and fruit quality. Regulation of starch content by β-amylase (BAM, EC: 3.2.1.2) contributes to cold tolerance in plants. In this study, we cloned the VaBAM3 gene from an extremely cold-tolerant grape, Vitis amurensis, and overexpressed it in tomato and Arabidopsis plants, as well as in grape callus for functional characterization. After exposure to cold stress, leaf wilting in the VaBAM3-overexpressing tomato plants was slightly less pronounced than that in wild-type tomato plants, and these plants were characterized by a significant accumulation of autophagosomes. Additionally, the VaBAM3-overexpressing Arabidopsis plants had a higher freezing tolerance than the wild-type counterparts. Under cold stress conditions, the activities of total amylase, BAM, peroxidase, superoxide dismutase, and catalase in VaBAM3-overexpressing plants were significantly higher than those in the corresponding wild-type plants. Furthermore, sucrose, glucose, and fructose contents in these lines were similarly significantly higher, whereas starch contents were reduced in comparison to the levels in the wild-type plants. Furthermore, we detected high CBF and COR gene expression levels in cold-stressed VaBAM3-overexpressing plants. Compared with those in VaBAM3-overexpressing grape callus, the aforementioned indicators tended to change in the opposite direction in grape callus with silenced VaBAM3. Collectively, our findings indicate that heterologous overexpression of VaBAM3 enhanced cold tolerance of plants by promoting the accumulation of soluble sugars and scavenging of excessive reactive oxygen species. These findings provide a theoretical basis for the cultivation of cold-resistant grape and support creation of germplasm resources for this purpose.

Investigating the synergistic effects of biochar, trans-zeatin riboside, and Azospirillum brasilense on soil improvement and enzymatic activity in water-stressed wheat

BackgroundWater stress is a major danger to crop yield, hence new approaches to strengthen plant resilience must be developed. To lessen the negative effects of water stress on wheat plants, present study was arranged to investigate the role of synergistic effects of biochar, trans-zeatin riboside (t-ZR), and Azospirillum brasilense on soil improvement and enzymatic activity in water-stressed wheat.ResultsIn a three-replication experiment comprising of four treatments (T0: Control, T1: Drought stress (DS), T2: DS + t-ZR with biochar, T3: DS + A. brasilense with biochar), we observed notable improvements in soil quality and enzymatic activities in water-stressed wheat plants with the application of t-ZR and A. brasilense with biochar. In drought stress, Treatment having the application of A. brasilense with biochar performs best as compared to the other and significant increased the enzymatic activities such as peroxidase (7.36%), catalase (8.53%), superoxide dismutase (6.01%), polyphenol oxidase (14.14%), and amylase (16.36%) in wheat plants. Different enzymatic activities showed different trends of results. Soil organic C, dissolved organic C, dissolved organic N also enhanced 29.46%, 8.59%, 22.70% respectively with the application of A. brasilense with biochar under drought stress condition.ConclusionsThe synergistic action of A. brasilense and biochar creates an effective microbiological environment that supports essential plant physiological processes during drought stress. This enhancement is attributed to improved soil fertility and increased organic matter content, highlighting the potential of these novel strategies in mitigating water stress effects and enhancing crop resilience.

Comparative Effect of Seed Coating and Biopriming of Bacillus aryabhattai Z-48 on Seedling Growth, Growth Promotion, and Suppression of Fusarium Wilt Disease of Tomato Plants.

