Search

Companion cells and sieve elements play an essential role in vascular plants, and yet the details of the metabolism that underpins their function remain largely unknown. Here, we construct a tissue-scale flux balance analysis (FBA) model to describe the metabolism of phloem loading in a mature Arabidopsis (Arabidopsis thaliana) leaf. We explore the potential metabolic interactions between mesophyll cells, companion cells, and sieve elements based on the current understanding of the physiology of phloem tissue and through the use of cell type-specific transcriptome data as a weighting in our model. We find that companion cell chloroplasts likely play a very different role to mesophyll chloroplasts. Our model suggests that, rather than carbon capture, the most crucial function of companion cell chloroplasts is to provide photosynthetically generated ATP to the cytosol. Additionally, our model predicts that the metabolites imported into the companion cell are not necessarily the same metabolites that are exported in phloem sap; phloem loading is more efficient if certain amino acids are synthesized in the phloem tissue. Surprisingly, in our model predictions, the proton-pumping pyrophosphatase (H+-PPiase) is a more efficient contributor to the energization of the companion cell plasma membrane than the H+-ATPase., Competing Interests: Conflict of interest statement. None declared., (© The Author(s) 2023. Published by Oxford University Press on behalf of American Society of Plant Biologists.) more...

Background: Idiopathic pulmonary fibrosis (IPF) is a chronic and progressive lung condition. Currently, care models predominantly focus on acute medical and pharmacological needs. As a step towards holistic care, the aim of this prospective study was to investigate the psychological and behavioural needs of IPF patients treated with pirfenidone from diagnosis until two years of follow-up., Methods: The following variables were selected from the literature on patients' needs and the COM-B model, a theoretical model explaining behaviour: medication adherence, barriers to adherence, importance and intentions of medication adherence, anxiety, depression, health literacy, knowledge, reported side effects, adherence to sun protection recommendations, alcohol use, physical activity, quality of life and health status. Linear and generalised linear models for longitudinal data were used to evaluate the evolution since treatment initiation., Results: We included 66 outpatients: 72.7% men, mean age of 70.3 years (range 50-87), predicted mean forced vital capacity of 85.8% (SD 17.4) and predicted mean diffusing capacity for monoxide of 56.9% (SD 15.7). The participants placed considerable importance on following the treatment recommendations. We noticed difficulties regarding health literacy, alcohol use, pirfenidone adherence (decline over time) and adherence to sun protection recommendations (early in follow-up care). There were low levels of physical activity (no effect of time), high body mass indices (decline over time) and moderate levels of depression and anxiety., Conclusion: When providing care to IPF patients, behavioural issues, health literacy and psychological well-being should be taken into consideration. There is a need to further explore interventions and care models to tackle these difficulties. Trial registration This study was registered in the ClinicalTrials.gov database (identifier NCT03567785) on May 9th, 2018., (© 2022. The Author(s).) more...

Reactive oxygen species (ROS) plays critical roles in modulating plant growth and stress response and its homeostasis is fine tuned using multiple peroxidases. H 2 O t>2 , a major kind of ROS, is removed rapidly and directly using three catalases, CAT1, CAT2, and CAT3, in Arabidopsis. Although the activity regulations of catalases have been well studied, their degradation pathway is less clear. Here, we report that CAT2 and CAT3 protein abundance was partially controlled using the 26S proteasome. To further identify candidate proteins that modulate the stability of CAT2, we performed yeast-two-hybrid screening and recovered several clones encoding a protein with RING and vWA domains, CIRP1 (CAT2 Interacting RING Protein 1). Drought and oxidative stress downregulated CIRP1 transcripts. CIRP1 harbored E3 ubiquitination activity and accelerated the degradation of CAT2 and CAT3 by direct interaction and ubiquitination. The cirp1 mutants exhibited stronger drought and oxidative stress tolerance, which was opposite to the cat2 and cat3 mutants. Genetic analysis revealed that CIRP1 acts upstream of CAT2 and CAT3 to negatively regulate drought and oxidative stress tolerance. The increased drought and oxidative stress tolerance of the cirp1 mutants was due to enhanced catalase (CAT) activities and alleviated ROS levels. Our data revealed that the CIRP1-CAT2/CAT3 module plays a vital role in alleviating ROS levels and balancing growth and stress responses in Arabidopsis., (© 2025 Institute of Botany, Chinese Academy of Sciences.) more...

