Lipids and proteins--major targets of oxidative modifications in abiotic stressed plants

Prospecting toxicity of the avobenzone sunscreen in plants

Avobenzone (AVO) is a sunscreen with high global production and is constantly released into the environment. Incorporating sewage biosolids for fertilization purposes, the leaching from cultivated soils, and the use of wastewater for irrigation explain its presence in the soil. There is a lack of information about the impact of this sunscreen on plants. In the present study, the ecotoxicity of AVO was tested at concentrations 1, 10, 100, and 1,000 ng/L. All concentrations caused a reduction in root growth of Allium cepa, Cucumis sativus, and Lycopersicum esculentum seeds, as well as a mitodepressive effect, changes in the mitotic spindle and a reduction in root growth of A. cepa bulbs. The cell cycle was disturbed because AVO disarmed the enzymatic defense system of root meristems, leading to an accumulation of hydroxyl radicals and superoxides, besides lipid peroxidation in cells. Therefore, AVO shows a high potential to cause damage to plants and can negatively affect agricultural production and the growth of non-cultivated plants.

Growth and antioxidant responses to water stress in eggplant MAGIC population parents, F1 hybrids and a subset of recombinant inbred lines

BACKGROUND

The generation of new eggplant (Solanum melongena L.) cultivars with drought tolerance is a main challenge in the current context of climate change. In this study, the eight parents (seven of S. melongena and one of the wild relative S. incanum L.) of the first eggplant MAGIC (Multiparent Advanced Generation Intercrossing) population, together with four F1 hybrids amongst them, five S5 MAGIC recombinant inbred lines selected for their genetic diversity, and one commercial hybrid were evaluated in young plant stage under water stress conditions (30% field capacity; FC) and control conditions (100% FC). After a 21-day treatment period, growth and biomass traits, photosynthetic pigments, oxidative stress markers, antioxidant compounds, and proline content were evaluated.

RESULTS

Significant effects (p < 0.05) were observed for genotype, water treatments and their interaction in most of the traits analyzed. The eight MAGIC population parental genotypes displayed a wide variation in their responses to water stress, with some of them exhibiting enhanced root development and reduced foliar biomass. The commercial hybrid had greater aerial growth compared to root growth. The four F1 hybrids among MAGIC parents differed in their performance, with some having significant positive or negative heterosis in several traits. The subset of five MAGIC lines displayed a wide diversity in their response to water stress.

CONCLUSION

The results show that a large diversity for tolerance to drought is available among the eggplant MAGIC materials, which can contribute to developing drought-tolerant eggplant cultivars.

Functional Characterization of the Soybean Glycine max Actin Depolymerization Factor GmADF13 for Plant Resistance to Drought Stress

Abiotic stress significantly affects plant growth and has devastating effects on crop production. Drought stress is one of the main abiotic stressors. Actin is a major component of the cytoskeleton, and actin-depolymerizing factors (ADFs) are conserved actin-binding proteins in eukaryotes that play critical roles in plant responses to various stresses. In this study, we found that GmADF13, an ADF gene from the soybean Glycine max, showed drastic upregulation under drought stress. Subcellular localization experiments in tobacco epidermal cells and tobacco protoplasts showed that GmADF13 was localized in the nucleus and cytoplasm. We characterized its biological function in transgenic Arabidopsis and hairy root composite soybean plants. Arabidopsis plants transformed with GmADF13 displayed a more robust drought tolerance than wild-type plants, including having a higher seed germination rate, longer roots, and healthy leaves under drought conditions. Similarly, GmADF13-overexpressing (OE) soybean plants generated via the Agrobacterium rhizogenes-mediated transformation of the hairy roots showed an improved drought tolerance. Leaves from OE plants showed higher relative water, chlorophyll, and proline contents, had a higher antioxidant enzyme activity, and had decreased malondialdehyde, hydrogen peroxide, and superoxide anion levels compared to those of control plants. Furthermore, under drought stress, GmADF13 OE activated the transcription of several drought-stress-related genes, such as GmbZIP1, GmDREB1A, GmDREB2, GmWRKY13, and GmANK114. Thus, GmADF13 is a positive regulator of the drought stress response, and it may play an essential role in plant growth under drought stress conditions. These results provide new insights into the functional elucidation of soybean ADFs. They may be helpful for breeding new soybean cultivars with a strong drought tolerance and further understanding how ADFs help plants adapt to abiotic stress.

Low-Temperature Adaptive Single-Atom Iron Nanozymes against Viruses in the Cold Chain

Outbreaks of viral infectious diseases, such as the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and influenza A virus (IAV), pose a great threat to human health. Viral spread is accelerated worldwide by the development of cold chain logistics; Therefore, an effective antiviral approach is required. In this study, it is aimed to develop a distinct antiviral strategy using nanozymes with low-temperature adaptability, suitable for cold chain logistics. Phosphorus (P) atoms are added to the remote counter position of Fe-N-C center to prepare FeN4P2-single-atom nanozymes (SAzymes), exhibiting lipid oxidase (OXD)-like activity at cold chain temperatures (-20, and 4 °C). This feature enables FeN4P2-SAzymes to disrupt multiple enveloped viruses (human, swine, and avian coronaviruses, and H1-H11 subtypes of IAV) by catalyzing lipid peroxidation of the viral lipid envelope. Under the simulated conditions of cold chain logistics, FeN4P2-SAzymes are successfully applied as antiviral coatings on outer packaging and personal protective equipment; Therefore, FeN4P2-SAzymes with low-temperature adaptability and broad-spectrum antiviral properties may serve as key materials for developing specific antiviral approaches to interrupt viral transmission through the cold chain.

Physiological and biochemical effects of 24-Epibrassinolide on drought stress adaptation in maize (Zea mays L.)

Maize production and productivity are affected by drought stress in tropical and subtropical ecologies, as the majority of the area under maize cultivation in these ecologies is rain-fed. The present investigation was conducted to study the physiological and biochemical effects of 24-Epibrassinolide (EBR) as a plant hormone on drought tolerance in maize. Two maize hybrids, Vivek hybrid 9 and Bio 9637, were grown under three different conditions: (i) irrigated, (ii) drought, and (iii) drought+EBR. A total of 2 weeks before the anthesis, irrigation was discontinued to produce a drought-like condition. In the drought+EBR treatment group, irrigation was also stopped, and in addition, EBR was applied as a foliar spray on the same day in the drought plots. It was observed that drought had a major influence on the photosynthesis rate, membrane stability index, leaf area index, relative water content, and leaf water potential; this effect was more pronounced in Bio 9637. Conversely, the activities of antioxidant enzymes such as catalase (CAT), ascorbate peroxidase (APX), and superoxide dismutase (SOD) increased in both hybrids under drought conditions. Specifically, Vivek hybrid 9 showed 74% higher CAT activity under drought conditions as compared to the control. Additionally, EBR application further enhanced the activity of this enzyme by 23% compared to plants under drought conditions. Both hybrids experienced a significant reduction in plant girth due to drought stress. However, it was found that exogenously applying EBR reduced the detrimental effects of drought stress on the plant, and this effect was more pronounced in Bio 9637. In fact, Bio 9637 treated with EBR showed an 86% increase in proline content and a 70% increase in glycine betaine content compared to untreated plants under drought conditions. Taken together, our results suggested EBR enhanced tolerance to drought in maize hybrids. Hence, pre-anthesis foliar application of EBR might partly overcome the adverse effects of flowering stage drought in maize.

LC-QTOF/MS-based non-targeted metabolomics to explore the toxic effects of di(2-ethylhexyl) phthalate (DEHP) on Brassica chinensis L

Di(2-ethylhexyl) phthalate (DEHP) is a widely used plasticizer known to pose health risks to humans upon exposure. Recognizing the toxic nature of DEHP, our study aimed to elucidate the response mechanisms in Brassica chinensis L. (Shanghai Qing) when subjected to varying concentrations of DEHP (2 mg kg-1, 20 mg kg-1, and 50 mg kg-1), particularly under tissue stress. The findings underscored the substantial impact of DEHP treatment on the growth of Brassica chinensis L., with increased DEHP concentration leading to a notable decrease in chlorophyll levels and alterations in the content of antioxidant enzyme activities, particularly superoxide dismutase (SOD) and peroxidase (POD). Moreover, elevated DEHP concentrations correlated with increased malondialdehyde (MDA) levels. Our analysis detected a total of 507 metabolites in Brassica chinensis L., with 331 in shoots and 176 in roots, following DEHP exposure. There was a significant difference in the number of metabolites in shoots and roots, with 79 and 64 identified, respectively (VIP > 1, p < 0.05). Metabolic pathway enrichment in Brassica chinensis L. shoots revealed significant perturbations in valine, leucine, and isoleucine biosynthesis and degradation, aminoacyl-tRNA, and glucosinolate biosynthesis. In the roots of Brassica chinensis L., varying DEHP levels exerted a substantial impact on the biosynthesis of zeatin, ubiquinone terpenoids, propane, piperidine, and pyridine alkaloids, as well as glutathione metabolic pathways. Notably, DEHP's influence was more pronounced in the roots than in the shoots, with higher DEHP concentrations affecting a greater number of metabolic pathways. This experimental study provides valuable insights into the molecular mechanisms underlying DEHP-induced stress in Brassica chinensis L., with potential implications for human health and food safety.

