GLABROUS INFLORESCENCE STEMS3 binds to and activates RHD2 and RHD4 genes to promote root hair elongation in Arabidopsis.

Root hairs are crucial in the uptake of essential nutrients and water in plants. This study showed that a zinc finger protein, GIS3 is involved in root hair growth in Arabidopsis. The loss-of-function gis3 and GIS3 RNAi transgenic line exhibited a significant reduction in root hairs compared to the wild type. The application of 1-aminocyclopropane-1-carboxylic acid (ACC), an exogenous ethylene precursor, and 6-benzyl amino purine (BA), a synthetic cytokinin, significantly restored the percentage of hair cells in the epidermis in gis3 and induced GIS3 expression in the wild type. More importantly, molecular and genetic studies revealed that GIS3 acts upstream of ROOT HAIR DEFECTIVE 2 (RHD2) and RHD4 by binding to their promoters. Furthermore, exogenous ACC and BA application significantly induced the expression of RHD2 and RHD4, while root hair phenotype of rhd2-1, rhd4-1, and rhd4-3 was insensitive to ACC and BA treatment. We can therefore conclude that GIS3 modulates root hair development by directly regulating RHD2 and RHD4 expression through ethylene and cytokinin signals in Arabidopsis.

Role of alternative splicing in fish immunity.

Alternative splicing serves as a pivotal source of complexity in the transcriptome and proteome, selectively connecting various coding elements to generate a diverse array of mRNAs. This process encodes multiple proteins with either similar or distinct functions, contributing significantly to the intricacies of cellular processes. The role of alternative splicing in mammalian immunity has been well studied. Remarkably, the immune system of fish shares substantial similarities with that of humans, and alternative splicing also emerges as a key player in the immune processes of fish. In this review, we offer an overview of alternative splicing and its associated functions in the immune processes of fish, and summarize the research progress on alternative splicing in the fish immunity. Furthermore, we review the impact of alternative splicing on the fish immune system's response to external stimuli. Finally, we present our perspectives on future directions in this field. Our aim is to provide valuable insights for the future investigations into the role of alternative splicing in immunity.

Bioinformatic Analysis of Roquin Family Reveals Their Potential Role in Immune System.

The Roquin family is a recognized RNA-binding protein family that plays vital roles in regulating the expression of pro-inflammatory target gene mRNA during the immune process in mammals. However, the evolutionary status of the Roquin family across metazoans remains elusive, and limited studies are found in fish species. In this study, we discovered that the RC3H genes underwent a single round of gene duplication from a primitive ancestor during evolution from invertebrates to vertebrates. Furthermore, there were instances of species-specific gene loss events or teleost lineage-specific gene duplications throughout evolution. Domain/motif organization and selective pressure analysis revealed that Roquins exhibit high homology both within members of the family within the same species and across species. The three rc3h genes in zebrafish displayed similar expression patterns in early embryos and adult tissues, with rc3h1b showing the most prominent expression among them. Additionally, the promoter regions of the zebrafish rc3h genes contained numerous transcription factor binding sites similar to those of mammalian homologs. Moreover, the interaction protein network of Roquin and the potential binding motif in the 3'-UTR of putative target genes analysis both indicated that Roquins have the potential to degrade target mRNA through mechanisms similar to those of mammalian homologs. These findings shed light on the evolutionary history of Roquin among metazoans and hypothesized their role in the immune systems of zebrafish.

Acetal-thiol Click-like Reaction: Facile and Efficient Synthesis of Dynamic Dithioacetals and Recyclable Polydithioacetals.