Beneficial plant microbes can enhance the growth and quality of field crops. However, the benefits of microbes using cheap and efficient inoculation methods are still uncommon. Seed coating with biocontrol agents can reduce the amount of inocula along with having the potential for large-scale application. Hence, in this research work, the comparative potential of tomato seed coating and biopriming with Bacillus aryabhattai Z-48, harboring multiple plant-beneficial traits, to suppress Fusarium wilt disease along with its beneficial effect on seedling and plant growth promotion was analyzed. Among two bacterial strains, B. aryabhattai Z-48 was able to antagonize the mycelial growth of Fusarium oxysporum f.sp. lycopersici in vitro and its application as a seed coating superiorly benefited seedling traits like the germination percentage, vigor index, and seedling growth index along with a reduced germination time. The seed coating with B. aryabhattai Z-48 resulted in significant increases in the shoot length, root length, dry biomass, and total chlorophyll contents when compared with the bioprimed seeds with the same bacterial strain and non-inoculated control plants. The seed coating with B. aryabhattai Z-48 significantly reduced the disease index (>60%) compared with the pathogen control during pot trials. Additionally, the seed coating with B. aryabhattai Z-48 resulted in a significantly higher production of total phenolics, peroxidase, polyphenol oxidase, and phenylalanine ammonia lyase enzyme in tomato plants. The GC/MS-based non-targeted metabolic profiling indicated that the seed coating with B. aryabhattai Z-48 could cause large-scale metabolite perturbations in sugars, sugar alcohols, amino acids, and organic acids to increase the fitness of tomato plants against biotic stress. Our study indicates that a tomato seed coating with B. aryabhattai Z-48 can improve tomato growth and suppress Fusarium wilt disease effectively under conventional agricultural systems.

Isobaric Tags for Relative and Absolute Quantitation-Based Proteomics Analysis Revealed Proteins Involved in Drought Response during the Germination Stage in Faba Bean.

The faba bean, a significant cool-season edible legume crop, is susceptible to drought during the germination stage. Research regarding the genetic regulation of drought tolerance throughout this stage in the faba bean is limited. The differentially expressed proteins (DEPs) in faba beans between the drought-tolerant variety C105 and the drought-sensitive variant E1 during seed germination were identified in this work, accomplished through isobaric tags for relative and absolute quantitation (iTRAQ) analysis. A total of 3827 proteins were identified in the two varieties of germinating seeds. Compared to those of variety E1, an increase in 108 DEPs and a decrease in 61 DEPs were observed in variety C105 under drought. Conversely, in the control group, variety C105 showed 108 significantly upregulated DEPs and 55 significantly downregulated DEPs. GO and KEGG analyses showed that the DEPs associated with glutathione metabolism and protein processing demonstrated significant increases in response to drought stress. Protein-protein interaction (PPI) analysis unveiled three closely connected functional modules of protein translation, DNA replication, and post-translational modification, originating from 22 DEPs derived from the germination period of two varieties under drought stress. To verify the proteomic function, we selected three differentially expressed protein coding genes, which were overexpressed or silenced in tobacco, thereby enhancing the drought resistance of tobacco. This was accompanied via altered levels of superoxide dismutase or peroxidase in transgenic plants under drought stress. The possible mechanism for drought tolerance in germinating seeds of faba bean involves increasing protein translation, decreasing DNA replication, and modifying chromatin. These findings offer invaluable insights into the reaction mechanism in response to drought stress in faba beans. The identified DEPs could be utilized in faba bean breeding initiatives to manage drought.

MsHDZ23, a Novel Miscanthus HD-ZIP Transcription Factor, Participates in Tolerance to Multiple Abiotic Stresses.

The homeodomain-leucine zipper (HD-ZIP) transcription factors, representing one of the largest plant-specific superfamilies, play important roles in the response to various abiotic stresses. However, the functional roles of HD-ZIPs in abiotic stress tolerance and the underlying mechanisms remain relatively limited in Miscanthus sinensis. In this study, we isolated an HD-ZIP TF gene, MsHDZ23, from Miscanthus and ectopically expressed it in Arabidopsis. Transcriptome and promoter analyses revealed that MsHDZ23 responded to salt, alkali, and drought treatments. The overexpression (OE) of MsHDZ23 in Arabidopsis conferred higher tolerance to salt and alkali stresses compared to wild-type (WT) plants. Moreover, MsHDZ23 was able to restore the hb7 mutant, the ortholog of MsHDZ23 in Arabidopsis, to the WT phenotype. Furthermore, MsHDZ23-OE lines exhibited significantly enhanced drought stress tolerance, as evidenced by higher survival rates and lower water loss rates compared to WT. The improved drought tolerance may be attributed to the significantly smaller stomatal aperture in MsHDZ23-OE lines compared to WT. Furthermore, the accumulation of the malondialdehyde (MDA) under abiotic stresses was significantly decreased, accompanied by dramatically enhanced activities in several antioxidant enzymes, including superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) in the transgenic plants. Collectively, these results demonstrate that MsHDZ23 functions as a multifunctional transcription factor in enhancing plant resistance to abiotic stresses.

