Catalase, superoxide dismutase and ascorbate-glutathione cycle enzymes confer drought tolerance of Amaranthus tricolor

Synergistic effects of Vachellia nilotica-derived zinc oxide nanoparticles and melatonin on drought tolerance in Fragaria × ananassa

This study investigates the synergistic effects of zinc oxide nanoparticles (ZnO NPs) and melatonin (MT) on Fragaria × ananassa (strawberry) plants under drought stress, focusing on growth, fruit biomass, and stress tolerance. ZnO NPs enhance nutrient uptake and stress resistance, while MT regulates growth hormones and boosts photosynthetic efficiency. Seven treatments were evaluated: T1 (no stress, 0.5 g/L ZnO NPs + 0.1 g/L MT), T2 (no stress, 0.5 g/L ZnO NPs), T3 (no stress, 0.1 g/L MT), T4 (drought stress, no application), T5 (drought stress, 0.5 g/L ZnO NPs + 0.1 g/L MT), T6 (drought stress, 0.5 g/L ZnO NPs), and T7 (drought stress, 0.1 g/L MT). Growth and stress parameters included shoot/root length, fruit biomass, bud number, chlorophyll content, oxidative stress markers (H₂O₂, MDA), and antioxidant enzyme activities in the leaves of Fragaria × ananassa. The combined treatment (ZnO NPs + MT) consistently outperformed others, achieving the highest growth metrics under both conditions: shoot length (22.33 ± 1.53 cm non-stress, 15.00 ± 1.53 cm drought), root length (18.67 ± 1.53 cm non-stress, 12.00 ± 1.53 cm drought), and fruit biomass (9.55 ± 0.31 g non-stress, 5.02 ± 0.23 g drought). Bud formation peaked at 3.33 ± 0.58 buds/plant non-stress and 2.00 ± 0.00 buds/plant drought. Under drought, the combined treatment also enhanced chlorophyll content (2.47 ± 0.20 mg/g FW) and significantly reduced H₂O₂ (28.67 ± 2.52 µmol/g FW) and MDA (4.21 ± 0.10 µmol/g FW) levels, while maximizing antioxidant enzyme activities (SOD: 121.67 ± 7.64 U/g FW, POD: 206.33 ± 14.84 U/g FW, CAT: 48.00 ± 3.61 U/g FW). These findings highlight the combined application of ZnO NPs and MT as a promising strategy to enhance growth and stress tolerance in strawberry plants, warranting further research on optimized concentrations, delivery methods, and molecular mechanisms.

Effect of elevated ammonium on biotic and abiotic stress defense responses and expression of related genes in cucumber (Cucumis sativus L.) plants

Ammonium (NH4+) enhances plant defense mechanisms but can be phytotoxic as the sole nitrogen source. To investigate the impact of a balanced NH4+ and NO3- ratio on plant defense parameters without adverse effects, cucumber plants (Cucumis sativus L.) were grown under control (14 mM NO3- + 2 mM NH4+) and elevated level of NH4+ (eNH4+, 8 mM NO3-+ 8 mM NH4+). Plants subjected to eNH4+ showed significantly increased shoot and root biomass by about 41% and 47%, respectively. Among the antioxidant enzymes studied, ascorbate peroxidase (EC 1.11.1.11) activity was increased up to 3.3 fold in eNH4+ compared with control plants, which was associated with enhanced resistance to paraquat. Upregulation of PATHOGENESIS RELATED PROTEIN 4 (PR4) and LIPOXYGENASE 1 (LOX1), accompanied by increased concentrations of salicylic acid and nitric oxide, conferred more excellent resistance of eNH4+ plants to powdery mildew infection. However, the expression levels of ACC OXIDASE 1 (ACO1) and RESPIRATORY BURST OXIDASE HOMOLOGS B (RBOHB) were lower in eNH4+ plants, which was consistent with decreased NADPH oxidase activity and lower leaf H2O2 levels. The biosynthesis of phenolics was enhanced, whereas the activities of polymerizing enzymes and lignin deposition were reduced by half in eNH4+ plants. Besides, a significant effect on plant biomass under salt or drought stress has not been observed between control and eNH4+ plants. These results showed that different defense pathways are distinctively affected by eNH4+ treatment, and the NH4+ to NO3- ratio may play a role in fine-tuning the plant defense response.

Efficacy of umbelliferone-loaded nanostructured lipid carrier in the management of bleomycin-induced idiopathic pulmonary fibrosis: experimental and network pharmacology insight

Idiopathic pulmonary fibrosis (IPF) is a severe and progressive lung disorder with an average survival rate of 3 to 5 years. IPF presents a significant challenge in clinical management, necessitating novel therapeutic approaches. Nanostructured lipid carriers (NLCs) have proven to be promising vehicles for targeted drug delivery to the lung tissues. This research focuses on formulating and evaluating umbelliferone (UMB)-loaded NLCs for the treatment of IPF. UMB-NLC was formulated using the hot emulsion ultrasonication method and was characterized. The formulation was then tested for its efficacy in a bleomycin-induced IPF mice model. Leukocyte infiltration and interleukin-6 were estimated in the bronchoalveolar lavage fluid (BALF). Various antioxidant activities were also assessed for the formulation, followed by histopathological analysis. Furthermore, an in silico mechanistic approach using network pharmacology was carried out to obtain genes of interest. Particle size analysis revealed a mean size of 174.9 ± 3.66 nm for UMB-NLC, ideal for lung tissue targeting. Zeta potential measurements indicated good stability (-34.3 ± 1.35 mV) for long-term storage. Fourier transform infrared spectroscopy (FTIR) confirmed the successful encapsulation of UMB within the lipid matrix of NLCs. X-ray diffraction (XRD) and differential scanning calorimetry (DSC) demonstrated the amorphous state of UMB-NLC, indicating enhanced solubility and bioavailability. Field emission scanning electron microscopy (FESEM) revealed uniform, spherical particles in the nanometer range. Drug entrapment efficiency (EE%) and loading capacity (DL%) were found to be 85.03 ± 2.36% and 17.01 ± 0.48%, respectively, indicating efficient drug incorporation. In vitro release study showed uniform sustained drug release over 48 h, indicating the potential for prolonged therapeutic effect. In vivo studies using UMB-NLC demonstrated significant improvements in bleomycin-induced IPF. A restoration in body weight and lung/body-weight (L/B) ratio was observed compared to disease controls. BALF analysis revealed reduced leukocyte infiltration and decreased inflammatory cytokine IL-6 levels (**p < 0.01). Biochemical assays showed enhanced antioxidant status and reduced oxidative stress in lung tissues. Hydroxyproline content (HPO, **p < 0.01), malondialdehyde (MDA, ***p < 0.001), and total protein content (**p < 0.01) were significantly reduced, while glutathione (GSH, ***p < 0.001), superoxide dismutase (SOD, **p < 0.01), and catalase (CAT, **p < 0.01) were elevated. Histopathological analysis confirmed the attenuation of lung fibrosis with maintained alveolar architecture and reduced fibrotic deposition. Furthermore, network pharmacology identified UMB targets and IPF-related genes with a Venn diagram, and cytoHubba analysis revealed key hub genes. Kyoto Encyclopedia of Genes and Genomes (KEGG) and Gene Ontology (GO) enrichment demonstrated UMB's involvement in IPF-related pathways, highlighting its therapeutic potential. Therefore, UMB-NLC may exhibit promising therapeutic potential in the treatment of IPF, offering targeted drug delivery, enhanced bioavailability, and improved efficacy in alleviating pulmonary inflammation and fibrosis.

Multi-Omics Analysis Provides Insights into Green Soybean in Response to Cold Stress

Green soybean (Glycine max (L.) Merrill) is a highly nutritious food that is a good source of protein and fiber. However, it is sensitive to low temperatures during the growing season, and enhancing cold tolerance has become a research hotspot for breeding improvement. Background/Objectives: The underlying molecular mechanisms of cold tolerance in green soybean are not well understood. Methods: Here, a comprehensive analysis of transcriptome and metabolome was performed on a cold-tolerant cultivar treated at 10 °C for 24 h. Results: Compared to control groups, we identified 17,011 differentially expressed genes (DEGs) and 129 differentially expressed metabolites (DEMs). The DEGs and DEMs were further subjected to KEGG functional analysis. Finally, 11 metabolites (such as sucrose, lactose, melibiose, and dehydroascorbate) and 17 genes (such as GOLS, GLA, UGDH, and ALDH) were selected as candidates associated with cold tolerance. Notably, the identified metabolites and genes were enriched in two common pathways: 'galactose metabolism' and 'ascorbate and aldarate metabolism'. Conclusions: The findings suggest that green soybean modulates the galactose metabolism and ascorbate and aldarate metabolism pathways to cope with cold stress. This study contributes to a deeper understanding of the complex molecular mechanisms enabling green soybeans to better avoid low-temperature damage.

Myco-assisted phytoextraction of heavy metals with vetiver grass: a green technology for cleaning tannery effluent contaminated sites

Metal toxicity affects practically all physiological systems of plants, both directly and indirectly. Amongst various techniques developed to remediate contaminated soils, arbuscular mycorrhizal fungus (AMF)-assisted phytoremediation is an emerging and unexplored eco-sustainable strategy for controlling and managing soil contamination. Hence, this study aims at exploring the myco-assisted phytoremediation of tannery effluent contaminated soil. A pot culture study was carried out using three different strains of AMF and vetiver grass with soil obtained from the tannery effluent contaminated sites of Tamil Nadu, India (Vellore (S1) and Dindigul (S2)) which were rich in chromium (S1-128 mg kg-1, S2-112 mg kg-1), cadmium (S1-1.17 mg kg-1, S2-2 mg kg-1), nickel (S1-39 mg kg-1, S2-14 mg kg-1) and lead (S1-56 mg kg-1, S2-30 mg kg-1). Results revealed that inoculation of vetiver grass with AMF including R. intraradices (T3), G. mosseae (T2) and mixed (commercial) culture (T4) in the contaminated soil has significantly increased the growth and biomass of the vetiver plants but the level of action varied with the fungus. Amongst several treatments under study, R. intraradices (T3) inoculation in vetiver yielded in shoot biomass (31.76 t ha-1) which was 8%, 18.8%, and 31.2% higher than treatments T2, T4 and T1 respectively, and the root biomass (23.71 t ha-1) was 10.6%, 15.3%, 32% higher than T2, T4 and T1 respectively. Vetiver growing in T3 has higher total C stored in its roots and shoots (24.99%) than in control soil. Furthermore, T3's overall carbon stock is 24.94% larger facilitating carbon sequestration than control's (T1). Furthermore, it was observed that AMF inoculation significantly increased the phytoextraction potential of vetiver and reduced the translocation of metals into the shoots. The treatment T3 (R. intraradices) recorded Cr (19.99 mg kg-1), Cd (0.1 mg kg-1), Ni (9.43 mg kg-1), and Pb (9.35 mg kg-1) in the root portion in S1 and was higher to the tune of 89.8%,50%, 88.5%, and 75.9% respectively, compared to the shoot portion. Additionally, the antioxidant enzymes like superoxide dismutase (SOD), catalase (CAT) and ascorbate peroxidase (APX) were found relatively higher in control where the plant undergone much larger stress than the other treatments. Hence, it can be concluded that AMF could possibly enhance the growth of Vetiver by improving nutrient (nitrogen, phosphorus and potassium) uptake capability while reducing the heavy metal uptake and accumulation in the shoots eventually protecting the plants from stress and metal toxicity.