Dithioacetals are heavily used in organic, material and medical chemistries, and exhibit huge potential to synthesize degradable or recyclable polymers. However, the current synthetic approaches of dithioacetals and polydithioacetals are overwhelmingly dependent on external catalysts and organic solvents. Herein, we disclose a catalyst- and solvent-free acetal-thiol click-like reaction for synthesizing dithioacetals and polydithioacetals. High conversion, higher than acid catalytic acetal-thiol reaction, can be achieved. High universality was confirmed by monitoring the reactions of linear and cyclic acetals (including renewable bio-sourced furan-acetal) with aliphatic and aromatic thiols, and the reaction mechanism of monomolecular nucleophilic substitution (SN1) and auto-protonation (activation) by thiol was clarified by combining experiments and density functional theory computation. Subsequently, we utilize this reaction to synthesize readily recyclable polydithioacetals. By simple heating and stirring, linear polydithioacetals with M ‾ ${\bar M}$ w of ~110 kDa were synthesized from acetal and dithiol, and depolymerization into macrocyclic dithioacetal and repolymerization into polydithioacetal can be achieved; through reactive extrusion, a semi-interpenetrating polymer dynamic network with excellent mechanical properties and continuous reprocessability was prepared from poly(vinyl butyral) and pentaerythritol tetrakis(3-mercaptopropionate). This green and high-efficient synthesis method for dithioacetals and polydithioacetals is beneficial to the sustainable development of chemistry.

OsRbohI Regulates Rice Growth and Development via Jasmonic Acid Signalling.

Reactive oxygen species (ROS) are highly reactive molecules, generated by nicotinamide adenine dinucleotide phosphate oxidases encoded by respiratory burst oxidase homologs. The functions of the OsRbohs gene family in rice are diverse and poorly understood. OsRbohI was recently identified as a newly evolved gene in the rice OsRbohs gene family. However, the function of OsRbohI in regulating rice growth is not yet reported. In this study, our results indicate that knockout (KO) OsRbohI mutants showed significantly shorter shoot and primary roots, along with lower ROS content than the control lines, whereas the overexpression (OE) lines displayed contrasting results. Further experiments showed that the abnormal length of the shoot and root is mainly caused by altered cell size. These results indicate that OsRbohI regulates rice shoot and root growth through the ROS signal. More importantly, RNA-seq analysis and jasmonic acid (JA) treatment demonstrated that OsRbohI regulates rice growth via the JA synthesis and signaling pathways. Compared with the control, the results showed that the KO mutants were more sensitive to JA, whereas the OE lines were less sensitive to JA. Collectively, our results reveal a novel pathway in which OsRbohI regulates rice growth and development by affecting their ROS homeostasis through JA synthesis and signaling pathway.

OsUGE1 is directly targeted by OsGRF6 to regulate root hair length in rice.

KEY MESSAGE: Root hairs are required for water and nutrient acquisition in plants. Here, we report a novel mechanism that OsUGE1 is negatively controlled by OsGRF6 to regulate root hair elongation in rice. Root hairs are tubular outgrowths generated by the root epidermal cells. They effectively enlarge the soil-root contact area and play essential roles for nutrient and water absorption. Here, in this study, we demonstrated that the Oryza sativa UDP-glucose 4-epimerase 1-like (OsUGE1) negatively regulated root hair elongation and was directly targeted by Oryza sativa growth regulating factor 6 (OsGRF6). Knockout mutants of OsUGE1 using CRISPR-Cas9 technology showed longer root hairs than those of wild type. In contrast, overexpression lines of OsUGE1 displayed shorter root hair compared with those of wild type. GUS staining showed that it could specifically express in root hair. Subcellular localization analysis indicates that OsUGE1 is located in endoplasmic reticulum, nucleus and plasma membrane. More importantly, ChIP-qPCR, Yeast-one-hybrid and BiFC experiments revealed that OsGRF6 could bind to the promoter of OsUGE1. Furthermore, knockout mutants of OsGRF6 showed shorter root hair than those of wild type, and OsGRF6 dominantly expressed in root. In addition, the expression level of OsUGE1 is significantly downregulated in Osgrf6 mutant. Taken together, our study reveals a novel pathway that OsUGE1 is negatively controlled by OsGRF6 to regulate root hair elongation in rice.

TOE1/TOE2 Interacting with GIS to Control Trichome Development in Arabidopsis.

