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The ubiquitin-proteasome system (UPS) is a key protein degradation pathway in eukaryotes, in which E3 ubiquitin ligases mediate protein ubiquitination, directly or indirectly targeting substrate proteins to regulate various biological processes, including plant growth, hormone signaling, immune responses, and adaptation to abiotic stress. In this study, we identified plant U-box protein 51 in Solanum tuberosum (StPUB51) as an E3 ubiquitin ligase through transcriptomic analysis, and used it as a candidate gene for gene-function analysis. Quantitative real-time PCR (qRT-PCR) was used to examine StPUB51 expression across different tissues, and its expression patterns under simulated drought stress induced by polyethylene glycol (PEG 6000) were assessed. Transgenic plants overexpressing StPUB51 and plants with down-regulated StPUB51 expression were generated to evaluate drought tolerance. The activities of key antioxidant enzymes-superoxide dismutase (SOD), catalase (CAT), and peroxidase (POD) as well as malondialdehyde (MDA) content in transgenic plants' leaves were measured under drought conditions. Protein–protein interactions involving StPUB51 were explored via yeast two-hybrid (Y2H) screening, with interaction verification by bimolecular fluorescence complementation (BiFC). StPUB51 was predominantly expressed in stems, with lower expression observed in tubers, and its expression was significantly upregulated in response to 20% PEG-6000 simulated drought. Subcellular localization assays revealed nuclear localization of the StPUB51 protein. Under drought stress, StPUB51-overexpressing plants exhibited enhanced SOD, POD, and CAT activities and reduced MDA levels, in contrast to plants with suppressed StPUB51 expression. Y2H and BiFC analyses identified two interacting proteins, StSKP2A and StGATA1, which may be functionally linked to StPUB51. Collectively, these findings suggest that StPUB51 plays a positive regulatory role in drought tolerance, enhancing resilience in potato growth and stress adaptation. [ABSTRACT FROM AUTHOR]

Iron (Fe) deficiency poses a major threat to pear (Pyrus spp.) fruit yield and quality. The Gretchen Hagen 3 (GH3) plays a vital part in plant stress responses. However, the GH3 gene family is yet to be characterized, and little focus has been given to the function of the GH3 gene in Fe deficiency responses. Here, we identified 15 GH3 proteins from the proteome of Chinese white pear (Pyrus bretschneideri) and analyzed their features using bioinformatics approaches. Structure domain and motif analyses showed that these PbrGH3s were relatively conserved, and phylogenetic investigation displayed that they were clustered into two groups (GH3 I and GH3 II). Meanwhile, cis-acting regulatory element searches of the corresponding promoters revealed that these PbrGH3s might be involved in ABA- and drought-mediated responses. Moreover, the analysis of gene expression patterns exhibited that most of the PbrGH3s were highly expressed in the calyxes, ovaries, and stems of pear plants, and some genes were significantly differentially expressed in normal and Fe-deficient pear leaves, especially for PbrGH3.5. Subsequently, the sequence of PbrGH3.5 was isolated from the pear, and the transgenic tomato plants with PbrGH3.5 overexpression (OE) were generated to investigate its role in Fe deficiency responses. It was found that the OE plants were more sensitive to Fe deficiency stress. Compared with wild-type (WT) plants, the rhizosphere acidification and ferric reductase activities were markedly weakened, and the capacity to scavenge reactive oxygen species was prominently impaired in OE plants under Fe starvation conditions. Moreover, the expressions of Fe-acquisition-associated genes, such as SlAHA4, SlFRO1, SlIRT1, and SlFER, were all greatly repressed in OE leaves under Fe depravation stress, and the free IAA level was dramatically reduced, while the conjugated IAA contents were notably escalated. Combined, our findings suggest that pear PbrGH3.5 negatively regulates Fe deficiency responses in tomato plants, and might help enrich the molecular basis of Fe deficiency responses in woody plants. [ABSTRACT FROM AUTHOR]

Soil salinization is one of the abiotic stresses that inhibit plant growth and development, which seriously restricts global crop production. WRKY transcription factors play an important role in regulating plant responses to stress such as salt stress. In our previous study, two WRKY family genes from okra, AeWRKY32 and AeWRKY70, were significantly up-regulated and down-regulated, respectively, in response to salt stress. In this study, subcellular localization showed that they were localized to the nucleus. The down-regulation of AeWRKY32 and AeWRKY70 via whole plant virus-induced gene silencing (VIGS) increased and decreased plant sensitivity to salt stress, respectively. Ectopic expression of AeWRKY32 and AeWRKY70 led to promoted and reduced salt tolerance in transgenic Arabidopsis, respectively. There was no significant difference between transgenic plants and wild type (WT) without salt treatment. Salt stress significantly inhibited plant growth. The decrease of chlorophyll content and the increase of anthocyanin content in AeWRKY32-overexpressed transgenic plants were lower than those in the WT, while AeWRKY70-overexpressed plants had the opposite effect. Under salt stress, the AeWRKY70-overexpressed plants had the highest malondialdehyde (MDA) content, followed by the WT, and the lowest in AeWRKY32-overexpressed plants. The hydrogen peroxide (H2O2) content and superoxide anion (O2•−) generation rate were only slightly increased. Moreover, salt stress significantly increased plant proline content and antioxidant enzyme activities, which was highest in AeWRKY70-overexpressed plants except superoxide dismutase (SOD). Taken together, these results suggest that AeWRKY32 and AeWRKY70 play positive and negative roles in plant in response to salt stress, respectively. [ABSTRACT FROM AUTHOR]

Raising rice (Oryza sativa L.) seedlings under LED lighting reduces nursing space and labor while ensuring health and quality. This study compared rice seedlings grown under natural light (NL) and LED lighting (AL), with and without inoculation of the beneficial fungus Falciphora oryzae. The results showed that NL-grown seedlings had greater stem diameters and shoot and root weights. The AL treatment induced higher plant height in some cultivars and longer root lengths in others. Microbial inoculation minimally affected phenotypes but increased root length in one cultivar. Chlorophyll content was unchanged across the treatments, while malondialdehyde (MDA) levels rose under AL in one cultivar, and catalase (CAT) levels were elevated in two cultivars under AL. Microbial inoculation reduced CAT levels under AL. The AL + M treatment increased rhizosphere prokaryotic community evenness and altered prokaryotic compositions in the rhizosphere and root endosphere, with Burkholderia and Paraburkholderia taxa showing differential responses to the treatments. These findings underscore the role of microbial inoculation in enhancing rice seedling health and resilience under artificial lighting, contributing to sustainable agriculture and food security. [ABSTRACT FROM AUTHOR]

Wheat is one of the most important crops to ensure food production globally. Understanding the mechanism of leaf senescence in wheat plays a crucial role in improving its productivity and resilience under various stress scenarios. In this study, we investigated biochemical, functional, and ultrastructural changes during leaf senescence in wheat genotypes with contrasting drought tolerance. For this, key parameters such as chlorophyll and total protein content, membrane stability, malondialdehyde level, and the activity of antioxidant enzymes (superoxide dismutase, ascorbate peroxidase, guaiacol peroxidase, benzidine peroxidase, and catalase) were comparatively analyzed during both natural and drought-induced senescence. Additionally, the expression of superoxide dismutase isoform genes functioning in different cellular compartments was studied, alongside ultrastructural changes in flag leaves. The experiments involved genotypes of bread wheat (Triticum aestivum L.) and durum (Triticum durum Desf.) wheat. The plants were grown in controlled environment chambers under control and drought conditions using a completely randomized design. After the booting stage, irrigation was discontinued for drought-treated plants. Flag leaves were sampled at 7, 14, 21, 28, and 35 days after anthesis. Drought-tolerant genotypes exhibited slower chlorophyll degradation, lower lipid peroxidation, enhanced membrane stability, and stronger antioxidant responses, allowing them to maintain cellular function longer, whereas sensitive genotypes showed accelerated leaf senescence. Transcript levels of FeSOD increased significantly post-flowering but declined as senescence progressed, while MnSOD expression exhibited a rise towards the later stages of ontogenesis across all studied genotypes. Ultrastructural analysis revealed progressive damage to chloroplast membranes, thylakoid structures, and mesophyll cell walls under stress conditions, particularly in sensitive genotypes. These findings contribute to a deeper understanding of the physiological and molecular responses of wheat to drought stress, offering potential targets for improving crop performance in water-limited environments. [ABSTRACT FROM AUTHOR]