Catalase-associated immune responses in plant-microbe interactions: A review

Catalase, an enzyme central to maintaining redox balance and combating oxidative stress in plants, has emerged as a key player in plant defense mechanisms and interactions with microbes. This review article provides a comprehensive analysis of catalase-associated immune responses in plant-microbe interactions. It underscores the importance of catalase in plant defense mechanisms, highlights its influence on plant susceptibility to pathogens, and discusses its implications for understanding plant immunity and host-microbe dynamics. This review contributes to the growing body of knowledge on catalase-mediated immune responses and offers insights that can aid in the development of strategies for improved plant health and disease resistance.

Insight into physiological and biochemical markers against formaldehyde stress in spider plant (Chlorophytum comosum L.)

Formaldehyde is a prominent volatile organic compound and also considered as an indoor air pollutant. Chlorophytum comosum, an indoor plant, has been reported to metabolize indoor formaldehyde. But the phytotoxic effects of formaldehyde, being a pollutant, on C. comosum are not well explored. Furthermore, C. comosum responses that can be considered as markers at the physiological and biochemical level against formaldehyde stress are not yet investigated. Therefore, the current research study was aimed to evaluate such potential markers against formaldehyde in C. comosum. Briefly, C. comosum was exposed to 5-, 10-, and 20-ppm formaldehyde doses in an airtight glass chamber. Plant samples were then taken to analyze morpho-anatomical, physiological, and biochemical responses after short (2, 4, and 6 h), medium (12 and 24 h), and extended durations (48 and 96 h) for each tested dose. Application of 10 and 20 ppm formaldehyde doses leads to a significant incline in enzymatic antioxidants. Formaldehyde concentration of 10 ppm leads to a maximum increase in catalase (30.30 U/mg of protein), guaiacol peroxidase (135.64 U/mg of protein), and superoxide dismutase (44.76 U/mg of protein) compared to their respective controls. A significant change is also observed in non-enzymatic parameters, including total phenolic content, which ranged from 3.62 mg GAE/g (control) to 10.51 mg GAE/g, total antioxidants vary from 27.37% (control) to 85.05% in 20 ppm formaldehyde, respectively. However, formaldehyde application negatively affected the physiological responses of C. comosum by reducing its photosynthetic rate, transpiration rate, and stomatal conductance. Additionally, extended exposure of C. comosum to 10- and 20-ppm formaldehyde doses leads to visible leaf damage. Principal component analysis indicated that enzymatic parameters including SOD, CAT, and GPX and non-enzymatic parameters including MDA, TPC, TFC, TAOs, carotenoids, TSS, and intercellular CO2 contributed the most to the total variance. Thus, these parameters have potential to serve as physiological and biochemical markers in C. comosum against formaldehyde stress.

Soil application potential of post-sorbents produced by co-sorption of humic substances and nutrients from sludge anaerobic digestion reject water

This study introduces a novel soil conditioning approach using humic substances (HSs) and nutrients co-recovered from reject water from sewage sludge anaerobic digestion. For the first time, HSs and nutrients were simultaneously recovered through sorption on low-cost, environmentally inert materials: natural rock opoka (OP) and waste autoclaved aerated concrete (WAAC). This innovative application of OP and WAAC as carriers and delivery agents for soil-relevant substances offers potential for resource recovery and soil conditioning. Results indicate that the post-sorption opoka (PS-OP) and post-sorption waste autoclaved aerated concrete (PS-WAAC) effectively release retained HSs at 350-480 μg g⁻1 d⁻1, respectively. These materials also show potential as NPK fertilizers, releasing 280-430 μg g⁻1 d⁻1 N-NH₄⁺, 80-150 μg g⁻1 d⁻1 P-PO₄³⁻, and 270-350 μg g⁻1 d⁻1 K⁺. Additionally, PS-OP demonstrated promising fungicide properties, reducing P. diachenii growth by 31% at a concentration of 1 g L⁻1. A two-way ANOVA indicated that the effects of PS-OP and PS-WAAC on soil physicochemical and biological parameters varied with plant species. Both post-sorbents improved the quality of soil collected from sand mining area, increasing cation exchange capacity by 7%-85% and organic matter content by 10%-58%. They also enhanced the functional potential of soil microbial communities, increasing their metabolic activities by 23%-36% in soils sown with clover and by 33%-39% in soils sown with rapeseed. An opposite effect was observed in soils sown with sorghum, suggesting these amendments may not universally act as plant biostimulants. The effectiveness of these post-sorbents in enhancing plant growth varied depending on plant species and the mineral base of the post-sorbent. PS-OP increased the total length of clover and sorghum by 41% and 36%, and their fresh biomass by 82% and 80%, respectively. In turn, PS-WAAC increased the total length of clover and sorghum by 76% and 17%, and their fresh biomass by 29% and 15%, respectively. It was notably more effective than PS-OP for rapeseed. This study proposes a strategy to decrease reliance on non-renewable resources and costly sorbents while minimizing environmental impact. It shows that PS-OP and PS-WAAC can enhance soil quality, microbial activity, and plant growth. Given their origins, these amendments are recommended for soil remediation, particularly in degraded areas. Future research should focus on optimizing their application across various plant species to maximize effectiveness.

Magnesium Hydride Confers Osmotic Tolerance in Mung Bean Seedlings by Promoting Ascorbate-Glutathione Cycle

Despite substantial evidence suggesting that hydrogen gas (H2) can enhance osmotic tolerance in plants, the conventional supply method of hydrogen-rich water (HRW) poses challenges for large-scale agricultural applications. Recently, magnesium hydride (MgH2), a hydrogen storage material in industry, has been reported to yield beneficial effects in plants. This study aimed to investigate the effects and underlying mechanisms of MgH2 in plants under osmotic stress. Mung bean seedlings were cultured under control conditions or with 20% polyethylene glycol (PEG)-6000, with or without MgH2 addition (0.01 g L-1). Under our experimental conditions, the MgH2 solution maintained a higher H2 content and longer retention time than HRW. Importantly, PEG-stimulated endogenous H2 production was further triggered by MgH2 application. Further results revealed that MgH2 significantly alleviated the inhibition of seedling growth and reduced oxidative damage induced by osmotic stress. Pharmacological evidence suggests the MgH2-reestablished redox homeostasis was associated with activated antioxidant systems, particularly the ascorbate-glutathione cycle. The above observations were further supported by the enhanced activities and gene transcriptional levels of ascorbate peroxidase, monodehydroascorbate reductase, dehydroascorbate reductase, and glutathione reductase. Overall, this study demonstrates the importance of MgH2 in mitigating osmotic stress in mung bean seedlings, providing novel insights into the potential agricultural applications of hydrogen storage materials.

Integrated PacBio SMRT and Illumina sequencing uncovers transcriptional and physiological responses to drought stress in whole-plant Nitraria tangutorum

Introduction

Nitraria tangutorum Bobr., a prominent xerophytic shrub, exhibits remarkable adaptability to harsh environment and plays a significant part in preventing desertification in northwest China owing to its exceptional drought and salinity tolerance.

Methods

To investigate the drought-resistant mechanism underlying N. tangutorum, we treated 8-week-old seedlings with polyethylene glycol (PEG)-6000 (20%, m/m) to induce drought stress. 27 samples from different tissues (leaves, roots and stems) of N. tangutorum at 0, 6 and 24 h after drought stress treatment were sequenced using PacBio single-molecule real-time (SMRT) sequencing and Illumina RNA sequencing to obtain a comprehensive transcriptome.

Results

The PacBio SMRT sequencing generated 44,829 non-redundant transcripts and provided valuable reference gene information. In leaves, roots and stems, we identified 1162, 2024 and 232 differentially expressed genes (DEGs), respectively. The Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis revealed that plant hormone signaling and mitogen-activated protein kinase (MAPK) cascade played a pivotal role in transmitting stress signals throughout the whole N. tangutorum plant following drought stress. The interconversion of starch and sucrose, as well as the biosynthesis of amino acid and lignin, may represent adaptive strategies employed by N. tangutorum to effectively cope with drought. Transcription factor analysis showed that AP2/ERF-ERF, WRKY, bHLH, NAC and MYB families were mainly involved in the regulation of drought response genes. Furthermore, eight physiological indexes, including content of proline, hydrogen peroxide (H2O2), malondialdehyde (MDA), total amino acid and soluble sugar, and activities of three antioxidant enzymes were all investigate after PEG treatment, elucidating the drought tolerance mechanism from physiological perspective. The weighted gene co-expression network analysis (WGCNA) identified several hub genes serve as key regulator in response to drought through hormone participation, ROS cleavage, glycolysis, TF regulation in N. tangutorum.

Discussion

These findings enlarge genomic resources and facilitate research in the discovery of novel genes research in N. tangutorum, thereby establishing a foundation for investigating the drought resistance mechanism of xerophyte.

Silicon nanoparticles (SiNPs) mediate GABA, SOD and ASA-GSH cycle to improve cd stress tolerance in Solanum lycopersicum

Contamination of agricultural products with Cadmium (Cd) is a global problem that should be considered for minimizing the risks to human health. Considering the potential effects of SiNPs in decreasing abiotic stress, a study was conducted to investigate the effect of SiNPs in the reduction of Cd stress on Solanum lycopersicum. SiNPs was used at 0, 25, 50 and 100 mg/l and CdCl2 at 0, 100 and 200 µM concentrations. The results showed that Cd stress caused a significant decrease in dry weight, content of GSH, ASA, significently increasing the activity of GR, APX, GST, SOD, as well as content of H2O2, MDA, proline, and GABA in shoots and roots compared to the control. SiNPs significantly increased shoot and root dry weight compared to the control. As a coenzyme, SiNPs induced the activity of antioxidant enzymes and significantly increased GST and GR gene expression compared to the control. SiNPs also caused a substantial increase in the content of ASA, GSH, proline and GABA compared to the control. By inducing the activity of antioxidant enzymes and metabolites of the ascorbate-glutathione (ASA-GSH) cycle, SiNPs removed a large content of H2O2 and significantly reduced the MDA content, and as a result led to the stability of cell membrane under Cd stress. Induction of ASA-GSH, GABA and SOD cycle by SiNPs clearly showed that SiNPs could be a potential tool to alleviate Cd stress in plants cultivated in areas contaminated with this heavy metal.

Manure-biochar compost mitigates the soil salinity stress in tomato plants by modulating the osmoregulatory mechanism, photosynthetic pigments, and ionic homeostasis

One of the main abiotic stresses that affect plant development and lower agricultural productivity globally is salt in the soil. Organic amendments, such as compost and biochar can mitigate the opposing effects of soil salinity (SS) stress. The purpose of this experiment was to look at how tomato growth and yield on salty soil were affected by mineral fertilization and manure-biochar compost (MBC). Furthermore, the study looked at how biochar (organic amendments) work to help tomato plants that are stressed by salt and also a mechanism by which biochar addresses the salt stress on tomato plants. Tomato yield and vegetative growth were negatively impacted by untreated saline soil, indicating that tomatoes are salt-sensitive. MBC with mineral fertilization increased vegetative growth, biomass yield, fruit yield, chlorophyll, and nutrient contents, Na/K ratio of salt-stressed tomato plants signifies the ameliorating effects on tomato plant growth and yield, under salt stress. Furthermore, the application of MBC with mineral fertilizer decreased H2O2, but increased leaf relative water content (RWC), leaf proline, total soluble sugar, and ascorbic acid content and improved leaf membrane damage, in comparison with untreated plants, in response to salt stress. Among the composting substances, T7 [poultry manure-biochar composting (PBC) (1:2) @ 3 t/ha + soil-based test fertilizer (SBTF)] dose exhibited better-improving effects on salt stress and had maintained an order of T7 > T9 > T8 > T6 in total biomass and fruit yield of tomato. These results suggested that MBC might mitigate the antagonistic effects of salt stress on plant growth and yield of tomatoes by improving osmotic adjustment, antioxidant capacity, nutrient accumulation, protecting photosynthetic pigments, and reducing ROS production and leaf damage in tomato plant leaves.