Trichomes are common appendages originating and projecting from the epidermal cell layer of most terrestrial plants. They act as a first line of defense and protect plants against different types of adverse environmental factors. GL3/EGL3-GL1-TTG1 transcriptional activator complex and GIS family genes regulate trichome initiation through gibberellin (GA) signaling in Arabidopsis. Here, our novel findings show that TOE1/TOE2, which are involved in developmental timing, control the initiation of the main-stem inflorescence trichome in Arabidopsis. Phenotype analysis showed that the 35S:TOE1 transgenic line increases trichome density of the main-stem inflorescence in Arabidopsis, while 35S:miR172b, toe1, toe2 and toe1toe2 have the opposite phenotypes. Quantitative RT-PCR results showed that TOE1/TOE2 positively regulate the expression of GL3 and GL1. In addition, protein-protein interaction analysis experiments further demonstrated that TOE1/TOE2 interacting with GIS/GIS2/ZFP8 regulate trichome initiation in Arabidopsis. Furthermore, phenotype and expression analysis also demonstrated that TOE1 is involved in GA signaling to control trichome initiation in Arabidopsis. Taken together, our results suggest that TOE1/TOE2 interact with GIS to control trichome development in Arabidopsis. This report could provide valuable information for further study of the interaction of TOE1/TOE2 with GIS in controlling trichome development in plants.

Simultaneous Synthesis and Self-Assembly of Bottlebrush Block Copolymers at Room Temperature via Photoinitiated RAFT Dispersion Polymerization.

Bottlebrush polymers exhibiting unique properties have attracted considerable attention for applications in many research areas. Herein, the first simultaneous synthesis and self-assembly of bottlebrush block copolymers at room temperature via photoinitiated polymerization-induced self-assembly (photo-PISA) using multifunctional macromolecular chain transfer agents (macro-CTAs) is reported. Comparing with linear block copolymers, the bottlebrush block copolymers can promote the formation of higher-order morphologies (e.g., vesicles) when targeting similar degrees of polymerization (DPs). Moreover, a higher polymerization rate is observed in the case of bottlebrush block copolymers. Gel permeation chromatography (GPC) analysis shows that good polymerization control is maintained when synthesizing bottlebrush block copolymers by photo-PISA. Finally, the obtained bottlebrush block copolymer vesicles are used as seeds for further chain extension and multicompartment nanoparticles with a sponge internal structure are formed. It is expected that this study will not only expand polymer architectures employed in PISA, but also provide a new strategy to synthesize polymer nanoparticles with unique structures.

Evolutionary and Expression Analysis of MOV10 and MOV10L1 Reveals Their Origin, Duplication and Divergence.

MOV10 and MOV10L1 both encode ATP-dependent RNA helicases. In mammals, MOV10 and MOV10L1 participate in various kinds of biological contexts, such as defense of RNA virus invasion, neuron system, germ cell and early development. However, mov10 and mov10l1 in zebrafish are obscure and the evolutionary relationships of mov10 among different species remain unclear. In this study, we found MOV10 and MOV10L1 had some variations despite they possessed the conserved feature of RNA helicase, however, they may originate from a single ancestor although they shared limited homology. A single MOV10L1 gene existed among all species, while MOV10 gene experienced lineage-specific intra-chromosomal gene duplication in several species. Interestingly, the mov10 gene expanded to three in zebrafish, which originating from a duplication by whole genome specific duplication of teleost lineage followed by a specific intra-chromosome tandem duplication. The mov10 and mov10l1 showed distinct expression profiles in early stages, however, in adult zebrafish, three mov10 genes exhibited similar diverse expression patterns in almost all tissues. We also demonstrated mov10 genes were upregulated upon virus challenge, highlighting they had redundant conserved roles in virus infection. These results provide valuable data for the evolution of MOV10 and MOV10L1 and they are important to the further functional exploration.

Ethylene participates in zinc oxide nanoparticles induced biochemical, molecular and ultrastructural changes in rice seedlings.