Salt stress has a detrimental impact on both plant growth and global crop yields. B-box proteins have emerged as pivotal players in plant growth and development regulation. Although the precise role of B-box proteins orchestrating salt stress responses in B. napus (Brassica napus) is not well understood in the current literature, further research and molecular explorations are required. Here, we isolated the B-box protein BnBBX22.A07 from B. napus. The overexpression of BnBBX22.A07 significantly improved the salt tolerance of Arabidopsis (Arabidopsis thaliana) and B. napus. Transcriptomic and histological analysis showed that BnBBX22.A07 enhanced the salt tolerance of B. napus by activating the expression of reactive oxygen species (ROS) scavenging-related genes and decreasing salt-induced superoxide anions and hydrogen peroxide. Moreover, BnBBX22.A07 interacted with BnHY5.C09, which specifically bound to and activated the promoter of BnWRKY33.C03. The presence of BnBBX22.A07 enhanced the activation of BnHY5.C09 on BnWRKY33.C03. Overexpression of BnHY5.C09 and BnWRKY33.C03 improved the salt tolerance of Arabidopsis. Functional analyses revealed that BnBBX22.A07-mediated salt tolerance was partly dependent on WRKY33. Taken together, we demonstrate that BnBBX22.A07 functions positively in salt responses not only by activating ROS scavenging-related genes but also by indirectly activating BnWRKY33.C03. Notably, our study offers a promising avenue for the identification of candidate genes that could be harnessed in breeding endeavours to develop salt-resistant transgenic crops., (© 2024 John Wiley & Sons Ltd.) more...

Leaf senescence is a complex developmental process influenced by abscisic acid (ABA) and reactive oxygen species (ROS), both of which increase during senescence. Understanding the regulatory mechanisms of leaf senescence can provide insights into enhancing crop yield and stress tolerance. In this study, we aimed to elucidate the role and mechanisms of rice (Oryza sativa) LONG GRAIN 3 (OsLG3), an APETALA2/ETHYLENE RESPONSIVE FACTOR (AP2/ERF) transcription factor, in orchestrating dark-induced leaf senescence. The transcript levels of OsLG3 gradually increased during dark-induced and natural senescence. Transgenic plants overexpressing OsLG3 exhibited delayed senescence, whereas CRISPR/Cas9-mediated oslg3 mutants exhibited accelerated leaf senescence. OsLG3 overexpression suppressed senescence-induced ABA signaling by downregulating OsABF4 (an ABA-signaling-related gene) and reduced ROS accumulation by enhancing catalase activity through upregulation of OsCATC. In vivo and in vitro binding assays demonstrated that OsLG3 downregulated OsABF4 and upregulated OsCATC by binding directly to their promoter regions. These results demonstrate the critical role of OsLG3 in fine-tuning leaf senescence progression by suppressing ABA-mediated signaling while simultaneously activating ROS-scavenging mechanisms. These findings suggest that OsLG3 could be targeted to enhance crop resilience and longevity., (© 2024 Society for Experimental Biology and John Wiley & Sons Ltd.) more...

Hydrogen peroxide (H 2 O 2 ) is naturally produced by plant cells during normal development and serves as a messenger that regulates cell metabolism. Despite its importance, the relationship between hydrogen peroxide and the target of rapamycin (TOR) pathway, as well as its impact on cell division, has been poorly analyzed. In this study, we explore the interaction of H 2 O 2 with TOR, a serine/threonine protein kinase that plays a central role in controlling cell growth, size, and metabolism in Arabidopsis thaliana. By applying two concentrations of H 2 O 2 exogenously (0.5 and 1 mM), we could correlate developmental traits, such as primary root growth, lateral root formation, and fresh weight, with the expression of the cell cycle gene CYCB1;1, as well as TOR expression. When assessing the expression of the ribosome biogenesis-related gene RPS27B, an increase of 94.34% was noted following exposure to 1 mM H 2 O 2 treatment. This increase was suppressed by the TOR inhibitor torin 2. The elimination of H 2 O 2 accumulation with ascorbic acid (AA) resulted in decreased cell division as well as TOR expression. The potential molecular mechanisms associated with the effects of H 2 O 2 on the cell cycle and TOR expression in roots are discussed in the context of the results., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Austria, part of Springer Nature.) more...

Micronutrients like iron (Fe), zinc (Zn), copper (Cu), manganese (Mn), boron (B), nickel (Ni), and molybdenum (Mo) perform significant roles in the regulation of plant metabolism, growth, and development. Micronutrients, namely Fe, Zn, Cu, Mn, and Ni, are involved in oxidative stress and antioxidant defense as they are cofactors or activators of various antioxidant enzymes, viz., superoxide dismutase (Fe, Cu/Zn, Mn, and Ni), catalase (Fe), and ascorbate peroxidase (Fe). An effort has been made to incorporate recent advances along with classical work done on the micronutrient deficiency-induced oxidative stress and associated antioxidant responses of plants. Deficiency of a micronutrient produces ROS in the cellular compartments. Enzymatic and non-enzymatic antioxidant defense systems are often modulated by micronutrient deficiency to regulate redox balance and scavenge deleterious ROS for the safety of cellular constituents. ROS can strike cellular constituents such as lipids, proteins, and nucleic acids and can destruct cellular membranes and proteins. ROS might act as a signaling molecule and activate the antioxidant proteins by interacting with signaling partners such as respiratory burst oxidase homolog (RBOH), G-proteins, Ca 2+ , mitogen activated protein kinases (MAPKs), and various transcription factors (TFs). Opinions on probable ROS signaling under micronutrient deficiency have been described in this review. However, further research is required to decipher micronutrient deficiency-induced ROS generation, perception, and associated downstream signaling events, leading to the development of antioxidant responses in plants., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.) more...