CDPK protein in cotton: genomic-wide identification, expression analysis, and conferring resistance to heat stress

BACKGROUND

Calcium-dependent protein kinase (CDPK) plays a key role in cotton tolerance to abiotic stress. However, its role in cotton heat stress tolerance is not well understood. Here, we characterize the GhCDPK gene family and their expression profiles with the aim of identifying CDPK genes associated with heat stress tolerance.

RESULTS

This study revealed 48 GhCDPK members in the cotton genome, distributed on 18 chromosomes. Tree phylogenetic analysis showed three main clustering groups of the GhCDPKs. Cis-elements revealed many abiotic stress and phytohormone pathways conserved promoter regions. Similarly, analysis of the transcription factor binding sites (TFBDS) in the GhCDPK genes showed many stress and hormone related sites. The expression analysis based on qRT-PCR showed that GhCDPK16 was highly responsive to high-temperature stress. Subsequent protein-protein interactions of GhCDPK16 revealed predictable interaction with ROS generating, calcium binding, and ABA signaling proteins. Overexpression of GhCDPK16 in cotton and Arabidopsis improved thermotolerance by lowering ROS compound buildup. Under heat stress, GhCDPK16 transgenic lines upregulated heat-inducible genes GhHSP70, GHSP17.3, and GhGR1, as demonstrated by qRT-PCR analysis. Contrarily, GhCDPK16 knockout lines in cotton exhibited an increase in ROS accumulation. Furthermore, antioxidant enzyme activity was dramatically boosted in the GhCDPK16-ox transgenic lines.

CONCLUSIONS

The collective findings demonstrated that GhCDPK16 could be a viable gene to enhance thermotolerance in cotton and, therefore, a potential candidate gene for improving heat tolerance in cotton.

Development of Rice Mutants with Enhanced Resilience to Drought Stress and Their Evaluation by Lab Assay, Field, and Multivariate Analysis

Drought is one of the foremost devastating abiotic stresses reported for rice crops. To improve the productivity of rice, diversity is being enlarged by induced mutation using a source of gamma rays. But this type of mutation rarely results in fruitful products because the chances of getting the desired mutant are very low. The present study aimed to evaluate the rice mutants against drought or osmotic stress. In this study, three experiments were conducted that comprised of seventy-one mutants originating from different doses of gamma rays (Cs137) along with parent RICF-160 and commercial variety (Kainat) were tested. In the first experiment, germination and seedling attributes were calculated under control and osmotic stress conditions created by using 16% (0.6 MPa) polyethylene glycol (PEG-6000). Results revealed that all the mutants exhibited significant (p < 0.01) responses to PEG-induced osmotic stress. Principal component biplot analysis (PCBA) revealed the first seventeen cumulative PCs with eigenvalues >1 contributed 88%. It was noted that the germination percentage (GP), germination rate (GR), coefficient velocity of germination (CVG), and seed vigor (SV) contributed maximum and positively in PC1. Results showed the highest germination percentage (GP) at 48 hrs in mutant NMSF-11 (88.9%) followed by NMSf-38 (73.3%). Similarly, the germination rate (GR) and coefficient velocity of germination (CVG) were measured highest in NMSF-11 (9.7 and 118.1%), respectively. In stress conditions, the mutants NMSF-35 and NMSF-36 depicted the highest GP, GR, and CVG. The maximum seed vigor (SV), shoot length (SL), root length (RL), and fresh weight (FW) were observed in mutants NMSF-50 and NMSF-51 under both conditions, whereas the mutants NMSF-59, NMSF-60, NMSF-64, and NMSF-67 showed lower values for SV, SL, RL, and FW. In the second experiment, a field trial was conducted at the Nuclear Institute for Agriculture and Biology (NIAB), Faisalabad, in two control and stress sets. A bit different trend was observed among all mutants for agronomic parameters under both conditions. In the third experiment, biochemical profiling was done in Marker Assisted Breeding (MAB) Lab-1, Plant Breeding and Genetics Division. A significant variation was seen in enzymatic antioxidants and chlorophyll content in both control and stress conditions. Under control conditions, the ascorbate peroxidase (APX) content was observed higher in mutant NMSF-49 (106.07 Units/g. f. wt.). In comparison with the stress, the ascorbate peroxidase activity was higher in NMSF-41 (82.34 Units/g. f. wt.). Catalase (CAT) activity was observed maximum in NMSF-29 (17.54 Units/g. f. wt.) and NMSF-40 (14.17 Units/g. f. wt.) under control and stress conditions, respectively. Peroxidase (POD) activity was observed maximum in NMSF-51 (22.55 Units/g. f. wt. and 10.84 Units/g. f. wt.) under control and stress conditions, respectively. In conclusion, to fit in the changing climate conditions for resilient rice crop production, the promising mutant lines may be used to transfer the desirable drought-tolerant/drought-resistant genes in rice germplasm.

Nanobiotechnology-mediated regulation of reactive oxygen species homeostasis under heat and drought stress in plants

Global warming causes heat and drought stress in plants, which affects crop production. In addition to osmotic stress and protein inactivation, reactive oxygen species (ROS) overaccumulation under heat and drought stress is a secondary stress that further impairs plant performance. Chloroplasts, mitochondria, peroxisomes, and apoplasts are the main ROS generation sites in heat- and drought-stressed plants. In this review, we summarize ROS generation and scavenging in heat- and drought-stressed plants and highlight the potential applications of plant nanobiotechnology for enhancing plant tolerance to these stresses.

Lentil adaptation to drought stress: response, tolerance, and breeding approaches

Lentil (Lens culinaris Medik.) is a cool season legume crop that plays vital roles in food and nutritional security, mostly in the least developed countries. Lentil is often cultivated in dry and semi-dry regions, where the primary abiotic factor is drought, which negatively impacts lentil growth and development, resulting in a reduction of yield. To withstand drought-induced multiple negative effects, lentil plants evolved a variety of adaptation strategies that can be classified within three broad categories of drought tolerance mechanisms (i.e., escape, avoidance, and tolerance). Lentil adapts to drought by the modulation of various traits in the root system, leaf architecture, canopy structure, branching, anatomical features, and flowering process. Furthermore, the activation of certain defensive biochemical pathways as well as the regulation of gene functions contributes to lentil drought tolerance. Plant breeders typically employ conventional and mutational breeding approaches to develop lentil varieties that can withstand drought effects; however, little progress has been made in developing drought-tolerant lentil varieties using genomics-assisted technologies. This review highlights the current understanding of morpho-physiological, biochemical, and molecular mechanisms of lentil adaptation to drought stress. We also discuss the potential application of omics-assisted breeding approaches to develop lentil varieties with superior drought tolerance traits.

Molecular priming with H2O2 and proline triggers antioxidant enzyme signals in maize seedlings during drought stress

BACKGROUND

Drought and water stress impose major limitations to crops, including Maize, as they affect the plant biology at multiple levels. Drought activates the cellular signalling machinery to maintain the osmotic and ROS homeostasis for controlling plant response and adaptation to stress. Molecular priming of seeds plays a significant role in imparting stress tolerance by helping plants to remember the stress, which improves their response when they encounter stress again.

METHODS

In this study, we examined the effect of priming maize seeds with H2O2 and proline, individually or in combination, on response to drought stress. We investigated the role of molecular priming on the physiological, biochemical and molecular response of maize seedlings during drought stress.

RESULTS

We observed that seed-priming played a significant role in mediating stress tolerance of seedlings under drought stress as indicated by changes in growth, biochemical properties, pigment and osmolyte accumulation, antioxidant enzyme activities, gas exchange parameters and gene expression. Seed-priming resulted in reduced expression of specific miRNAs to increase target transcripts associated with synthesis of osmolytes and maintenance of ROS homeostasis for reducing potential damage to the cellular components.

CONCLUSIONS

Seed-priming induced changes in the growth, biochemical properties, pigment and osmolyte accumulation, antioxidant enzyme activities, gas exchange parameters and gene expression, though the response was dependent on the genotype, as well as concentration and combination of the priming agents.

Comprehensive evaluation of drought tolerance of six Chinese chestnut varieties (clones) based on flavonoids and other physiological indexes

Flavonoids are crucial secondary metabolites that possess the ability to mitigate UV damage and withstand both biotic and abiotic stresses. Therefore, it is of immense significance to investigate the flavonoid content as a pivotal indicator for a comprehensive assessment of chestnut's drought tolerance. This study aimed to determine the flavonoid content and drought tolerance-related physiological and biochemical indices of six chestnut varieties (clones) grafted trees-Qianxi 42 (QX42), Qinglong 45 (QL45), Yanshanzaofeng (YSZF), Yanzi (YZ), Yanqiu (YQ), and Yanlong (YL)-under natural drought stress. The results were used to comprehensively analyze the drought tolerance ability of these varieties. The study revealed that the ranking of drought tolerance indices in terms of their ability to reflect drought tolerance was as follows: superoxide (oxide) dismutase (SOD) activity, ascorbate peroxidase (APX) activity, flavone content, catalase (CAT) activity, proline (PRO) content, soluble sugar content, peroxidase (POD) activity, betaine content, flavonol content, hydrogen peroxide (H2O2) content, soluble protein content, superoxide ion (OFR) content, superoxide (ion OFR) production rate, malondialdehyde (MDA) content, chlorophyll content. Through principal component analysis, the contents of flavonoids and flavonols can be used as indicators for comprehensive evaluation of drought tolerance of chestnut. The comprehensive evaluation order of drought tolerance of grafted trees of 6 chestnut varieties (Clones) was: QL45 > QX42 > YQ > YZ > YSZF > YL.

Enhancing saline stress tolerance in soybean seedlings through optimal NH4+/NO3- ratios: a coordinated regulation of ions, hormones, and antioxidant potential

BACKGROUND

Nitrogen (N) availability is crucial in regulating plants' abiotic stress resistance, particularly at the seedling stage. Nevertheless, plant responses to N under salinity conditions may vary depending on the soil's NH4+ to NO3- ratio.

METHODS

In this study, we investigated the effects of different NH4+:NO3- ratios (100/0, 0/100, 25/75, 50/50, and 75/25) on the growth and physio-biochemical responses of soybean seedlings grown under controlled and saline stress conditions (0-, 50-, and 100-mM L- 1 NaCl and Na2SO4, at a 1:1 molar ratio).

RESULTS

We observed that shoot length, root length, and leaf-stem-root dry weight decreased significantly with increased saline stress levels compared to control. Moreover, there was a significant accumulation of Na+, Cl-, hydrogen peroxide (H2O2), and malondialdehyde (MDA) but impaired ascorbate-glutathione pools (AsA-GSH). They also displayed lower photosynthetic pigments (chlorophyll-a and chlorophyll-b), K+ ion, K+/Na+ ratio, and weakened O2•--H2O2-scavenging enzymes such as superoxide dismutase, catalase, peroxidase, monodehydroascorbate reductase, glutathione reductase under both saline stress levels, while reduced ascorbate peroxidase, and dehydroascorbate reductase under 100-mM stress, demonstrating their sensitivity to a saline environment. Moreover, the concentrations of proline, glycine betaine, total phenolic, flavonoids, and abscisic acid increased under both stresses compared to the control. They also exhibited lower indole acetic acid, gibberellic acid, cytokinins, and zeatine riboside, which may account for their reduced biomass. However, NH4+:NO3- ratios caused a differential response to alleviate saline stress toxicity. Soybean seedlings supplemented with optimal ratios of NH4+:NO3- (T3 = 25:75 and T = 4 50:50) displayed lower Na+ and Cl- and ABA but improved K+ and K+/Na+, pigments, growth hormones, and biomass compared to higher NH4+:NO3- ratios. They also exhibited higher O2•--H2O2-scavenging enzymes and optimized H2O2, MDA, and AsA-GSH pools status in favor of the higher biomass of seedlings.