Simple Summary: Reactive oxygen species (ROS) are vital molecules for the growth and development of plants. Roots, as the primary organs for nutrient and water absorption, play a critical role in sustaining plant life. In this review, we explore the mechanisms of ROS production in plants, the developmental processes of plant roots, and how ROS influence root development. This synthesis aims to provide insights and guidance for future research on the interplay between ROS and root development. Roots are fundamental to the growth, development, and survival of plants. Beyond anchoring the plant, roots absorb water and nutrients, supporting the plant's ability to grow and function normally. Root systems, originating from the apical meristem, exhibit significant diversity depending on the plant species. ROS are byproducts of aerobic metabolism, present in both above- and below-ground plant tissues. While ROS were once considered merely harmful byproducts of oxygen metabolism, they are now recognized as critical signaling molecules that regulate plant growth and development. Under stress conditions, plants produce elevated levels of ROS, which can inhibit growth. However, moderate ROS levels act as signals that integrate various regulatory pathways, contributing to normal plant development. However, there is still a lack of comprehensive and systematic research on how ROS precisely regulate root growth and development. This review provides an overview of ROS production pathways and their regulatory mechanisms in plants, with a particular focus on their influence on root development. [ABSTRACT FROM AUTHOR]

Silica or silicon dioxide nanoparticles (SiNPs) are one of the most widely spread nanoparticles in the environment, particularly, in urban areas in the form of dust. Influence of SiNPs on plant cells is unclear. This research was conducted to test a hypothesis that plant cell relative fluorescence and SiNP toxicity differ depending on the genetic properties and environmental conditions. Young pollen cells of lime trees in the mid to late one-nucleate developmental stage were found to be more sensitive to detect the influence of SiNPs and UV irradiation. Alteration of cell relative fluorescence depending on tree growth conditions was observed. Cells from trees grown in the urban area of Rīga had much lower reaction to SiNPs in comparison with cells from trees grown in the greenhouse. Lime trees growing for a long time in urban areas have complex adaptive features to a variable environment and can used as source-material to propagate lime trees for growing in such conditions. Flow cytometry can be applied for evaluation of plant reaction to factors that affect plants in the urban environment. [ABSTRACT FROM AUTHOR]

Insect’s gut microbiota has diverse effects on their fitness, and a comprehensive understanding of gut microbiota functions requires analyzing its diversity. Apolygus lucorum is a highly destructive pest that threatens many economically important crops in China. This study investigated the gut microbiota of A. lucorum across its life cycle using both culture-dependent and culture-independent methods. A total of 87 gut bacterial isolates were identified, belonging to 4 phyla, 27 families, and 45 genera, while Miseq sequencing detected 91 amplicon sequence variants (ASVs) assigned to 5 phyla, 28 families, and 39 genera. Proteobacteria and Firmicutes were the predominant phyla, with Staphylococcus and Serratia as the major genera. There were significant differences in the relative abundance of these genera between the nymph and adult stages. Staphylococcus was significantly more abundant in nymphs than it in adults, while Serratia was significantly more abundant in sexually mature adults than in other developmental stages. Notably, Serratia is a common opportunistic pathogen in many insects. Injecting the gut-dominant isolate Serratia marcescens verified its high pathogenicity. Additionally, immune indicators of the bug at different developmental stages supported the hypothesis that Serratia is a pathogen of A. lucorum. This study provides a foundation for understanding the role of gut bacteria in the life history of A. lucorum and developing new pest control strategies based on microbes. [ABSTRACT FROM AUTHOR]

The effects of different doses of UV‐C irradiation (0, 0.5, 1.0, 2.0, and 4.0 kJ m−2) on the quality and antioxidant capacity of peach fruit were examined. Results showed that irradiation at 2.0 kJ m−2 led to higher firmness and total soluble solids, as well as lower weight loss and decay index. Additionally, peach fruits irradiated with 2.0 kJ m−2 UV‐C exhibited increased production of reactive oxygen species, which in turn stimulated the synthesis of total phenolics and total flavonoids and enhanced the activities of superoxide dismutase, catalase, peroxidase, and ascorbate peroxidase. Overall, the best abiotic stress effect was observed with 2.0 kJ m−2 UV‐C irradiation, resulting in improved shelf quality and increased antioxidant capacity of peach fruits during storage. Practical Application: This study provides a theoretical basis for the application of UV‐C irradiation in peach fruit preservation. [ABSTRACT FROM AUTHOR]

Artemia is a genus of aquatic microcrustaceans that belong to the class Branchiopoda. Encysted Artemia urmiana embryos are resistant to harsh environmental stressors, including repeated desiccation, prolonged anoxia, extreme temperatures, and high levels of UV radiation. The protein artemin has a chaperone activity and is believed to play a crucial role in protecting the organism against such stresses. To elucidate the potential functional roles of artemin in plants, the cDNA sequence of artemin was cloned into the pZPY122 binary plant expression vector. Agrobacterium -mediated transformation and the floral-dip technique were used to introduce this construct into Arabidopsis thaliana. Three independent transgenic lines (art1 , art2 , art3) were generated and subjected to heat stress at 45°C. Results showed a significant interaction between heat stress and genotype for germination rate, germination speed, vigor index, and seedling and root length. The transgenic lines with the artemin transgene (ART) exhibited remarkable heat stress tolerance compared with wild-type plants. They also had markedly lower levels of electrolyte leakage, hydrogen peroxide content, higher activities of catalase, superoxide dismutase and peroxidase, greater total protien content, and increased accumulation of proline. Under heat stress conditions, the expression of two key abiotic stress-responsive genes, DREB2A and HSFA3 , was significantly upregulated in the ART lines compared to the wild-type. These findings suggest that the ART gene from A. urmiana may act as molecular chaperone when expressed in Arabidopsis , thereby enhancing the plant's tolerance to heat stress. Extreme temperatures, as a result of global warming, cause significant reduction in agricultural yields. We introduced a chaperone from Artemia urmiana that helps other proteins to function properly in extreme environments into Arabidopsis thaliana. Our results indicated that the transgneic Arabidopsis plants were more tolerant to heat stress than the wild-type. [ABSTRACT FROM AUTHOR]

The fundamental key to increase photosynthetic efficiency of crop plants lies in optimizing the light energy use efficiency. In our study, we used tomato to evaluate the allocation of absorbed light energy in young and mature leaves, and to estimate if the extent of photoinhibition and photoprotection can be affected by the leaf age. A reduced efficiency of the oxygen-evolving complex, in young leaves compared to mature ones, resulted in a donor-side photoinhibition, as judged from the significantly lower Fv/Fm ratio, in young leaves. The detected increased 1O2 production in young leaves was probably due to a donor-side photoinhibition. The effective quantum yield of photosystem II (PSII) photochemistry (ΦPSII), at low light intensity (LLI, 426 μmol photons m−2 s−1), was significantly lower in young compared to mature leaves. Moreover, the non-significant increase in non-photochemical energy loss in PSII (ΦNPQ) could not counteract the decreased ΦPSII, and as a result the non-regulated energy loss in PSII (ΦNO) increased in young leaves, compared to mature ones. The significantly lower ΦPSII in young leaves can be attributed to the increased reactive oxygen species (ROS) creation that diminished the efficiency of the open PSII reaction centers (Fv'/Fm'), but without having any impact on the fraction of the open reaction centers. The reduced excess excitation energy, in mature leaves compared to young ones, at LLI, also revealed an enhanced PSII efficiency of mature leaves. However, there was almost no difference in the light energy use efficiency between young and mature leaves at the high light intensity (HLI, 1000 μmol photons m−2 s−1). The ability of mature tomato leaves to constrain photoinhibition is possible related to an enhanced photosynthetic function and a better growth rate. We concluded that the light energy use efficiency in tomato leaves is influenced by both the leaf age and the light intensity. Furthermore, the degrees of photoinhibition and photoprotection are related to the leaf developmental stage. [ABSTRACT FROM AUTHOR]

