Mechanisms of ROS Regulation of Plant Development and Stress Responses

Genome-Wide Analysis for TLDc domain-containing genes in Oryza sativa

OXidation Resistance (OXR) is a family of eukaryotic proteins characterized by the presence of the highly conserved TLDc (TBC (Tre2/Bub2/Cdc16), LysM (lysine motif), domain catalytic) domain at the C-terminal half which plays a crucial role in cellular defense mechanisms, particularly in response to oxidative stress. TLDc (TBC/LysM domain catalytic) domain-containing proteins are essential regulators of oxidative stress responses in plants, a key juncture for various stress signaling pathways. This study identified six putative TLDc genes in the rice (Oryza sativa L.) genome through a comprehensive in silico analysis. These genes were characterized by their conserved TLDc domain, with gene expression analysis via qRT-PCR confirming their significant upregulation under drought and salt stress conditions. These findings suggest a potential role for TLDc genes in enhancing stress tolerance through oxidative stress regulation, making them promising miRNA targets for modulating stress responses. Comparative phylogenetic analysis reveals that rice TLDc genes share close evolutionary bonds with Wheat, Maize, and Arabidopsis thaliana, suggesting a conserved role across species. Especially, the study finds that gene duplications contribute to the diversity of TLDc genes, and examines how these duplications may influence protein subcellular localization, primarily in the plasma membrane, nucleus, and chloroplast, which are crucial for stress signaling pathways. This work builds on existing research by expanding our understanding of TLDc genes in Oryza sativa, addressing gaps in the functional characterization of the gene family in stress responses, and offering valuable insights for further exploration of their roles in plant resilience.

Bacterial N-acyl-homoserine lactone enhances the degradation of sulfamethoxazole by microalgae and the associated metabolic regulatory mechanisms

Recent studies have revealed that N-acyl-homoserine lactones (AHLs), common quorum-sensing (QS) signal molecules in Gram-negative bacteria, can also influence microalgal cells. However, their role in regulating the metabolism of pollutants, such as antibiotics, within microalgae remains poorly understood. This study investigated the effects of N-hexanoyl-L-homoserine lactone (C6-HSL) on the degradation of sulfamethoxazole (SMX) in aquaculture wastewater by Chlorella vulgaris. The addition of 0.5 μM C6-HSL resulted in the highest biomass accumulation and the maximum SMX removal efficiency (95.6 %). At optimal concentrations, C6-HSL effectively modulated key secondary messenger signaling pathways including reactive oxygen species (ROS), nitric oxide (NO), and calcium ions (Ca2+) in microalgal cells. Additionally, it upregulated the activity of detoxification enzymes such as glutathione S-transferase (GST) and cytochrome P450 (CYP450), thereby altering SMX degradation pathways and significantly enhancing its removal. Transcriptomic analysis further demonstrated that exogenous C6-HSL upregulated critical genes associated with ROS, Ca2+, and NO signaling, along with genes encoding antioxidant enzymes and those involved in SMX metabolism. These findings indicated that C6-HSL, as a bacterial QS signal, could enhance microalgal tolerance and antibiotic degradation, offering a novel strategy to improve microalgae-based antibiotic removal in wastewater treatment.

Advancing agricultural efficiency and sustainability: Bio-inspired superabsorbent hydrogels for slow and controlled release fertilizers

Bio-inspired superabsorbent hydrogels (BiSAHs) represent a versatile polymeric material class that has garnered significant interest due to their multifunctional attributes and extensive range of applications. A thorough examination of the literature and patents on BiSAHs highlights their critical role across diverse sectors. This review provides an in-depth analysis of BiSAHs, focusing on their classification, synthesis methodologies, and potential applications in agriculture. It critically examines biopolymer-based SAHs as soil conditioners and slow and controlled, focusing on their classification, synthesis methodologies, and potential applications in agriculture. It critically examines biopolymer-based SAHs as soil conditioners and slow and controlled-release fertilizers, elucidating the mechanisms governing water retention, swelling capacity, and nutrient release kinetics. The review further presents detailed case studies illustrating the enhancement of crop growth and productivity facilitated by BiSAHs and their effectiveness as agrochemical carriers. Moreover, it explores the role of SAHs in crop protection, particularly in mitigating adverse abiotic stresses such as heavy metal toxicity, salinity, and drought. The ecological, economic, and societal impacts of BiSAH-based controlled-release fertilizers are evaluated, providing a balanced perspective on their sustainability. Ultimately, the review offers insights into future directions and emerging advancements in the development and application of BiSAHs in agricultural settings.

Regulation of seed germination: ROS, epigenetic, and hormonal aspects

BACKGROUND

The whole life of a plant is regulated by complex environmental or hormonal signaling networks that control genomic stability, environmental signal transduction, and gene expression affecting plant development and viability. Seed germination, responsible for the transformation from seed to seedling, is a key initiation step in plant growth and is controlled by unique physiological and biochemical processes. It is continuously modulated by various factors including epigenetic modifications, hormone transport, ROS signaling, and interaction among them. ROS showed versatile crucial functions in seed germination including various physiological oxidations to nucleic acid, protein, lipid, or chromatin in the cytoplasm, cell wall, and nucleus.

AIM

of review: This review intends to provide novel insights into underlying mechanisms of seed germination especially associated with the ROS, and considers how these versatile regulatory mechanisms can be developed as useful tools for crop improvement.

KEY SCIENTIFIC CONCEPTS OF REVIEW

We have summarized the generation and elimination of ROS during seed germination, with a specific focus on uncovering and understanding the mechanisms of seed germination at the level of phytohormones, ROS, and epigenetic switches, as well as the close connections between them. The findings exhibit that ROS plays multiple roles in regulating the ethylene, ABA, and GA homeostasis as well as the Ca2+ signaling, NO signaling, and MAPK cascade in seed germination via either the signal trigger or the oxidative modifier agent. Further, ROS shows the potential in the nuclear genome remodeling and some epigenetic modifiers function, although the detailed mechanisms are unclear in seed germination. We propose that ROS functions as a hub in the complex network regulating seed germination.

The CmTGA1-CmRbohD Cascade Confers Resistance Against Chrysanthemum White Rust by Promoting Reactive Oxygen Species Generation

Chrysanthemum white rust (CWR), caused by Puccinia horiana Heen., is a serious disease of chrysanthemum worldwide. This disease reduces the quality and yield of Chrysanthemum morifolium, leading to significant losses for chrysanthemum growers and industries. It is often referred to as the 'cancer' of chrysanthemum. The most effective approach to managing CWR is to utilise host resistance. Reactive oxygen species (ROS) are conserved basic defence compounds in higher plants that are generated in response to biotic stresses. This study reported the TGACG-binding (TGA) transcription factor 1 (CmTGA1) in chrysanthemum. Subcellular localisation analysis revealed that CmTGA1 is localised in the nucleus and cytoplasm. Overexpression or knockout of CmTGA1 in chrysanthemum increased or reduced CWR resistance by regulating ROS generation, the activities of antioxidant enzymes, and CmRbohD (a gene mediating ROS generation) expression. Yeast one-hybrid, dual-luciferase, and electrophoretic mobility shift assays showed that CmTGA1 bound directly to the as-1 element in the promoter region of CmRbohD. Subcellular localisation analysis revealed that CmRbohD was localised in the cytomembrane and cytoplasm. CmRbohD was induced by P. horiana infection and enhanced CWR resistance by promoting ROS generation, activating the antioxidant enzyme system, and catalysing lignin biosynthesis. Our results showed that CmTGA1 activated CmRbohD to improve the CWR resistance via the ROS pathway in chrysanthemum. Our findings provided novel insights into the regulatory pathways involving the CmTGA1-CmRbohD cascade-mediated regulation of CWR resistance, demonstrating an effective strategy to improve tolerance to P. horiana in chrysanthemum.

Cyclophilin 20-3 coordinates plant root hair growth and resistance against parasitic nematodes

Plant parasitic nematodes (PPN) are a major threat to agriculturally important crops, resulting in substantial yield losses and economic repercussions. However, the underlying modes of plant-PPN interactions remain largely elusive. Here, we describe a critical role of cyclophilin (CYP)20-3, a plastid dual enzyme [i.e., peptidyl-prolyl isomerase (PPIase) and reductase) in plant basal resistance against PPN attacks. Originally, in order to define a present working model of whether plant roots deploy hypersensitive response (HR) to restrict PPN infections, we co-imaged the 'real-time' interactions of a proposed HR system, cotton LONREN-1 vs. Rotylenchulus reniformis. The root imaginings, however, revealed no clear HR pattern, instead underpinning a negative relationship between PPN populations and extended root hair growth. The latter was then identified to couple with the spatial expression of PPIases, including homologs of CYP20-3, a known receptor of 12-oxophytodienoic acid (OPDA) signal. To elaborate these findings further, we employed a reverse generic approach using a model plant Arabidopsis, and illuminated that knockout cyp20-3 mutants i) abnormalize root hair formations and ii) enhance susceptibility to PPN, Meloidogyne hapla, challenges. Nevertheless, M. hapla infections did not induce OPDA synthesis and signaling marker gene expressions in Arabidopsis roots. In parallel, transgenic Arabidopsis plants overexpressing mutant CYP20-3s defective OPDA-binding/signaling (H140Q) or PPIase (F74L) could still improve plant PPN defenses, whereas the overexpression of CYP20-3C129S (-reductase) demonstrated WT-level galling formations. Thus, we conclude that OPDA-independent CYP20-3-reductase signaling plays a key role in the plant defense metabolic pathway, fortifying protective barriers and conferring innate resistance against PPN attacks.