Exploring Metabolic Characteristics in Different Geographical Locations and Yields of Nicotiana tabacum L. Using Gas Chromatography-Mass Spectrometry Pseudotargeted Metabolomics Combined with Chemometrics

The quality of crops is closely associated with their geographical location and yield, which is reflected in the composition of their metabolites. Hence, we employed GC-MS pseudotargeted metabolomics to investigate the metabolic characteristics of high-, medium-, and low-yield Nicotiana tabacum (tobacco) leaves from the Bozhou (sweet honey flavour) and Shuicheng (light flavour) regions of Guizhou Province. A total of 124 metabolites were identified and classified into 22 chemical categories. Principal component analysis revealed that the geographical location exerted a greater influence on the metabolic profiling than the yield. Light-flavoured tobacco exhibited increased levels of sugar metabolism- and glycolysis-related intermediate products (trehalose, glucose-6-phosphate, and fructose-6-phosphate) and a few amino acids (proline and leucine), while sweet honey-flavoured tobacco exhibited increases in the tricarboxylic acid cycle (TCA cycle) and the phenylpropane metabolic pathway (p-hydroxybenzoic acid, caffeic acid, and maleic acid). Additionally, metabolite pathway enrichment analysis conducted at different yields and showed that both Shuicheng and Bozhou exhibited changes in six pathways and four of them were the same, mainly C/N metabolism. Metabolic pathway analysis revealed higher levels of intermediates related to glycolysis and sugar, amino acid, and alkaloid metabolism in the high-yield samples, while higher levels of phenylpropane in the low-yield samples. This study demonstrated that GC-MS pseudotargeted metabolomics-based metabolic profiling can be used to effectively discriminate tobacco leaves from different geographical locations and yields, thus facilitating a better understanding of the relationship between metabolites, yield, and geographical location. Consequently, metabolic profiles can serve as valuable indicators for characterizing tobacco yield and geographical location.

Multi-phenotype response and cadmium detection of rice stem under toxic cadmium exposure

Rice stem is the sole conduit for cadmium translocation from underground to aboveground. The presence of cadmium can trigger responses of rice stem multi-phenotype, affecting metabolism, reducing yield, and altering composition, which is related to crop growth, food safety, and new energy utilization. Exploring the adversity response of plant phenotypes can provide a reliable assessment of growth status. However, the phytotoxicity and mechanism of cadmium stress on rice stem remain unclear. Here, we systematically revealed the response mechanisms of cadmium accumulation, adversity physiology, and morphological characteristic in rice stem under cadmium stress for the first time with concentration gradients of CK, 5, 25, 50, and 100 μM, and duration gradients of Day 5, Day 10, Day 15, and Day 20. The results indicated that cadmium stress led to a significant increase in cadmium accumulation, accompanied by the adversity response in stem phenotypes. Specifically, cadmium can cause fluctuations in soluble protein and disturbance of malondialdehyde (MDA), which reflects lipid peroxidation induced by cadmium accumulation. Lipid peroxidation inhibited rice growth by causing (1) a reduction in stem length, diameter, and weight, (2) suppression of air cavity, vascular bundle, parenchyma, and epidermal hair, and (3) disruption of cell structure. Furthermore, rapid detection of cadmium was realized based on the combination of laser-induced breakdown spectroscopy (LIBS) and machine learning, which took less than 3 min. The established qualitative model realized the precise discrimination of cadmium stress degrees with a prediction accuracy exceeding 92 %, and the quantitative model achieved the outstanding prediction effect of cadmium, with Rp of 0.9944. This work systematically revealed the phytotoxicity of cadmium on rice stem multi-phenotype from a novel perspective of lipid peroxidation and realized the rapid detection of cadmium in rice stem, which provided the technical tool and theoretical foundation for accurate prevention and efficient control of heavy metal risks in crops.

Methionine sulfoxide reductase 2 regulates Cvt autophagic pathway by altering the stability of Atg19 and Ape1 in Saccharomyces cerevisiae

The reversible oxidation of methionine plays a crucial role in redox regulation of proteins. Methionine oxidation in proteins causes major structural modifications that can destabilize and abrogate their function. The highly conserved methionine sulfoxide reductases protect proteins from oxidative damage by reducing their oxidized methionines, thus restoring their stability and function. Deletion or mutation in conserved methionine sulfoxide reductases leads to aging and several human neurological disorders and also reduces yeast growth on nonfermentable carbon sources. Despite their importance in human health, limited information about their physiological substrates in humans and yeast is available. For the first time, we show that Mxr2 interacts in vivo with two core proteins of the cytoplasm to vacuole targeting (Cvt) autophagy pathway, Atg19, and Ape1 in Saccharomyces cerevisiae. Deletion of MXR2 induces instability and early turnover of immature Ape1 and Atg19 proteins and reduces the leucine aminopeptidase activity of Ape1 without affecting the maturation process of Ape1. Additonally, Mxr2 interacts with the immature Ape1, dependent on Met17 present within the propeptide of Ape1 as a single substitution mutation of Met17 to Leu abolishes this interaction. Importantly, Ape1 M17L mutant protein resists oxidative stress-induced degradation in WT and mxr2Δ cells. By identifying Atg19 and Ape1 as cytosolic substrates of Mxr2, our study maps the hitherto unexplored connection between Mxr2 and the Cvt autophagy pathway and sheds light on Mxr2-dependent oxidative regulation of the Cvt pathway.

Application of Multi-Omics Technologies to the Study of Phytochromes in Plants

Phytochromes (phy) are distributed in various plant organs, and their physiological effects influence plant germination, flowering, fruiting, and senescence, as well as regulate morphogenesis throughout the plant life cycle. Reactive oxygen species (ROS) are a key regulatory factor in plant systemic responses to environmental stimuli, with an attractive regulatory relationship with phytochromes. With the development of high-throughput sequencing technology, omics techniques have become powerful tools, and researchers have used omics techniques to facilitate the big data revolution. For an in-depth analysis of phytochrome-mediated signaling pathways, integrated multi-omics (transcriptomics, proteomics, and metabolomics) approaches may provide the answer from a global perspective. This article comprehensively elaborates on applying multi-omics techniques in studying phytochromes. We describe the current research status and future directions on transcriptome-, proteome-, and metabolome-related network components mediated by phytochromes when cells are subjected to various stimulation. We emphasize the importance of multi-omics technologies in exploring the effects of phytochromes on cells and their molecular mechanisms. Additionally, we provide methods and ideas for future crop improvement.

Effects of Exogenous Abscisic Acid on the Physiological and Biochemical Responses of Camellia oleifera Seedlings under Drought Stress

This study comprehensively investigates the physiological and molecular regulatory mechanisms of Camellia oleifera seedlings under drought stress with a soil moisture content of about 30%, where exogenous abscisic acid (ABA) was applied via foliar spraying at concentrations of 50 µg/L, 100 µg/L, and 200 µg/L. The results demonstrated that appropriate concentrations of ABA treatment can regulate the physiological state of the seedlings through multiple pathways, including photosynthesis, oxidative stress response, and osmotic balance, thereby aiding in the restructuring of their drought response strategy. ABA treatment effectively activated the antioxidant system by reducing stomatal conductance and moderately inhibiting the photosynthetic rate, thus alleviating oxidative damage caused by drought stress. Additionally, ABA treatment promoted the synthesis of osmotic regulators such as proline, maintaining cellular turgor stability and enhancing the plant's drought adaptability. The real-time quantitative PCR results of related genes indicated that ABA treatment enhanced the plant's response to the ABA signaling pathway and improved disease resistance by regulating the expression of related genes, while also enhancing membrane lipid stability. A comprehensive evaluation using a membership function approach suggested that 50 µg/L ABA treatment may be the most-effective in mitigating drought effects in practical applications, followed by 100 µg/L ABA. The application of 50 µg/L ABA for 7 h induced significant changes in various biochemical parameters, compared to a foliar water spray. Notably, superoxide dismutase activity increased by 17.94%, peroxidase activity by 30.27%, glutathione content by 12.41%, and proline levels by 25.76%. The content of soluble sugars and soluble proteins rose by 14.79% and 87.95%, respectively. Additionally, there was a significant decrease of 31.15% in the malondialdehyde levels.

Response to Cadmium in Silene vulgaris Ecotypes Is Distinctly Affected by Priming-Induced Changes in Oxidation Status of Macromolecules

This study investigated the impact of several priming agents on metal-tolerant and sensitive Silene vulgaris ecotypes exposed to environmentally relevant cadmium dose. We analyzed how priming-induced changes in the level of lipid, protein, and DNA oxidation contribute to calamine (Cal) and non-calamine (N-Cal) ecotype response to Cd toxicity, and whether the oxidative modifications interrelate with Cd tolerance. In non-primed ecotypes, the levels of DNA and protein oxidation were similar whereas Cal Cd tolerance was manifested in reduced lipid peroxidation. In both ecotypes protective action of salicylic acid (SA) and nitric oxide (NO) priming was observed. SA stimulated growth and reduced lipid and DNA oxidation at most, while NO protected DNA from fragmentation. Priming with hydrogen peroxide reduced biomass and induced DNA oxidation. In N-Cal, priming diminished Cd accumulation and oxidative activity, whereas in Cal, it merely affected Cd uptake and induced protein carbonylation. The study showed that priming did not stimulate extra stress resistance in the tolerant ecotype but induced metabolic remodeling. In turn, the lack of adaptive tolerance made the sensitive ecotype more responsive to the benefits of the primed state. These findings could facilitate priming exploitation with a view of enhancing metallophyte and non-metallophyte suitability for phytoremediation and land revegetation.