Cryopreservation of receptacles or fertilized eggs is the main method for the preservation of indoor germplasm resources for the economic seaweed Sargassum fusiforme. However, none of these methods can achieve long-term preservation of germplasm resources. The holdfast represents the asexual reproductive organ of S. fusiforme and has a dense tissue that can be regenerated into seedlings under suitable conditions. Therefore, in this study, the holdfast was used as the experimental material to analyze the effects of different temperatures (8 °C, 10 °C, 13 °C) and salinities (29‰, 24‰, 19‰, 14‰) on the preservation of S. fusiforme germplasm. The results showed that 29‰ and 14‰ were not suitable for the long-term preservation of holdfasts regardless of temperatures, since both photosynthesis and growth rates of the holdfast decreased after 30 days of preservation at these salinities. However, 8 °C and 19‰ were found to be suitable for the long-term in vitro preservation of holdfasts, with a survival time being as long as 120 days. During the experiment, the photosynthesis activity of the holdfast also displayed less fluctuation in this experimental condition than in the others. After 120 days, the content of malondialdehyde in the holdfasts was the lowest, and the morphology remained intact. 8 °C and 19‰ could be suitable for long-term indoor preservation of S. fusiforme. These findings might provide technical support for solving the problem associated with the difficulty of preserving the germplasm of superior strains in the breeding process. They might also have important significance for crossbreeding and for establishing a germplasm resource bank for S. fusiforme in the future. [ABSTRACT FROM AUTHOR]

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Human activities have caused a rise in atmospheric carbon dioxide (CO2) levels, leading to greater absorption of CO2 by oceans and causing ocean acidification (OA). This phenomenon, marked by a reduction in pH, represents substantial risks to marine ecosystems, including seagrass meadows. Seagrasses are vital elements of coastal ecosystems, performing important functions in carbon storage, stabilizing shorelines, and preserving biodiversity; however, reactions to OA are not well understood, especially in molecular terms. This research study examined alterations in gene expression within seagrass meadows, namely Cymodocea nodosa, in reaction to simulated OA conditions. A climate chamber system was used to adjust CO2 levels to simulate future projections of OA, specifically following the RCP 8.5 scenario. Gene expression dynamics were assessed by collecting samples at different time intervals across a 36-h period. Research has demonstrated that genes related to photosynthesis are suppressed quickly after being exposed to increased amounts of CO2. Gene expression levels were found to change often over time, which is crucial for adaptation and acclimatization. However, antioxidant genes have varied responses to OA, with CAT and SOD being downregulated in distinct ways. Our findings offer valuable insights into the molecular mechanisms of seagrass responses to OA. They highlight the significance of examining short-term responses when evaluating the susceptibility of coastal ecosystems to climate change. [ABSTRACT FROM AUTHOR]

Tomato yellow leaf curl China virus (TYLCCNV) viruliferous Mediterranean (MED) whitefly infestation in tobacco plants elevated hydrogen peroxide (H2O2) levels more than non-viruliferous ones. To unravel the underlying mechanisms behind the phenomenon, comparative analyses of plant transcriptome and enzyme activities of reactive oxygen species (ROS) scavengers were conducted in this study. Compared to the control, a total of 4032 and 6853 differentially expressed genes (DEGs) were identified in the plants following the infestations of non-viruliferous and TYLCCNV-viruliferous MED, respectively. Gene ontology analysis of DEGs suggested substantial transcriptional reprogramming of diverse cellular processes, particularly in the biotic stress response pathways of tobacco plants. Respiratory burst oxidase homologs related genes and important kinases putatively involved in plant defense were differentially modulated in tobacco plants in response to the non-viruliferous and TYLCCNV-viruliferous whitefly MED infestation. The analysis reported here lays out a strong foundation for future investigations into the mechanisms of ROS-associated plant defense mediating the interactions between B. tabaci and begomoviruses. [ABSTRACT FROM AUTHOR]

Secondary metabolites serve a variety of ecological purposes, including defense against biotic and abiotic stressors. The aim of this study was to quantify the total phenol and flavonoid contents in sugarcane leaves that mediate resistance to yellow sugarcane aphids (YSA) (Sipha flava). A 7 × 2 factorial experiment was conducted in a complete randomized block design (CRBD). Seven sugarcane varieties namely 00-1165, 96-1107, ZN 8, ZN 9, ZN 10, ZN 3 L, and N14 under two aphid treatments [(uninfested (control) and infested] were used. 00-1165 showed medium resistance, as shown by its aphid quantity ratio (AQR), which fell between 0.30 and 0.60. Moreover, ZN 10 is regarded a high sensitive variety because its AQR was more than 1.50. Highly significant (p < 0.001) differences were recorded in both uninfested and infested treatments on total phenol and flavonoid content. In the YSA infested plots, 96-1107 recorded the highest phenol content of 50.31 µg/g, while ZN 3 L had the lowest (25.92 µg/g). Furthermore, N14 recorded the highest flavonoid content of 6.47 µg/g, whereas ZN 3 L produced the lowest (1.60 µg/g) in YSA infested plots. Notably, there was a significant positive correlation between the percentage change in phenol concentration and aphid number (p = 0.002, r = 0.58), and between the percentage change in flavonoid concentration and aphid number (p < 0.001, r = 0.70). Moreover, the regression results showed a significant positive correlation (p < 0.001, r = 0.70) between the percentage change in flavonoid concentration and the number of aphids. Feeding by YSA increased phenol and flavonoid induced resistance. There is a need to incorporate sugarcane varieties with high phenol and flavonoid content into the existing YSA management strategies. [ABSTRACT FROM AUTHOR]

Salinity has emerged as a critical abiotic stress factor, significantly limiting the growth, productivity, and quality of many crop species. As the global salinization of agricultural land continues to intensify, it is crucial to explore effective mitigation strategies to sustain crop yields. γ-Aminobutyric acid (GABA), a non-protein amino acid, is present in a variety of organisms, including plants, where it fulfills diverse roles under both optimal and stress conditions. In plants, GABA is intricately involved in nitrogen metabolism, amino acid biosynthesis, and the regulation of primary and secondary metabolic pathways. Functioning through the GABA shunt, it provides the carbon skeletons and energy required for biosynthetic processes and is vital for the regulation of carbon and nitrogen balance. Under abiotic stress conditions, particularly salinity, GABA rapidly accumulates, facilitating several protective mechanisms that help plants cope with stress. These include enhancing osmotic adjustment through the accumulation of osmolytes, protecting cellular structures such as chloroplasts, and improving chlorophyll fluorescence and photosynthetic efficiency. Moreover, GABA has been shown to boost antioxidant enzyme activity, reducing oxidative stress and mitigating the damage caused by reactive oxygen species (ROS) under salinity conditions. This study explores the multifaceted role of GABA in plants under saline environments, with a focus on its physiological, biochemical, and molecular mechanisms in enhancing plant resilience. By elucidating these mechanisms, we aim to highlight the potential of GABA as a natural biostimulant to improve crop performance and sustainability in saline soils. [ABSTRACT FROM AUTHOR]

Background: Charcoal rot of soybean is caused by the hemibiotrophic fungus Macrophomina phaseolina, a global crop destroyer and an important pathogen in the midwestern USA. The quantitative nature of host resistance and the complexity of the soybean-M. phaseolina interaction at the molecular level have hampered resistance breeding. A previous study showed that L-ascorbic acid (LAA) pre-treatment before M. phaseolina inoculation reduced charcoal rot lesion length in excised soybean stems. This study aimed to elucidate the genetic underpinnings of M. phaseolina-induced senescence and the mitigating effects of ascorbic acid on this physiological process within the same pathosystem. Results: RNA was sequenced from M. phaseolina-resistant and -susceptible soybean genotypes following M. phaseolina inoculation, LAA, and hydrogen peroxide (H2O2)—an oxidative stress inducer—application followed by inoculation. More genes were down-regulated in the resistant and susceptible genotypes than up-regulated when the M. phaseolina-inoculated treatments were compared to mock-inoculated control treatments. Gene ontology (GO) term and KEGG pathways analysis detected M. phaseolina-induced up-regulation of receptor-like kinase genes. In contrast, many genes related to antioxidants, defense, and hormonal pathways were down-regulated in both genotypes. LAA pre-treatment induced genes related to photosynthesis and reactive oxygen species responses in both genotypes. H2O2 pre-treatment following inoculation up-regulated many stress-response genes, while hormone signal transduction and photosynthesis-related genes were down-regulated in both genotypes. Conclusions: Results revealed transcriptional variation and genes associated with M. phaseolina-induced senescence in soybean. Ascorbic acid induced many photosynthetic genes, suggesting a complex regulation of defense and immunity in the plant against the hemibiotroph. Soybean plants also exhibited enhanced stress responsiveness when treated with H2O2 followed by inoculation with M. phaseolina. This study will broaden more research avenues related to transcriptional regulation during the M. phaseolina-soybean interaction and the potential role of receptor-like kinases, oxidative stress-responsive genes, ethylene-mediated signaling and enhanced photosynthetic gene expression when mounting host resistance to this important soybean pathogen. [ABSTRACT FROM AUTHOR]