Unveiling the key toxicity indicators and mechanisms on phytotoxicity of cerium dioxide nanoparticles in rice (Oryza sativa)

The splendid varieties of cerium dioxide nanoparticles (nCeO2) and their diverse applications stimulated their uncontrolled discharge in the biological system. So, in the present study, Oryza sativa was adopted as a model plant and its phytotoxic effects were studied with neutrally charged, >12 nm sized spherical nCeO2 (0 g/L, 2 g/L, 4 g/L, 6 g/L, 8 g/L & 10 g/L). The studies were also conducted with bulk ceria counterparts and compared. This work is focused on a systematic approach to evaluate the phytotoxicity of nCeO2 in Oryza sativa, in terms of key toxicity indicators, nanoparticle uptake, and aggregation mechanisms. With this study, we propose a new sensing approach with non-fluorescent/non-chemiluminescent molecules for the detection of the generation of reactive oxygen species (ROS) to study the mechanism of phytotoxicity. An aggregation mechanism was also detailed to explicate the ROS-induced phytotoxicity. The study demonstrates that an increase in the production of ROS causes progressive cellular damage in Oryza sativa only at lower exposure level concentrations of nCeO2 (≥4 g/L). Our findings revealed that the key toxicity indicators and the actual nanoparticle uptake and aggregation mechanisms will decide the extent of phytotoxicity of nCeO2 in Oryza sativa.

CarboTag: a modular approach for live and functional imaging of plant cell walls

Plant cells are contained within a rigid network of cell walls. Cell walls serve as a structural material and a crucial signaling hub vital to all aspects of the plant life cycle. However, many features of the cell wall remain enigmatic, as it has been challenging to map its functional properties in live plants at subcellular resolution. Here, we introduce CarboTag, a modular toolbox for live functional imaging of plant walls. CarboTag uses a small molecular motif, a pyridine boronic acid, that directs its cargo to the cell wall. We designed a suite of cell wall imaging probes based on CarboTag in various colors for multiplexing. Additionally, we developed new functional reporters for live quantitative imaging of key cell wall characteristics: network porosity, cell wall pH and the presence of reactive oxygen species. CarboTag paves the way for dynamic and quantitative mapping of cell wall responses at subcellular resolution.

Trichoderma afroharzianum T22 Induces Rhizobia and Flavonoid-Driven Symbiosis to Promote Tolerance to Alkaline Stress in Garden Pea

Soil alkalinity is a limiting factor for crops, yet the role of beneficial fungi in mitigating this abiotic stress in garden pea is understudied. In this study, Trichoderma afroharzianum T22 colonised the roots of garden pea cultivars exposed to soil alkalinity in a host-specific manner. In alkaline-exposed Sugar Snap, T22 improved growth parameters, consistent with increased tissue mineral content, particularly Fe and Mn, as well as enhanced rhizosphere siderophore levels. The split-root assay demonstrated that the beneficial effects of T22 on alkaline stress mitigation are the result of a whole-plant association rather than localised root-specific effects. RNA-seq analysis showed 575 and 818 differentially expressed genes upregulated and downregulated in the roots inoculated with T22 under alkaline conditions. The upregulated genes were mostly involved in the flavonoid biosynthetic pathway (monooxygenase activity, ammonia-lyase activity, 4-coumarate-CoA ligase), along with genes related to mineral transport and redox homoeostasis. Further, a flavonoid precursor restored plant health even in the absence of T22, confirming the role of microbial symbiosis in mitigating alkaline stress. Interestingly, T22 restored the abundance of rhizobia, particularly Rhizobium leguminosarum and Rhizobium indicum, along with the induction of NifA, NifD, and NifH in nodules, suggesting a connection between T22 and rhizobia under soil alkalinity. Further, the elevated rhizosphere siderophore, root flavonoid, expression of PsCoA (4-coumarate-CoA ligase) as well as the relative abundance of TaAOX1 and R. leguminosarum diminished when T22 was substituted with exogenous Fe. This suggests that exogenous Fe eliminates the need for microbiome-driven mineral mobilisation, while T22-mediated alkaline stress mitigation depends on flavonoid-driven symbiosis and R. leguminosarum abundance. It was further supported by the positive interaction of T22 on R. leguminosarum growth in alkaline media. Thus, the beneficial effect of T22 on rhizobia likely stems from their interactions, not solely from the improved mineral status, particularly Fe, in plants. This study provides the first mechanistic insights into T22 interactions with host and rhizobia, advancing microbiome strategies to alleviate soil alkalinity in peas and other legumes.

WGCNA analysis reveals hub genes in the Hemarthria compressa roots in response to waterlogging stress

Hemarthria compressa is a high-quality forage resource in China. In recent years, waterlogging has frequently occurred, adversely affecting the growth and development of H. compressa. In order to investigate the physiological and molecular response mechanisms of H. compressa under waterlogging stress and identify hub genes involved in waterlogging tolerance, H. compressa roots from the GY (waterlogging-tolerant) and N1291 (waterlogging-sensitive) cultivars were selected as experimental materials in this study. The physiological indexes of H. compressa were measured, and transcriptome sequencing was carried out after 8 h and 24 h of waterlogging stress, with 0 h used as the control group. Superoxide dismutase (SOD) and peroxidase (POD) activities were significantly increased in both GY and N1291 under waterlogging stress (P < 0.05). Weighted gene co-expression network analysis (WGCNA) identified a total of four modules significantly associated with waterlogging stress (r>|0.9|, P < 0.05). Gene ontology (GO) and Kyoto encyclopedia of genes and genomes (KEGG) enrichment results showed that differentially expressed genes (DEGs) were mainly enriched in the Starch and sucrose metabolism, Plant hormone signal transduction, Ribosome and Glutathione metabolism pathways. Seven hub genes were also retrieved, including Cluster-38255.67514 and Cluster-38255.80127, potentially associated with waterlogging tolerance. It is related to the Ribosome pathway and participates in the process of anti-waterlogging regulation. The results of this experiment provide new insights into the response mechanisms of H. compressa to waterlogging stress and a theoretical framework for the effective selection and breeding of waterlogging-tolerant cultivars.

Overexpression of Rboh enhances inorganic carbon acquisition through coordinating with carbonic anhydrase in Pyropia yezoensis

Pyropia yezoensis is an important intertidal economic macroalgae, which is periodically affected by various stresses, such as the limitation of inorganic carbon (Ci) deficiency. Under such environment, the redox homeostasis within the cells of P. yezoensis is seriously affected, and the reactive oxygen species (ROS) signal transduction system would be activated to regulate the photosynthetic activity. Therefore, how P. yezoensis manage ROS to maintain effective photosynthetic carbon fixation has aroused great interest. Here, we characterize transformants overexpressing respiratory burst oxidase homolog (Rboh), an important gene that can actively produce ROS, at the levels of cellular physiology, biochemistry, and transcriptomics. Our data indicated the expression of Rboh significantly increased, accompanied by a significant upregulated expression of alpha-type carbonic anhydrase 3 (αCA3) and increased extracellular carbonic anhydrase activity in the Rboh overexpressing strains. Interestingly, compared with the wild type, the photosynthetic activity of transgenic strains was significantly higher under the low Ci and high light condition, implying that the ROS signal triggered by overexpression of Rboh was involved in regulating the Ci absorption and utilization in P. yezoensis when the Ci source was limited. In summary, this study provided evidence supporting the correlation between the ROS production and the Ci utilization under stress environments in P. yezoensis.

Effects of exogenous chitosan concentrations on photosynthesis and functional physiological traits of hibiscus under salt stress

BACKGROUND

Soil salinity is a major barrier to plant growth and yield improvement. Chitosan, a versatile biomaterial, has shown potential in enhancing plant stress tolerance. This study evaluated the effectiveness of chitosan pretreatment in mitigating salt stress hibiscus (Hibiscus syriacus L.). Two-year-old hibiscus cuttings were treated with varying concentrations of chitosan (10 mg/L, 25 mg/L, 50 mg/L, 100 mg/L) via root irrigation and foliar spray in a 6‰ saline environment. Growth parameters, gas exchange rates, antioxidant enzyme activities, and osmotic regulatory compounds were analyzed.

RESULTS

The results showed that chitosan at 25 mg/L and 50 mg/L significantly improved physiological and ecological traits. These concentrations enhanced photosynthetic performance, protected photosynthetic electron transport chain, and reduced malondialdehyde (MDA) content and relative conductivity, thereby limiting cell membrane damage. Additionally, the accumulation of soluble proteins, soluble sugars, and proline increased, improving the plants' ability to cope with salt stress. Antioxidant enzyme activities, including superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), and ascorbate peroxidase (APX), were notably elevated, while levels of hydrogen peroxide (H₂O₂) and superoxide anion (O₂-) decreased.

CONCLUSIONS

The 25 mg/L and 50 mg/L treatments had the most pronounced effects, confirming that moderate chitosan concentrations effectively alleviate salt stress in hibiscus. This study underscores the role of chitosan in enhancing salt stress adaptability, offering insights for plant protection and greening efforts.

Mutation of TaNRAMP5 impacts cadmium transport in wheat

Cadmium (Cd) pollution significantly impacts the normal growth, development, and food safety of wheat. Employing modern molecular biology techniques represents an effective strategy for cultivating low-Cd wheat. Natural resistance-associated macrophage protein 5 (NRAMP5) is a critical heavy metal transporter, however, its function in wheat, particularly in response to Cd stress, remains largely unexplored. Here, we employed the CRISPR/Cas9 gene-editing technology to generate TaNRAMP5 knockout lines (KO). Cd content in wheat was detected by inductively coupled plasma mass spectrometry (ICP-MS). And RNA sequencing was used to explore the key factors of Cd stress response in wheat. The results indicated that under Cd stress, the KO lines exhibited significantly reduced Cd accumulation in the roots compared to the wild type (WT) plants, while the shoots showed an opposite trend. Notably, the knockout of TaNRAMP5 resulted in a 33.46 % reduction in Cd concentration in the grains. Furthermore, the knockout of TaNRAMP5 led to a decrease in wheat grain yield; however, the application increased amounts of compound fertilizers can mitigate the yield loss associated with the TaNRAMP5 mutant. Additionally, transcriptome sequencing revealed significant differences in gene expression profiles between KO and WT plants under Cd stress, particularly in the root samples. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis indicated that the differently expressed genes (DEGs) induced by Cd stress were primarily involved in processes of "plant hormone signal transduction", "starch and sucrose metabolism", and "phenylpropanoid biosynthesis". Overall, our results suggested that the knockout of TaNRAMP5 can effectively reduce Cd accumulation in wheat. These findings may provide a potential genetic basis for the improving of wheat varieties to reduce Cd contamination in grains and ensure food safety.