Soil salinity is a major constraint for sustainable agricultural productivity, which together with the incessant climate change may be transformed into a severe threat to the global food security. It is, therefore, a serious concern that needs to be addressed expeditiously. The overproduction and accumulation of reactive oxygen species (ROS) and reactive nitrogen species (RNS) are the key events occurring during salt stress, consequently employing nitro-oxidative stress and programmed cell death in plants. However, very sporadic studies have been performed concerning different aspects of nitro-oxidative stress in plants under salinity stress. The ability of plants to tolerate salinity is associated with their ability to maintain the cellular redox equilibrium mediated by both non-enzymatic and enzymatic antioxidant defense mechanisms. The present review emphasizes the mechanisms of ROS and RNS generation in plants, providing a detailed evaluation of how redox homeostasis is conserved through their effective removal. The uniqueness of this article stems from its incorporation of expression analyses of candidate genes for different antioxidant enzymes involved in ROS and RNS detoxification across various developmental stages and tissues of rice, utilizing publicly available microarray data. It underscores the utilization of modern biotechnological methods to improve salinity tolerance in crops, employing different antioxidants as markers. The review also explores how various transcription factors contribute to plants' ability to tolerate salinity by either activating or repressing the expression of stress-responsive genes. In summary, the review offers a thorough insight into the nitro-oxidative homeostasis strategy for extenuating salinity stress in plants., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.) more...

Reactive oxygen species (ROS) can serve as signaling molecules that are essential for plant growth and development but abiotic stress can lead to ROS increases to supraoptimal levels resulting in cellular damage. To ensure efficient ROS signaling, cells have machinery to locally synthesize ROS to initiate cellular responses and to scavenge ROS to prevent it from reaching damaging levels. This review summarizes experimental evidence revealing the role of ROS during multiple stages of plant reproduction. Localized ROS synthesis controls the formation of pollen grains, pollen-stigma interactions, pollen tube growth, ovule development, and fertilization. Plants utilize ROS-producing enzymes such as respiratory burst oxidase homologs and organelle metabolic pathways to generate ROS, while the presence of scavenging mechanisms, including synthesis of antioxidant proteins and small molecules, serves to prevent its escalation to harmful levels. In this review, we summarized the function of ROS and its synthesis and scavenging mechanisms in all reproductive stages from gametophyte development until completion of fertilization. Additionally, we further address the impact of elevated temperatures induced ROS on impairing these reproductive processes and of flavonol antioxidants in maintaining ROS homeostasis to minimize temperature stress to combat the impact of global climate change on agriculture., (© 2024 The Authors. Plant, Cell & Environment published by John Wiley & Sons Ltd.) more...

Key Message: CitCAT1 and CitCAT2 were cloned and highly expressed in mature leaves. High temperatures up-regulated CitCAT1 expression, while low temperatures and Diversispora versiformis up-regulated CitCAT2 expression, maintaining a low oxidative damage. Catalase (CAT), a tetrameric heme-containing enzyme, removes hydrogen peroxide (H 2 O 2 ) to maintain low oxidative damage in plants exposed to environmental stress. This study aimed to clone CAT genes from Citrus sinensis cv. "Oita 4" and analyze their expression patterns in response to environmental stress, exogenous abscisic acid (ABA), and arbuscular mycorrhizal fungal inoculation. Two CAT genes, CitCAT1 (NCBI accession: PP067858) and CitCAT2 (NCBI accession: PP061394) were cloned, and the open reading frames of their proteins were 1479 bp and 1539 bp, respectively, each encoding 492 and 512 amino acids predicted to be localized in the peroxisome, with CitCAT1 being a stable hydrophilic protein and CitCAT2 being an unstable hydrophilic protein. The similarity of their amino acid sequences reached 83.24%, and the two genes were distantly related. Both genes were expressed in stems, leaves, flowers, and fruits, accompanied by the highest expression in mature leaves. In addition, CitCAT1 expression was mainly up-regulated by high temperatures (37 °C), exogenous ABA, and PEG stress within a short period of time, whereas CitCAT2 expression was up-regulated by exogenous ABA and low-temperature (4 °C) stress. Low temperatures (0 °C) for 12 h just up-regulated CitCAT2 expression in Diversispora versiformis-inoculated plants, and D. versiformis inoculation up-regulated CitCAT2 expression, along with lower hydrogen peroxide and malondialdehyde levels in mycorrhizal plants at low temperatures. It is concluded that CitCAT2 has an important role in resistance to low temperatures as well as mycorrhizal enhancement of host resistance to low temperatures., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.) more...