Cold stress impedes the growth and development of plants, restricts the geographical distribution of plant species, and impacts crop productivity. In this study, we analyzed the Arabidopsis thaliana transcriptome to identify differentially expressed genes (DEGs) in 14-day-old plantlets exposed to temperatures of 0 °C, 4 °C, and 10 °C for 24 h, compared to the 22 °C control group. Among the top 50 cold-induced genes at each temperature, we identified 31 genes that were common across all three low temperatures, with nine genes common to 0–4 °C, eight genes to 4–10 °C, and two genes to 0–10 °C. Using q-RTPCR, we analyzed selected genes at 24, 48, and 72 h under the three low temperatures. Our data revealed that genes, such as galactinol synthase 3 (Gols3, At1g09350), CIR1 (At5g37260), DnaJ (At1g71000), and At5g05220 (unknown function), exhibited the highest expressions at 0 °C and 4 °C throughout all time points. We also studied genes from the UDP-glycosyltransferase (UGT78) family, including At5g17030 (D3), At5g17040 (D4), At5g17050 (D2), and At1g30530 (D1), which showed increased expression at low temperatures compared to plantlets at 22 °C for 24 h. Gene ontology analysis revealed that DEGs highly enriched were found in biological processes such as "RNA secondary structure unwinding" and "rRNA processing" induced at the three low temperatures, whereas processes related to photosynthesis were repressed. Our findings indicated upregulation in the expression of four RNA helicases (RH13, RH48, RH32, and RH29), belonging to the "RNA secondary structure unwinding" category, mainly at 0 °C and 4 °C. This study provides valuable information on the molecular mechanisms that activate Arabidopsis thaliana in its early response to these three low temperatures. [ABSTRACT FROM AUTHOR]

Resurrection plants present an attractive model for studying the mechanisms of desiccation tolerance. In addition to drought, the presence of light during desiccation is extremely dangerous. In the present study, we investigated the effect of light during the desiccation of shade and sun Haberlea rhodopensis from two different habitats by measuring the changes in electrolyte leakage, malondialdehyde and proline content, and photosynthetic and antioxidant activities. Moreover, the plasticity and acclimation ability of plants to changing light intensities were studied by desiccating shade plants under high light and sun plants under low light. The most significant differences between shade and sun plants were observed under moderate dehydration. Regardless of some decline in PSII activity in sun plants, it was much higher compared to shade plants. The lower PSII efficiency in the latter was accompanied by a higher extent of excitation pressure and consequently significant enhancement in non-photochemical quenching, Y(NPQ), and especially in the fraction of energy that is passively dissipated as heat and fluorescence, Y(NO). The activity of antioxidant enzymes remained high during the desiccation of H. rhodopensis, being higher in the sun compared to shade plants in an air-dried state. In addition, shade and sun plants showed high acclimation capacity when desiccated at opposite light intensities. [ABSTRACT FROM AUTHOR]

Catalase (CAT) plays a crucial role in plant responses to environmental stresses and maintaining redox homeostasis. However, its putative heat lability might compromise its activity and function, thus restricting plant thermotolerance. Herein, we verified Arabidopsis CAT3 was of poor thermostability that was then engineered by fusion expression in Escherichia coli. We found that our selected fusion partners, three hyperacidic mini-peptides and the short rubredoxin from hyperthermophile Pyrococcus furiosus, were commonly effectual to enhance the solubility and thermostability of CAT3 and enlarge its improvement on heat tolerance in E. coli and yeast. Most importantly, this finding was also achievable in plants. Fusion expression could magnify CAT3-mediated thermotolerance in tobacco. Under heat stress, transgenic lines expressing CAT3 fusions generally outperformed native CAT3 which in turn surpassed wild-type tobacco, in terms of seed germination, seedling survival, plant recovery growth, protection of chlorophyll and membrane lipids, elimination of H2O2, as well as mitigation of cell damage in leaves and roots. Moreover, we revealed that the introduced CAT3 or its fusions seemed solely responsible for the enhanced thermotolerance in tobacco. Prospectively, this fusion expression strategy would be applicable to other crucial plant proteins of intrinsic heat instability and thus provide an alternative biotechnological route for ameliorating plant heat tolerance. [ABSTRACT FROM AUTHOR]

When insects harm plants, they activate relevant enzyme systems for defense, and changes in enzyme activity, to a certain extent, reflect the host plant's ability to resist insect damage. Alfalfa leaf weevils (Hypera postica Gyllenhal) are the main economic insect pest of alfalfa, which seriously affect its yield and quality. To clarify the effects of feeding induction by alfalfa leaf weevil larvae and adults on defense enzymes in alfalfa, 'Zhongmu No. 1' variety was used as the experimental material. Comprehensive correlation analysis and principal component analysis were used to evaluate the corresponding patterns of 12 physiological indicators of alfalfa induced by insect feeding of different densities. Results showed that after feeding induction by adult and larval alfalfa leaf weevils, total antioxidant capacity (T-AOC), malondialdehyde (MDA), phenylalanine ammonia-lyase (PAL), tyrosine ammonia lyase (TAL), lipoxygenase (LOX), chymotrypsin inhibitors (CI), trypsin inhibitor (TI), and jasmonic acid (JA) in the alfalfa leaves increased with increasing feeding time. However, activities of catalase (CAT), peroxidase (POD), superoxide dismutase (SOD) and polyphenolic oxidase (PPO) in alfalfa leaves first increased and then decreased, showing a downward trend. [ABSTRACT FROM AUTHOR]

With global warming, heat stress has been recognized as a significant factor limiting grapevine development and fruit quality. MicroRNAs (miRNAs) are a class of small non-coding RNAs known to play crucial regulatory roles in stress resistance. Hence, there is an immediate requirement to cultivate and identify grapevine varieties that are resistant to heat and explore miRNA-mediated heat stress defense mechanisms. In this study, we assessed the thermal resistance of 38 grape germplasm resources and identified a series of miRNAs involved in heat stress resistance. The CK (25°C) and HS (45°C) groups of "Shenyue" cuttings of grapes were used as experimental materials for next-generation sequencing and construct libraries of small RNAs. A total of 177 known and 20 novel miRNAs were detected in the libraries. Differential expression analysis identified 65 differentially expressed miRNAs (DEMs) using the DE-Seq procedure. Furthermore, RT-qPCR validation confirmed complementary expression profiles of eight DEMs and their target genes between the HS and CK groups. Heterologous transformation further identified the function of Vvi-miR3633a downregulated under heat stress in Arabidopsis. In the heterologous expression lines, the survival rate was reduced by high temperature treatment indicating the ability of Vvi-miR3633a to regulate heat resistance. Assessing the heat resistance of grape species and the expression patterns of miRNA in response to high temperatures may reveal the molecular processes of heat resistance regulation mediated by miRNA in grapes under heat stress. [ABSTRACT FROM AUTHOR]

Citrus bacterial canker (CBC) is resulted from Xanthomonas citri subsp. citri (Xcc) infection and poses a significant threat to citrus production. Glutathione S-transferases (GSTs) are critical in maintaining redox homeostasis in plants, especially in relation to abiotic and biotic stress responses. However, the function of GSTs in resisting CBC remains unclear. Here, citrus glutathione S-transferases were investigated applying a genome-wide approach. In total, 69 CsGSTs belonging to seven classes were identified, and the phylogeny, chromosomal distribution, gene structures and conserved motifs were analyzed. Several CsGSTs responded to Xcc infection, as observed in the upregulation of CsGSTF1 and CsGSTU18 in the CBC-sensitive 'Wanjincheng' variety but not in the resistant 'Kumquat' variety. CsGSTF1 and CsGSTU18 were localized at the cytoplasm. Transient overexpression of CsGSTF1 and CsGSTU18 mediated reactive oxygen species (ROS) scavenging, whereas the virus-induced gene silencing (VIGS) of CsGSTF1 and CsGSTU18 caused strong CBC resistance and ROS burst. The present study investigated the characterization of citrus GST gene family, and discovered that CsGSTF1 and CsGSTU18 negatively contributed to CBC through modulating ROS homeostasis. These findings emphasize the significance of GSTs in infection resistance in plants. [ABSTRACT FROM AUTHOR]