Purification and partial characterization of a thermostable peroxidase isoenzyme from Bambara groundnut (Vigna subterranea L. Verdc) seedlings

Thermostable isoperoxidases, especially peroxidase A6, have already been found in seedlings of Vigna sp, indicating their potential for biotechnological applications. In this study, peroxidase A6 was purified from the roots of Bambara groundnut (Vigna subterranea L. Verdc) seedlings by a combination of gel filtration on Sephadex G-100, heat treatment, and ion exchange chromatography on CM cellulose and DEAE cellulose. The 41-kDa enzyme shows high catalytic efficiency in the oxidation of O-dianisidine, ABTS, TMB, DAB and OPD at acidic pH optimum and the reduction of H2O2. It has an optimum temperature of activity of 60 °C and a calculated activation energy of 221.5 KJ/mol for its thermal inactivation at pH 8. Mg2+ inhibits the enzyme. Ca2+ strongly increases its thermal stability, while Mn2+ and Zn2+ decrease it. The enzyme is inhibited by sodium azide at concentrations above 1 µM, with an IC50 value of about 10 µM. This inhibition, in addition to the RZ value of 2.4 (A403nm/A280nm), confirms the presence of a haem group in the active site, which is common for class III plant peroxidases. Due to its unique catalytic and thermal properties, peroxidase A6 has the potential to be a valuable tool for various biotechnological applications, especially for enzyme immunoassays and clinical diagnosis.

Field application of hydroxyapatite and humic acid for remediation of metal-contaminated alkaline soil.

The quality of soil is essential for ensuring the safety and quality of agricultural products. However, soils contaminated with toxic metals pose a significant threat to agricultural production and human health. Therefore, remediation of contaminated soils is an urgent task, and humic acid (HA) with hydroxyapatite (HAP) materials was applied for this study in contaminated alkaline soils to remediate Cd, Pb, Cu, and Zn. Physiochemical properties, improved BCR sequential extraction, microbial community composition in soils with superoxide dismutase (SOD), peroxidase (POD), and chlorophyll content in plants were determined. Among the studied treatments, application of HAP-HA (2:1) (T7) had the most significant impact on reducing the active forms of toxic metals from soil such as Cd, Pb, Cu, and Zn decreased by 18.59%, 9.12%, 11.83%, and 3.33%, respectively, but HAP and HA had a minor impact on metal accumulation in Juncao. HAP (T2) had a beneficial impact on reducing the TCleaf/root of Cd, Cu, and Zn, whereas HAP-HA (T5) showed the best performance for reducing Cd and Cu in EFleaf/soil. HAP-HA (T5 and T7) showed higher biomass (57.3%) and chlorophyll (17.9%), whereas HAP (T4) showed better performance in POD (25.8%) than T0 in Juncao. The bacterial diversity in soil was increased after applying amendments of various treatments and enhancing metal remediation. The combined application of HAP and HA effectively reduced active toxic metals in alkaline soil. HAP-HA mixtures notably improved soil health, plant growth, and microbial diversity, advocating for their use in remediating contaminated soils.

Arbuscular mycorrhizal fungi communities and promoting the growth of alfalfa in saline ecosystems of northern China.