The kinase ATM delays Arabidopsis leaf senescence by stabilizing the phosphatase MKP2 in a phosphorylation-dependent manner

Arabidopsis thaliana (Arabidopsis) Ataxia Telangiectasia Mutated (ATM) kinase plays a vital role in orchestrating leaf senescence; however, the precise mechanisms remain elusive. Here, our study demonstrates that ATM kinase activity is essential for mitigating age- and reactive oxygen species-induced senescence, as restoration of wild-type ATM reverses premature senescence in the atm mutant, while a kinase-dead ATM variant is ineffective. ATM physically interacts with and phosphorylates Mitogen-Activated Protein Kinase Phosphatase 2 (MKP2) to enhance stability under oxidative stress. Mutations in putative phosphorylation sites S15/154 on MKP2 disrupt its phosphorylation, stability, and senescence-delaying function. Moreover, mutation of mitogen-activated protein kinase 6, a downstream target of MKP2, alleviates the premature senescence phenotype of the atm mutant. Notably, the dual-specificity protein phosphatase 19 (HsDUSP19), a predicted human counter protein of MPK2, interacts with both ATM and HsATM and extends leaf longevity in Arabidopsis when overexpressed. These findings elucidate the molecular mechanisms underlying the role of ATM in leaf senescence and suggest that the ATM-MKP2 module is likely evolutionarily conserved in regulating the aging process across eukaryotes.

Anthocyanins promote the abundance of endophytic lactic acid bacteria by reducing ROS in Medicago truncatula

The microbial community residing on the phyllosphere is influenced by many factors, including the host plant's genotype as well as its secondary metabolites. Anthocyanins are a group of flavonoids renowned for their antioxidative properties and are widely distributed across plant tissues. However, the potential impact of anthocyanins on plant-associated microbial communities remains unknown. In the model legume Medicago truncatula, we isolated a mutant named purple leaves (pl) that produces purple leaves at a young stage due to over-accumulated anthocyanins. Through sequencing 16S rRNA amplicons of phyllosphere microbes in the pl mutant, we show that anthocyanins significantly enhance the abundance of endophytic lactic acid bacteria within plant leaves. Further in vitro study revealed that anthocyanins derived from pl can significantly promote the growth of lactic acid bacteria under anaerobic conditions. The accumulated anthocyanins in pl leaves reduced reactive oxygen species (ROS), thereby creating a favorable environment for the growth of facultative anaerobic lactic acid bacteria and resultantly increasing the abundance of phyllosphere lactic acid bacteria. Our findings elucidate the role of anthocyanins in modulating the community structure of phyllosphere microbiota in M. truncatula and provide new insights into the relationship between plant secondary metabolites and phyllosphere microbiota.

Arbuscular mycorrhiza inoculation mitigates the adverse effects of heat stress on yield and physiological responses in strawberry plants

Arbuscular mycorrhizal fungi (AMF) form a beneficial symbiotic relationship with plant roots, providing them with ample water and nutrients, especially under stressful conditions. It is inevitable to experience heat stress (HS) due to climate changes. The objective of this study was to investigate the possible role of AMF (with AMF = +AMF and without AMF = -AMF) on the strawberry cvs. ('Paros' and 'Queen Eliza')-resilience to HS at temperatures (control (23), 30, 35, 40, and 45 °C). The experiment was completely randomised and designed as a factorial arrangement with four replicates. The findings indicated that as the temperature increased, there was an increase in electrolyte leakage, proline, soluble carbohydrate contents and the activity of antioxidant enzymes including superoxide dismutase (SOD), catalase (CAT), and peroxidase (POX). The presence of AMF at high temperatures improved the relative water content (RWC), maximum quantum efficiency yield of photosystem II (Fv/Fm), chlorophyll a, b, and total chlorophyll compared to the -AMF. AMF promoted root colonization and the content of phosphorus and potassium, which was more in the cv. 'Paros' than the cv. 'Queen Eliza'. Primary and secondary fruit weights and plant yield were reduced by HS; however, the AMF effectively increased average fruit weight and yield in comparison to plants without AMF. Yield was positively correlated with RWC and Fv/Fm, and root colonization was positively associated with phosphorus concentration. Adding AMF to rhizosphere improved plant growth and nutrient uptake and increased strawberry-resilience to HS. They have achieved this by increasing antioxidative activity, proline, soluble carbohydrates, and RWC. The symbiotic relationship with AMF greatly enhanced the strawberry's ability to tolerate HS.

A rice DELLA protein OsSLR1 positively regulates rice resistance to southern rice black-streaked dwarf virus infection

BACKGROUND

In the course of long-term confrontation with pathogens, plants have developed complex defense mechanisms to protect themselves from various pathogens. Previous studies have reported that the gibberellin (GA) signaling pathway negative regulator SLENDER RICE 1 (SLR1) in rice activates jasmonic acid (JA)-mediated broad-spectrum antiviral immunity, but the exploration regarding whether OsSLR1 exerts effects on alternative antiviral immune pathways remains limited.

RESULTS

Here, we identified that OsSLR1 was significantly induced after virus infection and overexpression of OsSLR1 in rice enhance the resistance of rice to southern rice black-streaked dwarf virus (SRBSDV) in rice. Transcriptome analysis revealed that a total of 2,336 differentially expressed genes (DEGs) were detected upon overexpression of OsSLR1 in rice, including 1,607 upregulated genes and 729 downregulated genes. Gene ontology (GO) enrichment analysis and RT-qPCR analysis revealed that genes related to JA and reactive oxygen species (ROS) were significantly upregulated, while genes associated with abscisic acid (ABA) were significantly downregulated.

CONCLUSIONS

These results suggest that OsSLR1 positively regulates the antiviral immunity of rice by modulating multiple pathways.

Overexpression of OsPIN5b Alters Plant Architecture and Impairs Cold Tolerance in Rice (Oryza sativa L.)

Auxin plays a versatile role in regulating plant growth and development. The auxin efflux carrier PIN-FORMED (PIN) proteins dictate the distribution and maximum of auxin within various tissues. Despite extensive research on OsPINs in recent years, their functions in abiotic stress resistance, particularly cold tolerance, remain poorly understood. Here, we investigated the role of OsPIN5b in rice (Oryza sativa L.) growth and development, as well as its contribution to cold tolerance using overexpression technology. Overexpression of OsPIN5b (OE) resulted in reduced shoot height and a lower number of adventitious roots at the seedling stage. Transgenic rice plants exhibited an earlier heading date, stunted growth, and compromised agronomic traits, including shortened panicle length, decreased grain number per panicle, reduced seed size, and lower seed setting rate during the reproductive stage. Auxin content in the transgenic lines was significantly elevated, as indicated by the upregulation of the auxin-responsive gene OsIAA20 and increased auxin levels quantified using a newly developed method. Compared with wild-type plants, the cold tolerance of OE plants was markedly reduced, as evidenced by lower survival rates, higher levels of electrolyte leakage, and increased malondialdehyde (MDA) production following cold treatment. In line with this, the transgenic lines produced less soluble sugar and proline, while accumulating more hydrogen peroxide (H2O2) and superoxide anion radicals (O2-) after cold treatment. Furthermore, the activities of antioxidant enzymes, including catalase (CAT), superoxide dismutase (SOD), and peroxidase (POD), were notably decreased upon cold treatment compared with those in WT plants. Additionally, OsRBOHH, which plays a role in ROS production, was significantly upregulated in transgenic lines both before and after chilling stress, suggesting that OsRBOHH plays a potential role in regulating ROS production. Collectively, overexpression of OsPIN5b substantially disturbs auxin homeostasis, resulting in impaired plant architecture and agronomic traits. More importantly, the upregulation of OsPIN5b compromises rice cold tolerance by perturbing ROS homeostasis and adversely influencing the accumulation of soluble sugar and proline.

Genome-wide identification and characterization of NCED gene family in soybean (Glycine max L.) and their expression profiles in response to various abiotic stress treatments

The NCED (9-cis-epoxy carotenoid dioxygenase) enzyme regulates the biosynthesis of abscisic acid (ABA), which is responsible for plant growth, development, and response to various environmental challenges. However, no genome-wide identification, characterization, functional regulatory element analysis, and expression profiles in response to different abiotic stresses of the NCED gene family have yet to be investigated in an economically important legume plant species, soybean (Glycine max L.). Through comprehensive analysis, 16 NCED genes (named GmNCED1 to GmNCED16) belonging to the RPE65 domain were identified in the soybean genome and found to be unequally distributed over 9 distinct chromosomes. The distinct intron-exon structures of GmNCED genes were categorized into six groups and shared a close relationship with the grapevine. Segmental gene duplication events and the purifying selection process were evident in GmNCED genes, according to evolutionary studies. Cis-acting regulatory element analysis revealed that GmNCED genes were largely associated with light response as well as stress response. ERF, MYB, bZIP, and LBD emerged as the major transcription factors in GmNCED genes. The protein-protein interactions demonstrated the close relationship between GmNCED and Arabidopsis thaliana proteins, while micro-RNA analysis revealed the involvement of GmNCED genes in plant growth and development as well as in the regulation of abiotic stress. The expression profiles of GmNCED2, GmNCED11, and GmNCED12 provided evidence of their engagement in dehydration and sodium salt stress, whereas GmNCED14 and GmNCED15 were up-regulated in drought stress. Moreover, the up-regulation of GmNCED13 and GmNCED14 genes in heat tolerant germinated seed stages at high temperature delta region. More specifically, GmNCED14 might be used as a novel candidate gene under drought stress, and influencing seed germination at high temperature. Overall, this study identified the crucial role of GmNCED in conferring resistance against abiotic stress such as dehydration, salt, and drought, and also uncovering the detailed regulatory mechanism of ABA biosynthesis during seed germination.