Nowadays, the applications of engineered nanoparticles (ENPs) have been significantly increased, thereby negatively affecting crop production and ultimately contaminating the food chain worldwide. Zinc oxide nanoparticles (ZnO NPs) induced oxidative stress has been clarified in previous studies. But until now, it has not been investigated that how ethylene mediates or participates in ZnO NPs-induced toxicity and related cellular ultrastructural changes in rice seedlings. Here, we reported that 500 mg/L of ZnO NPs reduced the fresh weight (54.75% and 55.64%) and dry weight (40.33% and 47.83%) in shoot and root respectively as compared to control. Furthermore, ZnO NPs (500 mg/L) reduced chlorophyll content (72% Chla, 70% Chlb), induced the stomatal closure and ultrastructural damages by causing oxidative stress in rice seedlings. These cellular damages were significantly increased by exogenous applications of ethylene biosynthesis precursor (ACC) in the presence of ZnO NPs. In contrary, ZnO NPs induced damages on the above-mentioned attributes were reversed through the exogenous supply of ethylene signaling and biosynthesis antagonists such as silver (Ag) and cobalt (Co) respectively. Interestingly, ZnO NPs accelerate ethylene biosynthesis by up-regulating the transcriptome of ethylene biosynthesis responsive genes. The antioxidant enzymes activities and related gene expressions were further increased in ethylene signaling and biosynthesis associated antagonists (Ag and Co) treated seedlings as compared to sole ZnO NPs treatments. In contrary, the above-reported attributes were further decreased by ACC together with ZnO NPs. In a nutshell, ethylene effectively contributes in ZnO NPs induced toxicity and causing ultrastructural and stomatal damage in rice seedlings. Such findings could have potential implications in producing genetic engineered crops, which will be able to tolerate nanoparticles toxicity in the environment.

Nitrate regulation of lateral root and root hair development in plants.

Nitrogen (N) is one of the most important macronutrients for plant growth and development. However, the concentration and distribution of N varies in soil due to a variety of environmental factors. In response, higher plants have evolved a developmentally flexible root system to efficiently take up N under N-limited conditions. Over the past decade, significant progress has been made in understanding this form of plant 'root-foraging' behavior, which is controlled by both a local and a long-distance systemic nitrate signaling pathway. In this review, we focus on the key components of nitrate perception, signaling, and transduction and its role in lateral root development. We also highlight recent findings on the molecular mechanisms of the nitrate systemic signaling pathway, including small signaling peptides involved in long-distance shoot-root communication. Furthermore, we summarize the transcription factor networks responsible for nitrate-dependent lateral root and root hair development.

A novel hepatic lectin of zebrafish Danio rerio is involved in innate immune defense.

ASGPR (asialoglycoprotein receptor, also known as hepatic lectin) was the first identified animal lectin, which participated in a variety of physiological processes. Yet its detailed immune functions are not well studied in lower vertebrates. After reporting a zebrafish hepatic lectin (Zhl), we identified a novel hepatic lectin (zebrafish hepatic lectin-like, Zhl-l) in zebrafish. The zhl-l was mainly expressed in liver in a tissue specific manner. And challenge with LPS/LTA induced a significant change of zhl-l expression. What's more, recombinant C-type lectin domain (rCTLD) of Zhl-l had the activity of agglutinating and binding to both Gram-negative and Gram-positive bacteria. It promoted the phagocytosis of bacteria by carp macrophages. Moreover, rCTLD could bind to insoluble lipopolysaccharide (LPS), lipoteichoic acid (LTA) and peptidoglycan (PGN) independent of Ca2+, which was inhibited by galactose. Interestingly, Zhl-l was located in the membrane, and its overexpression could upregulate the production of pre-inflammatory cytokines. Taken together, these results indicated that Zhl-l played a role in immune defense, and would provide further information to understand functions of C-type lectin family and the innate immunity in vertebrates.

CLD1/SRL1 modulates leaf rolling by affecting cell wall formation, epidermis integrity and water homeostasis in rice.