Background: Plants of Nitraria, belonging to the Zygophyllaceae family, are not only widely distributed at an altitude of about 1000 m but also at an altitude of about 3000 m, which is a rare phenomenon. However, little is known about the effect of altitude on the accumulation of metabolites in plants of Nitraria. Furthermore, the mechanism of the high–altitude adaptation of Nitraria has yet to be fully elucidated. Methods: In this study, metabolomics and transcriptomics were used to investigate the differential accumulation of metabolites of Nitraria berries and the regulatory mechanisms in different altitudes. Results: As a result, the biosynthesis of flavonoids is the most significant metabolic pathway in the process of adaptation to high altitude, and 5 Cyanidins, 1 Pelargonidin, 3 Petunidins, 1 Peonidin, and 4 Delphinidins are highly accumulated in high–altitude Nitraria. The results of transcriptomics showed that the structural genes C4H (2), F3H, 4CL (2), DFR (2), UFGT (2), and FLS (2) were highly expressed in high–altitude Nitraria. A network metabolism map of flavonoids was constructed, and the accumulation of differential metabolites and the expression of structural genes were analyzed for correlation. Conclusions: In summary, this study preliminarily offers a new understanding of metabolic differences and regulation mechanisms in plants of Nitraria from different altitudes. [ABSTRACT FROM AUTHOR]

During their life cycle, plants constantly respond to environmental changes. Abiotic stressors affect the photosynthetic and respiratory processes of plants. Reactive oxygen species (ROS) are produced during aerobic metabolism and play an important role as regulatory mediators in signaling processes, activating the plant's protective response to abiotic stress and restoring "oxidation-reduction homeostasis". Cells develop normally if the rates of ROS production and the ability to neutralize them are balanced. To implement oxidation-reduction signaling, this balance must be disrupted either by an increase in ROS concentration or a decrease in the activity of one or more antioxidant systems. Under abiotic stress, plants accumulate excessive amounts of ROS, and if the ROS content exceeds the threshold amount dangerous for living organisms, it can lead to damage to all major cellular components. Adaptive resistance of plants to abiotic stressors depends on a set of mechanisms of adaptation to them. The accumulation of ROS in the cell depends on the type of abiotic stress, the strength of its impact on the plant, the duration of its impact, and the recovery period. The aim of this review is to provide a general understanding of the processes occurring during ROS homeostasis in plants, oxidation-reduction processes in cellular compartments in response to abiotic stress, and the participation of ROS in signaling processes activating adaptation processes to abiotic stress. [ABSTRACT FROM AUTHOR]

Simple Summary: Soybean is a globally important resource crop of oil and protein but is sensitive to salinity. Soybean growth was significantly reduced under salt stress; however, it was restored and comparable to control values by ethanol application even under stress. To study the positive mechanism of ethanol on soybean growth, a proteomic approach was carried out. The categories with the greatest changes in protein numbers were protein metabolism, transport, and cell organization in biological processes. Reactive oxygen species enzymes were increased under salt stress; among them, mitochondrial ascorbate peroxidase was further accumulated by ethanol application. Among the cell wall and membrane-associated proteins, xyloglucan xyloglucosyl transferase and H+-ATPase increased and decreased, respectively, under salt stress; however, they were restored to control levels by ethanol application. These results suggest that soybeans were adversely affected by salt stress and recovered with ethanol application via the regulation of cell wall and membrane functions through the detoxification of reactive oxygen species. Finding solutions to mitigate the impact of salinity on crops is important for global food security because soil salinity significantly reduces plant growth and grain yield. Ethanol may play an important role in mitigating the negative salt-induced effects on crops. Soybean root growth was significantly reduced under salt stress; however, it was restored and comparable to control values by ethanol application even under stress. To study the positive mechanism of ethanol on soybean growth, a proteomic approach was carried out. The categories with the greatest changes in protein numbers were protein metabolism, transport, and cell organization in biological processes, nucleus and cytosol in cellular components, and nucleic acid binding activity in molecular functions. Proteomic data were confirmed using immunoblot analysis. Reactive oxygen species enzymes increased under salt stress; among them, mitochondrial ascorbate peroxidase was further accumulated by ethanol application. Among the cell wall and membrane-associated proteins, xyloglucan xyloglucosyl transferase and H+-ATPase increased and decreased, respectively, under salt stress; however, they were restored to control levels by ethanol application. These results suggest that soybeans were adversely affected by salt stress and recovered with ethanol application via the regulation of cell wall and membrane functions through the detoxification of reactive oxygen species. [ABSTRACT FROM AUTHOR]

Background: Bleaching is a conservative treatment option to deliver esthetic smile makeover for discoloured tooth. Various concentration of bleaching agents can influence the bonding of the restoration to the tooth. Aims and Objectives: The aim of the study was to determine the effect of glutathione on bond strength of composite resin to enamel following extra coronal bleaching at two different time intervals. Materials and Methods: Forty molars were randomly assigned into four groups of ten each. Group A: Bleaching followed by immediate composite build up and no antioxidant application. Group B: bleaching followed by application of 20% Glutathione and immediate composite built-up was done. Group C: Bleaching followed by composite restoration after one week. Group D: Bleaching followed by application of 20% Glutathione before composite build up after one week. Shear bond strength was tested using a universal testing machine and fracture analysis was done using scanning electron microscope (SEM). Data were analyzed by one-way ANOVA and Post Hoc test with 95% level of significance (p<0.05). Results: Group D, which was treated with glutathione and restored after one week, revealed the highest shear bond strength compared to group B which was immediately restored following treatment with glutathione. Conclusion: Addition of 20% Glutathione as an antioxidant increased the shear bond strength of composite resin to enamel following extra-coronal bleaching using 40% hydrogen peroxide. [ABSTRACT FROM AUTHOR]

Fumarylacetoacetate hydrolase (FAH) catalyzes the final step of the tyrosine degradation pathway. In this study, we isolated and characterized two homologous BnaFAH genes in Brassica napus L. variant Westar, and then used CRISPR/Cas9-mediated targeted mutagenesis to generate a series of transgene-free mutant lines either with single or double-null bnafah alleles. Among these mutant lines, the aacc (bnafah) double-null mutant line, rather than the aaCC (bnaa06fah) mutant line, exhibited programmed cell death (PCD) under short days (SD). Histochemical staining and content measurement confirmed that the accumulation of reactive oxygen species (ROS) in bnafah was significantly higher than that in bnaa06fah. To further elucidate the mechanism of PCD, we performed transcriptomic analyses of bnaa06fah and bnafah at different SD stages. A heatmap cluster of differentially expressed genes (DEGs) revealed that PCD may be related to various redox regulatory genes involved in antioxidant activity, ROS-responsive regulation and calcium signaling. Combined with the results of previous studies, our work revealed that the expression levels of BnaC04CAT2, BnaA09/C09SAL1, BnaA08/C08ACO2, BnaA07/C06ERO1, BnaA08ACA1, BnaC04BIK1, BnaA09CRK36 and BnaA03CPK4 were significantly different and that these genes might be candidate hub genes for PCD. Together, our results underscore the ability of different PCD phenotypes to alter BnaFAH orthologs through gene editing and further elucidated the molecular mechanisms of oxidative stress-induced PCD in plants. [ABSTRACT FROM AUTHOR]

Loquat (Eriobotrya japonica Lindl.), a rare fruit native to China, has a long history of cultivation in China. Low temperature is the key factor restricting loquat growth and severely affects yield. Low temperature induces the regeneration and metabolism of reduced glutathione (GSH) to alleviate stress damage via the participation of glutathione S-transferases (GSTs) in plants. In this study, 16 GSTs were identified from the loquat genome according to their protein sequence similarity with Arabidopsis GSTs. On the basis of domain characteristics and phylogenetic analysis of AtGSTs, these EjGSTs can be divided into 4 subclasses: Phi, Theta, Tau and Zeta. The basic properties, subcellular localization, structures, motifs, chromosomal distribution and collinearity of the EjGST proteins or genes were further analyzed. Tandem and segmental gene duplications play pivotal roles in EjGST expansion. Cis -elements that respond to various hormones and stresses, especially those associated with low-temperature responsiveness, were predicted to be present in the promoters of EjGSTs. Moreover, analysis of gene expression profiles revealed that 9 of 16 EjGSTs may be involved in the low-temperature responsiveness of loquat leaves. In agriculture, 5-aminolevulinic acid (ALA), a potential multifunctional plant growth regulator, can improve the stress response of plants. Among the 9 low-temperature-responsive EjGSTs , the expression of EjGSTU1 and EjGSTF1 significantly differed under cold stress in response to exogenous 5-aminolevulinic acid (ALA) pretreatment. The remarkable increase in GST activity and GSH/GSSG ratio reflected the increase in the cold response ability of loquat plants caused by exogenous ALA, thereby alleviating H2O2accumulation and membrane lipid preoxidation. Overall, this study provides an initial exploration of the cold tolerance function of GSTs in loquat, offering a theoretical foundation for the development of cold-resistant loquat cultivars and new antifreeze agents. [ABSTRACT FROM AUTHOR]