Peptides and Reactive Oxygen Species Regulate Root Development

Like phytohormones, peptide hormones participate in many cellular processes, participate in intercellular communications, and are involved in signal transmission. The system of intercellular communications based on peptide-receptor interactions plays a critical role in the development and functioning of plants. One of the most important molecules are reactive oxygen species (ROS). ROS participate in signaling processes and intercellular communications, including the development of the root system. ROS are recognized as active regulators of cell division and differentiation, which depend on the oxidation-reduction balance. The stem cell niche and the size of the root meristem are maintained by the intercellular interactions and signaling networks of peptide hormone and ROS. Therefore, peptides and ROS can interact with each other both directly and indirectly and function as regulators of cellular processes. Peptides and ROS regulate cell division and stem cell differentiation through a negative feedback mechanism. In this review, we focused on the molecular mechanisms regulating the development of the main root, lateral roots, and nodules, in which peptides and ROS participate.

Magnetic Nanoparticles in Agriculture: Unraveling the Impact of Nickel Ferrite Nanoparticles on Peanut Growth and Seed Nutritional Quality

Nanotechnology has been a source of innovation in various fields in recent years, and its application in agriculture has attracted much attention, particularly for its potential to enhance crop growth and optimize nutritional quality. This study systematically investigated the effects of nickel ferrite nanoparticles (NiFe2O4 NPs) on peanut (Arachis hypogaea L.) growth, nutrient dynamics, and biochemical responses, highlighting their potential as sustainable alternatives to conventional fertilizers. The results showed that an optimum concentration of 50 mg/kg soil significantly improved photosynthetic efficiency, biomass accumulation, seed yield, and nutritional quality, with 1000 seed weight and total yield increasing by 12.3% and 15.6%, respectively. In addition, we hypothesized that NiFe2O4 NPs would activate the antioxidant system and increase plant resistance. According to the risk assessment, the target hazard quotient (THQ = 0.081) is well below the safety threshold of 1. These findings provide strong evidence for the application of NiFe2O4 NPs as next-generation nano-fertilizers, offering a dual advantage of improved agronomic performance and biosafety. However, further research is needed to optimize their application strategies and assess potential long-term environmental impacts.

Genome-wide analysis of ascorbate peroxidase and functional characterization of SpAPX249b and SpAPX285c for salt tolerance in Sesuvium portulacastrum L

KEY MESSAGE

We have identified 33 SpAPXs from S. portulacastrum genome and found SpAPX249b and SpAPX285c are important for halophyte salt tolerance. Ascorbate peroxidase (APX) is a vital antioxidant enzyme, involved in plant development and stress response by scavenging excessive reactive oxygen species (ROS). APX genes have been characterized in many plant species. However, their role in Sesuvium portulacastrum L. has not yet to be fully investigated. Here, we identified 33 SpAPXs from its genome and divided them into five subgroups across the 16 chromosomes. Cis-element analysis of their promoters indicated that all the detected SpAPXs showed potential roles in response to biotic and abiotic stresses as well as phytohormone effects on the plant growth and development. Transcriptomic data of the different tissues revealed that 9 SpAPX genes were specifically expressed in root and 13 ones were specifically expressed in leaves, with SpAPX249b prominently expressed in root and SpAPX285c in leaves. Moreover, quantitative real-time PCR analysis revealed that both SpAPX249b and SpAPX285c genes expressed only after NaCl application and were sharply induced in the high concentration of NaCl treatments. Our findings suggested that SpAPX249b and SpAPX285c may associate with plant salt tolerance and can serve as valuable genes for enhancing salt tolerance in other plants. By introducing these genes into other plants, it is possible to develop new varieties of salt-tolerant crops, thereby expanding the utilization of saline-alkali land and increasing agricultural productivity. In coastal saline-alkali wetlands, this halophyte can thrive in large numbers due to its inherent salt-tolerant genes, contributing to the restoration of polluted or ecologically degraded coastal saline-alkali wetlands.

Comparative Analysis of Salt Tolerance and Transcriptomics in Two Varieties of Agropyron desertorum at Different Developmental Stages

BACKGROUND

Most of the grasslands in China are experiencing varying degrees of degradation, desertification, and salinization (collectively referred to as the "three degradations"), posing a serious threat to the country's ecological security. Agropyron desertorum, known for its wide distribution, strong adaptability, and resistance, is an excellent grass species for the ecological restoration of grasslands affected by the "three degradations". This study focused on two currently popular varieties of A. desertorum, exploring their salt tolerance mechanisms and identifying candidate genes for salt and alkali tolerance.

METHODS

Transcriptome sequencing was performed on two varieties of A. desertorum during the seed germination and seedling stages under varying degrees of saline-alkali stress. At the seed stage, we measured the germination rate, relative germination rate, germination index, and salt injury rate under different NaCl concentrations. During the seedling stage, physiological indicators, including superoxide dismutase (SOD), peroxidase (POD), malondialdehyde (MDA), proline (PRO), soluble protein (SP), and catalase (CAT), were analyzed after exposure to 30, 60, 120, and 180 mM NaCl for 12 days. Analysis of differentially expressed genes (DEGs) at 6 and 24 h post-treatment with 120 mM NaCl revealed significant differences in the salt stress responses between the two cultivars.

RESULTS

Our study indicates that during the seed stage, A. desertorum (Schult.) exhibits a higher relative germination potential, relative germination rate, and relative germination index, along with a lower relative salt injury rate compared to A. desertorum cv. Nordan. Compared with A. desertorum cv. Nordan, A. desertorum (Schult.) has higher salt tolerance, which is related to its stronger antioxidant activity and different antioxidant-related pathways. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses were used to identify the key biological processes and pathways involved in salt tolerance, including plant hormone signal transduction, antioxidant defense, and cell membrane stability.

CONCLUSIONS

A. desertorum (Schult.) exhibits stronger salt tolerance than A. desertorum cv. Nordan. Salt stress at a concentration of 30-60 mM promotes the germination of the seeds of both Agropyron cultivars. The two Agropyron plants mainly overcome the damage caused by salt stress through the AsA-GSH pathway. This study provides valuable insights into the molecular mechanisms of salt tolerance in Agropyron species and lays the groundwork for future breeding programs aimed at improving salt tolerance in desert grasses.

Enzyme evolution and antioxidant defense in salt-stressed Kunthali rice: A pathway to sustainable biocatalytic solutions for crop improvement

Kunthali (KTL), an indigenous rice variety from Tamil Nadu, India, was tested for its salt-tolerant capacity compared to commercial rice variety, IR64. Present study uncovered that KTL had a more effective response to salinity stress stimulus, as this cultivar uses reactive oxygen species scavenging mechanism through antioxidative enzymes like Superoxide dismutase, Catalase and Peroxidase. While KTL had lower levels of these enzymes compared to IR64, showed better modulation of total chlorophyll, carotenoids, anthocyanin, hydrogen peroxide, ascorbic acid, malondialdehyde, and proline contents also showed significant (p < 0.05) moderation upon salinity stress. In KTL, there was a significant correlation between the levels of H2O2 and antioxidant enzymes activity, which was not observed inIR64. Morphological, functional and biochemical investigations unveiled KTL as a promising candidate for salt-tolerance in TN, India. Advanced analysis using deep and machine learning techniques was used to analyze and predict the features essential for sustaining the salinity stress condition in rice. Principal component analysis and factor loadings provided a better understanding of salt-tolerant rice variables and placed apart the salt-sensitive rice. Correlation and regression charts gave a clear variable relationship between salt-tolerant and separated salt-sensitive rice. Comparatively, deep neural networks (DNN) predicted better features and models than machine learning techniques.

Effects of Varying Nitrogen Concentrations on the Locule Number in Tomato Fruit

Tomato seedlings were treated with nutrient solutions containing varying nitrogen concentrations (50, 150, and 250 mg·L-1) after germination until the completion of flower bud differentiation. The changes in nutrient content, enzyme activity, endogenous hormone levels, and gene expression in the stem apex were analyzed to explore the mechanisms regulating the number of locules in tomatoes at different nitrogen concentrations. The results indicated that an increase in nitrogen concentration facilitated the differentiation of tomato flower buds, increased the number of fruit locules, and increased the contents of soluble sugar, soluble protein, starch, and sucrose, as well as the activities of the enzymes POD, NR, and PPO in the seedling stem apex. The contents of soluble sugars and soluble proteins, as well as the activities of POD, NR, and PPO, were closely correlated with the number of fruit locules. An increase in nitrogen concentration was also found to elevate cytokinin levels while reducing auxin content in the stem apex. The transcriptome analysis screened for peroxidase genes, auxin response genes, and cytokinin synthesis genes. The analysis of gene expression patterns suggests that CKX and LOG6 play significant roles in flower development. Additionally, combined physiological changes indicated that an increase in nitrogen concentration during the tomato seedling stage leads to a higher number of fruit locules, which may be associated with elevated cytokinin content, primarily involving the key genes CKX and LOG6.