CONCLUSIONS

In summary, the NH4+ and NO3- ratios followed the order of 50:50 > 25:75 > 0:100 > 75:25 > 100:0 for regulating the morpho-physio-biochemical responses in seedlings under SS conditions. Accordingly, we suggest that applying optimal ratios of NH4+ and NO3- (25/75 and 50:50) can improve the resistance of soybean seedlings grown in saline conditions.

Nanoparticle-mediated enhancement of plant cryopreservation: Cultivar-specific insights into morphogenesis and biochemical responses in Lamprocapnos spectabilis (L.) Fukuhara 'Gold Heart' and 'Valentine'

The integration of nanoparticles (NPs) holds promising potential to bring substantial advancements to plant cryopreservation, a crucial technique in biodiversity conservation. To date, little attention has been focused on using nanoparticles in cryobiology research. This study aimed to assess the effectiveness of NPs in enhancing the efficiency of plant cryopreservation. In-vitro-derived shoot tips of bleeding heart (Lamprocapnos spectabilis (L.) Fukuhara) 'Gold Heart' and 'Valentine' were used as the plant material. The encapsulation-vitrification cryopreservation protocol included preculture, encapsulation, dehydration, storage in liquid nitrogen, rewarming, and recovery steps. Gold (AuNPs), silver (AgNPs), or zinc oxide (ZnONPs) nanoparticles were added at various concentrations either into the preculture medium or the protective bead matrix during encapsulation. The explant survival and further morphogenic and biochemical events were studied. Results showed that the impact of NPs on cryopreservation outcomes was cultivar-specific. In the 'Valentine' cultivar, incorporating 5 ppm AgNPs within the alginate bead matrix significantly improved cryopreservation efficiency by up to 12%. On the other hand, the 'Gold Heart' cultivar benefited from alginate supplementation with 5 ppm AgNPs and 5-15 ppm ZnONPs, leading to an over 28% increase in the survival rate of shoot tips. Interestingly, adding NPs to the preculture medium was less effective and sometimes counterproductive, despite promoting greater shoot proliferation and elongation in 'Valentine' explants compared to the control. Moreover, nanoparticles often induced oxidative stress (and enhanced the activity of APX, GPOX, and SOD enzymes), which in turn affected the biosynthesis of plant primary and secondary metabolites. It was found that supplementation of preculture medium with higher concentration (15 ppm) of gold, silver and zinc oxide nanoparticles stimulated the production of plant pigments, but in a cultivar-dependent matter. Our study confirmed the beneficial action of nanoparticles during cryopreservation of plant tissues.

Exploring the dynamics of ISR signaling in maize upon seed priming with plant growth promoting actinobacteria isolated from tea rhizosphere of Darjeeling

Plant growth-promoting rhizobacteria (PGPR) offer an eco-friendly alternative to agrochemicals for better plant growth and development. Here, we evaluated the plant growth promotion abilities of actinobacteria isolated from the tea (Camellia sinensis) rhizosphere of Darjeeling, India. 16 S rRNA gene ribotyping of 28 isolates demonstrated the presence of nine different culturable actinobacterial genera. Assessment of the in vitro PGP traits revealed that Micrococcus sp. AB420 exhibited the highest level of phosphate solubilization (i.e., 445 ± 2.1 µg/ml), whereas Kocuria sp. AB429 and Brachybacterium sp. AB440 showed the highest level of siderophore (25.8 ± 0.1%) and IAA production (101.4 ± 0.5 µg/ml), respectively. Biopriming of maize seeds with the individual actinobacterial isolate revealed statistically significant growth in the treated plants compared to controls. Among them, treatment with Paenarthrobacter sp. AB416 and Brachybacterium sp. AB439 exhibited the highest shoot and root length. Biopriming has also triggered significant enzymatic and non-enzymatic antioxidative defense reactions in maize seedlings both locally and systematically, providing a critical insight into their possible role in the reduction of reactive oxygen species (ROS) burden. To better understand the role of actinobacterial isolates in the modulation of plant defense, three selected actinobacterial isolates, AB426 (Brevibacterium sp.), AB427 (Streptomyces sp.), and AB440 (Brachybacterium sp.) were employed to evaluate the dynamics of induced systemic resistance (ISR) in maize. The expression profile of five key genes involved in SA and JA pathways revealed that bio-priming with actinobacteria (Brevibacterium sp. AB426 and Brachybacterium sp. AB440) preferably modulates the JA pathway rather than the SA pathway. The infection studies in bio-primed maize plants resulted in a delay in disease progression by the biotrophic pathogen Ustilago maydis in infected maize plants, suggesting the positive efficacy of bio-priming in aiding plants to cope with biotic stress. Conclusively, this study unravels the intrinsic mechanisms of PGPR-mediated ISR dynamics in bio-primed plants, offering a futuristic application of these microorganisms in the agricultural fields as an eco-friendly alternative.

Nutritional and bioactive properties and antioxidant potential of Amaranthus tricolor, A. lividus, A viridis, and A. spinosus leafy vegetables

Climate change results in continuous warming of the planet, threatening sustainable crop production around the world. Amaranth is an abiotic stress-tolerant, climate-resilient, C4 leafy orphan vegetable that has grown rapidly with great divergence and potential usage. The C4 photosynthesis allows amaranth to be grown as a sustainable future food crop across the world. Most amaranth species grow as weeds in many parts of the world, however, a few amaranth species can be also found in cultivated form. Weed species can be used as a folk medicine to relieve pain or reduce fever thanks to their antipyretic and analgesic properties. In this study, nutritional value, bioactive pigments, bioactive compounds content, and radical scavenging potential (RSP) of four weedy and cultivated (WC) amaranth species were evaluated. The highest dry matter, carbohydrate content, ash, content of iron, copper, sodium, boron, molybdenum, zinc, β-carotene and carotenoids, vitamin C, total polyphenols (TP), RSP (DPPH), and RSP (ABTS+) was determined in Amaranthus viridis (AV). On the other hand, A. spinosus (AS) was found to have the highest content of protein, fat, dietary fiber, manganese, molybdenum, and total flavonoids (TF). In A. tricolor (AT) species the highest total chlorophyll, chlorophyll a and b, betaxanthin, betacyanin, and betalain content was determined. A. lividus (AL) was evaluated as the highest source of energy. AV and AT accessions are underutilized but promising vegetables due to their bioactive phytochemicals and antioxidants.

Potassium augments growth, yield, nutrient content, and drought tolerance in mung bean (Vigna radiata L. Wilczek.)

Uneven rainfall and high temperature cause drought in tropical and subtropical regions which is a major challenge to cultivating summer mung bean. Potassium (K), a major essential nutrient of plants can alleviate water stress (WS) tolerance in plants. A field trial was executed under a rainout shelter with additional K fertilization including recommended K fertilizer (RKF) for relieving the harmful impact of drought in response to water use efficiency (WUE), growth, yield attributes, nutrient content, and yield of mung bean at the Regional Agricultural Research Station, BARI, Ishwardi, Pabna in two successive summer season of 2018 and 2019. Drought-tolerant genotype BMX-08010-2 (G1) and drought-susceptible cultivar BARI Mung-1 (G2) were grown by applying seven K fertilizer levels (KL) using a split-plot design with three replications, where mung bean genotypes were allotted in the main plots, and KL were assigned randomly in the sub-plots. A considerable variation was observed in the measured variables. Depending on the different applied KL and seed yield of mung bean, the water use efficiency (WUE) varied from 4.73 to 8.14 kg ha-1 mm-1. The treatment applying 125% more K with RKF (KL7) under WS gave the maximum WUE (8.14 kg ha-1 mm-1) obtaining a seed yield of 1093.60 kg ha-1. The treatment receiving only RKF under WS (KL2) provided the minimum WUE (4.73 kg ha-1 mm-1) attaining a seed yield of 825.17 kg ha-1. Results showed that various characteristics including nutrients (N, P, K, and S) content in stover and seed, total dry matter (TDM) in different growth stages, leaf area index (LAI), crop growth rate (CGR), root volume (RV), root density (RD), plant height, pod plant-1, pod length, seeds pod-1, seed weight, and seed yield in all pickings increased with increasing K levels, particularly noted with KL7. The highest grain yield (32.52%) was also obtained from KL7 compared to lower K with RKF. Overall, yield varied from 1410.37 kg ha-1 using 281 mm water (KL1; well-watered condition with RKF) to 825.17 kg ha-1 using 175 mm water (KL2). The results exhibited that the application of additional K improves the performance of all traits under WS conditions. Therefore, mung beans cultivating under WS requires additional K to diminish the negative effect of drought, and adequate use of K contributes to accomplishing sustainable productivity.

Molecular characterization and evaluation of novel management options for Burkholderia glumae BG1, the causative agent of panicle blight of rice (Oryza sativa L.)

BACKGROUND

Bacterial panicle blight, incited by Burkholderia glumae, has impacted rice production globally. Despite its significance, knowledge about the disease and the virulence pattern of the causal agent is very limited. Bacterial panicle blight is a major challenge in the rice-growing belts of North-western India, resulting in yield reduction. However, the management of B. glumae has become a challenge due to the lack of proper management strategies.

METHODOLOGY AND RESULTS

Twenty-one BG strains have been characterized using the 16S rRNA and the gyrB gene-based sequence approach in the present study. The gyrB gene-based phylogenetic analysis resulted in geographic region-specific clustering of the BG isolates. The virulence screening of twenty-one BG strains by inoculating the pathogenic bacterial suspension of 1 × 10-8 cfu/ml at the booting stage (55 DAT) revealed the variation in the disease severity and the grain yield of rice plants. The most virulent BG1 strain resulted in the highest disease incidence (82.11%) and lowest grain yield (11.12 g/plant), and the least virulent BG10 strain resulted in lowest disease incidence of 18.94% and highest grain yield (24.62 g/plant). In vitro evaluation of various biocontrol agents and nano copper at different concentrations by agar well diffusion method revealed that nano copper at 1000 mg/L inhibited the colony growth of B. glumae. Under net house conditions, nano copper at 1000 mg/L reduced the disease severity to 21.23% and increased the grain yield by 20.91% (31.76 g per plant) compared to the positive control (COC 0.25% + streptomycin 200 ppm). Remarkably, pre-inoculation with nano copper at 1000 mg/L followed by challenge inoculation with B. glumae enhanced the activity of enzymatic antioxidants viz., Phenyl ammonia-lyase (PAL), Polyphenol oxidase (PPO) and Peroxidase (POX) and non-enzymatic antioxidant phenol. Additionally, we observed a substantial transcript level upregulation of six defense-related genes to several folds viz., OsPR2, OsPR5, OsWRKY71, OsPAL1, OsAPX1, and OsPPO1 in comparison to the pathogen control and healthy control.

CONCLUSIONS

Overall, our study provides valuable insights into the potential and practical application of nano copper for the mitigation of bacterial panicle blight, offering promising prospects for commercial utilization in disease management.