Introduction: With increasing drought stress due to climate change and water scarcity, the agricultural sector has sought innovative strategies to mitigate the detrimental effects on crop productivity. One approach that has received significant attention is the use of fertilizers and biostimulants as potential means of alleviating drought stress. Methods: In this study, five different irrigation levels including 100% (control), 80% (slight stress), 60% (mild stress), 40% (moderate stress), and 20% (severe stress) of field capacity (FC) and seaweed extract (SWE) at three concentrations (0, 5, and 10 g/L) were applied to the pots containing one-year-old licorice (Glycyrrhiza glabra L.) plants in a factorial completely randomized design experiment with three replications for eight weeks. Results and discussion: The glycyrrhizic acid content increased with water stress intensity without the application of SWE until severe (20% FC) water stress treatment. The application of 10 g/L SWE under 100% FC led to a significant increase in the glycyrrhizic acid value (32.5±0.889 mg/g DW) compared with non-SWE application (30.0±1.040 mg/g DW). The maximum glabridin content (0.270±0.010 mg/g DW) was obtained under irrigation of 20% field capacity with 10 g/L SWE application. In addition, the activity of the all studied enzymes such as APX (ascorbate peroxidase), CAT (catalase), POD (peroxidase), and SOD (superoxide dismutase) were boosted by increasing the water stress levels. The use of SWE further enhanced the increase of some of these metabolites and enzymes, which, in turn, helped the plant to tolerate stress conditions through the scavenging of more ROS (Reactive oxygen species), wherein for this purpose, the SWE 10 g/L was more effective than other concentration. The plants efficiently eliminated ROS driven from drought stress by both non-enzymatic and enzymatic systems. [ABSTRACT FROM AUTHOR]

Wheat genotypes Halna, HD2967, K911, K9006, NW 1014 and HD 2733 were grown in field condition in differential date of sowing for detection genetic variability for high temperature tolerance traits in wheat during Rabi season 2021-22. The high temperature stress was given to wheat genotypes by 60 days late from normal sowing (15 November) for exposing terminal stage of crop under high temperature stress. The high temperature stress significantly influenced membrane stability index (MSI), canopy temperature depression (CTD), total chlorophyll content and ultimately grain yield irrespective of wheat varieties. The high MSI, CTD and less reduction in chlorophyll were recorded in Halna, K911and NW 1014. It is also linked with long stay green duration at grain filling stage. The maximum percent reduction in total chlorophyll content and grain yield were observed in HD2967, HD2733 and K9006 as it showed low MSI and CTD under high temperature stress. The high Catalase and Peroxidase activities were appeared in Halna, K 911 and NW 1014 over other varieties under high temperature. The high MSI and CTD had positive correlation with grain yield. Therefore, high MSI, CTD, Catalase, Peroxidase activity and long green duration can be used as physiological traits for evaluating wheat varieties for high temperature tolerance. [ABSTRACT FROM AUTHOR]

Salt stress significantly impairs plant growth, presenting a challenge to agricultural productivity. Exploring the regulatory mechanisms underlying salt stress responses is critically important. Here, we identified a significant role for the maize LESION-SIMULATING DISEASE transcription factor, ZmLSD1, in enhancing salt stress response. Subcellular localization analysis indicated that ZmLSD1-GFP was localized in the nucleus in the maize protoplast. Overexpressing ZmLSD1 in maize obviously enhanced the tolerance of plants to salt stress. Physiological analysis indicated that overexpressed ZmLSD1 in maize could mitigate the accumulation of H2O2 and MDA content exposed to salt stress. RNA-seq and qPCR-PCR analyses showed that ZmLSD1 positively regulated ZmWRKY29 expression. ChIP-qPCR and EMSA experiments demonstrated that ZmLSD1 could directly bind to the promoter of ZmWRKY29 through the GTAC motif both in vitro and in vivo. Overall, our findings suggest that ZmLSD1 plays a positive role in enhancing the tolerance of maize to salt by affecting ZmWRKY29 expression. [ABSTRACT FROM AUTHOR]

Hydrogen peroxide (H2O2) in plants is produced in relatively large amounts and plays a universal role in plant defense and physiological responses, including the regulation of growth and development. In the Rhizobium–legume symbiosis, hydrogen peroxide plays an important signaling role throughout the development of this interaction. In the functioning nodule, H2O2 has been shown to be involved in bacterial differentiation into the symbiotic form and in nodule senescence. In this study, the pattern of H2O2 accumulation in pea (Pisum sativum L.) wild-type and mutant nodules blocked at different stages of the infection process was analyzed using a cytochemical reaction with cerium chloride. The observed dynamics of H2O2 deposition in the infection thread walls indicated that the distribution of H2O2 was apparently related to the stiffness of the infection thread wall. The dynamics of H2O2 accumulation was traced, and its patterns in different nodule zones were determined in order to investigate the relationship of H2O2 localization and distribution with the stages of symbiotic nodule development in P. sativum. The patterns of H2O2 localization in different zones of the indeterminate nodule have been partially confirmed by comparative analysis on mutant genotypes. [ABSTRACT FROM AUTHOR]

Plants are able to perceive diverse environmental factors and form an appropriate systemic functional response. Systemic responses are induced by stimulus-specific long-distance signals that carry information about the stimulus. Variation potential is proposed as a candidate for the role of such a signal. Here, we focus on the mechanisms that determine the specificity of the variation potential under the action of different local stimuli. Local stimuli such as heating, burning and wounding cause variation potential, the parameters of which differ depending on the type of stimulus. It was found that the stimulus-specific features of the hydraulic signal monitored by changes in leaf thickness and variation potential, such as a greater amplitude upon heating and burning and a significant amplitude decrement upon burning and wounding, were similar. The main features of these signals are the greater amplitude upon heating and burning, and a significant amplitude decrement upon burning and wounding. Together with the temporal correspondence of signal propagation, this evidence indicates a role for the hydraulic signal in the induction of stimulus-specific variation potential. Experiments using mechanosensitive channel inhibitors have demonstrated that the hydraulic signal contributes more to the induction of the variation potential in the case of rapidly growing stimuli, such as burning and wounding, than in the case of gradual heating. For thermal stimuli (gradual heating and burning), a greater contribution, compared to wounding, of the chemical signal related to reactive oxygen species to the induction of the variation potential was demonstrated. Thus, the specificity of the parameters of the variation potential is determined by the different contributions of hydraulic and chemical signals. [ABSTRACT FROM AUTHOR]

The glyoxalase pathway, consisting of glyoxalase I (GLYI) and glyoxalase II (GLYII), is an enzymatic system that converts cytotoxic methylglyoxal to non-toxic S-D-lactoylglutathione. Although the GLY gene family has been analyzed in Arabidopsis, rice, grape, cabbage, and soybean, cucumber studies are lacking. Here, we analyzed the cucumber GLY gene family, identifying 13 CsGLYI and 2 CsGLYII genes. Furthermore, we investigated the physicochemical properties, phylogenetic relationships, chromosomal localization and colinearity, gene structure, conserved motifs, cis-regulatory elements, and protein–protein interaction networks of the CsGLY family. They were primarily localized in the cytoplasm, chloroplasts, and mitochondria, with a minor presence in the nucleus. The classification of CsGLYI and CsGLYII genes into five classes closely resembled the homologous genes in Arabidopsis and soybean. Additionally, hormone-responsive elements dominated the promoter region of GLY genes, alongside light- and stress-responsive elements. The predicted interaction proteins of CsGLYIs and CsGLYIIs exerted a significant role in cellular respiration, amino acid synthesis, and metabolism, as well as methylglyoxal catabolism. In addition, the expression profiles of GLY genes were distinct in different tissues of cucumber as well as under diverse abiotic stresses. This study is conducive to the further exploration of the functional diversity among glyoxalase genes and the mechanisms of stress responses in cucumber. [ABSTRACT FROM AUTHOR]