Curcumin, a polyphenol found in Curcuma longa, exhibits diverse biological activities, including antioxidant, anti-inflammatory, anti-infectious, and anti-carcinogenic properties. To enhance drug efficacy, improve bioavailability, water solubility, and pharmacokinetics in both in vitro and in vivo settings, curcumin nanoparticles offer an efficient drug delivery system. In our study, we synthesized curcumin-PLGA nanoparticles and evaluated their anthelmintic potential. Curcumin nanoparticles were synthesized by the single emulsion solvent evaporation method. Characterization of the synthesized nanoparticles was carried out by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), UV-Vis spectrum and zeta potential analysis. SEM revealed uniform circular spheres of curcumin of sizes ranging from 0.1 to 10 µm. FTIR spectrum establishes the presence of specific functional groups in curcumin thus confirming the formation of curcumin nanoparticles. UV–Vis spectrum revealed a single peak of absorption, and zeta potential revealed a single negative charge over the surface of the formed nanoparticles. Fresh adult worms of Fasciola gigantica were obtained from infected livers of slaughtered buffaloes and were incubated in RPMI 1640 medium containing different concentrations of curcumin-PLGA nanoparticles along with the control lacking the test compounds. Based on our findings, it is suggested that curcumin-PLGA nanoparticles impact the motility of adult F. gigantica worms. Higher concentrations of nanoparticles appear to contribute to a progressive reduction in motility over time. Higher nanoparticle concentrations induced a marked increase in reactive oxygen species, malondialdehyde, and protein carbonylation levels, while superoxide dismutase, glutathione, glutathione S-transferase, glutathione peroxidase, and glutathione reductase activities were significantly reduced in a dose-dependent manner. These findings underscore the far-reaching influence of curcumin-PLGA nanoparticles on cellular redox balance, oxidative stress responses, and detoxification processes. It is concluded that the curcumin nanoparticles offer an enhanced anthelmintic potential of curcumin against tropical liver fluke F. gigantica. [ABSTRACT FROM AUTHOR] more...

Phenylalanine (Phe), an aromatic amino acid, is a key precursor of flavonoids, which are crucial for plant growth and development. Arogenate dehydratase (ADT) catalyzes the final step in Phe biosynthesis. This study identified eleven ADT genes in G. hirsutum, twelve in G. barbadense, six in G. arboreum, and six in G. raimondii. Among them, GhADT5 exhibited the highest upregulation under alkali stress. Silencing GhADT5 using virus-induced gene silencing (VIGS) reduced cotton tolerance to alkali stress. GhADT5 silencing also led to decreased plant phenylalanine content, total flavonoid content, and activities of superoxide dismutase (SOD), catalase (CAT), and peroxidase (POD). These reductions caused intracellular accumulation of Malondialdehyde (MDA) and reactive oxygen species (ROS). This oxidative damage ultimately reduced tolerance to alkali stress. In addition, silenced plants displayed reduced stomatal aperture, cellular deformation, and irregular intercellular breaks in the leaf epidermis. In summary, these findings suggest that GhADT5 may enhance resistance to alkali stress by regulating enzymatic and non-enzymatic antioxidant systems. This study highlights the role of GhADT5 under alkali stress and provides novel insights for breeding cotton varieties with improved stress tolerance. [ABSTRACT FROM AUTHOR] more...

Introduction: Hemipteran gall vascular traits result from the access, piercing, and sucking of the inducer mouth parts directly in the xylem and phloem conductive cells. Herein, our focus relies on mapping the features of phloem cells in the proximal, median, and distal regions of Malus pumila stem galls and adjacent galled stems. Methods: Phloem cells were dissociated from gall fragments, the stem portions above and below the galls, and the proximal and distal regions of M. pumila stem galls. were measured. The comparison of the higher length and diameter of the sieve tube elements (STE) was evaluated considering the priority of nutrient flow to gall portions. Results: In the M. pumila - E. lanigerum system, there were no significant differences in the dimensions of the STE in the galls compared with those of the stem portions above and below the galls. Discussion: At the cytological level, the callose deposited in gall STE and the decrease in the cell lumen area in the stem portion above the gall due to thickened nacreous cell walls have implications for nutrient flow. Peculiarly, the smaller sieve pores in the sieve plates of the STE located in the galls and stem portions above and below them and the deposition of P-protein in the stem portions below the galls limit the bidirectional transport of nutrients, benefiting the transport of photoassimilates to the gall proximal region and reducing the vigor of apple tree stems. [ABSTRACT FROM AUTHOR] more...