Arbuscular mycorrhizal fungi (AMF) are universally distributed in soils, including saline soils, and can form mycorrhizal symbiosis with the vast majority of higher plants. This symbiosis can reduce soil salinity and influence plant growth and development by improving nutrient uptake, increasing plant antioxidant enzyme activity, and regulating hormone levels. In this study, rhizosphere soil from eight plants in the Songnen saline-alkaline grassland was used to isolate, characterize, and screen the indigenous advantageous AMF. The promoting effect of AMF on alfalfa (Medicago sativa L.) under salt treatment was also investigated. The findings showed that 40 species of AMF in six genera were identified by high-throughput sequencing. Glomus mosseae (G.m) and Glomus etunicatum (G.e) are the dominant species in saline ecosystems of northern China. Alfalfa inoculated with Glomus mosseae and Glomus etunicatum under different salt concentrations could be infested and form a symbiotic system. The mycorrhizal colonization rate and mycorrhizal dependence of G.m inoculation were significantly higher than those of G.e inoculation. With increasing salt concentration, inoculation increased alfalfa plant height, fresh weight, chlorophyll content, proline (Pro), soluble sugar (SS), soluble protein (SP), peroxidase (POD), superoxide dismutase (SOD), and catalase (CAT) activity while decreasing the malondialdehyde (MDA) content and superoxide anion production rate. The results highlight that inoculation with G.m and G.e effectively alleviated salinity stress, with G.m inoculation having a significant influence on salt resistance in alfalfa. AMF might play a key role in alfalfa growth and survival under harsh salt conditions.

Transcriptome analysis of foxtail millet inflorescence tissue in response to Sclerospora graminicola infection

Floral reversion caused by Sclerospora graminicola infection seriously affects development and grain formation of floral organs in foxtail millet. Herein, we observed morphological changes to infected panicles from stamen and pistil differentiation to flowering stages, and used RNA sequencing and weighted correlation network analysis (WGCNA) to analyse the key genes and pathways involved in interactions between foxtail millet and S. graminicola. All floral organs of infected panicles, including glume, lemma and palea, transformed into leaf-like structures, leading to malformed inflorescence. Transcriptome analysis showed that S. graminicola infection regulated host physiology and hormone metabolism, and differentially expressed genes (DEGs) were mainly enriched in disease resistance responses involving plant hormone metabolism, peroxidase activity and flavonoid biosynthesis pathways. Subsequently, 8 % of identified DEGs were predicted to be transcription factors, including bHLH and WRKY members related to biotic stress. Plant physiological measurements showed that infection and stress caused by S. graminicola led to changes in antioxidant enzymes superoxide dismutase and peroxidase, and defence hormones jasmonic acid, salicylic acid and 1-aminocyclopropane-1-carboxylic acid in foxtail millet. WGCNA identified 17 hub genes in four key modules (black, magenta, green and turquoise) including a MYB domain protein (Si2g07390), an ethylene-responsive transcription factor ERF094 (Si8g10010) and an NAC domain protein (Si5g40460). The results indicate that transcriptional expression, hormones and oxidation-reduction participate in inflorescence reversion in foxtail millet caused by S. graminicola.

Hydroxamate siderophores secreted by plant endophytic Pseudomonas putida elicit defense against blast disease in rice incited by Magnaporthe oryzae.

Our study focuses on hydroxamate-type siderophores from Pseudomonas putida BP25, known for chelating ferric iron and aiding microbial growth in iron-deficient environments. Confirmed through CAS-agar and tetrazolium tests, a purified siderophore extract was obtained via ion-exchange chromatography. Applying varying concentrations of this siderophore to rice seedlings demonstrated concentration-dependent effects on shoot and root phenotypes. Prophylactic application on rice leaves significantly reduced blast severity (68.7%-97.0%), surpassing curative application (47.5%-86.87%). Additionally, the siderophore treatment elevated peroxidase, polyphenol oxidase, and total phenols in rice plants. Defense-related genes linked to salicylic acid (OsPR1.1, OsNPR1, and OsPDF2.2), and other pathways (Oshox24, OsCLE, and OsGLP3-3, OsEIN2.4, and OsCSE) promoting blast suppression showed upregulation. However, the OsACS6 gene associated with ethylene-induced internodal elongation was significantly downregulated. Overall, our findings propose that the siderophore from P. putida BP25 induces defense gene transcription, offering potential for sustainable rice production via bio-formulation.