Leaf rolling is considered as one of the most important agronomic traits in rice breeding. It has been previously reported that SEMI-ROLLED LEAF 1 (SRL1) modulates leaf rolling by regulating the formation of bulliform cells in rice (Oryza sativa); however, the regulatory mechanism underlying SRL1 has yet to be further elucidated. Here, we report the functional characterization of a novel leaf-rolling mutant, curled leaf and dwarf 1 (cld1), with multiple morphological defects. Map-based cloning revealed that CLD1 is allelic with SRL1, and loses function in cld1 through DNA methylation. CLD1/SRL1 encodes a glycophosphatidylinositol (GPI)-anchored membrane protein that modulates leaf rolling and other aspects of rice growth and development. The cld1 mutant exhibits significant decreases in cellulose and lignin contents in secondary cell walls of leaves, indicating that the loss of function of CLD1/SRL1 affects cell wall formation. Furthermore, the loss of CLD1/SRL1 function leads to defective leaf epidermis such as bulliform-like epidermal cells. The defects in leaf epidermis decrease the water-retaining capacity and lead to water deficits in cld1 leaves, which contribute to the main cause of leaf rolling. As a result of the more rapid water loss and lower water content in leaves, cld1 exhibits reduced drought tolerance. Accordingly, the loss of CLD1/SRL1 function causes abnormal expression of genes and proteins associated with cell wall formation, cuticle development and water stress. Taken together, these findings suggest that the functional roles of CLD1/SRL1 in leaf-rolling regulation are closely related to the maintenance of cell wall formation, epidermal integrity and water homeostasis.

OsUGE2 Regulates Plant Growth through Affecting ROS Homeostasis and Iron Level in Rice.

BACKGROUND: The growth and development of rice (Oryza sativa L.) are affected by multiple factors, such as ROS homeostasis and utilization of iron. Here, we demonstrate that OsUGE2, a gene encoding a UDP-glucose 4-epimerase, controls growth and development by regulating reactive oxygen species (ROS) and iron (Fe) level in rice. Knockout of this gene resulted in impaired growth, such as dwarf phenotype, weakened root growth and pale yellow leaves. Biochemical analysis showed that loss of function of OsUGE2 significantly altered the proportion and content of UDP-Glucose (UDP-Glc) and UDP-Galactose (UDP-Gal). Cellular observation indicates that the impaired growth may result from decreased cell length. More importantly, RNA-sequencing analysis showed that knockout of OsUGE2 significantly influenced the expression of genes related to oxidoreductase process and iron ion homeostasis. Consistently, the content of ROS and Fe are significantly decreased in OsUGE2 knockout mutant. Furthermore, knockout mutants of OsUGE2 are insensitive to both Fe deficiency and hydrogen peroxide (H2O2) treatment, which further confirmed that OsUGE2 control rice growth possibly through Fe and H2O2 signal. Collectively, these results reveal a new pathway that OsUGE2 could affect growth and development via influencing ROS homeostasis and Fe level in rice.

A peroxisomal cinnamate:CoA ligase-dependent phytohormone metabolic cascade in submerged rice germination.

The mechanism underlying the ability of rice to germinate underwater is a largely enigmatic but key research question highly relevant to rice cultivation. Moreover, although rice is known to accumulate salicylic acid (SA), SA biosynthesis is poorly defined, and its role in underwater germination is unknown. It is also unclear whether peroxisomes, organelles essential to oilseed germination and rice SA accumulation, play a role in rice germination. Here, we show that submerged imbibition of rice seeds induces SA accumulation to promote germination in submergence. Two submergence-induced peroxisomal Oryza sativa cinnamate:CoA ligases (OsCNLs) are required for this SA accumulation. SA exerts this germination-promoting function by inducing indole-acetic acid (IAA) catabolism through the IAA-amino acid conjugating enzyme GH3. The metabolic cascade we identified may potentially be adopted in agriculture to improve the underwater germination of submergence-intolerant rice varieties. SA pretreatment is also a promising strategy to improve submerged rice germination in the field.

Cement-Augmented Screw Fixation with PHILOS Plating for Osteoporotic Proximal Humeral Fractures: An Observation of Mid- and Long-Term Curative Efficacy.