Benzophenone-3 sunscreen causes phytotoxicity and cytogenotoxicity in higher plants

The benzophenone-3 (BP-3) sunscreen is recurrently released into the environment from different sources, however, evaluations of its adverse effects on plants do not exist in the literature. In this study, BP-3 was evaluated, at concentrations 2; 20, and 200 µg/L, regarding phytotoxicity, based on germination and root elongation in seeds, in Lactuca sativa L., Cucumis sativus L. and Allium cepa L., and phytotoxicity, cytogenotoxicity and oxidative stress in A. cepa bulb roots. The BP-3 concentrations, except for the 200 µg/L concentration in L. sativa, caused no significant reduction in seed germination. All concentrations tested significantly reduced the elongation of roots from seeds and roots from bulbs. The 20 and 200 µg/L concentrations caused oxidation in cells, disturbances in the cell cycle, and alterations in prophase and metaphase, as well as the induction of micronuclei, in A. cepa root meristems. Furthermore, the three concentrations induced a high number of prophases in root tips. Such disorders were caused by excess H2O2 and superoxide produced in cells due to exposure to BP-3, which triggered significant phytotoxicity, cytotoxicity, and genotoxicity in root meristems. Thus, the recurrent contamination of agricultural and non-agricultural soils with BP-3, even at a concentration of 2 µg/L, represents an environmental risk for plants. These results point to the impending need to set limits for the disposal of this sunscreen into the environment since BP-3 has been used in industry for several decades.

The damage caused by Cd toxicity to photosynthesis, cellular ultrastructure, antioxidant metabolism, and gene expression in young cacao plants are mitigated by high Mn doses in soil

Manganese (Mn) is one of the essential mineral micronutrients most demanded by cacao. Cadmium (Cd) is highly toxic to plants and other living beings. There are indications that Mn can interact with Cd and mitigate its toxicity. The objective of this study was to evaluate the action of Mn on the toxic effect of Cd in young plants of the CCN 51 cacao genotype, subjected to different doses of Mn, Cd, and Mn+Cd in soil, through physiological, biochemical, molecular, and micromorphological and ultrastructural changes. High soil Mn doses favored the maintenance and performance of adequate photosynthetic processes in cacao. However, high doses of Cd and Mn+Cd in soil promoted damage to photosynthesis, alterations in oxidative metabolism, and the uptake, transport, and accumulation of Cd in roots and leaves. In addition, high Cd concentrations in roots and leaf tissues caused irreversible damage to the cell ultrastructure, compromising cell function and leading to programmed cell death. However, there was a mitigation of Cd toxicity when cacao was grown in soils with low Cd doses and in the presence of Mn. Thus, damage to the root and leaf tissues of cacao caused by Cd uptake from contaminated soils can be attenuated or mitigated by the presence of high Mn doses in soil.

Assessing phytotoxicity and cyto-genotoxicity of two insecticides using a battery of in-vitro biological assays

Intensive use of chemical pesticides in agriculture poses environmental risks and may have negative impacts on agricultural productivity. The potential phytotoxicity of two chemical pesticides, chlorpyrifos (CPS) and fensulfothion (FSN), were evaluated using Cicer arietinum and Allium cepa as model crops. Different concentrations (0-100 μgmL-1) of both CPS and FSN decreased germination and biological attributes of C. arietinum. High pesticide doses significantly (p ≤ 0.05) caused membrane damage by producing thiobarbituric acid reactive substances (TBARS) and increasing proline (Pro) content. Pesticides elevated ROS levels and substantially increased the superoxide anions and H2O2 concentrations, thus aggravating cell injury. Plants exposed to high pesticide dosages displayed significantly higher antioxidant levels to combat pesticide-induced oxidative stress. Ascorbate peroxidase (APX), guaiacol peroxidase (GPX), catalase (CAT), peroxidase (POD), and superoxide dismutase (SOD) increased by 48%, 93%, 71%, 52% and 94%, respectively, in C. arietinum roots exposed to 100 µgFSNmL-1. Under CLSM, pesticide-exposed C. arietinum and 2',7'-dichlorodihydrofluorescein diacetate (2'7'-DCF) and 3,3'-diaminobenzidine stained roots exhibited increased ROS production in a concentration-dependent manner. Additionally, enhanced Rhodamine 123 (Rhd 123) and Evan's blue fluorescence in roots, as well as changes in mitochondrial membrane potential (ΔΨm) and cellular apoptosis, were both associated with high pesticide dose. Allium cepa chromosomal aberration (CAs) assay showed a clear reduction in mitotic index (MI) and numerous chromosomal anomalies in root meristematic cells. Additionally, a-dose-dependent increase in DNA damage in root meristematic cells of A. cepa and conversion of the super-coiled form of DNA to open circular in pBR322 plasmid revealed the genotoxic potential of pesticides. The application of CPS and FSN suggests phytotoxic and cyto-genotoxic effects that emphasize the importance of careful monitoring of current pesticide level in soil before application and addition at optimal levels to soil-plant system. It is appropriate to prepare both target-specific and slow-release agrochemical formulations for crop protection with concurrent safeguarding of agroecosystems.

Protective Effect of Orbitides from Linseed (Linum usitatissimum L.) against Ultraviolet B-induced Photoaging in Zebrafish

Excessive ultraviolet (UV) exposure is the primary environmental factor that contributes to skin aging. Orbitides have been considered as important functional components in linseed, and they are complex and multiple. In this study, linseed orbitides (LOs) were divided into oxidized linseed orbitides (OLOs) and reduced linseed orbitides (RLOs) and used to investigate protection against ultraviolet B-induced photoaging in zebrafish. First, the results of the zebrafish embryo acute toxicity test showed that the OLOs had obvious embryo toxicity compared with RLOs. And RLOs had better effect in ultraviolet B-treated zebrafish, which may significantly reduce the reactive oxygen species levels and inhibit the degradation of collagen. Besides, we also found that RLOs could effectively inhibit the oxidation of proteins and lipids and regulate the activity of antioxidant enzymes. Furthermore, neutrophil recruitment to the dorsal and caudal fin regions was observed in UVB-treated zebrafish, and RLOs effectively alleviated this migration. In conclusion, RLOs have strong photoprotective effects and potential to be used as antiphotoaging ingredients.

Some Physiological Effects of Nanofertilizers on Wheat-Aphid Interactions

The increasing use of nanofertilizers in modern agriculture and their impact on crop yield and pest management require further research. In this study, the effects of nano-Fe, -Zn, and -Cu (which are synthesized based on nanochelating technology), and urea (N) fertilizers on the antioxidant activities of wheat plants (cv. Chamran), and the wheat green aphid Schizaphis graminum (Rondani) are investigated. The authors observed the highest levels of phenolics in non-infested nano-Zn-treated plants (26% higher compared with control). The highest H₂O₂ levels are in the infested and non-infested nano-Zn-treated and infested nano-Fe-treated plants (in infested nano-Zn and nano-Fe treated plants, 18% and non-infested nano-Zn-treated plants, 28% higher compared with control). The highest peroxidase (POX) activity is observed in the infested and non-infested N-treated and non-infested water-treated plants (almost 14%, 37%, and 46% higher than control, respectively). The lowest activity is in the infested plants' nano-Zn and -Fe treatments (almost 7 and 5 folds lower compared to the control, respectively). The highest and lowest catalase (CAT) activity are in the infested N-treated plants (almost 42% higher than control) and water-treated plants, respectively. The infested nano-Zn, -Fe, -Cu and Hoagland-treated plants showed the highest superoxide dismutase (SOD) activity. Regarding the antioxidant enzyme activities of S. graminum, the highest POX activity is in the nano-Cu treatment (more than two folds higher compared with control); the highest CAT and SOD activities are in the nano-Cu and -Zn treatments. It can be concluded that the application of nanofertilizers caused increasing effects on the wheat plant's antioxidant system and its resistance to S. graminum.

Genome-wide identification and analysis of glyceraldehyde-3-phosphate dehydrogenase family reveals the role of GmGAPDH14 to improve salt tolerance in soybean (Glycine max L.)

Introduction

Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) is an essential key enzyme in the glycolytic pathway and plays an important role in stress responses. Although GAPDH family genes have been found in different plant species, the determination of their gene family analysis and their functional roles in soybean are still unknown.

Methods

In this study, gene sequence and expression data were obtained using online tools, and systematic evolution, expression profile analysis, and qRT-PCR analysis were conducted.

Results and Discussion

Here a total of 16 GmGAPDH genes were identified on nine chromosomes, which were classified into three clusters. Additionally, all GmGAPDH genes harbor two highly conserved domains, including Gp_dh_N (PF00044) and Gp_dh_C (PF02800). The qRTPCR analysis also showed that most GmGAPDH genes significantly responded to multiple abiotic stresses, including NaHCO3, polyethylene glycol, cold, and salt. Among them, GmGAPDH14 was extraordinarily induced by salt stress. The GmGAPDH14 gene was cloned and overexpressed through soybean hair roots. The overexpressed transgenic soybean plants of the GmGAPDH14 gene have also shown better growth than that of control plants. Moreover, the overexpressed transgenic plants of GmGAPDH14 gene had higher activities of superoxide dismutase but lower malonaldehyde (MDA) content than those of control plants under salt stress. Meanwhile, a total of four haplotypes were found for the GmGAPDH14 gene, and haplotypes 2, 3, and 4 were beneficial for the tolerance of soybean to salt stress. These results suggest that the GmGAPDH14 gene might be involved in the process of soybean tolerance to salt stress. The results of this study will be valuable in understanding the role of GAPDH genes in the abiotic stress response of soybean.