Identification and validation of hub genes associated with biotic and abiotic stresses by modular gene co-expression analysis in Oryza sativa L

Rice, a staple food consumed by half of the world's population, is severely affected by the combined impact of abiotic and biotic stresses, with the former causing increased susceptibility of the plant to pathogens. Four microarray datasets for drought, salinity, tungro virus, and blast pathogen were retrieved from the Gene Expression Omnibus database. A modular gene co-expression (mGCE) analysis was conducted, followed by gene set enrichment analysis to evaluate the upregulation of module activity across different stress conditions. Over-representation analysis was conducted to determine the functional association of each gene module with stress-related processes and pathways. The protein-protein interaction network of mGCE hub genes was constructed, and the Maximal Clique Centrality (MCC) algorithm was applied to enhance precision in identifying key genes. Finally, genes implicated in both abiotic and biotic stress responses were validated using RT-qPCR. A total of 11, 12, 46, and 14 modules containing 85, 106, 253, and 143 hub genes were detected in drought, salinity, tungro virus, and blast. Modular genes in drought were primarily enriched in response to heat stimulus and water deprivation, while salinity-related genes were enriched in response to external stimuli. For the tungro virus and blast pathogen, enrichment was mainly observed in the defence and stress responses. Interestingly, RPS5, PKG, HSP90, HSP70, and MCM were consistently present in abiotic and biotic stresses. The DEG analysis revealed the upregulation of MCM under the tungro virus and downregulation under blast and drought in resistant rice, indicating its role in viral resistance. HSP70 showed no changes, while HSP90 was upregulated in susceptible rice during blast and drought. PKG increased during drought but decreased in japonica rice under salinity. RPS5 was highly upregulated during blast in both resistant and susceptible rice. The RT-qPCR analysis showed that all five hub genes were upregulated in all treatments, indicating their role in stress responses and potential for crop improvement.

Root-zone oxygen supply mitigates waterlogging stress in tomato by enhancing root growth, photosynthetic performance, and antioxidant capacity

Water-air coupled oxygen supply to the root zone can significantly enhance crop yield and quality under non-waterlogged conditions. However, its impact on crops subjected to waterlogging-induced hypoxia remains unclear. In this study, tomatoes were chosen as the model crop due to their economic value and sensitivity to waterlogged conditions. Two tomato cultivars, "Micro-Tom" and "Omanda-3," were subjected to waterlogging and treated with varying levels of water-air coupled oxygen supply. The results demonstrated that supplying 25 mL or 50 mL of air per plant to the root zone significantly improved biomass compared to waterlogged plants without additional oxygen. Notably, root dry weight increased by over 73.0% in both varieties. Root morphological analysis revealed that oxygen supply in the root zone greatly promoted root growth, with marked increases in surface area (149.7%), root length (181.2%), fork number (198.4%), and tip number (165.4%). Furthermore, photosynthesis and antioxidant assays showed substantial increases in the leaf net photosynthetic rate, transpiration rate, stomatal conductance, as well as catalase and peroxidase activity in response to oxygen supply. Consequently, fruit yield increased by 86.2% in Micro-Tom and 24.3% in Omanda-3. In conclusion, oxygen supplementation through the water-air coupling technique effectively enhanced root growth, photosynthesis, and antioxidant capacity in waterlogged tomato plants, alleviating hypoxic stress and associated yield losses. These findings offer a theoretical basis and practical recommendations for managing waterlogged farmland in diverse agricultural contexts.

Flash drought as possible contributor to seedling dieback in the endangered conifer Abies koreana

Tree species grown at high altitudes experience significantly greater stress than those at lower altitudes. A notable example is Abies koreana, a conifer recently classified as endangered due to a decline in normal seedling distribution within Korean natural forests. While several hypotheses have been proposed to explain this phenomenon, the underlying causes remain unclear. Recent studies highlight that Korean forest tree species are increasingly vulnerable to flash drought (FD) events. However, it is still unknown whether this intense FD event affects the growth and distribution of high-altitude grown and endangered species like Abies koreana. To address this gap, we investigated the effects of FD on root carbon allocation, volatile biosynthesis, fatty acid modulation, and genome-wide modifications. Exposure to FD in three-year-old A. koreana seedlings primarily disrupted leaf chlorophyll biosynthesis, likely due to the depletion of root water and non-structural carbohydrates (NSC) transport to above-ground parts. Additionally, FD caused severe morphological changes, including reductions in root collar diameter along with root cortical senescence. These alterations are linked to transcriptomic variations, particularly mRNA decay and the repression of genes coding for ribosomal proteins. Seedlings exposed to FD also exhibited increased levels of abscisic acid (ABA) and poly-unsaturated fatty acids. The observed patterns and molecular mechanisms in FD-treated seedlings differed significantly from those observed for control and mild drought (MD) treatments. These findings suggest that FD conditions trigger rapid carbon reserve depletion and gene repression associated with root structural integrity, potentially leading to seedling mortality in Abies koreana seedlings.

Tolerance to combined drought and heat stress in edamame is associated with enhanced antioxidative responses and cell wall modifications

Drought and heat stress often co-occur in nature, and their combined effects are a major driver of crop losses, causing more severe damage to plant metabolism than when they occur individually. This study investigates the responses of three edamame cultivars (AGS429, UVE14, and UVE17) to combined drought and heat (DH) stress, with emphasis on the reactive oxygen species (ROS), antioxidative mechanisms and cell wall modifications. Malondialdehyde (MDA), electrolyte leakage (EL), and hydrogen peroxide (H2O2) were used to measure oxidative stress and membrane damage. The non-enzymatic (ascorbic acid, AsA) and enzymatic (superoxide dismutase, ascorbate peroxidase (APX), guaiacol peroxidase, and glutathione reductase) antioxidant responses were determined spectrophotometrically. Cell wall biomass composition (cellulose, hemicellulose, lignin, and phenols) was determined using Fourier transform Infrared Spectroscopy and spectrophotometry. Ascorbate peroxidase activity and AsA content in DH-stressed AGS429 at flowering strongly correlated to reduced lipid peroxidation (r2 = -0.97 and - 0.98). Cultivar UVE14 accumulated high AsA under DH stress at both growth stages, which, in turn, was positively associated with total phenolic content (r2 = 0.97), APX activity, and holocellulose, suggesting enhanced ROS-dependent oxidative polymerisation. On the contrary, poor ROS quenching in UVE17 led to MDA accumulation (p ≤ 0.05), leading to high EL and poor cellulose synthesis at pod-filling (r2 = -0.88). Therefore, at the physio-biochemical level, AGS429 and UVE14 showed DH stress tolerance through enhanced antioxidative responses and cell wall modifications, while UVE17 was susceptible. Identifying the key biochemical traits linked to DH stress tolerance in edamame offers novel insights for breeding more resilient edamame cultivars.

Comparative transcriptomic analysis reveals the reactive oxygen species metabolism involving in melatonin-alleviated chilling injury in postharvest banana fruit

Banana fruit is susceptible to chilling injury (CI) during cold storage, which causes quality deterioration and commodity value decline. Here, the effects of melatonin on CI alleviation and reactive oxygen species (ROS) metabolism in postharvest banana were studied. The results displayed that 500 μmol L-1 melatonin treatment effectively inhibited CI development in cold-stored banana during the 96 h of storage. Additionally, lower O2.- productive rate and H2O2 content, but higher contents of ascorbic acid (AsA) and glutathione (GSH) were found in melatonin-treated banana, compared with control fruits. Also, melatonin inhibited the declined activities of antioxidant enzymes. Moreover, a total of 1858 and 330 differentially expressed genes (DEGs) were identified between the comparison of CK48h (control bananas at 48 h) and MT48h (melatonin-treated bananas at 48 h), and CK96h (control bananas at 96 h) and MT96h (melatonin-treated bananas at 96 h) through comparative transcriptome analysis of banana fruit, respectively. Further KEGG displayed that DEGs were enriched in secondary metabolites biosynthesis, MAPK signaling pathway-plant and plant hormone signal transduction. The transcriptome expression profiling and RT-qPCR exhibited melatonin treatment improved the expressions of antioxidant enzyme genes (MaSOD, MaCAT, MaAPX and MaGR) but inhibited the expression of ROS production gene (MaRBOH). Collectively, these findings provide a comprehensive view of ROS metabolism associated with the melatonin-alleviated CI in cold-stored banana fruit.

Ca2+-dependent H2O2 response in roots and leaves of barley - a transcriptomic investigation

BACKGROUND

Ca2+ and H2O2 are second messengers that regulate a wide range of cellular events in response to different environmental and developmental cues. In plants, stress-induced H2O2 has been shown to initiate characteristic Ca2+ signatures; however, a clear picture of the molecular connection between H2O2-induced Ca2+ signals and H2O2-induced cellular responses is missing, particularly in cereal crops such as barley. Here, we employed RNA-seq analyses to identify transcriptome changes in roots and leaves of barley after H2O2 treatment under conditions that inhibited the formation of cytosolic Ca2+ transients. To that end, plasma membrane Ca2+ channels were blocked by LaCl3 application prior to stimulation of barley tissues with H2O2.

RESULTS

We examined the expression patterns of 4246 genes that had previously been shown to be differentially expressed upon H2O2 application. Here, we further compared their expression between H2O2 and LaCl3 + H2O2 treatment. Genes showing expression patterns different to the previous study were considered to be Ca2+-dependent H2O2-responsive genes. These genes, numbering 331 in leaves and 1320 in roots, could be classified in five and four clusters, respectively. Expression patterns of several genes from each cluster were confirmed by RT-qPCR. We furthermore performed a network analysis to identify potential regulatory paths from known Ca2+-related genes to the newly identified Ca2+-dependent H2O2 responsive genes, using the recently described Stress Knowledge Map. This analysis indicated several transcription factors as key points of the responses mediated by the cross-talk between H2O2 and Ca2+.