Physio-biochemical and DNA methylation analysis of the defense response network of wheat to drought stress

In the present work, physio-biochemical and DNA methylation analysis were conducted in wheat (Triticum aestivum L.) cultivars "Bolani" (drought-tolerant) and "Sistan" (drought-sensitive) during drought treatments: well-watered (at 90% field capacity (FC)), mild stress (at 50% FC, and severe stress (at 25% FC). During severe stress, O2•- and H2O2 content in cultivar Sistan showed significant increase (by 1.3 and 2.5-fold, respectively) relative to cultivar Bolani. In Bolani, the increased levels of radical scavenging activity (by 32%), glycine betaine (GB) (by 11.44%), proline (4-fold), abscisic acid (by 63.76%), and more stability of relative water content (RWC) (2-fold) were observed against drought-induced oxidative stress. Methylation level significantly decreased from 70.26% to 60.64% in Bolani and from 69.06% to 59.85% in Sistan during stress, and higher decreased tendency was related to CG and CHG in Bolani but CG in Sistan under severe stress. Methylation patterns showed that the highest polymorphism in Bolani was mainly as CG. As the intensity of stress increased, the enhanced physio-biochemical responses of Bolani cultivar were accompanied by a more decrease in the number of unchanged bands. According to heat map analysis, the highest difference (84.38%) in methylation patterns was observed between control and severe stress. Multivariate analysis using principal component analysis (PCA) showed a cultivar-specific methylation during stress and that methylation changes between cultivars are much higher than that of within a cultivar. Higher methylation to demethylation in Bolani (30.06 vs. 22.12%) compared to that of cultivar Sistan (23.21 vs. 30.15%) indicated more demethylation did not induce tolerance responses in Sistan. Sequencing differentially methylated fragments along with qRT-PCR analysis showed the efficient role of various DNA fragments, including demethylated fragments such as phosphoenol pyruvate carboxylase (PEPC), beta-glucosidase (BGlu), glycosyltransferase (GT), glutathione S-transferase (GST) and lysine demethylase (LSD) genes and methylated fragments like ubiquitin E2 enzyme genes in the development of drought tolerance. These results suggested the specific roles of DNA methylation in development of drought tolerance in wheat landrace.

Deciphering the Genomic Characterization of the GGP Gene Family and Expression Verification of CmGGP1 Modulating Ascorbic Acid Biosynthesis in Melon Plants

Ascorbic acid (AsA), also known as vitamin C, is a well-known antioxidant found in living entities that plays an essential role in growth and development, as well as in defensive mechanisms. GDP-L-galactose phosphorylase (GGP) is a candidate gene regulating AsA biosynthesis at the translational and transcriptional levels in plants. In the current study, we conducted genome-wide bioinformatic analysis and pinpointed a single AsA synthesis rate-limiting enzyme gene in melon (CmGGP1). The protein prediction analysis depicted that the CmGGP1 protein does not have a signaling peptide or transmembrane structure and mainly functions in the chloroplast or nucleus. The constructed phylogenetic tree analysis in multispecies showed that the CmGGP1 protein has a highly conserved motif in cucurbit crops. The structural variation analysis of the CmGGP1 gene in different domesticated melon germplasms showed a single non-synonymous type-base mutation and indicated that this gene was selected by domestication during evolution. Wild-type (WT) and landrace (LDR) germplasms of melon depicted close relationships to each other, and improved-type (IMP) varieties showed modern domestication selection. The endogenous quantification of AsA content in both the young and old leaves of nine melon varieties exhibited the major differentiations for AsA synthesis and metabolism. The real-time quantitative polymerase chain reaction (qRT-PCR) analysis of gene co-expression showed that AsA biosynthesis in leaves was greater than AsA metabolic consumption, and four putative interactive genes (MELO3C025552.2, MELO3C007440.2, MELO3C023324.2, and MELO3C018576.2) associated with the CmGGP1 gene were revealed. Meanwhile, the CmGGP1 gene expression pattern was noticed to be up-regulated to varying degrees in different acclimated melons. We believe that the obtained results would provide useful insights for an in-depth genetic understanding of the AsA biosynthesis mechanism, aimed at the development of improving crop plants for melon.

Metabolomics reveals the phytotoxicity mechanisms of foliar spinach exposed to bulk and nano sizes of PbCO3

PbCO3 is an ancient raw material for Pb minerals and continues to pose potential risks to the environment and human health through mining and industrial processes. However, the specific effects of unintentional PbCO3 discharge on edible plants remain poorly understood. This study unravels how foliar application of PbCO3 induces phytotoxicity by potentially influencing leaf morphology, photosynthetic pigments, oxidative stress, and metabolic pathways related to energy regulation, cell damage, and antioxidant defense in Spinacia oleracea L. Additionally, it quantifies the resultant human health risks. Plants were foliarly exposed to PbCO3 nanoparticles (NPs) and bulk products (BPs), as well as Pb2+ at 0, 5, 10, 25, 50, and 100 mg·L-1 concentrations once a day for three weeks. The presence and localization of PbCO3 NPs inside the plant cells were confirmed by TEM-EDS analysis. The maximum accumulation of total Pb was recorded in the root (2947.77 mg·kg-1 DW for ion exposure), followed by the shoot (942.50 mg·kg-1 DW for NPs exposure). The results revealed that PbCO3 and Pb2+ exposure had size- and dose-dependent inhibitory effects on spinach length, biomass, and photosynthesis attributes, inducing impacts on the antioxidase activity of CAT, membrane permeability, and nutrient elements absorption and translocation. Pb2+ exhibited pronounced toxicity in morphology and chlorophyll; PbCO3 BP exposure accumulated the most lipid peroxidation products of MDA and H2O2; and PbCO3 NPs triggered the largest cell membrane damage. Furthermore, PbCO3 NPs at 10 and 100 mg·L-1 induced dose-dependent metabolic reprogramming in spinach leaves, disturbing the metabolic mechanisms related to amino acids, antioxidant defense, oxidative phosphorylation, fatty acid cycle, and the respiratory chain. The spinach showed a non-carcinogenic health risk hierarchy: Pb2+ > PbCO3 NPs > PbCO3 BPs, with children more vulnerable than adults. These findings enhance our understanding of PbCO3 particle effects on food security, emphasizing the need for further research to minimize their impact on human dietary health.

Differential responses of two fenugreek (Trigonella foenum-graecum L.) landraces pretreated with melatonin to prolonged drought stress and subsequent recovery

BACKGROUND

Drought impairs growth, disturbs photosynthesis, and induces senescence in plants, which results in crop productivity reduction and ultimately jeopardizes human food security. The objective of this study was to determine major parameters associated with drought tolerance and recovery ability of fenugreek (Trigonella foenum-graecum L.), by examining differential biochemical and phenological responses and underlying enzyme activities as well as melatonin roles during drought stress and re-watering for two contrasting landraces. Moreover, the relative expression of three key genes involved in the biosynthesis pathway of diosgenin, including SQS, CAS, and BG, was investigated.

RESULTS

Depending on the conditions, drought stress enhanced the activity of antioxidant enzymes and the osmoregulating compounds, non-enzymatic antioxidants, hydrogen peroxide content, and lipid peroxidation levels in most cases. Severe drought stress accelerated flowering time in Shushtar landrace (SHR) but had no significant effects on Varamin (VR). Pretreatment with melatonin delayed flowering time in SHR and caused high drought resistance in this landrace. Furthermore, melatonin significantly enhanced drought adaptability in VR by improving plant recovery ability.

DISCUSSION

Based on our results plants' responses to drought stress and melatonin pretreatment were completely landrace-specific. Drought stress caused an increase in the relative expression of CAS gene and ultimately the accumulation of steroidal saponins in SHR. Melatonin compensated for the decrease in biomass production due to drought stress and finally increased steroidal saponins performance in SHR. Our study showed that melatonin can improve drought stress and recovery in fenugreek, but different factors such as genotype, melatonin concentration, and plant age should be considered.

Biofilm producing plant growth promoting bacteria in combination with glycine betaine uplift drought stress tolerance of maize plant

Introduction

The escalating threat of drought poses a significant challenge to sustainable food production and human health, as water scarcity adversely impacts various aspects of plant physiology. Maize, a cornerstone in staple cereal crops, faces the formidable challenge of drought stress that triggers a series of transformative responses in the plant.

Methods

The present study was carried out in two sets of experiments. In first experiment, drought stress was applied after maintaining growth for 45 days and then irrigation was skipped, and plant samples were collected at 1st, 3rd and 6th day of drought interval for evaluation of changes in plant growth, water relation (relative water content) and antioxidants activity by inoculating indigenously isolated drought tolerant biofilm producing rhizobacterial isolates (Bacillus subtilis SRJ4, Curtobacterium citreum MJ1). In the second experiment, glycine betaine was applied as osmoregulator in addition to drought tolerant PGPR to perceive modulation in photosynthetic pigments (Chlorophyll a and b) and plant growth under varying moisture stress levels (100, 75 and 50% FC).

Results and discussion

Results of the study revealed upsurge in root and shoot length, fresh and dry biomass of root and shoot besides increasing chlorophyll contents in water stressed inoculated plants compared to uninoculated plants. Glycine betaine application resulted in an additional boost to plant growth and photosynthetic pigments, when applied in combination with bacterial inoculants. However, both bacterial inoculants behaved differently under drought stress as evident from their biochemical and physiological attributes. Isolate SRJ4 proved to be superior for its potential to express antioxidant activity, leaf water potential and relative water contents and drought responsive gene expression while isolate MJ1 showed exclusive increase in root dry biomass and plant P contents. Though it is quite difficult to isolate the bacterial isolates having both plant growth promoting traits and drought tolerance together yet, such biological resources could be an exceptional option to be applied for improving crop productivity and sustainable agriculture under abiotic stresses. By exploring the combined application of PGPR and glycine betaine, the study seeks to provide insights into potential strategies for developing sustainable agricultural practices aimed at improving crop resilience under challenging environmental conditions.

Multifaceted response mechanisms of Oryza sativa L. 'KDML105' to high arsenite and arsenate stress levels

Toxicity resulting from high levels of inorganic arsenic (iAs), specifically arsenite (AsIII) and arsenate (AsV), significantly induces oxidative stress and inhibits the growth of rice plants in various ways. Despite its economic importance and significance as a potent elite trait donor in rice breeding programmes, Khao Dawk Mali 105 (KDML105) has received limited attention regarding its responses to As stress. Therefore, this study aimed to comprehensively investigate how KDML105 responds to elevated AsIII and AsV stress levels. In this study, the growth, physiology, biochemical attributes and levels of As stress-associated transcripts were analysed in 45-day-old rice plants after exposing them to media containing 0, 75, 150, 300 and 600 µM AsIII or AsV for 1 and 7 days, respectively. The results revealed that AsIII had a more pronounced impact on the growth and physiological responses of KDML105 compared to AsV at equivalent concentrations. Under elevated AsIII treatment, there was a reduction in growth and photosynthetic efficiency, accompanied by increased levels of hydrogen peroxide (H2O2) and malondialdehyde (MDA). Notably, the total contents of antioxidants, such as proline, phenolics and flavonoids in the shoot, increased by 8.1-fold, 1.4-fold and 1.6-fold, respectively. Additionally, the expression of the OsABCC1 gene in the roots increased by 9.5-fold after exposure to 150 µM AsIII for 1 day. These findings suggest that KDML105's prominent responses to As stress involve sequestering AsIII in vacuoles through the up-regulation of the OsABCC1 gene in the roots, along with detoxifying excessive stress in the leaves through proline accumulation. These responses could serve as valuable traits for selecting As-tolerant rice varieties.