Auxin response factor (ARF), a transcription factor, is crucial in controlling growth, development, and response to environmental stress. Orchardgrass (Dactylis glomerata) is an economically significant, widely cultivated forage grass. However, information on the genome-wide information and functional characterization of ARFs in orchardgrass is limited. This study identified 27 ARF genes based on the orchardgrass genome database. These DgARFs were unevenly distributed across the seven orchardgrass chromosomes and clustered into four classes. Phylogenetic analysis with multispecies of ARF proteins indicated that the ARFs exhibit a relatively conserved evolutionary path. Focusing on hormone signaling responses, DgARF7 demonstrated a potential positive regulatory role in response to 3-indole acetic acid, methyl jasmonate, gibberellin, salicylic acid, and abscisic acid signals. Additionally, exposure to drought stress induced noticeable oscillatory changes in DgARF7 gene. Notably, DgARF7 enhanced drought tolerance through heterologous expression in yeast and overexpression in Arabidopsis. Overexpressed Arabidopsis lines of DgARF7 exhibited a markedly higher relative water content and superoxide dismutase activity, while the malondialdehyde content was significantly decreased compared to wild type under drought stress. DgARF7 also accelerated flowering time by inducing the flowering-related gene expression levels in Arabidopsis. This research provides important insights into the role of DgARF7 in orchardgrass and provides further understanding in molecular breeding. [ABSTRACT FROM AUTHOR] more...

Drying wheat (Triticum durum) seeds within their spikes may improve the seed desiccation tolerance. This study aimed to understand the effect of drying wheat seeds within their spikes on their desiccation tolerance in association with GABA (γ-aminobutyric acid) content, malondialdehyde (MDA), the expression of three dehydrin genes (dhn , wcor , dreb) during seed development. Seeds of wheat variety 'Hourani-Nawawi' were harvested at five developmental stages: (1) milk (ML); (2) soft dough (SD); (3) hard dough (HD); (4) physiological maturity (PM); and (5) harvest maturity (HM) and dried either attached to or detached from their spikes. Drying the seeds attached to their spikes improved desiccation tolerance, speed of germination, and seedling length at ML stage. Before drying (freshly harvested), the seeds harvested at ML and HM had higher GABA than those at SD, HD, and PM. The attached-dried seeds had higher GABA content from ML to PM than at HM, and higher glutamate content at ML, SD, and HD than at the PM stage. Detached-dried seeds had the highest alanine at ML and PM. Attached-dried seeds had lower MDA than detached-dried seeds. Expression of dhn was highest in freshly-harvested and attached-dried seeds at SD. Highest expression of wcor in the attached-dried seeds was detected at SD and HM. Drying the seeds within their spikes increased the expression of dreb gene compared with the freshly-harvested seeds, except at the HD stage. In conclusion, drying the seeds within their spikes enhanced seed germination in association with higher GABA, lower MDA, and higher gene expression. Drying wheat (Triticum durum) seeds attached to their spikes improved seed germination (desiccation tolerance), mean germination time, and seedling length at the milk stage of seed development compared with seed dried detached from spikes. The improvement of seed germination of spiked-dried seeds was associated with high accumulation of GABA metabolites, lower MDA content, higher expression of dehydrin genes (dhn , wcor , and dreb). [ABSTRACT FROM AUTHOR] more...

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

Dimocarpus longan Lour. is an evergreen tree of the genus Longan in the Sapindaceae family, native to tropical and subtropical regions. Longan embryonic development is closely related to fruit set and fruit quality. An in-depth study of the mechanism of longan embryonic development could therefore contribute to the development of the longan industry. DIMBOA is the principal compound representing benzoxazinoids (BXs), and is closely linked to auxin biosynthesis and signal transduction. Auxin is one of the crucial hormones for inducing somatic embryogenesis (SE) in plants. Previous research has shown that DIMBOA promotes morphogenesis in the early somatic embryogenesis of longan, but the specific regulatory mechanism has not yet been clarified. To elucidate the molecular mechanism by which DIMBOA affects early somatic embryogenesis in longan, we chose longan embryogenic cultures grown under 0 mg/L DIMBOA as the control group (the check, CK), and longan embryogenic cultures grown under 0.1 mg/L DIMBOA as the treatment group (D) to be analyzed by transcriptomic sequencing. A total of 478 differentially expressed genes (DEGs) are detected in check vs. D, of which 193 are upregulated and 285 are downregulated. These DEGs are significantly enriched in the biosynthetic and metabolic functions of various substances such as vitamin B6 (VB6) biosynthesis, phenylpropanoid pathways, and carbohydrate metabolism. DIMBOA affects SE processes in longan via TFs, including MYB, ZF, bHLH, LBD, NAC, WRKY, etc. After DIMBOA treatment, the expression of most of the key genes for IAA synthesis was significantly downregulated, VB6 content was significantly reduced, and H2O2 content was significantly increased. Therefore, it is suggested that DIMBOA directly or indirectly affects the H2O2 content through the VB6 metabolic pathway, thereby regulating the endogenous IAA level to modulate the early SE morphogenesis of longan. [ABSTRACT FROM AUTHOR] more...