Alterations in Physiological, Biochemical, and Molecular Responses of Impatiens walleriana to Drought by Methyl Jasmonate Foliar Application

Drought stress affects plant growth and development through several mechanisms, including the induction of oxidative stress. To cope with drought, plants have drought tolerance mechanisms at the physiological, biochemical, and molecular levels. In this study, the effects of foliar application of distilled water and methyl jasmonate (MeJA) (5 and 50 µM) on the physiological, biochemical, and molecular responses of Impatiens walleriana during two drought regimes (15 and 5% soil water content, SWC) were investigated. The results showed that plant response depended on the concentration of the elicitor and the stress intensity. The highest chlorophyll and carotenoid contents were observed at 5% SWC in plants pre-treated with 50 µM MeJA, while the MeJA did not have a significant effect on the chlorophyll a/b ratio in drought-stressed plants. Drought-induced formation of hydrogen peroxide and malondialdehyde in plants sprayed with distilled water was significantly reduced in plant leaves pretreated with MeJA. The lower total polyphenol content and antioxidant activity of secondary metabolites in MeJA-pretreated plants were observed. The foliar application of MeJA affected the proline content and antioxidant enzyme activities (superoxide dismutase, peroxidase, and catalase) in plants that suffered from drought. The expression of abscisic acid (ABA) metabolic genes (IwNCED4, IwAAO2, and IwABA8ox3) was the most affected in plants sprayed with 50 µM MeJA, while of the four analyzed aquaporin genes (IwPIP1;4, IwPIP2;2, IwPIP2;7, and IwTIP4;1), the expression of IwPIP1;4 and IwPIP2;7 was strongly induced in drought-stressed plants pre-treated with 50 µM MeJA. The study's findings demonstrated the significance of MeJA in regulating the gene expression of the ABA metabolic pathway and aquaporins, as well as the considerable alterations in oxidative stress responses of drought-stressed I. walleriana foliar sprayed with MeJA. The results improved our understanding of this horticulture plant's stress physiology and the field of plant hormones' interaction network in general.

Process variables that defined the phytofiltration efficiency of invasive macrophytes in aquatic system

Phytofiltration is an eco-friendly and cost-effective approach to the management of pollutants in aquatic system. The present study aimed at elucidating the process variables that defined the phytofiltration efficiency of invasive macrophytes in aquatic system. The invasion of macrophytes, such as Pistia stratiotes, of water bodies is an undesirable experience because of the challenges synonymous with their occurrence. Owing to the unfettered proliferation, high and rich biomass generation, and nutrient uptake capability, these macrophytes outcompete the native vegetation and reduce the distinctiveness of the biological communities at various scales. However, these same intrinsic features positioned them as an ideal phytofiltration species for the decontamination of polluted aqua systems. Herein, we provided an overview of the process of phytofiltration in an aquatic system, and the need to create a balanced ecological system through the exploitation of the potentials of macrophytes as phytoremediators. The translocation factor, type, and concentration of pollutants in the matrix, pH value, type of macrophyte employed are among the factors identified as determinants of the success or failure of invasive macrophytes as pollutant remediators in the aqua system. Therefore, the optimization of these variables, to enhance the phytoremediation potentials of the different macrophytes were critically appraised.

LC-ESI-MS/MS Analysis of Sulfolipids and Galactolipids in Green and Red Lettuce (Lactuca sativa L.) as Influenced by Sulfur Nutrition

Sulfur (S) deprivation leads to abiotic stress in plants. This can have a significant impact on membrane lipids, illustrated by a change in either the lipid class and/or the fatty acid distribution. Three different levels of S (deprivation, adequate, and excess) in the form of potassium sulfate were used to identify individual thylakoid membrane lipids, which might act as markers in S nutrition (especially under stress conditions). The thylakoid membrane consists of the three glycolipid classes: monogalactosyl- (MGDG), digalactosyl- (DGDG), and sulfoquinovosyl diacylglycerols (SQDG). All of them have two fatty acids linked, differing in chain length and degree of saturation. LC-ESI-MS/MS served as a powerful method to identify trends in the change in individual lipids and to understand strategies of the plant responding to stress. Being a good model plant, but also one of the most important fresh-cut vegetables in the world, lettuce (Lactuca sativa L.) has already been shown to respond significantly to different states of sulfur supply. The results showed a transformation of the glycolipids in lettuce plants and trends towards a higher degree of saturation of the lipids and an increased level of oxidized SQDG under S-limiting conditions. Changes in individual MGDG, DGDG, and oxidized SQDG were associated to S-related stress for the first time. Promisingly, oxidized SQDG might even serve as markers for further abiotic stress factors.

Tutorial review on the processing and performance of fabrics with antipathogenic inorganic agents

Functionalized textiles have been increasingly used for enhancing antimicrobial or antiviral (antipathogenic) action. Those pathogens can cause recurring diseases by direct or indirect transmission. Particularly, airborne microorganisms may cause respiratory diseases or skin infections like allergies and acne and the use of inorganic agents such as metal and metal oxides has proven effective in antipathogen applications. This review is a tutorial on how to obtain functional fabric with processes easily applied for industrial scale. Also, this paper summarizes relevant textiles and respective incorporated inorganic agents, including their antipathogenic mechanism of action. In addition, the processing methods and functional finishing, on a laboratory and industrial scale, to obtain a functional textile are shown. Characterization techniques, including antipathogenic activity and durability, mechanical properties, safety, and environmental issues, are presented. Challenges and perspectives on the broader use of antipathogenic fabrics are discussed.

The Key Roles of ROS and RNS as a Signaling Molecule in Plant-Microbe Interactions

Reactive oxygen species (ROS) and reactive nitrogen species (RNS) play a pivotal role in the dynamic cell signaling systems in plants, even under biotic and abiotic stress conditions. Over the past two decades, various studies have endorsed the notion that these molecules can act as intracellular and intercellular signaling molecules at a very low concentration to control plant growth and development, symbiotic association, and defense mechanisms in response to biotic and abiotic stress conditions. However, the upsurge of ROS and RNS under stressful conditions can lead to cell damage, retarded growth, and delayed development of plants. As signaling molecules, ROS and RNS have gained great attention from plant scientists and have been studied under different developmental stages of plants. However, the role of RNS and RNS signaling in plant-microbe interactions is still unknown. Different organelles of plant cells contain the enzymes necessary for the formation of ROS and RNS as well as their scavengers, and the spatial and temporal positions of these enzymes determine the signaling pathways. In the present review, we aimed to report the production of ROS and RNS, their role as signaling molecules during plant-microbe interactions, and the antioxidant system as a balancing system in the synthesis and elimination of these species.

Prospecting toxicity of octocrylene in Allium cepa L. and Eisenia fetida Sav

Octocrylene sunscreen is found in different environmental compartments. Unlike aquatic organisms, there are few studies evaluating the adverse effects caused by this pollutant on terrestrial plants, and no studies on soil fauna. In this study, octocrylene was evaluated at concentrations of 10, 100, and 1000 µg/L for phytotoxicity, cytogenotoxicity, and oxidative stress in Allium cepa L., and acute toxicity and oxidative stress in Eisenia fetida Sav. In A. cepa, at concentrations of 100 and 1000 µg/L, octocrylene reduced the germination potential in seeds, inhibited root elongation, and caused disturbance in cell division in roots. In E. fetida, the concentration of 1000 µg/L promoted an avoidance rate of 80%, while 10 µg/L caused a hormesis effect. The concentrations 100 and 1000 µg/L caused lipid peroxidation in A. cepa and E. fetida. Based on the results, the recurrent use of biosolids in soil fertilization, as well as the irrigation of plants with wastewater, with the presence of octocrylene can negatively impact the survival of different species that depend directly or indirectly on the soil.

The intervention of classical and molecular breeding approaches to enhance flooding stress tolerance in soybean - An review

Abiotic stresses and climate changes cause severe loss of yield and quality of crops and reduce the production area worldwide. Flooding stress curtails soybean growth, yield, and quality and ultimately threatens the global food supply chain. Flooding tolerance is a multigenic trait. Tremendous research in molecular breeding explored the potential genomic regions governing flood tolerance in soybean. The most robust way to develop flooding tolerance in soybean is by using molecular methods, including quantitative trait loci (QTL) mapping, identification of transcriptomes, transcription factor analysis, CRISPR/Cas9, and to some extent, genome-wide association studies (GWAS), and multi-omics techniques. These powerful molecular tools have deepened our knowledge about the molecular mechanism of flooding stress tolerance. Besides all this, using conventional breeding methods (hybridization, introduction, and backcrossing) and other agronomic practices is also helpful in combating the rising flooding threats to the soybean crop. The current review aims to summarize recent advancements in breeding flood-tolerant soybean, mainly by using molecular and conventional tools and their prospects. This updated picture will be a treasure trove for future researchers to comprehend the foundation of flooding tolerance in soybean and cover the given research gaps to develop tolerant soybean cultivars able to sustain growth under extreme climatic changes.