CONCLUSION

Our study indicates that about 70% of the H2O2-responsive genes in barley roots require a transient increase in cytosolic Ca2+ concentrations for alteration in their transcript abundance, whereas in leaves, the Ca2+ dependency was much lower at about 33%. Targeted gene analysis and pathway modeling identified not only known components of the Ca2+ signaling cascade in plants but also genes that are not yet connected to stimuli-associated signaling. Potential key transcription factors identified in this study can be further analyzed in barley and other crops to ultimately disentangle the underlying mechanisms of H2O2-associated signal transduction mechanisms. This could aid breeding for improved stress resistance to optimize performance and productivity under increasing climate challenges.

Exogenous bacterial cellulose induces plant tissue regeneration through the regulation of cytokinin and defense networks

Regeneration is a unique feature of postembryonic development extensively observed in plants. The capacity to induce regeneration exogenously is limited and usually confined to meristematic-like tissues. We show that bacterial cellulose (BC), but not other structurally similar matrixes, induces postwounding regeneration in nonmeristematic plant tissues via a distinctive route to callus-mediated regenerative programs. The BC-specific program involves cytokinin operating concurrently with strongly activated plant biotic response genes to induce plant regeneration. A reactive oxygen species (ROS) burst, normally associated with defense responses, is sustained upon BC application, involving a network of tightly interconnected transcription factors, where WRKY8, known for regulating stress responses, shows a clustering and hierarchical prevalence. WRKY8 regulates BC-mediated plant regeneration and ROS homeostasis, including superoxide anion accumulation, to potentially promote cell proliferation after wounding. Collectively, our results demonstrate that the cytokinin- and ROS-associated defense responses can be targeted by BC application to promote plant wound regeneration through alternative regenerative programs.

Characterization of green-synthesized zinc oxide nanoparticles and its influence on post-harvest shelf-life of garlic against black mold disease caused by Aspergillus niger

Garlic is an important spice crop used for flavoring food and has a long history of use in traditional medicine. However, black mold is a common fungal disease affecting garlic, which was caused by an Aspergillus infection. This disease significantly impacts both the production and quality of garlic. Therefore, this study aimed to evaluate the antifungal activity of novel green-synthesized zinc oxide nanoparticles (ZnO-NPs) against black mold diseases in garlic. An environmentally friendly green synthesis technique was used to produce ZnO-NPs using zinc-tolerant bacteria Serratia sp. (ZTB24). In the present study the experimental analysis viz. UV-Vis spectroscopy at 380 nm, transmission electron microscopy (TEM), dynamic light scattering (DLS), and zeta potential confirmed the successful biosynthesis of green ZnO-NPs from Serratia sp. The poisoned food technique and spore germination test revealed the antifungal activities of ZnO-NPs against A. niger under in vitro conditions. The presence of disease-causing A. niger fungus was confirmed through its isolation from infected garlic bulbs, and it was further identified at the molecular level using inter-transcribed sequence (ITS) rDNA sequencing. ZnO-NPs reduced the mycelial growth up to 90% and the 73% spore germination at 250 μg ml-1 concentration of ZnO-NPs. The ZnO-NPs were further used in vivo at different concentrations (50, 100, 250, and 500 ppm) in the post-harvest treatment of garlic. The percentage of disease severity was assessed after 7 and 14 days, and the application of 500 ppm of ZnO-NPs exhibited 0% disease severity in the pre-inoculation method, while disease severity of black mold disease in garlic plant was recorded at 1.10% after 7 days and 0.90% after 14 days in the post-inoculation method, compared to the control group. Hence, the antifungal activity of ZnO-NPs synthesized using the green technique paves the way for the development of natural fungicides, offering a sustainable and renewable alternative to traditional chemical control methods.

Stress sensing and response through biomolecular condensates in plants

Plants have developed intricate mechanisms for rapid and efficient stress perception and adaptation in response to environmental stressors. Recent research highlights the emerging role of biomolecular condensates in modulating plant stress perception and response. These condensates function through numerous mechanisms to regulate cellular processes such as transcription, translation, RNA metabolism, and signaling pathways under stress conditions. In this review, we provide an overview of current knowledge on stress-responsive biomolecular condensates in plants, including well-defined condensates such as stress granules, processing bodies, and the nucleolus, as well as more recently discovered plant-specific condensates. By briefly referring to findings from yeast and animal studies, we discuss mechanisms by which plant condensates perceive stress signals and elicit cellular responses. Finally, we provide insights for future investigations on stress-responsive condensates in plants. Understanding how condensates act as stress sensors and regulators will pave the way for potential applications in improving plant resilience through targeted genetic or biotechnological interventions.

ELONGATED HYPOCOTYL 5 promotes root growth by maintaining redox homeostasis and repressing oxidative stress response

Oxidative stress is a major threat to plant growth and survival. To understand how plants cope with oxidative stress, we carried out a genetic screen for Arabidopsis (Arabidopsis thaliana) mutants with altered response to hydrogen peroxide (H2O2) in root growth. Herein, we report the characterization of one of the hypersensitive mutants obtained. This mutant had slightly shorter roots in normal growth medium, and this phenotype became more pronounced in H2O2-containing medium. Through genome-wide resequencing and complementation experiments, we identified the gene with the causal mutation as ELONGATED HYPOCOTYL 5 (HY5). Histochemical staining revealed that the apical meristem of hy5 roots had an elevated level of H2O2 but a lower level of superoxide. In further experiments, we showed that genes involved in redox homeostasis and oxidative response were altered in hy5 roots and that MYB DOMAIN PROTEIN 30 (MYB30), GLUTATHIONE S-TRANSFERASE PHI 2 (GSTF2), and GLUTATHIONE S-TRANSFERASE TAU 19 (GSTU19) are directly repressed by HY5. Interestingly, overexpression of MYB30, a master regulator of the oxidative stress response, exacerbated the root growth defect in hy5, whereas knocking it down by RNAi largely rescued the mutant's hypersensitivity to H2O2 without affecting the content of reactive oxygen species (ROS). Intriguingly, knocking down GSTF2 also rescued the H2O2 hypersensitivity and ROS homeostasis defects in hy5 roots. In addition to H2O2, we showed that hy5 was also hypersensitive to high salinity, Cd, and salicylic acid. Based on these results, we conclude that HY5 plays a positive role in root growth mainly under abiotic stress by modulating both redox homeostasis and oxidative stress response.

Deciphering Regulatory Networks Governing Seedling Emergence in Deep-Sown Direct-Seeded Rice Cultivation

The rise of direct-seeded rice cultivation as a suitable alternative to transplanted puddled rice depends on developing genotypes with high seedling emergence under deep sown conditions. Two rice genotypes (IRGC 128442 and PR126) were screened for contrasting seedling emergence and subjected to high-throughput RNA sequencing under varying sowing depths (4 cm and 10 cm) and time intervals (5, 10, and 15 days after sowing). On average, a total of 2702 differentially expressed genes were identified across twelve inter- and intra-genotypic pairwise differential expression analyses, with a false discovery rate ≤ 0.05 and log2 fold change ≥ ± 2. The DEGs specifically showing differential expression under deep-sowing stress were prioritized and further refined based on their corresponding gene ontology terms, gene set enrichment analysis and KEGG and plant reactome pathway. From this pool of DEGs, 24 genes were validated using qRT-PCR. Among these, two genes (LOC_Os04g51460 and LOC_Os02g45450) contribute to cell wall remodelling and membrane stability, while three genes (LOC_Os04g48484, LOC_Os06g04399, and LOC_Os07g15440) play key roles in mitigating abiotic stress. Transcriptional regulators (LOC_Os06g33940 and LOC_Os01g45730) drive stress responses and growth. Notably, high fold changes in LOC_Os03g22720 and LOC_Os07g01960 underscore their importance in early stress responses and metabolic adjustments. The transcriptome analysis also highlighted the role of 29 heat shock proteins in response to deep sowing stress. Differential expression of key components in the abscisic acid (ABA)-mediated signalling pathway such as OsABI5 (LOC_Os01g64000), phosphatase 2C-like (PP2C) (LOC_Os09g15670) and OsPYL (LOC_Os06g36670) indicated downregulation of ABA signalling in the genotype IRGC 128442. Additionally, a role for miRNA-mediated regulation of auxin response factors was hypothesized in seedling emergence regulation. The study brings us closer to understanding the genetic control of seedling emergence under deep sown conditions. Functional validation of the key candidate genes and pathways could provide new targets for genetic improvement, potentially contributing to the development of rice cultivars optimized for direct-seeded rice cultivation.

Lead accumulation and concomitant reactive oxygen species (ROS) scavenging in Robinia pseudoacacia are dependent on nitrogen nutrition

Heavy metal pollution combined with nitrogen (N) limitation is a major factor preventing revegetation of contaminated land. Woody N2-fixing legumes are a natural choice for phytoremediation. However, the physiological responses of woody legumes to lead (Pb) with low N exposure are currently unknown. In the present study, a common Robinia cultivar from Northeast China, inoculated and non-inoculated with rhizobia, was exposed to -Pb or + Pb at moderate (norN) or low N application (lowN). Our results showed that without inoculation, independent of N application, Pb taken up by the roots was allocated to the shoot and inhibited photosynthesis and biomass production. In non-inoculated Robinia, Pb-mediated oxidative stress resulted in reduced H2O2 scavenging as indicated by increased ascorbate peroxidase (APX) activity in the leaves and proline contents in the roots, independent of N application. Combined lowN∗Pb exposure significantly increased malondialdehyde (MDA) contents in roots and leaves and enhanced APX and dehydroascorbate reductase activities in leaves compared to individual Pb exposure. Rhizobia inoculation raised the abundance of nodules and promoted Pb uptake by roots. Under Pb exposure, inoculation with rhizobia reduced MDA contents, increased proline contents in leaves and roots and enhanced activity of nitrate reductase in the leaves, independent of N application. Under Pb exposure, nitrogenase activity of inoculated Robinia under low- and norN application were similar indicating that enhanced of N2-fixation at lowN was counteracted by Pb exposure. These results show that inoculation of Robinia with rhizobia can alleviate Pb toxicity at combined lowN and Pb exposure by reducing oxidative stress.