Soil salinization is a widespread hindrance that endangers agricultural production and ecological security. High salt concentrations in saline soils are primarily caused by osmotic stress, ionic toxicity and oxidative stress, which have a negative impact on plant growth and development. In order to withstand salt stress, plants have developed a series of complicated physiological and molecular mechanisms, encompassing adaptive changes in the structure and function of various plant organs, as well as the intricate signal transduction networks enabling plants to survive in high-salinity environments. This review summarizes the recent advances in salt perception under different tissues, physiological responses and signaling regulations of plant tolerance to salt stress. We also examine the current knowledge of strategies for breeding salt-tolerant plants, including the applications of omics technologies and transgenic approaches, aiming to provide the basis for the cultivation of salt-tolerant crops through molecular breeding. Finally, future research on the application of wild germplasm resources and muti-omics technologies to discover new tolerant genes as well as investigation of crosstalk among plant hormone signaling pathways to uncover plant salt tolerance mechanisms are also discussed in this review. [ABSTRACT FROM AUTHOR]

Anthropogenic activities and subsequent global climate change instigate drastic crop productivity and yield changes. These changes comprise a rise in the number and severity of plant stress factors, which can arise simultaneously or sequentially. When abiotic stress factors are combined, their impact on plants is more substantial than that of a singleton stress factor. One such impact is the alteration of redox cellular homeostasis, which, in turn, can regulate downstream stress-responsive gene expression and resistance response. The epigenetic regulation of gene expression in response to varied stress factors is an interesting phenomenon, which, conversely, can be stable and heritable. The epigenetic control in plants in response to abiotic stress combinations and their interactions with cellular redox alteration is an emerging field to commemorate crop yield management under climate change. The article highlights the integration of the redox signaling pathways and epigenetic regulations as pivotal components in the complex network of plant responses against multicombinatorial stresses across time and space. This review aims to lay the foundation for developing novel approaches to mitigate the impact of environmental stresses on crop productivity, bridging the gap between theoretical understanding and practical solutions in the face of a changing climate and anthropogenic disturbances. [ABSTRACT FROM AUTHOR]

GABA (gamma-aminobutyric acid) is an amino acid whose numerous regulatory functions have been identified in animal organisms. More and more research indicate that in plants, this molecule is also involved in controlling basic growth and development processes. As recent studies have shown, GABA plays an essential role in triggering plant resistance to unfavorable environmental factors, which is particularly important in the era of changing climate. The main sources of GABA in plant cells are glutamic acid, converted in the GABA shunt pathway, and polyamines subjected to oxidative degradation. The action of GABA is often related to the activity of other messengers, including phytohormones, polyamines, NO, H2O2, or melatonin. GABA can function as an upstream or downstream element in the signaling pathways of other regulators, acting synergistically or antagonistically with them to control cellular processes. Understanding the role of GABA and its interactions with other signaling molecules may be important for developing crop varieties with characteristics that enable adaptation to a changing environment. [ABSTRACT FROM AUTHOR]

Helical growth of the root tip (circumnutation) that permits surface exploration facilitates root penetration into soil. Here, we reveal that rice actin-binding protein RMD aids in root circumnutation, manifested by wavy roots as well as compromised ability to efficiently explore and avoid obstacles in rmd mutants. We demonstrate that root circumnutation defects in rmd depend on brassinosteroid (BR) signaling, which is elevated in mutant roots. Suppressing BR signaling via pharmacological (BR inhibitor) or genetic (knockout of BR biosynthetic or signaling components) manipulation rescues root defects in rmd. We further reveal that mutations in MAPK6 suppress BR signaling and restore normal root circumnutation in rmd, which may be mediated by the interaction between MAPK6, MAPKK4 and BR signaling factor BIM2. Our study thus demonstrates that RMD and MAPK6 control root circumnutation by modulating BR signaling to facilitate early root growth. [ABSTRACT FROM AUTHOR]

Selecting the right rootstock is crucial for successful fruit production and managing both biotic and abiotic stresses in commercial fruit orchards. To enhance the resilience of peach orchards, this study evaluated the physiological and biochemical responses of Prunus spp. rootstocks , 'Flordaguard' and 'MP‐29,' under normoxia (sufficient oxygen content) or short‐term hypoxia (low‐oxygen content) and ambient or high temperature (40°C) in the root zone. Physiological responses measured were net photosynthesis, stomatal conductance, transpiration, intercellular CO2 concentration, water use efficiency, the leaf chlorophyll index, and the maximum potential quantum efficiency of photosystem II. The leaf concentrations of nitrogen, phosphorus, potassium, magnesium, calcium, sulfur, boron, zinc, manganese, iron, and copper were also analyzed. Reactive oxygen species (ROS) and antioxidants analyzed were superoxide dismutase (SOD) activity, peroxidase (POD) activity, catalase (CAT) activity, ascorbate peroxidase (APX) activity, glutathione peroxidase (GPX) activity, proline content, glycine betaine content (GB), lipid peroxidation (LPO), superoxide (O2−) concentration, and hydrogen peroxide (H2O2) concentration. When subjected to root zone hypoxia or high temperature individually, 'MP‐29' performed better physiologically than 'Flordaguard'. However, when root zone hypoxia and high temperature were combined, 'MP‐29' performed better biochemically with enhanced antioxidant activity, osmolyte content, and nutrient absorption. Nutrient analysis of leaves revealed that 'MP‐29' had higher N, P, K, Ca, and B concentrations than 'Flordaguard'. Consequently, 'MP‐29' demonstrated greater tolerance to short‐term exposure to the combined effects of high root zone temperature and hypoxia. This research contributes to identifying a suitable rootstock within the Prunus genus able to withstand root zone conditions that often result from severe weather events commonly experienced in Florida and other parts of the world. [ABSTRACT FROM AUTHOR]

Cold storage is one of the most effective methods to maintain postharvest fruit quality. However, loquat fruits are prone to chilling injury (CI) during cold storage, appearing as symptoms such as browning and pitting, which leads to quality deterioration and economic losses. In this study, the effects of melatonin on CI alleviation and the potential role of reactive oxygen species (ROS) metabolism in loquat fruit were investigated. The results showed that 50 μM melatonin was the optimal concentration to inhibit the increase in CI index and cell membrane permeability. Moreover, compared to control fruits, 50 μM melatonin inhibited the malonaldehyde (MDA) content, O2−. production rate and H2O2 content (ROS accumulation) by 17.8%, 7.2% and 11.8%, respectively, during cold storage. Compared to non-treated loquats, 50 μM melatonin maintained higher levels of 1-diphenyl-2-picrylhydrazyl radical-scavenging ability and reducing power, as well as the contents of ascorbic acid (AsA) and glutathione (GSH). Additionally, 50 μM melatonin enhanced the activities of antioxidant enzymes, such as superoxide dismutase (SOD), catalase (CAT) and ascorbate peroxidase (APX) by increasing relevant gene expressions. The activities of SOD, CAT and APX were increased by up to 1.1-, 1.1- and 1.1-times (16 d) by melatonin, as compared with the control fruits. These findings indicate that melatonin mitigation of CI is involved in maintaining cellular redox apphomeostasis in loquat fruit during cold storage. [ABSTRACT FROM AUTHOR]

Introduction: Stem rust disease of wheat, caused by Puccinia graminis f. sp. tritici, (Pgt) is the most devastating disease affecting wheat crops. Findings have demonstrated that antioxidant enzymes play a vital role in conferring resistance to biotic stresses, particularly against biotrophic fungi. This study aims to compare the effects of three distinct races of Pgt on the activity of antioxidant enzymes in susceptible and resistant wheat cultivars at three time points 24, 48, and 72 hours after inoculation (hai). Materials and methods: Seeds of two wheat genotypes including susceptible (Morocco) and resistant (Btsr24Agt) to stem rust and spores of three stem rust races (PTRTF, TKTTF and TTKTK) were obtained from Seed and Seedling Breeding and Production Research Institute of Karaj, Iran. The experiment was carried out as a factorial in a completely randomized design with three replications. The seeds were planted in 24 cm diameter pots containing a mixture of peat moss, sand, and soil and were maintained under conditions of 16 hours of light and 8 hours of darkness at 22-24°C. Inoculation of Pgt races on the whole leaf surface of seedlings was carried out by a brush paint when they were in stage 12 of the Zadox scale. Control seedlings were treated in the same way with sterile distilled water. In order to establish the disease, the inoculated and control plants were kept in the darkness for 18 hours at 18°C with 100% relative humidity and then maintained in a growth chamber with the above conditions. The leaves of the inoculated and control plants were harvested at 24, 48 and 72 hours after inoculation and the activities of superoxide dismutase (SOD) and guaiacol peroxidase (GPX) were measured. Results: The activity of the GPX enzyme was significantly increased in infected plants compared to the control at all time points. The lowest GPX activity was recorded at 24 hours, followed by increases at 48 and 72 hai, and the highest activity was observed at 72 hai. Notably, the resistant genotype exhibited higher GPX activity than the susceptible cultivar. In contrast, SOD enzyme activity increased in both cultivars at 24 hai compared to 48 and 72 hai. The PTRTF and TKTTF races showed a significant increase in SOD activity compared to the controls, while the TTKTK race did not exhibit any changes. Additionally, the susceptible cultivar demonstrated increased enzyme activity compared to the controls, whereas the resistant cultivar showed no significant changes. Conclusion: The resistant genotype consistently had higher GPX activity than the susceptible cultivar. Across all time points and races, this enzyme likely plays a crucial role in scavenging reactive oxygen species (ROS) induced by pathogens, thereby contributing to the plant's defense mechanisms. In plant-biotrophic pathogen interactions, the activity of antioxidant enzymes is influenced by the type of interaction (compatible or incompatible) and the specific race, host variety, and hours after inoculation. [ABSTRACT FROM AUTHOR]