Relationship between suppression of plant defence systems by Meloidogyne javanica with the distance of different parts of the plant from the nematode establishment site

Suppression of plant defence systems by plant-parasitic nematodes is an important aspect of research on resistance induction in plants. The present work aimed to address the question of whether this suppressive ability by nematodes can be spread systemically and equally to other parts of the plant. The root-knot nematode, Meloidogyne javanica, and the host plant, tomato, was used with salicylic acid (SA) as a potent inducer of the plant defence systems. SA was sprayed on the second and fifth leaves, as near and far from the nematode establishment site, respectively. The results of hydrogen peroxide and phenylalanine ammonia lyase enzyme evaluation in the root (site of nematode establishment), crown, second and fifth leaves showed that, firstly, the amount of defence compounds induced by SA in the leaves was not equal in all parts of the plant and gradually decreased from the aerial parts (treatment site) towards the roots. Furthermore, the synthesis and accumulation of the evaluated compounds in the younger parts of the plant (fifth leaf) was more than the older parts (second leaf), and the crown and root. Although the suppression of the plant defence systems by the nematode was transferred to other parts of the plant, the amount of this suppression gradually decreased in the parts farthest from the site of the nematode establishment. Based on the results, it is inferred that the success of a resistance induction strategy in plant disease management depends on the type of pathogen, type of inducer, place of application of the inducer on the plant and the induction area.

Effects of high- and low-fiber diets on intestinal oxidative stress in growing-finishing pigs

Feed is the most expensive facet of commercial pork production. In order to reduce feed costs, using high-fiber ingredients has become a common practice. Moderate levels of fiber can maintain intestinal physiological function and promote intestinal health. Oxidative stress is linked to impaired nutrient absorption and growth performance. This study investigated the effects of high-fiber (5.26% crude fiber) and low-fiber (2.46% crude fiber) diets on growth performance and intestinal oxidative stress parameters in growing-finishing pigs. Forty growing pigs with initial body weight (27.07 ± 1.26 kg) were randomly assigned to 2 treatment groups with 10 replicates of 2 pigs per pen. Pigs were weighed on day 35, 42, and 70. The feed intake was recorded daily to calculate growth performance parameters. On day 70, eight pigs in each treatment group were randomly selected and euthanized to obtain jejunum to measure oxidative stress status. Pigs fed a high-fiber diet were heavier than those fed a low-fiber diet on days 35, 42, and 70 (P < 0.05). During the whole feeding period, pigs fed a high-fiber diet had a higher average daily gain than those fed a low-fiber diet (P < 0.05). The low-fiber diet resulted in increased levels of malondialdehyde (P < 0.05) in the jejunum, suggesting that the low-fiber diet contributed to oxidative stress in the jejunum. The low-fiber diet also led to a significant increase in glutathione and oxidized glutathione levels (P < 0.05) in the jejunum, indicating that pigs fed a low-fiber diet needed to produce more antioxidant substances to cope with oxidative stress in the intestine. This was accompanied by a significant increase in the expression of glutathione synthesizing enzymes in the jejunum of the low-fiber group (P < 0.05). These results suggest that the high-fiber diet can improve growth performance and maintain intestinal health in growing-finishing pigs by reducing intestinal oxidative stress.

Exposure to strong irradiance exacerbates photoinhibition and suppresses N resorption during leaf senescence in shade-grown seedlings of fullmoon maple (Acer japonicum)

Leaves of fullmoon maple (Acer japonicum) turn brilliant red with anthocyanins synthesis in autumn. Based on field observations, autumn coloring mainly occurs in outer-canopy leaves exposed to sun, whereas inner-canopy leaves remain green for a certain longer period before finally turn yellowish red with a smaller amount of anthocyanins. Here, we hypothesized that outer-canopy leaves protect themselves against photooxidative stress via anthocyanins while simultaneously shading inner canopy leaves and protecting them from strong light (holocanopy hypothesis). To test this hypothesis, we investigated photoinhibition and leaf N content during autumn senescence in leaves of pot-grown seedlings of fullmoon maple either raised under shade (L0, ≈13% relative irradiance to open) or transferred to full sunlight conditions on 5^th (LH1), 12^th (LH2), or 18^th (LH3) Oct, 2021. Dry mass-based leaf N (N_mass) in green leaves in shade-grown seedlings was ≈ 30 mg N g^-1 in summer. N_mass in shed leaves (25^th Oct to 1^st Nov) was 11.1, 12.0, 14.6, and 10.1 mg N g^-1 in L0, LH1, LH2, and LH3 conditions, respectively. Higher N_mass was observed in shed leaves in LH2, compared to other experimental conditions, suggesting an incomplete N resorption in LH2. F_v/F_m after an overnight dark-adaptation, measured on 19^th Oct when leaf N was actively resorbed, ranked L0: 0.72 > LH3: 0.56 > LH1: 0.45 > LH2: 0.25. As decreased F_v/F_m indicates photoinhibition, leaves in LH2 condition suffered the most severe photoinhibition. Leaf soluble sugar content decreased, but protein carbonylation increased with decreasing F_v/F_m across shade-grown seedlings (L0, LH1, LH2, and LH3) on 19^th Oct, suggesting impaired photosynthetic carbon gain and possible membrane peroxidation induced by photooxidative stress, especially in LH2 condition with less N resorption efficiency. Although the impairment of N resorption seems to depend on the timing and intensity of strong light exposure, air temperature, and consequently the degree of photoinhibition, the photoprotective role of anthocyanins in outer-canopy leaves of fullmoon maple might also contribute to allow a safe N resorption in inner-canopy leaves by prolonged shading.

The use of ecological analytical tools as an unconventional approach for untargeted metabolomics data analysis: the case of Cecropia obtusifolia and its adaptive responses to nitrate starvation

Plant metabolomics studies haves revealed new bioactive compounds. However, like other omics disciplines, the generated data are not fully exploited, mainly because the commonly performed analyses focus on elucidating the presence/absence of distinctive metabolites (and/or their precursors) and not on providing a holistic view of metabolomic changes and their participation in organismal adaptation to biotic and abiotic stress conditions. Therefore, spectral libraries generated from Cecropia obtusifolia cell suspension cultures in a previous study were considered as a case study and were reanalyzed herein. These libraries were obtained from a time-course experiment under nitrate starvation conditions using both electrospray ionization modes. The applied methodology included the use of ecological analytical tools in a systematic four-step process, including a population analysis of metabolite α diversity, richness, and evenness (i); a chemometrics analysis to identify discriminant groups (ii); differential metabolic marker identification (iii); and enrichment analyses and annotation of active metabolic pathways enriched by differential metabolites (iv). Our species α diversity results referring to the diversity of metabolites represented by mass-to-charge ratio (m/z) values detected at a specific retention time (rt) (an uncommon way to analyze untargeted metabolomic data) suggest that the metabolome is dynamic and is modulated by abiotic stress. A total of 147 and 371 m/z_rt pairs was identified as differential markers responsive to nitrate starvation in ESI^- and ESI⁺ modes, respectively. Subsequent enrichment analysis showed a high degree of completeness of biosynthetic pathways such as those of brassinosteroids, flavonoids, and phenylpropanoids.

ROS scavenging and ion homeostasis is required for the adaptation of halophyte Karelinia caspia to high salinity

The halophyte Karelinia caspia has not only fodder and medical value but also can remediate saline-alkali soils. Our previous study showed that salt-secreting by salt glands is one of main adaptive strategies of K. caspia under high salinity. However, ROS scavenging, ion homeostasis, and photosynthetic characteristics responses to high salinity remain unclear in K. caspia. Here, physio-biochemical responses and gene expression associated with ROS scavenging and ions transport were tested in K. caspia subjected to 100-400 mM NaCl for 7 days. Results showed that both antioxidant enzymes (SOD, APX) activities and non-enzymatic antioxidants (chlorogenic acid, α-tocopherol, flavonoids, polyamines) contents were significantly enhanced, accompanied by up-regulating the related enzyme and non-enzymatic antioxidant synthesis gene (KcCu/Zn-SOD, KcAPX6, KcHCT, KcHPT1, Kcγ-TMT, KcF3H, KcSAMS and KcSMS) expression with increasing concentrations of NaCl. These responses are beneficial for removing excess ROS to maintain a stable level of H2O2 and O2 - without lipid peroxidation in the K. caspia response to high salt. Meanwhile, up-regulating expression of KcSOS1/2/3, KcNHX1, and KcAVP was linked to Na+ compartmentalization into vacuoles or excretion through salt glands in K. caspia. Notably, salt can improve the function of PSII that facilitate net photosynthetic rates, which is helpful to growing normally in high saline. Overall, the findings suggested that ROS scavenging systems and Na+/K+ transport synergistically contributed to redox equilibrium, ion homeostasis, and the enhancement of PSII function, thereby conferring high salt tolerance.

Determination of Reactive Oxygen or Nitrogen Species and Novel Volatile Organic Compounds in the Defense Responses of Tomato Plants against Botrytis cinerea Induced by Trichoderma virens TRS 106

In the present study, Trichoderma virens TRS 106 decreased grey mould disease caused by Botrytis cinerea in tomato plants (S. lycopersicum L.) by enhancing their defense responses. Generally, plants belonging to the ‘Remiz’ variety, which were infected more effectively by B. cinerea than ‘Perkoz’ plants, generated more reactive molecules such as superoxide (O₂⁻) and peroxynitrite (ONOO⁻), and less hydrogen peroxide (H₂O₂), S-nitrosothiols (SNO), and green leaf volatiles (GLV). Among the new findings, histochemical analyses revealed that B. cinerea infection caused nitric oxide (NO) accumulation in chloroplasts, which was not detected in plants treated with TRS 106, while treatment of plants with TRS 106 caused systemic spreading of H₂O₂ and NO accumulation in apoplast and nuclei. SPME-GCxGC TOF-MS analysis revealed 24 volatile organic compounds (VOC) released by tomato plants treated with TRS 106. Some of the hexanol derivatives, e.g., 4-ethyl-2-hexynal and 1,5-hexadien-3-ol, and salicylic acid derivatives, e.g., 4-hepten-2-yl and isoamyl salicylates, are considered in the protection of tomato plants against B. cinerea for the first time. The results are valuable for further studies aiming to further determine the location and function of NO in plants treated with Trichoderma and check the contribution of detected VOC in plant protection against B. cinerea.