Enriched endogenous free Spd and Spm in alfalfa (Medicago sativa L.) under drought stress enhance drought tolerance by inhibiting H2O2 production to increase antioxidant enzyme activity

Drought stress is a major factor limiting agricultural development, and exogenous polyamines (PAs) can increase plant drought resistance by enhancing antioxidant activity, but few studies have examined whether endogenous PAs enhance the plant antioxidant system. Here, to investigate the effects of endogenous PAs on the antioxidant system of alfalfa under drought stress and the underlying mechanisms, two alfalfa cultivars, Longzhong (drought resistant) and Gannong No. 3 (drought sensitive), were used as test materials, and their seedlings were treated with polyethylene glycol (PEG-6000) for 8 days at -1.2 MPa to simulate drought stress. The levels of free PAs [putrescine (Put), spermidine (Spd) and spermine (Spm)], hydrogen peroxide (H2O2), malondialdehyde (MDA), key PA metabolism enzyme [arginine decarboxylase (ADC), ornithine decarboxylase (ODC), S-adenosylmethionine decarboxylase (SAMDC), polyamine oxidase (PAO), and diamine oxidase (DAO)] activities, and antioxidant enzyme [superoxide dismutase (SOD), catalase (CAT), and peroxidase (POD)] activities were measured. These physiological indicators were used for correlation analysis to investigate the relationship between PA metabolism and the antioxidant enzyme system. The results showed that PA synthesis in alfalfa under drought stress was dominated by the ADC pathway. Spd and Spm played an important role in improving drought tolerance. The high levels of ADC and SAMDC activities were facilitated by the conversion of Put to Spd and Spm. H2O2 generation by oxidative decomposition of PAs was mainly dependent on the oxidative decomposition of DAO but not PAO. Low DAO activity favored low H2O2 production. Spd, Spm, ADC, ODC and SAMDC were positively correlated with the antioxidant enzymes SOD, CAT and POD in both cultivars under drought. Therefore, we concluded that high ADC and SAMDC activities in alfalfa promoted the conversion of Put to Spd and Spm, leading to high accumulation of Spd and Spm and low Put accumulation. Low Put levels led to low H2O2 production through low DAO activity, and low H2O2 levels induced the expression of antioxidant enzyme-encoding genes to improve antioxidant enzyme activity and reduce MDA accumulation and thereby enhanced drought resistance in alfalfa.

Metabolic Mechanisms Underlying Heat and Drought Tolerance in Lentil Accessions: Implications for Stress Tolerance Breeding

Climate change has significantly exacerbated the effects of abiotic stresses, particularly high temperatures and drought stresses. This study aims to uncover the mechanisms underlying heat and drought tolerance in lentil accessions. To achieve this objective, twelve accessions were subjected to high-temperature stress (32/20 °C), while seven accessions underwent assessment under drought stress conditions (50% of field capacity) during the reproductive stage. Our findings revealed a significant increase in catalase activity across all accessions under both stress conditions, with ILL7814 and ILL7835 recording the highest accumulations of 10.18 and 9.33 under drought stress, respectively, and 14 µmol H2O2 mg protein-1 min-1 under high temperature. Similarly, ascorbate peroxidase significantly increased in all tolerant accessions due to high temperatures, with ILL6359, ILL7835, and ILL8029 accumulating the highest values with up 50 µmol ascorbate mg protein-1 min-1. In contrast, no significant increase was obtained for all accessions subjected to water stress, although the drought-tolerant accessions accumulated more APX activity (16.59 t to 25.08 µmol ascorbate mg protein-1 min-1) than the sensitive accessions. The accessions ILL6075, ILL7814, and ILL8029 significantly had the highest superoxide dismutase activity under high temperature, while ILL6363, ILL7814, and ILL7835 accumulated the highest values under drought stress, each with 22 to 25 units mg protein-1. Under both stress conditions, ILL7814 and ILL7835 recorded the highest contents in proline (38 to 45 µmol proline/g FW), total flavonoids (0.22 to 0.77 mg QE g-1 FW), total phenolics (7.50 to 8.79 mg GAE g-1 FW), total tannins (5.07 to 20 µg CE g-1 FW), and total antioxidant activity (60 to 70%). Further, ILL7814 and ILL6338 significantly recorded the highest total soluble sugar content under high temperature (71.57 and 74.24 mg g-1, respectively), while ILL7835 achieved the maximum concentration (125 mg g-1) under drought stress. The accessions ILL8029, ILL6104, and ILL7814 had the highest values of reducing sugar under high temperature with 0.62 to 0.79 mg g-1, whereas ILL6075, ILL6363, and ILL6362 accumulated the highest levels of this component under drought stress with 0.54 to 0.66 mg g-1. Overall, our findings contribute to a deeper understanding of the metabolomic responses of lentil to drought and heat stresses, serving as a valuable reference for lentil stress tolerance breeding.

Investigating the Chemical Composition of Lepidium sativum Seeds and Their Ability to Safeguard against Monosodium Glutamate-Induced Hepatic Dysfunction

Monosodium glutamate (MSG) is one of the most frequently used food additives that endanger public health. The antioxidant, hyperlipidemic, and cytoprotective properties of Lepidium sativum seeds (LSS) as a natural remedy can minimize the harmful effects of MSG. This study investigated the potential protective effect of LSS against MSG-induced hepatotoxicity in rats. Male albino Sprague Dawley rats (n = 24) were equally divided into four groups for 30 days: the control group (G1) received a basal diet without supplement, group (G2) was fed a basal diet + MSG (30 g/kg b.w.) as a model group, group (G3) was fed a basal diet + MSG (30 g/kg b.w.) + LSS (30 g/kg b.w.), and group (G4) was fed a basal diet + MSG (30 g/kg b.w.) + LSS (60 g/kg b.w.). LSS enhanced serum alkaline phosphatase activity as well as total cholesterol, triglyceride, and glucose levels. It can decrease peroxide content in serum lipids and inhibit glutathione reductase and superoxide dismutase in hepatic cells. The dietary supplementation with LSS provided cytoprotection by enhancing the histoarchitecture of the liver and decreasing the number of apoptotic cells. Due to their antioxidant and anti-apoptotic properties, LSS effectively protect against the hepatotoxicity of MSG. These findings are of the highest significance for drawing attention to incorporating LSS in our food industry and as a health treatment in traditional medicine to combat MSG-induced hepatic abnormalities.

Enhancing defense against rice blast disease: Unveiling the role of leaf endophytic firmicutes in antifungal antibiosis and induced systemic resistance

Rice remains the primary staple for more than half of the world's population, yet its cultivation faces numerous challenges, including both biotic and abiotic stresses. One significant obstacle is the prevalence of rice blast disease, which substantially diminishes productivity and increases cultivation costs due to frequent fungicide applications. Consequently, the presence of fungicide residues in rice raises concerns about compliance with international maximum residue limits (MRLs). While host resistance has proven effective, it often remains vulnerable to new variants of the Magnaporthe oryzae pathogen. Therefore, there is a critical need to explore innovative management strategies that can complement or enhance existing methods. An unexplored avenue involves harnessing endophytic bacterial communities. To this end, the present study investigates the potential of eleven endophytic Bacillus spp. in suppressing Pyricularia oryzae, promoting plant growth, and eliciting a defense response through phyllobacterization. The results indicate that the secreted metabolome and volatilome of seven tested isolates demonstrate inhibitory effects against P.oryzae, ranging from a minimum of 40% to a maximum of 70%. Bacillus siamensis L34, B. amyloliquefaciens RA37, B. velezensis L12, and B. subtilis B18 produce antifungal antibiotics targeting P.oryzae. Additionally, B. subtilis S4 and B. subtilis S6 emerge as excellent inducers of systemic resistance against blast disease, as evidenced by elevated activity of biochemical defense enzymes such as peroxidase, polyphenol oxidase, and total phenol content. However, a balance between primary metabolic activity (e.g., chlorophyll content, chlorophyll fluorescence, and photosynthetic rate) and defense activity is observed. Furthermore, specific endophytic Bacillus spp. significantly stimulates defense-related genes, including OsPAD4, OsFMO1, and OsEDS1. These findings underscore the multifaceted potential of endophytic Bacillus in managing blast disease through antibiosis and induced systemic resistance. In conclusion, this study highlights the promising role of endophytic Bacillus spp. as a viable option for blast disease management. Their ability to inhibit the pathogen and induce systemic resistance makes them a valuable addition to the existing strategies. However, it is crucial to consider the trade-off between primary metabolic activity and defense response when implementing these bacteria-based approaches.

Proteomics and phosphoproteomics reveal the different drought-responsive mechanisms of priming with (Z)-3-hexenyl acetate in two tea cultivars

Drought is an important abiotic stress that constrains the quality and quantity of tea plants. The green leaf volatiles Z-3-hexenyl acetate (Z-3-HAC) have been reported to play an essential role in stress responses. However, the underlying mechanisms of drought tolerance in tea plants remain elusive. This study investigated the physiological, proteomic, and phosphoproteomic profiling of two tea plant varieties of Longjingchangye (LJCY) and Zhongcha 108 (ZC108) with contrasting drought tolerance characteristics under drought stress. Physiological data showed that spraying Z-3-HAC exhibited higher activities of superoxide dismutase (SOD) and catalase (CAT) in both LJCY and ZC108 but lower content of malondialdehyde (MDA) in LJCY under drought stress. The proteomic and phosphoproteomic analysis suggested that the drought tolerance mechanism of Z-3-HAC in LJCY and ZC108 was different. Proteomic analyses revealed that Z-3-HAC enhanced the drought tolerance of LJCY by fructose metabolism while enhancing the drought tolerance of ZC108 by promoting glucan biosynthesis and galactose metabolism. Furthermore, the differential abundance phosphoproteins (DAPPs) related to intracellular protein transmembrane transport and protein transmembrane transport were enriched in LJCY, and the regulation of response to osmotic stress and regulation of mRNA processing were enriched in ZC108. In addition, protein-phosphoprotein interactions (PPI) analyses suggested that energy metabolism and starch and sucrose metabolic processes might play critical roles in LJCY and ZC108, respectively. These results will help to understand the mechanisms by which Z-3-HAC enhances the drought resistance of tea plants at the protein level. SIGNIFICANT: Green leaf volatiles (GLVs) are important volatile organic compounds that play essential roles in plant defense against biotic and abiotic stresses. To understand the mechanisms of Z-3-HAC in improving the drought tolerance of tea plants, two contrasting drought tolerance varieties (LJCY and ZC108) were comparatively evaluated by proteomics and phosphoproteomics. This analysis evidenced changes in the abundance of proteins involved in energy metabolism and starch and sucrose metabolic processes in LJCY and ZC108, respectively. These proteins may elucidate new molecular aspects of the drought resistance mechanism of Z-3-HAC, providing a theoretical basis for drought resistance breeding of tea plants.