In recent decades, the frequency of flooding has increased as a result of global climate change. Flooding has become one of the major abiotic stresses that seriously affect the growth and development of plants. Mulberry (Morus alba L.) is an important economic tree in China. Flooding stress is among the most severe abiotic stresses that affect the production of mulberry. However, the physiological and molecular biological mechanisms of mulberry responses to flooding stress are still unclear. In the present study, reactive oxygen species (ROS) metabolism, antioxidant mechanism, and plant hormones in mulberry associated with the response to flooding stress were investigated using physiological and transcriptomic analysis methods. The results showed significant increases in the production rate of superoxide anion (O2•−) and the content of hydrogen peroxide (H2O2) in leaves on the 5th day of flooding stress. This led to membrane lipid peroxidation and elevated malondialdehyde (MDA) levels. Antioxidant enzymes such as catalase (CAT), superoxide dismutase (SOD), and peroxidase (POD) exhibited enhanced activities initially, followed by fluctuations. The ascorbic acid–glutathione (AsA-GSH) cycle played a crucial role in scavenging ROS, promoting the reduction of oxidized glutathione (GSSG) to reduced glutathione (GSH). Transcriptomic analysis revealed the up-regulation of the gene-encoding antioxidant enzymes (APX, MDHAR, GPX, GR, GST) involved in ROS scavenging and stress tolerance mechanisms. Jasmonic acid (JA) levels and the expression of JA synthesis-related genes increased significantly in mulberry leaves under flooding stress. This activation of the JA signaling pathway contributed to the plant's adaptability to flooding conditions. Proline (Pro) and soluble sugar (SS) contents increased notably in response to flooding stress. Proline helped maintain cell turgor and protected enzymes and membranes from damage, while soluble sugars supported anaerobic respiration and energy supply. However, soluble protein (SP) content decreased, suggesting inhibition of protein synthesis. The study provides insights into mulberry's flooding tolerance mechanisms, guiding future molecular breeding efforts. This summary captures the key findings and implications of the study on mulberry's response to flooding stress, focusing on physiological and molecular mechanisms identified in the research. [ABSTRACT FROM AUTHOR]

Reactive oxygen species (ROS) are key players in the regulation of plant development, stress responses, and programmed cell death. Previous studies indicated that depending on the type of ROS (hydrogen peroxide, superoxide, or singlet oxygen) or its subcellular production site (plastidic, cytosolic, peroxisomal, or apoplastic), a different physiological, biochemical, and molecular response is provoked. We used transcriptome data generated from ROS-related microarray experiments to assess the specificity of ROS-driven transcript expression. Data sets obtained by exogenous application of oxidative stress-causing agents (methyl viologen, Alternaria alternata toxin, 3-aminotriazole, and ozone) and from a mutant (fluorescent) and transgenic plants, in which the activity of an individual antioxidant enzyme was perturbed (catalase, cytosolic ascorbate peroxidase, and copper/zinc superoxide dismutase), were compared. In total, the abundance of nearly 26,000 transcripts of Arabidopsis (Arabidopsis thaliana) was monitored in response to different ROS. Overall, 8,056, 5,312, and 3,925 transcripts showed at least a 3-, 4-, or 5-fold change in expression, respectively. In addition to marker transcripts that were specifically regulated by hydrogen peroxide, superoxide, or singlet oxygen, several transcripts were identified as general oxidative stress response markers because their steady-state levels were at least 5-fold elevated in most experiments. We also assessed the expression characteristics of all annotated transcription factors and inferred new candidate regulatory transcripts that could be responsible for orchestrating the specific transcriptomic signatures triggered by different ROS. Our analysis provides a framework that will assist future efforts to address the impact of ROS signals within environmental stress conditions and elucidate the molecular mechanisms of the oxidative stress response in plants.

In plants, reactive oxygen species and, more particularly, hydrogen peroxide (H(2)O(2)) play a dual role as toxic by-products of normal cell metabolism and as regulatory molecules in stress perception and signal transduction. Peroxisomal catalases are an important sink for photorespiratory H(2)O(2). Using ATH1 Affymetrix microarrays, expression profiles were compared between control and catalase-deficient Arabidopsis (Arabidopsis thaliana) plants. Reduced catalase levels already provoked differences in nuclear gene expression under ambient growth conditions, and these effects were amplified by high light exposure in a sun simulator for 3 and 8 h. This genome-wide expression analysis allowed us to reveal the expression characteristics of complete pathways and functional categories during H(2)O(2) stress. In total, 349 transcripts were significantly up-regulated by high light in catalase-deficient plants and 88 were down-regulated. From this data set, H(2)O(2) was inferred to play a key role in the transcriptional up-regulation of small heat shock proteins during high light stress. In addition, several transcription factors and candidate regulatory genes involved in H(2)O(2) transcriptional gene networks were identified. Comparisons with other publicly available transcriptome data sets of abiotically stressed Arabidopsis revealed an important intersection with H(2)O(2)-deregulated genes, positioning elevated H(2)O(2) levels as an important signal within abiotic stress-induced gene expression. Finally, analysis of transcriptional changes in a combination of a genetic (catalase deficiency) and an environmental (high light) perturbation identified a transcriptional cluster that was strongly and rapidly induced by high light in control plants, but impaired in catalase-deficient plants. This cluster comprises the complete known anthocyanin regulatory and biosynthetic pathway, together with genes encoding unknown proteins.

In plants, hydrogen peroxide (H(2)O(2)) plays a major signaling role in triggering both a defense response and cell death. Increased cellular H(2)O(2) levels and subsequent redox imbalances are managed at the production and scavenging levels. Because catalases are the major H(2)O(2) scavengers that remove the bulk of cellular H(2)O(2), altering their levels allows in planta modulation of H(2)O(2) concentrations. Reduced peroxisomal catalase activity increased sensitivity toward both ozone and photorespiratory H(2)O(2)-induced cell death in transgenic catalase-deficient Arabidopsis thaliana. These plants were used as a model system to build a comprehensive inventory of transcriptomic variations, which were triggered by photorespiratory H(2)O(2) induced by high-light (HL) irradiance. In addition to an H(2)O(2)-dependent and -independent type of transcriptional response during light stress, microarray analysis on both control and transgenic catalase-deficient plants, exposed to 0, 3, 8, and 23 h of HL, revealed several specific regulatory patterns of gene expression. Thus, photorespiratory H(2)O(2) has a direct impact on transcriptional programs in plants.

Plants are capable of regenerating adventitious roots (ARs), which is important for plant response to stress and survival. Although great advances in understanding AR formation of leaf explants have been made, the regulatory mechanisms of AR formation still need to be investigated. In this study, irr1-1 (impaired root regeneration) was isolated with the inhibition of adventitious rooting from Arabidopsis leaf explants. The β-glucuronidase (GUS) signals of IRR1pro::GUS in detached leaves could be detected at 2-6 days after culture. IRR1 is annotated to encode a Class III peroxidase localized in the cell wall. The total peroxidase (POD) activity of irr1 mutants was significantly lower than that of the wild type. Detached leaves of irr1 mutants showed enhanced reactive oxygen species (ROS) accumulation 4 days after leaves were excised from seedlings. Moreover, thiourea, a ROS scavenger, was able to rescue the adventitious rooting rate in leaf explants of irr1 mutants. Addition of 0.1 μM indole-3-acetic acid (IAA) improved the adventitious rooting from leaf explants of irr1 mutants. Taken together, these results indicated that IRR1 was involved in AR formation of leaf explants, which was associated with ROS homeostasis to some extent., (© 2023 Scandinavian Plant Physiology Society.)