Transcriptomics Integrated with Metabolomics: Assessing the Central Metabolism of Different Cells after Cell Differentiation in Aureobasidium pullulans NG

When organisms are stimulated by external stresses, oxidative stress is induced, resulting in the production of large amounts of reactive oxygen species (ROS) that inhibit cell growth and accelerate cellular aging until death. Understanding the molecular mechanisms of abiotic stress is important to enhance cellular resistance, and Aureobasidium pullulans, a highly resistant yeast-like fungus, can use cellular differentiation to resist environmental stress. Here, swollen cells (SCs) from two different differentiation periods in Aureobasidium pullulans NG showed significantly higher antioxidant capacity and stress defense capacity than yeast-like cells (YL). The transcriptome and the metabolome of both cells were analyzed, and the results showed that amino acid metabolism, carbohydrate metabolism, and lipid metabolism were significantly enriched in SCs. Glyoxylate metabolism was significantly upregulated in carbohydrate metabolism, replacing the metabolic hub of the citric acid (TCA) cycle, helping to coordinate multiple metabolic pathways and playing an important role in the resistance of Aureobasidium pullulans NG to environmental stress. Finally, we obtained 10 key genes and two key metabolites in SCs, which provide valuable clues for subsequent validation. In conclusion, these results provide valuable information for assessing central metabolism-mediating oxidative stress in Aureobasidium pullulans NG, and also provide new ideas for exploring the pathways of eukaryotic resistance to abiotic stress.

Physiological and Transcriptome Analysis on Diploid and Polyploid Populus ussuriensis Kom. under Salt Stress

Populus ussuriensis Kom. is a valuable forest regeneration tree species in the eastern mountainous region of Northeast China. It is known that diploid P. ussuriensis (CK) performed barely satisfactorily under salt stress, but the salt stress tolerance of polyploid (i.e., triploid (T12) and tetraploid (F20)) P. ussuriensis is still unknown. In order to compare the salt stress tolerance and salt stress response mechanism between diploid and polyploid P. ussuriensis, phenotypic observation, biological and biochemistry index detections, and transcriptome sequencing (RNA-seq) were performed on CK, T12, and F20. Phenotypic observation and leaf salt injury index analysis indicated CK suffered more severe salt injury than T12 and F20. SOD and POD activity detections indicated the salt stress response capacity of T12 was stronger than that of CK and F20. MDA content, proline content and relative electric conductivity detections indicated CK suffered the most severe cell-membrane damage, and T12 exhibited the strongest osmoprotective capacity under salt stress. Transcriptome analysis indicated the DEGs of CK, T12, and F20 under salt stress were different in category and change trend, and there were abundant WRKY, NAM, MYB and AP2/ERF genes among the DEGs in CK, T12, and F20 under salt stress. GO term enrichment indicated the basic growth progresses of CK, and F20 was obviously influenced, while T12 immediately launched more salt stress response processes in 36 h after salt stress. KEGG enrichment indicated the DEGs of CK mainly involved in plant−pathogen interaction, ribosome biogenesis in eukaryotes, protein processing in endoplasmic reticulum, degradation of aromatic compounds, plant hormone signal transduction, photosynthesis, and carbon metabolism pathways. The DEGs of T12 were mainly involved in plant−pathogen interaction, cysteine and methionine metabolism, phagosomes, biosynthesis of amino acids, phenylalanine, tyrosine and tryptophan biosynthesis, plant hormone signal transduction, and starch and sucrose metabolism pathways. The DEGs of F20 were mainly involved in plant hormone signal transduction, plant−pathogen interaction, zeatin biosynthesis, and glutathione metabolism pathways. In conclusion, triploid exhibited stronger salt stress tolerance than tetraploid and diploid P. ussuriensis (i.e., T12 > F20 > CK). The differences between the DEGs of CK, T12, and F20 probably are the key clues for discovering the salt stress response signal transduction network in P. Ussuriensis.

Exogenous nitric oxide alleviates manganese toxicity in bean plants by modulating photosynthesis in relation to leaf lipid composition

Nitric oxide (NO) is a signaling molecule controlling several steps of plant development and defense process under stress conditions. NO-induced alleviation of manganese (Mn) toxicity was investigated on bean plants submitted for 28 days to 500 µM MnCl₂. Manganese excess decreased plant dry weight and elongation and increased levels of reactive oxygen species and lipid peroxidation leading to up-regulation of superoxide dismutase, catalase, and ascorbate peroxidase activities. The inhibitory effects of Mn on plant growth were associated to reduction of light-saturated carbon assimilation (A_max), stomatal conductance (g_s), and transpiration (E). By contrast, Mn induced significant increase in the apparent quantum yield (ɸ) and light compensation point (LCP). Interestingly, intracellular CO₂ (Ci) remains stable under Mn stress. Concomitantly, leaf membrane lipids have drastically reduced under high Mn concentration. After Mn exposition, leaf fatty acids exhibited a significant loss of linolenic acid, accompanied by an accumulation of palmitoleic, stearic, and linoleic acids leading to alteration of lipid desaturation. NO supply reversed Mn toxicity as evidenced by enhancement of growth biomass and recovery of A_max, E, ɸ, and LCP. Similarly, NO addition has positive effects on leaf lipid content and composition leading to restoration of lipid unsaturation. The modulation of fatty acid composition can be a way to reduce leaf membrane damages and maintain optimal photosynthesis and plant growth. Despite the absence of enough evidences in how NO is involved in lipid and photosynthesis recovery under Mn stress conditions, it is assumed that NO beneficial effects are attributable to NO/Mn cross-talk.

Potential involvement of proline and flavonols in plant responses to ozone

Ozone is considered to be a major phytotoxic pollutant. It is an oxidizing molecule with harmful effects that can affect human health and vegetation. Due to its phytotoxicity, it constitutes a threat to food security in a context of climate change. Proline accumulation is induced in response to numerous stresses and is assumed to be involved in plant antioxidant defense. We therefore addressed the question of the putative involvement of proline in plant ozone responses by analyzing the responses of two Arabidopsis mutants (obtained in the Col-0 genetic background) altered in proline metabolism and different ecotypes with various degrees of ozone sensitivity, to controlled ozone treatments. Among the mutants, the p5cs1 mutant plants accumulated less proline than the double prodh1xprodh2 (p1p2) mutants. Ozone treatments did not induce accumulation of proline in Col-0 nor in the mutant plants. However, the variation of the photosynthetic parameter Fv/Fm in the p1p2 mutant suggests a positive effect of proline. Proline accumulation induced by ozone was only observed in the most ozone-sensitive ecotypes, Cvi-0 and Ler. Contrary to our expectations, proline accumulation could not be correlated with variations in protein oxidation (carbonylation). On the other hand, flavonols content, measured here, using non-destructive methods, reflected exactly the genotypes ranking according to ozone sensitivity.

Transcriptomic Profiling Provides Molecular Insights Into Hydrogen Peroxide-Enhanced Arabidopsis Growth and Its Salt Tolerance

Salt stress is an important environmental factor limiting plant growth and crop production. Plant adaptation to salt stress can be improved by chemical pretreatment. This study aims to identify whether hydrogen peroxide (H2O2) pretreatment of seedlings affects the stress tolerance of Arabidopsis thaliana seedlings. The results show that pretreatment with H2O2 at appropriate concentrations enhances the salt tolerance ability of Arabidopsis seedlings, as revealed by lower Na+ levels, greater K+ levels, and improved K+/Na+ ratios in leaves. Furthermore, H2O2 pretreatment improves the membrane properties by reducing the relative membrane permeability (RMP) and malonaldehyde (MDA) content in addition to improving the activities of antioxidant enzymes, including superoxide dismutase, and glutathione peroxidase. Our transcription data show that exogenous H2O2 pretreatment leads to the induced expression of cell cycle, redox regulation, and cell wall organization-related genes in Arabidopsis, which may accelerate cell proliferation, enhance tolerance to osmotic stress, maintain the redox balance, and remodel the cell walls of plants in subsequent high-salt environments.

The ability of Meloidogyne javanica to suppress salicylic acid-induced plant defence responses

Suppression of the defence system of plants by some plant pathogens is an important mechanism of their parasitism, and plant-parasitic nematodes use several mechanisms to affect different parts of the plant defence system. This study was designed to investigate the ability of a root-knot nematode, Meloidogyne javanica, to reduce or suppress the plant (tomato) immune system, before or after activation by a strong inducer, salicylic acid (SA). The experimental treatments were tomato plants inoculated with nematodes alone, plants pre-treated with SA and then nematodes (‘SA then nematode’), plants treated with SA after nematode inoculation (‘nematode then SA’), plants treated with SA alone, and plants treated with sterile distilled water. The results showed that treatment of the plants with SA before or after nematode infection reduced nematode disease indices compared to the control (nematode alone). The number of eggs per individual egg mass, in ‘nematode then SA’ treatment was significantly greater than the control, which shows the effect of nematodes on reducing the plant defence mechanism in this treatment. Evaluation of the activity of some defence enzymes such as chitinase, protease, phenylalanine ammonia lyase, catalase and density of hydrogen peroxide also showed that M. javanica is able to suppress these compounds in the ‘SA then nematode’ treatment, and to a greater extent in the ‘nematode then SA’ treatment. Suppression of plant defence responses by phytonematodes is of great importance in their synergistic relationship with secondary pathogens and plants.