Leaf proteomic profiles in cacao scion-rootstock combinations tolerant and intolerant to cadmium toxicity

Cd contamination in cacao beans is one of the major problems faced by cocoa producing countries in Latin America. Cacao scion-rootstock combinations influence the Cd accumulation in the shoot of the plant. The objective of this work was to carry out a comparative analysis between cacao scion rootstock combinations (CCN 51/BN 34, CCN 51/PS 13.19, CCN 51/PH 16 and CCN 51/CCN 51), contrasting for tolerance to cadmium (Cd) toxicity, by means of leaf proteomic profiles, in order to elucidate molecular mechanisms involved in tolerance to Cd toxicity. Cacao scion-rootstock combinations were grown in soil with 150 mg Cd kg-1 soil, together with the control treatment. Leaf samples were collected 96 h after treatments were applied. There were alterations in the leaf proteome of the cacao scion-rootstock combinations, whose molecular responses to Cd toxicity varied depending on the combination. Leaf proteomic analyzes provided important information regarding the molecular mechanisms involved in the tolerance and intolerance of cacao scion-rootstock combinations to Cd toxicity. Enzymatic and non-enzymatic antioxidant systems, efficient for eliminating ROS, especially the expressions of APX and SOD, in addition to the increase in the abundance of metalloproteins, such as ferredoxins, rubredoxin, ALMT, Trx-1 and ABC-transporter were key mechanisms used in the Cd detoxification in cacao scion-rootstock combinations tolerant to Cd toxicity. Carboxylic acid metabolism, glucose activation and signal transduction were also important processes in the responses of cacao scion-rootstock combinations to Cd toxicity. The results confirmed CCN 51/BN 34 as a cacao scion-rootstock combination efficient in tolerance to Cd toxicity.

Physiological and biochemical traits positively modulate tissue-specific withanolides and untargeted metabolites in Withania somnifera (L.) dunal under salinity stress

Withania somnifera (L.) Dunal (Ashwagandha) has been used in herbal medicines worldwide and in the Indian traditional medicinal system for 3000 years. It is a member of the Solanaceae family distributed across Asia, Africa, Australia, and Europe. Its bioactive secondary metabolite (withanolide) biosynthesis is sensitive to salinity stress, though the mechanism remains unexplored. Therefore, we investigated the effect of Sodium chloride (NaCl) on growth, photosynthesis, biochemical traits, tissue-specific withanolide, and untargeted metabolites in W. somnifera. Ashwagandha plants were raised in pots containing soil mixture and treated with different NaCl concentrations (0 as control, 10, 30, and 50 mM) for one month inside the greenhouse. NaCl stress significantly enhanced withaferin A (WFA) (3.79 mg/g), withanolide A (WA) (0.51 mg/g), and withanone (WN) (0.022 mg/g) at 50 mM NaCl groups in the shoot. Similarly, in the root, a significant increase in WFA (0.19 mg/g) and WN (0.0016 mg/g) were observed at 10 mM, WA (0.059 mg/g) at 30 mM, and withanolide B (WB) (0.013 mg/g) at 50 mM NaCl groups compared to control. LC-MS-based untargeted metabolite profiling revealed 37 differentially accumulated metabolites in all groups. Maximum abundance of glycyl-hydroxyproline (8X) followed by tyrosyl-valine (2X) and 3-hydroxy-beta-ionone (2X) were recorded at 50 mM NaCl groups compared to the control. This study showed for the first time that low NaCl stress enhances the biosynthesis of tissue-specific withanolides through physio-biochemical and metabolites adjustment. Overall, we demonstrated a multifaceted approach for cultivating medicinal crops in salt-affected areas with enhanced bioactive metabolites for healthcare and pharmaceutical industries.

Growth, Physiology and Nutritional Quality of C4 Halophyte Portulaca oleracea L. Grown Aeroponically in Different Percentages of Artificial Seawater under Different Light-Emitting Diode Spectral Qualities

Edible halophyte Portulaca oleracea L., known as purslane, was grown in two percentages of artificial seawater (ASW) under two combined red (R) and blue (B) LED spectra. High salinity (40% ASW) negatively affected shoot productivity and leaf growth of purslane compared to those grown in 10% ASW. Photosynthetic pigment and total reduced nitrogen concentrations were significantly higher in purslane grown in 10% ASW than in 40% ASW. However, LED spectral quality did not markedly influence these parameters. Grown in 10% ASW under R/B 2.2, purslane had the highest maximum nitrate reductase activity, while those in 40% ASW under R/B 2.2 had the highest activation state. Under both light qualities, purslane had a sevenfold increase in proline concentration in 40% ASW than in 10% ASW. Total phenolic compounds' concentration was the highest in 10% ASW under R/B 0.9, while there were no significant differences in the accumulation of total soluble sugars and ascorbic acids among all plants. Antioxidant enzymes activities were lower in 40% ASW under R/B 2.2 compared to the other conditions. In conclusion, salinity affected the yield, physiology and nutritional quality of purslane. The impacts of LED spectral quality on purslane were only reflected by certain physiological and nutritional parameters.

Evaluation of yield attributes and bioactive phytochemicals of twenty amaranth genotypes of Bengal floodplain

Twenty vegetable amaranth (VA) genotypes were evaluated to assess the variability, associations, path coefficient, and principal component analysis (PCA) of morpho-chemical traits. The genotypes exhibited adequate antioxidant colorants, phytochemicals, and antiradical capacity with significant variations across genotypes. Genetic parameters revealed selection criteria for the majority of the traits for improving amaranth foliage yield (FY). Based on correlation coefficient, stem weight, stem base diameter, root weight, plant height, and shoot weight for significant development of FY of VA. Observing significant genotypic correlation with high positive direct effects on FY, the path coefficient (PC) of root weight, stem base diameter, stem weight, and shoot weight could contribute to the noteworthy development of FY of VA. The genotypes AA5, AA6, AA8, AA10, AA11, AA19, and AA20 might be selected for high FY, antioxidant colorants, and antiradical phytochemicals to utilize as colorants and antiradical rich superior high yielding cultivars. The first PC accounted for 37.8% of the variances, which implies a larger proportion of variable information explained by PC1. The features that contributed more to PC1 were FY, SW, STW, RW, and PH, whereas Chl b, total Chl, and Chl a contributed to the second PC. This suggests that there are significant genetic differences between amaranths in terms of biochemical and agro-morphological characteristics. The findings of the current work support plant breeders to investigate the genetic potential of the amaranth germplasm, notably in biochemical parameters. High colorants enrich genotypes that can be selected for extracting natural colorants to use in food processing industries.

Effectiveness of silver nitrate application on plant growth and bioactive compounds in Agastache rugosa (Fisch. & C.A.Mey.) kuntze

The objective of this study was to determine the optimal dose of silver nitrate (AgNO3) for plant growth and to increase the main bioactive compounds in A. rugosa cultivated in a hydroponic system. The application of soaked diniconazole (120 μmol mol-1) to all plants at 7 days after transplanting (DAT) for dwarfing plant height, optimizing cultivation space in the plant factory. Subsequently, plants were soaked with 50, 100, 200, and 400 μmol mol-1 AgNO3 for 10 min at 25 DAT and harvested at 39 DAT. The results indicated that 200 and 400 μmol mol-1 treatments tended to severely decrease plant growth parameters compared to treatments with lower concentrations. The net photosynthetic rate was significantly reduced by the 200 and 400 μmol mol-1 treatments compared to treatments with other concentrations. The 400 μmol mol-1 treatment led to the lowest concentrations of chlorophyll a, chlorophyll a/b, total carotenoid, chlorophyll b, and the total chlorophyll. However, 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity was considerably increased in 50, 100, 200, and 400 μmol mol-1 compared to that of the control plants. A higher rosmarinic acid (RA) concentration in the whole plant was noticed with the 400 μmol mol-1 treatment compared with that of the untreated plants. The 100 μmol mol-1 treatment exhibited the highest concentration and content of tilianin in the whole plant. Concentration of acacetin 1 significantly increased in the whole plant with 100 and 200 μmol mol-1 treatments compared with that of the untreated plants. Concentrations of acacetin 2 and 3 in the whole plant were the highest with 100 and 200 μmol mol-1 treatments, respectively. The results demonstrated that 100 μmol mol-1 treatments can be used to increase bioactive compounds without severely limiting the plant growth and reducing chlorophyll concentrations of A. rugosa. Implementing this optimal dose can enable growers and researchers to cultivate A. rugosa more efficiently, enhancing bioactive compound content and overall plant performance, thus harnessing the potential health benefits of this valuable plant species.

Response of seed yield and biochemical traits of Eruca sativa Mill. to drought stress in a collection study

Drought tolerance is a complex trait in plants that involves different biochemical mechanisms. During two years of study (2019-2020), the responses of 64 arugula genotypes to drought stress were evaluated in a randomized complete block design with three replications under field conditions. Several metabolic traits were evaluated, i.e. relative water content, photosynthetic pigments (chlorophyll and carotenoids), proline, malondialdehyde, enzymatic antioxidants (catalase, ascorbate peroxidase, and peroxidase), total phenolic and flavonoid contents and seed yield. On average, the drought stress significantly increased the proline content (24%), catalase (42%), peroxidase (60%) and malondialdehyde activities (116%) over the two years of study. As a result of the drought stress, the seed yield (18%), relative water content (19.5%) and amount of photosynthetic pigments (chlorophyll and carotenoids) dropped significantly. However, the total phenolic and flavonoid contents showed no significant changes. Under drought stress, the highest seed yields were seen in the G50, G57, G54, G55 and G60 genotypes, while the lowest value was observed in the G16 genotype (94 g plant-1). According to the findings, when compared to the drought-sensitive genotypes, the drought-tolerant arugula genotypes were marked with higher levels of proline accumulation and antioxidant enzyme activity. Correlation analysis indicated the positive effects of peroxidase, catalase and proline on seed yield under drought conditions. These traits can be considered for the selection of drought-tolerant genotypes in breeding programs.

Biostimulant red seaweed (Gracilaria tenuistipitata var. liui) extracts spray improves yield and drought tolerance in soybean

Drought has a deleterious impact on the growth, physiology, and yield of various plants, including soybean. Seaweed extracts are rich in various bioactive compounds, including antioxidants, and can be used as biostimulants for improving yield and alleviating the adverse effect of drought stress. The purpose of this study was to evaluate the effect of soybean growth and yield with different concentrations (0.0%, 5.0%, and 10.0% v/v) of water extracts of the red seaweed Gracilaria tenuistipitata var. liui under well-watered (80% of field capacity (FC) and drought (40% of FC)) conditions. Drought stress decreased soybean grain yield by 45.58% compared to well-watered circumstances but increased the water saturation deficit by 37.87%. It also decreased leaf water, chlorophyll content, plant height, and the fresh weight of the leaf, stem, and petiole. Drought stress decreased soybean grain yield by 45.58% compared to well-watered circumstances but increased the water saturation deficit by 37.87%. It also decreased leaf water, chlorophyll content, plant height, and the fresh weight of the leaf, stem, and petiole. Under both drought and well-watered situations, foliar application of seaweed extracts dramatically improved soybean growth and production. Under drought and well-watered situations, 10.0% seaweed extract increased grain yield by 54.87% and 23.97%, respectively in comparison to untreated plants. The results of this study suggest that red seaweed extracts from Gracilaria tenuistipitata var. liui may be used as a biostimulant to improve soybean yield and drought tolerance in the presence of insufficient water. However, the actual mechanisms behind these improvements need to be further investigated in field conditions.