Blackleg disease, caused by the hemibiotrophic fungal pathogen Leptosphaeria maculans, poses a serious threat to Brassica crops and requires a broad understanding of the plant defence mechanisms. The Brassica. napus-L. maculans pathosystem provides a useful model to understand plant resistance response to hemibiotrophs. This review aims to explain the mechanisms underlying R-Avr interaction, signalling cascades, and the hypersensitive response (HR) produced by B. napus towards L. maculans, causing local cell death that restricts the pathogen to the site of infection. The role of transcription factors is pivotal to the process of HR, coordinating the regulation of genes involved in pathogen recognition and the activation of SA responsive genes and production of secondary metabolites. The R-Avr interaction signalling cascade involves production of reactive oxygen species (ROS), calcium ion influx, Salicylic acid (SA) hormonal signalling and mitogen activated protein kinases (MAPKs), which are critical in the HR in B. napus. The in-depth understanding of molecular signalling pathway of the R-Avr interaction between B. napus-L. maculans pathosystem provides valuable information for future research endeavours regarding enhancing disease resistance in Brassica crops. [ABSTRACT FROM AUTHOR] more...

Aspirin (Asp) is extensively used in human health as an anti-inflammatory, antipyretic, and anti-thrombotic drug. In this study, we investigated if the foliar application of Asp on tomato plants has comparable beneficial effects on photosynthetic function to that of salicylic acid (SA), with which it shares similar physiological characteristics. We assessed the consequences of foliar Asp-spray on the photosystem II (PSII) efficiency of tomato plants, and we estimated the reactive oxygen species (ROS) generation and the chloroplast ultrastructural changes. Asp acted as an osmoregulator by increasing tomato leaf water content and offering antioxidant protection. This protection kept the redox state of plastoquinone (PQ) pull (qp) more oxidized, increasing the fraction of open PSII reaction centers and enhancing PSII photochemistry (ΦPSII). In addition, Asp foliar spray decreased reactive oxygen species (ROS) formation, decreasing the excess excitation energy on PSII. This resulted in a lower singlet oxygen (1O2) generation and a lower quantum yield for heat dissipation (ΦNPQ), indicating the photoprotective effect provided by Asp, especially under excess light illumination. Simultaneously, we observed a decrease in stomatal opening by Asp, which reduced the transpiration. Chloroplast ultrastructural data revealed that Asp, by offering a photoprotective effect, decreased the need for the photorespiration process, which reduces photosynthetic performance. It is concluded that Asp shares similar physiological characteristics with SA, having an equivalent beneficial impact to SA by acting as a biostimulant of the photosynthetic function for an enhanced crop yield. [ABSTRACT FROM AUTHOR] more...

Understanding the intricate interplay between abiotic and biotic stresses is crucial for deciphering plant responses and developing resilient cultivars. Here, we investigate the combined effects of elevated light intensity and nematode infection on tomato seedlings. Chlorophyll fluorescence analysis revealed significant enhancements in PSII quantum yield and photochemical fluorescence quenching under high light conditions. qRT-PCR analysis of stress-related marker genes exhibited differential expression patterns in leaves and roots, indicating robust defense and antioxidant responses. Despite root protection from light, roots showed significant molecular changes, including downregulation of genes associated with oxidative stress and upregulation of genes involved in signaling pathways. Transcriptome analysis uncovered extensive gene expression alterations, with light exerting a dominant influence. Notably, light and nematode response synergistically induced more differentially expressed genes than individual stimuli. Functional categorization of differentially expressed genes upon double stimuli highlighted enrichment in metabolic pathways, biosynthesis of secondary metabolites, and amino acid metabolism, whereas the importance of specific pathogenesis-related pathways decreased. Overall, our study elucidates complex plant responses to combined stresses, emphasizing the importance of integrated approaches for developing stress-resilient crops in the face of changing environmental conditions. [ABSTRACT FROM AUTHOR] more...

Plants often encounter challenging environmental factors, including intense sunlight, drought, extreme heat, cold temperatures, salinity, excessive metals, and nutrient shortages, which can heavily affect their growth and survival. In this regard, L-ascorbic acid (AsA) is not only an essential nutrient for human health but also plays a significant role in plant responses to environmental stresses, regulating various functions during growth and development, redox signaling, and phytohormone biosynthesis. The growing need to cope with climate change, together with the advancement of CRISPR/Cas9-editing technologies, stimulated new opportunities to enhance AsA biosynthesis to improve crop stress tolerance. In this review, we discuss the biosynthesis and regulation of AsA in abiotic stress response mechanisms. We also explore the latest advancements of CRISPR/Cas9 technologies, their applications, and their challenges as tools for modifying genes associated with AsA metabolism, aiming to develop crops more tolerant and resilient to environmental changes. [ABSTRACT FROM AUTHOR] more...