Transcriptomics highlights dose-dependent response of poplar to a phenanthrene contamination

Polycyclic aromatic hydrocarbon (PAH) contamination in industrial soils poses significant environmental challenges, necessitating cost-effective bioremediation approaches like tree-based phytoremediation. However, the defence mechanisms and adaptability of trees to PAH exposure remain poorly understood, while the identification of molecular markers could help in the detection of toxicity symptoms. This study explores the molecular response of Populus canadensis to a phenanthrene (PHE) contamination gradient (from 100 to 2000 mg kg-1) using RNA-seq analysis of roots and leaves after 4 weeks of exposure. Both differentially expressed genes (DEGs) and DRomics, a dose-response tool, identified transcriptomic changes, with about 50% of deregulated genes responding significantly at a benchmark dose (i.e. minimal dose that produces a significant effect) below 400 mg PHE kg-1. The highest number of DEGs was found both at a low concentration (200 and 700 mg kg-1) and at the highest concentrations (1500-2000 mg kg-1) for both roots and leaves. Ethylene signalling genes were activated via ABA-independent pathways at low concentrations and ABA-dependent pathways at high concentrations. Across the gradient, responses to oxidative stress were triggered, including reactive oxygen species scavenging and phenylpropanoid biosynthesis, specifically at 1500-2000 mg kg-1. Additionally, PHE disrupted pathways related to plant responses to biotic stress. These findings revealed unexpected dose-dependent transcriptomic shifts, demonstrating poplar's adaptive defence mechanisms against PHE toxicity.

Cell cycle arrest via DNA Damage Response (DDR) pathway induced by extracellular self-DNA (esDNA) application in rice root

Conspecific plant growth is inhibited by extracellular fragments in a concentration-dependent manner. Although several reports have addressed this self-DNA inhibition, the underlying mechanism remains unclear. In this investigation, we evaluated the progression of cell cycle of rice roots in responding to extracellular-self DNA (esDNA). We analyzed root growth, hydrogen peroxide (H2O2) production, Catalase (CAT) and Ascorbate Peroxidase (APX) enzyme activities, DNA Damage Response (DDR)-related gene expression, and cell cycle progression. Our results suggest that esDNA-induced root growth inhibition on days 7 and 10 and might associated with cell cycle arrest initiated several hours after esDNA treatment. The esDNA-induced cell cycle arrest is facilitated through the DDR pathway, activated by DNA damage resulting from elevated reactive oxygen species (ROS) induced by esDNA. Specifically, esDNA upregulates DDR-related gene expression including OsATM (Oryza sativa ataxia telangiectasia mutated), OsATR (Oryza sativa ATM and Rad3-related), OsSOG1 (Oryza sativa SUPPRESSOR OF GAMMA RESPONSE 1), OsWEE1 (Oryza sativa WEE1-like kinase 1), and OsSMR4 (Oryza sativa SIAMESE-RELATED 4), leading to cell cycle arrest. Finally, we propose that cell cycle arrest might be a plausible explanation for the phenomenon of root growth inhibition by esDNA. This result highlights the significance of DDR signaling in the plant's response to esDNA. This finding will be helpful as initial information for developing green herbicides to control monocot weeds in agriculture.

Physiological and metabolome characterization of Amaranthus hybridus L. grown under cypermethrin stress: an insight of Jasmonic acid treatment

The indiscriminate use of pesticides compromises physiology and metabolism in crops, posing health risks through residue accumulation in edible tissues. Amaranthus hybridus L., a fast growing, nutritionally and medicinally valuable crop was studied here to assess the impact of cypermethrin (CYP) at recommended (R1, 100 ppm) and double dose (R2, 200 ppm) alongside foliar application of jasmonic acid (JA) at 50 µM, 100 µM, and 200 µM concentrations. CYP at R1 dose induced hormesis, while R2 was toxic, elevating the production of ROS molecules (H2O2, SOR, MDA). JA application upregulated the antioxidant activity of SOD, POD, APX, GST, DHAR, GSH, and proline to alleviate oxidative stress and improve growth indicators, including shoot length, leaf area, chlorophyll content, Fv/Fm ratio, and biomass. JA at 100 µM yielded the highest increase in biomass, 11.52% and 13.7% for R1 and R2 treated plants, respectively and also led to reduced accumulation of CYP residues. The UHPLC-MS analysis of leaf tissue revealed increase in the contents of carotenoids, flavonoids, phenolics, phenylpropanoids, steroids content in the plant group combinedly treated with JA and CYP compared to those treated with CYP alone, indicating a protective and growth-promoting role of JA under pesticide stress conditions. Overall, 100 µM concentration of JA proved to be effective against the stress induced by the either dose of CYP in the study. These insights could offer strategies to reduce pesticide-induced damage in vegetable crops, advancing sustainable agriculture.

Crosstalk Between Abiotic and Biotic Stresses Responses and the Role of Chloroplast Retrograde Signaling in the Cross-Tolerance Phenomena in Plants

In the natural environment, plants are simultaneously exposed to multivariable abiotic and biotic stresses. Typical abiotic stresses are changes in temperature, light intensity and quality, water stress (drought, flood), microelements availability, salinity, air pollutants, and others. Biotic stresses are caused by other organisms, such as pathogenic bacteria and viruses or parasites. This review presents the current state-of-the-art knowledge on programmed cell death in the cross-tolerance phenomena and its conditional molecular and physiological regulators, which simultaneously regulate plant acclimation, defense, and developmental responses. It highlights the role of the absorbed energy in excess and its dissipation as heat in the induction of the chloroplast retrograde phytohormonal, electrical, and reactive oxygen species signaling. It also discusses how systemic- and network-acquired acclimation and acquired systemic resistance are mutually regulated and demonstrates the role of non-photochemical quenching and the dissipation of absorbed energy in excess as heat in the cross-tolerance phenomenon. Finally, new evidence that plants evolved one molecular system to regulate cell death, acclimation, and cross-tolerance are presented and discussed.

Consequences of Volcanic Ash on Antioxidants, Nutrient Composition, Heavy Metal Accumulation, and Secondary Metabolites in Key Crops of Cotopaxi Province, Ecuador

This study investigates the consequences of volcanic ash on the antioxidant properties, nutrient composition, heavy metal levels, and secondary metabolites in Phaseolus vulgaris L. (common bean) and Zea mays L. (yellow corn), two crucial crops in Ecuador. The objective is to determine how volcanic ash exposure affects these crops, focusing on antioxidant properties and potential heavy metal accumulation. Field experiments were conducted in Cotopaxi Province, where both crops were cultivated under varying volcanic ash conditions. Secondary metabolites, particularly total phenols and flavonoids, were quantified using spectrophotometric methods, while heavy metal content was assessed via atomic absorption spectroscopy. Results showed a notable increase in the synthesis of secondary metabolites, especially phenols and flavonoids, in crops exposed to volcanic ash, enhancing their antioxidant capacity. Importantly, no significant heavy metal accumulation was detected, indicating that the benefits of volcanic ash application can be harnessed without associated toxicity risks. This research highlights the potential of volcanic ash to boost beneficial metabolites in yellow corn and common bean, advocating for careful agricultural practices in volcanic regions to optimize health benefits while mitigating toxicity risks.

The MADS-box gene XAANTAL1 participates in Arabidopsis thaliana primary root growth and columella stem cell patterns in response to ROS, via direct regulation of PEROXIDASE 28 and RETINOBLASTOMA-RELATED genes

The balance between cell growth, proliferation, and differentiation emerges from gene regulatory networks coupled to various signal transduction pathways, including reactive oxygen species (ROS) and transcription factors (TFs), enabling developmental responses to environmental cues. The primary root of Arabidopsis thaliana has become a valuable system for unravelling such networks. Recently, the role of TFs that mediate ROS inhibition of primary root growth has begun to be characterized. This study demonstrates that the MADS-box TF gene XAANTAL1 (XAL1) is an essential regulator of hydrogen peroxide (H2O2) in primary root growth and root stem cell niche identity. Interestingly, our findings indicated that XAL1 acts as a positive regulator of H2O2 concentration in the root meristem by directly regulating genes involved in oxidative stress response, such as PEROXIDASE 28 (PER28). Moreover, we found that XAL1 is necessary for the H2O2-induced inhibition of primary root growth through the negative regulation of peroxidase and catalase activities. Furthermore, XAL1, in conjunction with RETINOBLASTOMA-RELATED (RBR), is essential for positively regulating the differentiation of columella stem cells and for participating in primary root growth inhibition in response to oxidative stress induced by H2O2 treatment.

Review of cancer cell volatile organic compounds: their metabolism and evolution

Cancer is ranked as the top cause of premature mortality. Volatile organic compounds (VOCs) are produced from catalytic peroxidation by reactive oxygen species (ROS) and have become a highly attractive non-invasive cancer screening approach. For future clinical applications, however, the correlation between cancer hallmarks and cancer-specific VOCs requires further study. This review discusses and compares cellular metabolism, signal transduction as well as mitochondrial metabolite translocation in view of cancer evolution and the basic biology of VOCs production. Certain cancerous characteristics as well as the origin of the ROS removal system date back to procaryotes and early eukaryotes and share commonalities with non-cancerous proliferative cells. This calls for future studies on metabolic cross talks and regulation of the VOCs production pathway.