Genome-Wide Analysis of the Soybean Calmodulin-Binding Protein 60 Family and Identification of GmCBP60A-1 Responses to Drought and Salt Stresses

Calmodulin-binding protein 60 (CBP60) members constitute a plant-specific protein family that plays an important role in plant growth and development. In the soybean genome, nineteen CBP60 members were identified and analyzed for their corresponding sequences and structures to explore their functions. Among GmCBP60A-1, which primarily locates in the cytomembrane, was significantly induced by drought and salt stresses. The overexpression of GmCBP60A-1 enhanced drought and salt tolerance in Arabidopsis, which showed better state in the germination of seeds and the root growth of seedlings. In the soybean hairy roots experiment, the overexpression of GmCBP60A-1 increased proline content, lowered water loss rate and malondialdehyde (MDA) content, all of which likely enhanced the drought and salt tolerance of soybean seedlings. Under stress conditions, drought and salt response-related genes showed significant differences in expression in hairy root soybean plants of GmCBP60A-1-overexpressing and hairy root soybean plants of RNAi. The present study identified GmCBP60A-1 as an important gene in response to salt and drought stresses based on the functional analysis of this gene and its potential underlying mechanisms in soybean stress-tolerance.

Melatonin Promotes the Chilling Tolerance of Cucumber Seedlings by Regulating Antioxidant System and Relieving Photoinhibition

Chilling adversely affects the photosynthesis of thermophilic plants, which further leads to a decline in growth and yield. The role of melatonin (MT) in the stress response of plants has been investigated, while the mechanisms by which MT regulates the chilling tolerance of chilling-sensitive cucumber remain unclear. This study demonstrated that MT positively regulated the chilling tolerance of cucumber seedlings and that 1.0 μmol⋅L-1 was the optimum concentration, of which the chilling injury index, electrolyte leakage (EL), and malondialdehyde (MDA) were the lowest, while growth was the highest among all treatments. MT triggered the activity and expression of antioxidant enzymes, which in turn decreased hydrogen peroxide (H2O2) and superoxide anion (O2 ⋅-) accumulation caused by chilling stress. Meanwhile, MT attenuated the chilling-induced decrease, in the net photosynthetic rate (Pn) and promoted photoprotection for both photosystem II (PSII) and photosystem I (PSI), regarding the higher maximum quantum efficiency of PSII (Fv/Fm), actual photochemical efficiency (ΦPSII), the content of active P700 (ΔI/I0), and photosynthetic electron transport. The proteome analysis and western blot data revealed that MT upregulated the protein levels of PSI reaction center subunits (PsaD, PsaE, PsaF, PsaH, and PsaN), PSII-associated protein PsbA (D1), and ribulose-1,5-bisphosphate carboxylase or oxygenase large subunit (RBCL) and Rubisco activase (RCA). These results suggest that MT enhances the chilling tolerance of cucumber through the activation of antioxidant enzymes and the induction of key PSI-, PSII-related and carbon assimilation genes, which finally alleviates damage to the photosynthetic apparatus and decreases oxidative damage to cucumber seedlings under chilling stress.

Exogenous Application of Alpha-Lipoic Acid Mitigates Salt-Induced Oxidative Damage in Sorghum Plants through Regulation Growth, Leaf Pigments, Ionic Homeostasis, Antioxidant Enzymes, and Expression of Salt Stress Responsive Genes

In plants, α-Lipoic acid (ALA) is considered a dithiol short-chain fatty acid with several strong antioxidative properties. To date, no data are conclusive regarding its effects as an exogenous application on salt stressed sorghum plants. In this study, we investigated the effect of 20 µM ALA as a foliar application on salt-stressed sorghum plants (0, 75 and 150 mM as NaCl). Under saline conditions, the applied-ALA significantly (p ≤ 0.05) stimulated plant growth, indicated by improving both fresh and dry shoot weights. A similar trend was observed in the photosynthetic pigments, including Chl a, Chl b and carotenoids. This improvement was associated with an obvious increase in the membrane stability index (MSI). At the same time, an obvious decrease in the salt induced oxidative damages was seen when the concentration of H₂O₂ and malondialdehyde (MDA) was reduced in the salt stressed leaf tissues. Generally, ALA-treated plants demonstrated higher antioxidant enzyme activity than in the ALA-untreated plants. A moderate level of salinity (75 mM) induced the highest activities of superoxide dismutase (SOD), guaiacol peroxidase (G-POX), and ascorbate peroxidase (APX). Meanwhile, the highest activity of catalase (CAT) was seen with 150 mM NaCl. Interestingly, applied-ALA led to a substantial decrease in the concentration of both Na and the Na/K ratio. In contrast, K and Ca exhibited a considerable increase in this respect. The role of ALA in the regulation of K⁺/Na⁺ selectivity under saline condition was confirmed through a molecular study (RT-PCR). It was found that ALA treatment downregulated the relative gene expression of plasma membrane (SOS1) and vacuolar (NHX1) Na⁺/H⁺ antiporters. In contrast, the high-affinity potassium transporter protein (HKT1) was upregulated.

Using some growth stimuli, a comparative study of salt tolerance in two tomatoes cultivars and a related wild line with special reference to superoxide dismutases and related micronutrients

Salinity is a major global problem that threatens the agricultural sector, especially in areas that suffer from a shortage of water. It motivates ionic toxicity, osmotic and oxidative stresses, which greatly inhibits plant performances and crop productivites. However, micronutrients (MNs) or plant extracts, like germinated maize grain extract (gMGE), have been reported to minimize the effects of salt stress on plant growth and returns. Therefore, this study aimed at evaluating the influences of MNs or gMGE applied as foliar sprays on growth, physio-biochemical indices, and antioxidative system components in three genotypes of tomato plants stressed by 9 dS m⁻¹ NaCl. This salinity level markedly increased Na⁺ content, lipid peroxidation, ion leakage, and markers related to oxidative stress (superoxide; O₂^•− and hydrogen peroxide; H₂O₂). Besides, marked increases in activities of enzymatic (especially different forms of superoxide dismutase; SODs) and non-enzymatic antioxidants and osmoprotectant compounds were also observed. In contrast, growth, photosynthetic capacity including hill reaction activity (HRA), K⁺/Na⁺ ratio, tissue cell integrity (e.g., cell water content and membrane stability), and K⁺ and MNs contents decreased significantly under stress. However, compared to MNs, gMGE significantly improved the activities of the antioxidative system components (particularly SODs) and osmoprotectants, which were reflected in reduced Na⁺ accumulation, lipid peroxidation, ion leakage, and oxidative stress. These results were coupled with remarkable elevations in photosynthetic capacity including HRA, K⁺/Na⁺ ratio, tissue cell integrity, K⁺ content, and MNs contents, all of which were reflected in the enhancement of plant growth. Compared to local tomato cultivars (e.g., Castle Rock and C10), the wild line “0043-1” had better results. The interaction of three factors; salt stress, promoters, and tomato genotypes was significant. The wild tomato line “0043-1” as the best salt-tolerant is a good candidate for implication in breeding programs for tolerance to salinity to produce salt-tolerant cultivars for use to maximize tomato growth and productivity in saline environments.

OsANN4 modulates ROS production and mediates Ca2+ influx in response to ABA

BACKGROUND

Plant annexins are calcium- and lipid-binding proteins that have multiple functions, and a significant amount of research on plant annexins has been reported in recent years. However, the functions of annexins in diverse biological processes in rice are largely unclear.

RESULTS

Herein, we report that OsANN4, a calcium-binding rice annexin protein, was induced by abscisic acid (ABA). Under ABA treatment, the plants in which OsANN4 was knocked down by RNA interference showed some visible phenotypic changes compared to the wild type, such as a lower rooting rate and shorter shoot and root lengths. Moreover, the superoxide dismutase (SOD) and catalase (CAT) activities of the RNAi lines were significantly lower and further resulted in higher accumulation of O₂^.- and H₂O₂ than those of the wild-type. A Non-invasive Micro-test Technology (NMT) assay showed that ABA-induced net Ca²⁺ influx was inhibited in OsANN4 knockdown plants. Interestingly, the phenotypic differences caused by ABA were eliminated in the presence of LaCl₃ (Ca²⁺ channel inhibitor). Apart from this, we demonstrated that OsCDPK24 interacted with and phosphorylated OsANN4. When the phosphorylated serine residue of OsANN4 was substituted by alanine, the interaction between OsANN4 and OsCDPK24 was still observed, however, both the conformation of OsANN4 and its binding activity with Ca²⁺ might be changed.

CONCLUSIONS

OsANN4 plays a crucial role in the ABA response, partially by modulating ROS production, mediating Ca²⁺ influx or interacting with OsCDPK24.