Simple Summary: This study explored the effects of γ-aminobutyric acid (GABA) on growth, immunity, erythropoiesis, and angiogenesis in Gibel carp (Carassius auratus gibelio). Gibel carp were fed with five levels of GABA for a total of eight weeks. This study showed that the growth performance of Gibel carp was improved, the immune performance was enhanced, and the expression of erythropoietic and angiogenic genes was also enhanced. In conclusion, GABA had a positive effect on the growth of Gibel carp. This experiment aimed to investigate the effect of dietary supplementation of γ-aminobutyric acid (GABA) on the growth performance, immune response, and oxygen-transport-related factors of Gibel carp (Carassius auratus gibelio). An eight-week culturing experiment was designed with five experimental diets, with the actual GABA content being 368 mg/kg (G1, control group), 449 mg/kg (G2), 527 mg/kg (G3), 602 mg/kg (G4), and 675 mg/kg (G5). The results showed that the level of 527 mg/kg (G3) of GABA significantly increased the specific growth rate (SGR), weight gain rate (WGR), and final body weight (FBW) of Gibel carp, while the levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), total cholesterol (TC), and glucose (GLU) were also increased significantly. In addition, 527 mg/kg (G3) and 602 mg/kg (G4) of GABA significantly increased the total antioxidant capacity (T-AOC). The mRNA expression of tnf-α, tgf-β, and il-10 was significantly increased at the level of 449 mg/kg (G2). In terms of oxygen-carrying capacity, the mRNA expression of epo, tf, tfr1, ho-1, and vegf was markedly increased at the level of 449 mg/kg (G2). In conclusion, dietary GABA supplementation can boost growth performance, enhance the immune system, and increase oxygen-carrying capacity in Gibel carp. [ABSTRACT FROM AUTHOR] more...

Main conclusion: Significant changes in the proteome highlight essential metabolic adaptations for development and oxidative signaling induced by the treatment of young sugarcane plants with hydrogen peroxide. These adaptations suggest that hydrogen peroxide acts not only as a stressor but primarily as a signaling molecule, triggering specific metabolic pathways that regulate growth and plant resilience. Sugarcane is a crucial crop for sugar and ethanol production, often influenced by environmental signals. Hydrogen peroxide (H2O2) is increasingly recognized as an important signaling molecule that regulates plant development and adaptation. In this study, two-month-old sugarcane plants were treated with varying concentrations of H2O2 to investigate how this molecule acts as a signal at the cellular, biochemical, and proteomic levels. Antioxidant enzyme activity exhibited fluctuations, suggesting a dynamic response to oxidative signaling. Lipid peroxidation, observed through TBARs and scanning electron microscopy, highlighted early membrane modifications. Proteomic analysis (ProteomeXchange PXD048142) identified 2,699 proteins, with 155 showing significant expression changes in response to H2O2 signaling. Bioinformatics, including Principal Component Analysis, revealed distinct proteomic profiles in roots and leaves, indicating tissue-specific metabolic reprogramming. Functional annotation through Gene Ontology and KEGG pathway enrichment showed that oxidative signaling led to the repression of photosynthesis-related pathways in leaves, while promoting pathways related to protein processing, glycolysis, and carbon metabolism in roots. Additionally, bioinformatic tools identified proteins involved in amino acid metabolism, the TCA cycle, and carbohydrate metabolism as critical components of sugarcane's adaptive signaling response. The data suggest that sugarcane plants responded to oxidative signals by adjusting their metabolic networks, promoting sustained development and potential pathways for targeted plant breeding. [ABSTRACT FROM AUTHOR] more...

Savory (Satureja rechingeri L.) is one of Iran's most important medicinal plants, having low irrigation needs, and thus is considered one of the most valuable plants for cultivation in arid and semi-arid regions, especially under drought conditions. The current research was carried out to develop a genetic algorithm-based artificial neural network (ΑΝΝ) model able of simulating the levels of antioxidants in savory when using soil amendments [biochar (BC) and superabsorbent (SA)] under drought. Data under different watering schemes and different levels of soil amendments showed that both BC and SA have mitigating effects over drought stress by optimizing enzymatic and non-enzymatic antioxidant traits (POD, CTA, and APX enzymes). Specifically, using biochar and superabsorbent led to improved homeostasis under water deficit as reflected by lower MDA levels. An ANN model with a 3-10-6 topology was found to be the best model to predict polyphenols (PHE), proline (PRO), peroxidase (POX), catalase (CAT), ascorbate peroxidase (APX) levels, and indicator of oxidative stress malondialdehyde (MDA). The model's efficiency was established using the R-value as the statistical parameter, and simulated GA-ANN data were highly correlated with experimental findings. Across enzymatic antioxidants, APX had the best model fit, having an R-value of 0.9733. On the other hand, POX had a lower predictive correlation (R = 0.8737), indicating a lower capacity of the ANN system in forecasting this parameter. On the other hand, MDA (R = 0.9690) had an elevated assimilation performance over PHE (R = 0.9604) and PRO (R = 0.9245) levels. The current study shows the potential of the ANN model in predicting the content of enzymatic and non-enzymatic antioxidants in savory plants under drought stress as a non-invasive, low-cost experimental alternative. [ABSTRACT FROM AUTHOR] more...