Identification and expression analysis of lncRNAs in rice roots (Oryza sativa L.) under elevated CO2 concentration and/or cadmium stress

The gradual rise of CO2 is one of the global climate changes, Cd stress is also a major abiotic stress factor that affects rice (Oryza sativa L.). The rice seedlings were treated under two CO2 concentrations and two CdCl2 concentrations for 7 days (treatments names: 400 ± 20 μmol mol-1 CO2 and 0 μmol L-1 CdCl2 concentrations, AC; 400 ± 20 μmol mol-1 CO2 and 150 μmol L-1 CdCl2 concentrations, Cd; 800 ± 20 μmol mol-1 CO2 and 0 μmol L-1 CdCl2 concentrations, EC; 800 ± 20 μmol mol-1 CO2 and 150 μmol L-1 CdCl2 concentrations, EC + Cd). The lncRNAs informations were analyzed and excavated using high-throughput sequencing, target genes annotation, and qRT-PCR analysis techniques so as to reveal the regulatory mechanism of lncRNAs in rice roots under high CO2 concentrations and/or Cd stress. The results show that: (1) 326 (AC vs Cd), 331 (AC vs EC), 343 (AC vs EC + Cd), 112 (Cd vs EC + Cd) DE-lncRNAs were identified. (2) MAPK signaling pathway-plant (relevant genes Os04g0534166, Os05g0399800 regulated by MSTRG.18576.11, MSTRG.20864.1) and diterpenoid biosynthesis (relevant genes Os12g0491800, Os02g0570400 regulated by MSTRG.8965.1, MSTRG.11509.1) were annotated in AC vs Cd; Under EC relative to AC, DE-lncRNAs were annotated significantly to the flavonoid biosynthesis (relevant genes Os10g0196100, Os10g0320100, Os11g0116300, Os03g0819600 regulated by MSTRG.4612.1, MSTRG.4668.1, MSTRG.6051.1, MSTRG.16669.1); Under composite treatments, relative to AC, DE-lncRNAs were mainly annotated in the plant hormone signal transduction pathway (relevant genes Os03g0180800, Os03g0180900, Os03g0181100 regulated by MSTRG.13776.1). Under combined treatment, elevated CO2 alleviates Cd stress damage by regulating phenylpropanoid biosynthesis through DE-lncRNAs (relevant genes Os09g0419200 regulated by MSTRG. 29,573.1).

Electrochemical sensors for plant signaling molecules

Plant signaling molecules can be divided into plant messenger signaling molecules (such as calcium ions, hydrogen peroxide, Nitric oxide) and plant hormone signaling molecules (such as auxin (mainly indole-3-acetic acid or IAA), salicylic acid, abscisic acid, cytokinin, jasmonic acid or methyl jasmonate, gibberellins, brassinosteroids, strigolactone, and ethylene), which play crucial roles in regulating plant growth and development, and response to the environment. Due to the important roles of the plant signaling molecules in the plants, many methods were developed to detect them. The development of in-situ and real-time detection of plant signaling molecules and field-deployable sensors will be a key breakthrough for botanical research and agricultural technology. Electrochemical methods provide convenient methods for in-situ and real-time detection of plant signaling molecules in plants because of their easy operation, high sensitivity, and high selectivity. This article comprehensively reviews the research on electrochemical detection of plant signaling molecules reported in the past decade, which summarizes the various types electrodes of electrochemical sensors and the applications of multiple nanomaterials to enhance electrode detection selectivity and sensitivity. This review also provides examples to introduce the current research trends in electrochemical detection, and highlights the applicability and innovation of electrochemical sensors such as miniaturization, non-invasive, long-term stability, integration, automation, and intelligence in the future. In all, the electrochemical sensors can realize in-situ, real-time and intelligent acquisition of dynamic changes in plant signaling molecules in plants, which is of great significance for promoting basic research in botany and the development of intelligent agriculture.

Tetraspanin 5 orchestrates resilience to salt stress through the regulation of ion and reactive oxygen species homeostasis in rice

Tetraspanins (TETs) are integral membrane proteins, characterized by four transmembrane domains and a unique signature motif in their large extracellular loop. They form dynamic supramolecular complexes called tetraspanin-enriched microdomains (TEMs), through interactions with partner proteins. In plants, TETs are involved in development, reproduction and immune responses, but their role in defining abiotic stress responses is largely underexplored. We focused on OsTET5, which is differentially expressed under various abiotic stresses and localizes to both plasma membrane and endoplasmic reticulum. Using overexpression and underexpression transgenic lines we demonstrate that OsTET5 contributes to salinity and drought stress tolerance in rice. OsTET5 can interact with itself in yeast, suggesting homomer formation. Immunoblotting of native PAGE of microsomal fraction enriched from OsTET5-Myc transgenic rice lines revealed multimeric complexes containing OsTET5, suggesting the potential formation of TEM complexes. Transcriptome analysis, coupled with quantitative PCR-based validation, of OsTET5-altered transgenic lines unveiled the differential expression patterns of several stress-responsive genes, as well as those coding for transporters under salt stress. Notably, OsTET5 plays a crucial role in maintaining the ionic equilibrium during salinity stress, particularly by preserving an elevated potassium-to-sodium (K+/Na+) ratio. OsTET5 also regulates reactive oxygen species homeostasis, primarily by modulating the gene expression and activities of antioxidant pathway enzymes and proline accumulation. Our comprehensive investigation underscores the multifaceted role of OsTET5 in rice, accentuating its significance in developmental processes and abiotic stress tolerance. These findings open new avenues for potential strategies aimed at enhancing stress resilience and making valuable contributions to global food security.

FAD and NADPH binding sites of YUCCA6 are essential for chaperone activity and oxidative stress tolerance in Arabidopsis thaliana

Phytohormone auxin plays a pivotal role in governing plant growth, development, and responses to abiotic stresses. YUCCA6 (YUC6), an auxin biosynthetic enzyme belonging to the flavin monooxygenase (FMO) subfamily, converts indole-3-pyruvic acid to indole-3-acetic acid. Our prior investigation uncovered that YUC6 also functions as a thiol-reductase and chaperone in a Cys85-dependent manner, resulting in conferred tolerance to nickel heavy metal stress and drought and delayed leaf senescence. Notably, the conserved co-factor binding sites (FAD and NADPH) in YUC6, shared with FMOs and thioredoxin reductase, prompted our exploration into their significance for holdase chaperone activity and oxidative stress tolerance in Arabidopsis. We demonstrate that YUC6 transcripts are upregulated in response to methyl viologen (MV)-induced oxidative stress, implicating YUC6 in oxidative stress response. Mutations in co-factor binding sites markedly diminish the chaperone activity of YUC6, and reduce the YUC6-mediated oxidative stress tolerance in Arabidopsis. Furthermore, YUC6 proteins exist as oligomeric states under native conditions, formed by disulfide-bond bridges. Oligomeric YUC6 displays enhanced chaperone activity compared to its monomeric YUC6. We found here that co-factor binding sites of YUC6 are necessary for its chaperone properties.

Individual and interactive effects of temperature and blue light on canola growth, lignin biosynthesis and methane emissions

It is now well documented that plants produce methane (CH4) under aerobic conditions. However, the mechanisms of methane production in plants, its potential precursors, and the factors that are involved in the process are not fully understood. Few studies have considered the effects of blue light on methane emissions from plants; however, the combined effects of temperature and blue light have not been studied. We studied the effects of two temperature regimes (22/18 °C and 28/24 °C; 16 h light/8 h dark), and three blue light levels (0, 4, and 8 mW cm-2; 400-500 nm) on the growth, lignin, and methane emissions of canola (Brassica napus). Plants were grown under experimental conditions for three weeks, and then methane, monolignols and other plant traits, including growth, biomass, growth index, photosynthesis, chlorophyll fluorescence, and photosynthetic pigments, were measured. Blue light significantly increased methane emissions, stem height, and growth rate, but decreased stem diameter, leaf number and area, biomass, specific leaf mass, leaf area ratio, shoot/root mass ratio, photosynthetic pigments, sinapyl alcohol, and coniferyl aldehyde. Higher temperature significantly decreased stem diameter, non-photochemical quenching, sinapyl alcohol, and coniferyl aldehyde. Methane emission was negatively correlated with plant dry mass, leaf area per plant, and maximum quantum yield of photosystem II. However, no significant relationships were found between methane and monolignols. In conclusion, plants emitted more methane under stress conditions; however, further studies are required to understand the potential precursors of methane and the mechanism of its synthesis in plants.

Selective synergistic effects of oxalic acid and salicylic acid in enhancing amino acid levels and alleviating lead stress in Zea mays L

Lead is one of the major environmental pollutants which is highly toxic to plants and living beings. The current investigation thoroughly evaluated the synergistic effects of oxalic acid (OA) and salicylic acid (SA) on Zea mays L. plants subjected to varying durations (15, 30, 30, and 45 days) of lead (Pb) stress. Besides, the effects of oxalic acid (OA) combined with salicylic acid (SA) for different amino acids at various periods of Pb stress were also investigated on Zea mays L. The soil was treated with lead nitrate Pb (NO3)2 (0.5 mM) to induce Pb stress while the stressed plants were further treated using oxalic acid (25 mg/L), salicylic acid (25 mg/L), and their combination OA + SA (25 mg/L each). Measurements of protein content, malondialdehyde (MDA) levels, guaiacol peroxidase (GPOX) activity, catalase (CAT) activity, GSH content, and Pb concentration in maize leaves were done during this study. MDA levels increased by 71% under Pb stress, while protein content decreased by 56%, GSH content by 35%, and CAT activity by 46%. After treatment with SA, OA, and OA+SA, there was a significant reversal of these damages, with the OA+SA combination showing the highest improvement. Specifically, OA+SA treatment led to a 45% increase in protein content and a 39% reduction in MDA levels compared to Pb treatment alone. Moreover, amino acid concentrations increased by 68% under the Pb+OA+SA treatment, reflecting the most significant recovery (p < 0.0001).