OBJECTIVES: The mid- and long-term clinical outcomes of cement-augmented screws in the treatment of osteoporotic proximal humeral fractures have rarely been reported. The aim of this study was to observe the mid- and long-term efficacy of combined cement-augmented screw fixation and PHILOS plating in the treatment of osteoporotic fractures of the proximal humerus. METHODS: This study retrospectively analyzed data from 19 patients with osteoporotic fractures of the proximal humerus who had undergone internal fixation at the Guizhou Provincial People's Hospital from February 2017 to May 2021. The cohort was comprised of six males and 13 females, aged 75-87 (mean age: 82.52 ± 1.24) years. According to the Neer classification, three, 12, and four patients had two-part, three-part, and four-part fractures, respectively. All patients were treated with open reduction internal fixation with cement-augmented screws and PHILOS plating. Time until fracture healing was recorded postoperatively. Patients were observed for postoperative complications, including humeral head necrosis, loosening or breaking of the augmented screws, screw perforation of the humeral head, and varus fracture displacement. Visual analog scale and Constant scores of the shoulder joint were compared 1, 3, 6, and 12 months after surgery. Scores at the most recent follow-up were used to evaluate shoulder joint function. Measured data conforming to a normal distribution were expressed as mean ± SD. Analysis of variance or rank sum tests were used for intergroup comparisons. A value of p < 0.05 was considered significant. RESULTS: All 19 patients followed up for 1-4 (average: 2.13 ± 0.61) years. Fractures united in all cases, with a healing time of 8-14 (average: 10.25 ± 1.72) weeks. There were no cases of humeral head necrosis, screw loosening, fractures, or perforation of the humeral head. One patient had mild varus fracture displacement with a reduced neck-shaft angle. There were significant differences in visual analog scale and Constant scores 1, 3, and 6 months after surgery (p < 0.05). The visual analog scale score was 0 at final follow-up in all cases. The Constant score of the shoulder joint was excellent, good, fair, and poor in two, 12, four, and one case, respectively, yielding an excellent and good rate of 73.68%. CONCLUSIONS: Cement-augmented screw fixation combined with PHILOS plating of osteoporotic proximal humeral fractures had good mid- and long-term clinical efficacy. It should be considered a new option for fracture treatment in such patients.

The evolution and immunomodulatory role of Zc3h12 proteins in zebrafish (Danio rerio).

Zc3h12 family is an important RNA-binding protein family regulating mRNA of inflammatory cytokines in mammals. However, there are few studies on their post-transcriptional level regulation of inflammatory cytokines in fish. Here, we investigated the evolution of zebrafish Zc3h12 family and explored their immunomodulatory role. Phylogenetic and syntenic analysis indicated the number of zc3h12 family members had increased ranging from a single member in invertebrates to a single copy of four members in mammals. As the most evolutionarily diverse group of vertebrates, the number of zc3h12 family members was more complex and diverse in the teleost, each member experienced different fates and followed different rules in multiple rounds of whole-genome duplication events. Thereinto, zebrafish contained three zc3h12 genes, among which zc3h12aa and zc3h12ab were duplicated from the same gene. Zebrafish Zc3h12 family could recognize the 3'-UTR regions of inflammatory cytokines through binding to the specific RNA secondary structure and negatively regulate their expression. Deletion of either Zc3h12 domains or mutation of the key amino acid in RNAase domain attenuated their modulatory effect, suggesting both domain and RNAase activity are important to the immunomodulatory role. These results elucidated the evolution of Zc3h12 family and uncovered Zc3h12-mediated post-transcriptional regulation of cytokines in zebrafish.

A metabolic intervention strategy to break evolutionary adaptability of tumor for reinforced immunotherapy.

The typical hallmark of tumor evolution is metabolic dysregulation. In addition to secreting immunoregulatory metabolites, tumor cells and various immune cells display different metabolic pathways and plasticity. Harnessing the metabolic differences to reduce the tumor and immunosuppressive cells while enhancing the activity of positive immunoregulatory cells is a promising strategy. We develop a nanoplatform (CLCeMOF) based on cerium metal-organic framework (CeMOF) by lactate oxidase (LOX) modification and glutaminase inhibitor (CB839) loading. The cascade catalytic reactions induced by CLCeMOF generate reactive oxygen species "storm" to elicit immune responses. Meanwhile, LOX-mediated metabolite lactate exhaustion relieves the immunosuppressive tumor microenvironment, preparing the ground for intracellular regulation. Most noticeably, the immunometabolic checkpoint blockade therapy, as a result of glutamine antagonism, is exploited for overall cell mobilization. It is found that CLCeMOF inhibited glutamine metabolism-dependent cells (tumor cells, immunosuppressive cells, etc.), increased infiltration of dendritic cells, and especially reprogrammed CD8+ T lymphocytes with considerable metabolic flexibility toward a highly activated, long-lived, and memory-like phenotype. Such an idea intervenes both metabolite (lactate) and cellular metabolic pathway, which essentially alters overall cell fates toward the desired situation. Collectively, the metabolic intervention strategy is bound to break the evolutionary adaptability of tumors for reinforced immunotherapy.