Triple-zero tillage and system intensification lead to enhanced productivity, micronutrient biofortification and moisture-stress tolerance ability in chickpea in a pearlmillet-chickpea cropping system of semi-arid climate

Pearlmillet-chickpea cropping system (PCCS) is emerging as an important sequence in semi-arid regions of south-Asia owing to less water-requirement. However, chickpea (dry-season crop) faces comparatively acute soil moisture-deficit over pearlmillet (wet-season crop), limiting overall sustainability of PCCS. Hence, moisture-management (specifically in chickpea) and system intensification is highly essential for sustaining the PCCS in holistic manner. Since, conservation agriculture (CA) has emerged is an important climate-smart strategy to combat moisture-stress alongwith other production-vulnerabilities. Hence, current study comprised of three tillage systems in main-plots viz., Complete-CA with residue retention (CAc), Partial-CA without residue-retention (CAp), and Conventional-tillage (ConvTill) under three cropping systems in sub-plots viz., conventionally grown pearlmillet-chickpea cropping system (PCCS) alongwith two intensified systems i.e. pearlmillet-chickpea-fodder pearlmillet cropping system (PCFCS) and pearlmillet-chickpea-mungbean cropping system (PCMCS) in split-plot design. The investigation outcomes mainly focused on chickpea (dry-season crop) revealed that, on an average, there was a significant increase in chickpea grain yield under CAc to the tune of 27, 23.5 and 28.5% under PCCS, PCFCS and PCMCS, respectively over ConvTill. NPK uptake and micronutrient (Fe and Zn) biofortification in chickpea grains were again significantly higher under triple zero-tilled CAc plots with residue-retention; which was followed by triple zero-tilled CAp plots without residue-retention and the ConvTill plots. Likewise, CAc under PCMCS led to an increase in relative leaf water (RLW) content in chickpea by ~ 20.8% over ConvTill under PCCS, hence, ameliorating the moisture-stress effects. Interestingly, CA-management and system-intensification significantly enhanced the plant biochemical properties in chickpea viz., super-oxide dismutase, ascorbate peroxidase, catalase and glutathione reductase; thus, indicating their prime role in inducing moisture-stress tolerance ability in moisture-starved chickpea. Triple zero-tilled CAc plots also reduced the N2O fluxes in chickpea but with slightly higher CO2 emissions, however, curtailed the net GHG-emissions. Triple zero-tilled cropping systems (PCFCS and PCMCS) both under CAc and Cap led to a significant improvement in soil microbial population and soil enzymes activities (alkaline phosphatase, fluorescein diacetate, dehydrogenase). Overall, the PCCS system-intensification with mungbean (PCMCS) alongwith triple zero-tillage with residue-retention (CAc) may amply enhance the productivity, micronutrient biofortification and moisture-stress tolerance ability in chickpea besides propelling the ecological benefits under semi-arid agro-ecologies. However, the farmers should preserve a balance while adopting CAc or CAp where livestock equally competes for quality fodder.

Glutathione-mediated changes in productivity, photosynthetic efficiency, osmolytes, and antioxidant capacity of common beans (Phaseolus vulgaris) grown under water deficit

Globally, salinity and drought are severe abiotic stresses that presently threaten vegetable production. This study investigates the potential exogenously-applied glutathione (GSH) to relieve water deficits on Phaseolus vulgaris plants cultivated in saline soil conditions (6.22 dS m^-1) by evaluating agronomic, stability index of membrane, water satatus, osmolytes, and antioxidant capacity responses. During two open field growing seasons (2017 and 2018), foliar spraying of glutathione (GSH) at 0.5 (GSH₁) or 1.0 (GSH₁) mM and three irrigation rates (I₁₀₀ = 100%, I₈₀ = 80% and I₆₀ = 60% of the crop evapotranspiration) were applied to common bean plants. Water deficits significantly decreased common bean growth, green pods yield, integrity of the membranes, plant water status, SPAD chlorophyll index, and photosynthetic capacity (F_v/F_m, PI), while not improving the irrigation use efficiency (IUE) compared to full irrigation. Foliar-applied GSH markedly lessened drought-induced damages to bean plants, by enhancing the above variables. The integrative I₈₀ + GSH₁ or GSH₂ and I₆₀ + GSH₁ or GSH₂ elevated the IUE and exceeded the full irrigation without GSH application (I₁₀₀) treatment by 38% and 37%, and 33% and 28%, respectively. Drought stress increased proline and total soluble sugars content while decreased the total free amino acids content. However, GSH-supplemented drought-stressed plants mediated further increases in all analyzed osmolytes contents. Exogenous GSH enhanced the common bean antioxidative machinery, being promoted the glutathione and ascorbic acid content as well as up-regulated the activity of superoxide dismutase, catalase, ascorbate peroxidase, and glutathione peroxidase. These findings demonstrate the efficacy of exogenous GSH in alleviating water deficit in bean plants cultivated in salty soil.

New seed coating containing Trichoderma viride with anti-pathogenic properties

Background

To ensure food security in the face of climate change and the growing world population, multi-pronged measures should be taken. One promising approach uses plant growth-promoting fungi (PGPF), such as Trichoderma, to reduce the usage of agrochemicals and increase plant yield, stress tolerance, and nutritional value. However, large-scale applications of PGPF have been hampered by several constraints, and, consequently, usage on a large scale is still limited. Seed coating, a process that consists of covering seeds with low quantities of exogenous materials, is gaining attention as an efficient and feasible delivery system for PGPF.

Methods

We have designed a new seed coating composed of chitin, methylcellulose, and Trichoderma viride spores and assessed its effect on canola (Brassica napus L.) growth and development. For this purpose, we analyzed the antifungal activity of T. viride against common canola pathogenic fungi (Botrytis cinerea, Fusarium culmorum, and Colletotrichum sp.). Moreover, the effect of seed coating on germination ratio and seedling growth was evaluated. To verify the effect of seed coating on plant metabolism, we determined superoxide dismutase (SOD) activity and expression of the stress-related RSH (RelA/SpoT homologs).

Results

Our results showed that the T. viride strains used for seed coating significantly restricted the growth of all three pathogens, especially F. culmorum, for which the growth was inhibited by over 40%. Additionally, the new seed coating did not negatively affect the ability of the seeds to complete germination, increased seedling growth, and did not induce the plant stress response. To summarize, we have successfully developed a cost-effective and environmentally responsible seed coating, which will also be easy to exploit on an industrial scale.

An intrinsically disordered region-containing protein mitigates the drought-growth trade-off to boost yields

Drought stress poses a serious threat to global agricultural productivity and food security. Plant resistance to drought is typically accompanied by a growth deficit and yield penalty. Herein, we report a previously uncharacterized, dicotyledon-specific gene, Stress and Growth Interconnector (SGI), that promotes growth during drought in the oil crop rapeseed (Brassica napus) and the model plant Arabidopsis (Arabidopsis thaliana). Overexpression of SGI conferred enhanced biomass and yield under water-deficient conditions, whereas corresponding CRISPR SGI mutants exhibited the opposite effects. These attributes were achieved by mediating reactive oxygen species (ROS) homeostasis while maintaining photosynthetic efficiency to increase plant fitness under water-limiting environments. Further spatial-temporal transcriptome profiling revealed dynamic reprogramming of pathways for photosynthesis and stress responses during drought and the subsequent recovery. Mechanistically, SGI represents an intrinsically disordered region-containing protein that interacts with itself, catalase isoforms, dehydrins, and other drought-responsive positive factors, restraining ROS generation. These multifaceted interactions stabilize catalases in response to drought and facilitate their ROS-scavenging activities. Taken altogether, these findings provide insights into currently underexplored mechanisms to circumvent trade-offs between plant growth and stress tolerance that will inform strategies to breed climate-resilient, higher yielding crops for sustainable agriculture.

Sensitivity of the Photosynthetic Apparatus in Maize and Sorghum under Different Drought Levels

Drought is one of the main environmental stress factors affecting plant growth and yield. The impact of different PEG concentrations on the photosynthetic performance of maize (Zea mays L. Mayflower) and sorghum (Sorghum bicolor L. Foehn) was investigated. The activity of the photosynthetic apparatus was assessed using chlorophyll fluorescence (PAM and JIP test) and photooxidation of P₇₀₀. The data revealed that water deficiency decreased the photochemical quenching (qP), the ratio of photochemical to nonphotochemical processes (Fv/Fo), the effective quantum yield of the photochemical energy conversion in PSII (Φ_PSII), the rate of the electron transport (ETR), and the performance indexes PI_total and PI_ABS, as the impact was stronger in sorghum than in maize and depended on drought level. The PSI photochemistry (P₇₀₀ photooxidation) in sorghum was inhibited after the application of all studied drought levels, while in maize, it was registered only after treatment with higher PEG concentrations (30% and 40%). Enhanced regulated energy losses (Φ_NPQ) and activation of the state transition under drought were also observed in maize, while in sorghum, an increase mainly in nonregulated energy losses (Φ_NO). A decrease in pigment content and relative water content and an increase in membrane damage were also registered after PEG treatment. The experimental results showed better drought tolerance of maize than sorghum. This study provides new information about the role of regulated energy losses and state transition for the protection of the photosynthetic apparatus under drought and might be a practical approach to the determination of the drought tolerance of plants.

The Impact of Heavy Metal Accumulation on Some Physiological Parameters in Silphium perfoliatum L. Plants Grown in Hydroponic Systems

Heavy metals like cadmium (Cd), copper (Cu), lead (Pb), and zinc (Zn), resulting from anthropogenic activities, are elements with high persistence in nature, being able to accumulate in soils, water, and plants with significant impact to human and animal health. This study investigates the phytoremediation capacity of Silphium perfoliatum L. as a specific heavy metal hyperaccumulator and the effects of Cu, Zn, Cd, and Pb on some physiological and biochemical indices by growing plants under floating hydroponic systems in nutrient solutions under the presence of heavy metals. One-year-old plants of S. perfoliatum grown for 20 days in Hoagland solution with the addition of (ppm) Cu-400, Zn-1200, Cd-20, Pb-400, and Cu+Zn+Cd+Pb (400/1200/20/400) were investigated with respect to the control. The level of phytoremediation, manifested by the ability of heavy metal absorption and accumulation, was assessed. In addition, the impact of stress on the proline content, photosynthetic pigments, and enzymatic activity, as being key components of metabolism, was determined. The obtained results revealed a good absorption and selective accumulation capacity of S. perfoliatum plants for the studied heavy metals. Therefore, Cu and Zn mainly accumulate in the stems, Cd in the roots and stems, while Pb mainly accumulates in the roots. The proline tended to increase under stress conditions, depending on the pollutant and its concentration, with higher values in leaves and stems under the associated stress of the four metals and individually for Pb and Cd. In addition, the enzymatic activity recorded different values depending on the plant organ, its type, and the metal concentration on its substrate. The obtained results indicate a strong correlation between the metal type, concentration, and the mechanisms of absorption/accumulation of S. perfoliatum species, as well as the specific reactions of metabolic response.

Seed Priming with the Selenium Nanoparticles Maintains the Redox Status in the Water Stressed Tomato Plants by Modulating the Antioxidant Defense Enzymes

In the present research, selenium nanoparticles (SeNPs) were tested for their use as seed priming agents under field trials on tomatoes (Solanum lycopersicum L.) for their efficacy in conferring drought tolerance. Four different seed priming regimes of SeNPs were created, comprising 25, 50, 75, and 100 ppm, along with a control treatment of 0 ppm. Seeds were planted in split plots under two irrigation regimes comprising water and water stress. The results suggest that seed priming with SeNPs can improve tomato crop performance under drought stress. Plants grown with 75 ppm SeNPs-primed seeds had lower hydrogen peroxide (H₂O₂) and malondialdehyde (MDA) levels by 39.3% and 28.9%, respectively. Seed priming with 75 ppm SeNPs further increased the superoxide dismutase (SOD) and catalase (CAT) functions by 34.9 and 25.4%, respectively. The same treatment increased the total carotenoids content by 13.5%, α-tocopherols content by 22.8%, total flavonoids content by 25.2%, total anthocyanins content by 19.6%, ascorbic acid content by 26.4%, reduced glutathione (GSH) content by 14.8%, and oxidized glutathione (GSSG) content by 13.12%. Furthermore, seed priming with SeNPs upregulated the functions of enzymes of ascorbate glutathione cycle. Seed priming with SeNPs is a smart application to sustain tomato production in arid lands.