Biostimulants for the Regulation of Reactive Oxygen Species Metabolism in Plants under Abiotic Stress

Global food security for a growing population with finite resources is often challenged by multiple, simultaneously occurring on-farm abiotic stresses (i.e., drought, salinity, low and high temperature, waterlogging, metal toxicity, etc.) due to climatic uncertainties and variability. Breeding for multiple stress tolerance is a long-term solution, though developing multiple-stress-tolerant crop varieties is still a challenge. Generation of reactive oxygen species in plant cells is a common response under diverse multiple abiotic stresses which play dual role of signaling molecules or damaging agents depending on concentration. Thus, a delicate balance of reactive oxygen species generation under stress may improve crop health, which depends on the natural antioxidant defense system of the plants. Biostimulants represent a promising type of environment-friendly formulation based on natural products that are frequently used exogenously to enhance abiotic stress tolerance. In this review, we illustrate the potential of diverse biostimulants on the activity of the antioxidant defense system of major crop plants under stress conditions and their other roles in the management of abiotic stresses. Biostimulants have the potential to overcome oxidative stress, though their wider applicability is tightly regulated by dose, crop growth stage, variety and type of biostimulants. However, these limitations can be overcome with the understanding of biostimulants’ interaction with ROS signaling and the antioxidant defense system of the plants.

The Effect of Plasma Activated Water on Maize (Zea mays L.) under Arsenic Stress

Plasma activated water (PAW) is a source of various chemical species useful for plant growth, development, and stress response. In the present study, PAW was generated by a transient spark discharge (TS) operated in ambient air and used on maize corns and seedlings in the 3 day paper rolls cultivation followed by 10 day hydroponics cultivation. For 3 day cultivation, two pre-treatments were established, “priming PAW” and “rolls PAW”, with corns imbibed for 6 h in the PAW and then watered daily by fresh water and PAW, respectively. The roots and the shoot were then analyzed for guaiacol peroxidase (G-POX, POX) activity, root tissues for their lignification, and root cell walls for in situ POX activity. To evaluate the potential of PAW in the alleviation abiotic stress, ten randomly selected seedlings were hydroponically cultivated for the following 10 days in 0.5 Hoagland nutrient solutions with and without 150 μM As. The seedlings were then analyzed for POX and catalase (CAT) activities after As treatment, their leaves for photosynthetic pigments concentration, and leaves and roots for As concentration. The PAW improved the growth of the 3 day-old seedlings in terms of the root and the shoot length, while roots revealed accelerated endodermal development. After the following 10 day cultivation, roots from PAW pre-treatment were shorter and thinner but more branched than the control roots. The PAW also enhanced the POX activity immediately after the imbibition and in the 3 day old roots. After 10 day hydroponic cultivation, antioxidant response depended on the PAW pre-treatment. CAT activity was higher in As treatments compared to the corresponding PAW treatments, while POX activity was not obvious, and its elevated activity was found only in the priming PAW treatment. The PAW pre-treatment protected chlorophylls in the following treatments combined with As, while carotenoids increased in treatments despite PAW pre-treatment. Finally, the accumulation of As in the roots was not affected by PAW pre-treatment but increased in the leaves.

Coordinated Role of Nitric Oxide, Ethylene, Nitrogen, and Sulfur in Plant Salt Stress Tolerance

Salt stress significantly contributes to major losses in agricultural productivity worldwide. The sustainable approach for salinity-accrued toxicity has been explored. The use of plant growth regulators/phytohormones, mineral nutrients and other signaling molecules is one of the major approaches for reversing salt-induced toxicity in plants. Application of the signaling molecules such as nitric oxide (NO) and ethylene (ETH) and major mineral nutrient such as nitrogen (N) and sulfur (S) play significant roles in combatting the major consequences of salt stress impacts in plants. However, the literature available on gaseous signaling molecules (NO/ETH) or/and mineral nutrients (N/S) stands alone, and major insights into the role of NO or/and ETH along with N and S in plant-tolerance to salt remained unclear. Thus, this review aimed to (a) briefly overview salt stress and highlight salt-induced toxicity, (b) appraise the literature reporting potential mechanisms underlying the role of gaseous signaling molecules and mineral nutrient in salt stress tolerance, and (c) discuss NO and ETH along with N and S in relation to salt stress tolerance. In addition, significant issues that have still to be investigated in this context have been mentioned.

Abscisic Acid in Coordination with Nitrogen Alleviates Salinity-Inhibited Photosynthetic Potential in Mustard by Improving Proline Accumulation and Antioxidant Activity

This investigation was done to assess the role of abscisic acid (ABA; 25 µM) and/or nitrogen (N; 10 mM) in the alleviation of salinity (NaCl; 100 mM)-induced reduction in photosynthetic activity and growth, N and sulfur (S) assimilation of mustard (Brassica juncea L.) cv. RH0-749. Salinity treatment caused oxidative stress and significantly elevated the content of both H2O2 and thiobarbituric acid reactive substances (TBARS), and impaired photosynthetic activity and growth, but increased the content of nitrogenous osmolyte proline and the activity of antioxidant enzymes involved in the metabolism of reactive oxygen species. The application of 25 µM ABA under a controlled condition negatively affected photosynthesis and growth. However, ABA, when combined with N, minimized oxidative stress and mitigated the salinity-inhibited effects by increasing the activity of antioxidant enzymes (superoxide dismutase, SOD; glutathione reductase, GR; ascorbate peroxidase, APX) and proline content. Overall, the supplementation of 10 mM N combined with 25 µM ABA provides an important strategy for enhancing the photosynthetic potential of B. juncea under saline conditions.

Regulation of Reactive Oxygen Species and Antioxidant Defense in Plants under Salinity

The generation of oxygen radicals and their derivatives, known as reactive oxygen species, (ROS) is a part of the signaling process in higher plants at lower concentrations, but at higher concentrations, those ROS cause oxidative stress. Salinity-induced osmotic stress and ionic stress trigger the overproduction of ROS and, ultimately, result in oxidative damage to cell organelles and membrane components, and at severe levels, they cause cell and plant death. The antioxidant defense system protects the plant from salt-induced oxidative damage by detoxifying the ROS and also by maintaining the balance of ROS generation under salt stress. Different plant hormones and genes are also associated with the signaling and antioxidant defense system to protect plants when they are exposed to salt stress. Salt-induced ROS overgeneration is one of the major reasons for hampering the morpho-physiological and biochemical activities of plants which can be largely restored through enhancing the antioxidant defense system that detoxifies ROS. In this review, we discuss the salt-induced generation of ROS, oxidative stress and antioxidant defense of plants under salinity.

Differences in lipid homeostasis and membrane lipid unsaturation confer differential tolerance to low temperatures in two Cycas species

BACKGROUND

C. panzhihuaensis is more tolerant to freezing than C. bifida but the mechanisms underlying the different freezing tolerance are unclear. Photosynthesis is one of the most temperature-sensitive processes. Lipids play important roles in membrane structure, signal transduction and energy storage, which are closely related to the stress responses of plants. In this study, the chlorophyll fluorescence parameters and lipid profiles of the two species were characterized to explore the changes in photosynthetic activity and lipid metabolism following low-temperature exposure and subsequent recovery.

RESULTS

Photosynthetic activity significantly decreased in C. bifida with the decrease of temperatures and reached zero after recovery. Photosynthetic activity, however, was little affected in C. panzhihuaensis. The lipid composition of C. bifida was more affected by cold and freezing treatments than C. panzhihuaensis. Compared with the control, the proportions of all the lipid categories recovered to the original level in C. panzhihuaensis, but the proportions of most lipid categories changed significantly in C. bifida after 3 d of recovery. In particular, the glycerophospholipids and prenol lipids degraded severely during the recovery period of C. bifida. Changes in acyl chain length and double bond index (DBI) occurred in more lipid classes immediately after low-temperature exposure in C. panzhihuaensis compare with those in C. bifida. DBI of the total main membrane lipids of C. panzhihuaensis was significantly higher than that of C. bifida following all temperature treatments.

CONCLUSIONS

The results of chlorophyll fluorescence parameters confirmed that the freezing tolerance of C. panzhihuaensis was greater than that of C. bifida. The lipid metabolism of the two species had differential responses to low temperatures. The homeostasis and plastic adjustment of lipid metabolism and the higher level of DBI of the main membrane lipids may contribute to the greater tolerance of C. panzhihuaensis to low temperatures.

Evaluation of physiological and biochemical responses of pistachio plants (Pistacia vera L.) exposed to pesticides

Pesticides may manipulate plant physiology as non-target organisms. In this study, we examined biochemical responses of pistachio plants (Pistacia vera L.) to imidacloprid and phosalone as common pesticides used to control pistachio psyllids. Enzymatic characterization in treated plants with pesticides showed greater specific activities of superoxide dismutase, catalase, ascorbate peroxidase, guaiacol peroxidase, phenylalanine ammonia-lyase, glutathione reductase, and glutathione S-transferase compared with untreated plants during 14 days after treatment. Further experiments displayed elevated levels of total phenols and total proteins coupled with significant increases in proline and total soluble carbohydrate contents in treated plants in comparison to untreated plants. Moreover, pesticide treatment leads to a significant decrease in polyphenol oxidase activity. Nevertheless, no significant changes in contents of hydrogen peroxide, malondialdehyde, total chlorophyll, and electrolyte leakage index were obtained in treated plants. Pesticides' impacts on host plant physiology resulted in similar responses between two pesticides with differences in peak days. Overall, the findings of this study provide an insight into the side effects of phosalone and imidacloprid, chemicals with no specific target site in plants, on the physiology and biochemistry of pistachio plants at recommended rates.