Melatonin-mediated resistance to copper oxide nanoparticles-induced toxicity by regulating the photosynthetic apparatus, cellular damages and antioxidant defense system in maize seedlings.

The pollution of nanoparticles (NPs) has linked with severe negative effects on crop productivity. Thus, effective strategies are needed to mitigate the phytotoxicity of NPs. The aim of present study was to evaluate the efficacy of exogenously applied melatonin (MT) in mitigating the toxic effects of copper oxide nanoparticles (CuO NPs) from maize seedlings. Therefore, we comprehensively investigated the inhibitory effects of MT against CuO NPs-induced toxicity on morpho-physiological, biochemical and ultrastructural levels in maize. Our results show that CuO NPs (300 mg L-1) exposure displayed significantly reduction in all plant growth traits and induced toxicity in maize. Furthermore, 50 µM MT provided maximum plant tolerance against CuO NPs-induced phytotoxicity. It was noticed that MT improved plant growth, biomass, photochemical efficiency (Fv/Fm), chlorophyll contents (Chl a and Chl b), SPAD values and gas exchange attributes (stomatal conductance, net photosynthetic rate, intercellular CO2 concentration and transpiration rate) under CuO NPs stress. In addition, MT enhanced the antioxidant defense system and conferred protection to ultrastructural (mainly chloroplast, thylakoids membrane and plastoglobuli) damages and stomatal closure in maize plants subjected to CuO NPs stress. Together, it can be stated that the exogenous supply of MT improves the resilience of maize plants against the CuO NPs-induced phytotoxicity. Our current findings can be useful for the enhancement of plant growth and yield attributes in CuO NPs-contaminated soils. The reported information can provide insight into the MT pathways that can be used to improve crop stress tolerance in a challenging environment.

Ethylene accelerates copper oxide nanoparticle-induced toxicity at physiological, biochemical, and ultrastructural levels in rice seedlings.

The enormous use of metal-based nanoparticles (NPs) in different sectors may result in enhanced accumulation in agricultural soil, which could impose negative effects on crop productivity. Hence, strategies are needed to explore the mechanisms of copper oxide nanoparticle (CuO NP)-induced toxicity in crops. The present study aimed to investigate the involvement of ethylene in CuO NP-induced toxicity in rice seedlings. Here, our results indicate that 450 mg L-1 of CuO NPs induced toxic effects in rice seedlings. Thus, it was evidenced by the reduced plant biomass accumulation, enhanced oxidative stress indicators, and cellular ultrastructural damages. More importantly, the exogenous supply of ethylene biosynthesis and signaling antagonists cobalt (Co) and silver (Ag) respectively provided tolerance and improved the defense system of rice seedlings against CuO NP toxicity. The ethylene antagonists could significantly reduce the extent of ultrastructural and stomatal damage by controlling the ROS accumulation in rice seedlings under CuO NP stress. Furthermore, Co and Ag augmented the antioxidant defense system against CuO NP-induced toxicity. Contrary to that, all oxidative damage attributes were further enhanced exogenous application of ethylene biosynthesis precursor [1-aminocyclopropane-1-carboxylic acid (ACC)] in the presence of CuO NPs. In addition, ACC could increase the CuO NP-induced stomatal and ultrastructural damages by reducing the ROS-scavenging ability in rice seedlings. Taken together, these results indicate the involvement of ethylene in CuO NP-induced toxicity in rice seedlings.