B-box (BBX) transcription factors play crucial roles in plant growth, development, and defense responses to biotic and abiotic stresses. In this study, we cloned a BBX transcription factor gene, CsCOL9I, from cucumber and analyzed its role in the plant's defense against the feeding of Bemisia tabaci. CsCOL9 is expressed throughout all developmental stages in cucumber, with the highest expression in the leaves. CsCOL9 is induced by B. tabaci feeding, salicylic acid (SA), methyl jasmonate (MeJA), and hydrogen peroxide (H2O2). Cucumber plants with CsCOL9 silence (TRV2-CsCOL9) and overexpression (1301-CsCOL9) were obtained and analyzed. After CsCOL9 silencing, survival rates and host selectivity for B. tabaci increased; however, the expression levels of genes encoding enzymes (CsSOD, CsRBOH, CsPOD), activities of superoxide dismutase (SOD) and peroxidase (POD), and content of H2O2 in plants were all reduced. CsCOL9 overexpression led to decreased survival rates and host selectivity for B. tabaci. Conversely, the expression levels of genes (CsSOD, CsRBOH and CsPOD), activities of SOD and POD, and content of H2O2 increased after CsCOL9 overexpression in plants. Collectively, our results demonstrate CsCOL9 positively regulates cucumber resistance to B. tabaci by activating reactive oxygen species bursts. This study lays a theoretical foundation for the application of CsCOL9 in cucumber resistance breeding and green pest control of B. tabaci. [ABSTRACT FROM AUTHOR] more...

Reactive oxygen species (ROS) are essential molecules involved in intercellular communication, signal transduction, and metabolic processes. Abiotic stresses cause the accumulation of excess ROS in plant cells. The issue of regulating the antioxidant protection of plants using natural and synthetic compounds with antioxidant activity still remains one of the most important and relevant areas of fundamental and applied research. Glutathione (GSH) plays an important role in the stress resistance and redox homeostasis of plant cells and effectively protects the cell from the stress-induced generation of ROS. An increase in the GSH content in plant cells can contribute to an increase in plant resistance to various types of stressors. We have shown that growing Nicotiana tabacum in the presence of tetrapeptide AEDL (AlaGluAspLeu) contributes to an increase in the GSH content by 3.24 times. At the same time, the tobacco plant was more developed, especially its root system. A scheme of the mechanism behind the regulation of the redox balance in the stem cell niche and the participation of the AEDL and GSH peptides in the regulation of the fate of stem cells was proposed. [ABSTRACT FROM AUTHOR] more...

Nickel (Ni), an essential heavy metal, is transformed from an element with vital functions to a hazardous contaminant within agricultural environments, owing to its extensive utilization across diverse applications, spanning from everyday household items to various industrial processes. Understanding Ni’s bioavailability in soil, associated risks, phytodetoxification processes, and current remediation techniques is crucial for sustainable ecosystem management. Although Ni occurs naturally in very small concentrations in soil, water, and air, its absorption by plants from soil to roots is vital for both activating enzymes and supporting plant growth. Ni plays pivotal roles in numerous physiological functions, including photosynthesis, nitrogen metabolism, and growth regulation. However, excessive Ni can induce toxic effects in plants through the production of reactive oxygen species (ROS) that interferes with their biochemical, physiological, and morphological processes. Eventually, there are only a number of feasible strategies for the mitigation of Ni-polluted soils. The present review critically examines the origins and dynamics of Ni in soil–plant systems and its detrimental effects on plants at morphological, biochemical, physiological, and molecular levels. The review also explores the detoxification mechanisms in higher plants and current remediation technologies for decision-making and sustainable management of Ni contamination in the environment. The review concludes that there is a need of friendly effective and environmentally sustainable technologies for the mitigation of Ni toxicity in terrestrial ecosystems and environmental sustainability. [ABSTRACT FROM AUTHOR] more...

2,6-Dichloro-1,4-benzoquinone (2,6-DCBQ) is an emerging chlorinated disinfection byproduct (DBP) in bodies of water. However, this compound poses an unknown toxic effect on cyanobacteria. In this study, the toxicological mechanisms of 2,6-DCBQ in Microcystis aeruginosa (M. aeruginosa) were investigated through physiological and nontargeted metabolomic assessments. The results show that 2,6-DCBQ inhibited the growth of M. aeruginosa, reduced its photosynthetic pigment and protein contents, increased the levels of reactive oxygen species, damaged the antioxidant defense system, and aggravated the cytomembrane. Meanwhile, 2,6-DCBQ stimulated the production and release of microcystin-LR (MC-LR) and altered the transcripts of genes associated with its synthesis (mcyA, mcyD) and transport (mcyH). In addition, nontargeted metabolomics of M. aeruginosa cells exposed to 0.1 mg/L 2,6-DCBQ identified 208 differential metabolites belonging to 10 metabolic pathways and revealed the considerable interference caused by 2,6-DCBQ among ABC transporters, the two-component system, and folate biosynthesis. This study deepens the understanding of the physiological and nontargeted metabolomic responses of M. aeruginosa exposed to 2,6-DCBQ, offers insights into the toxic effect of 2,6-DCBQ on M. aeruginosa, and provides a theoretical basis for the ecological risk assessment of emerging DBPs in accordance with water quality criteria. [ABSTRACT FROM AUTHOR] more...

The impact of combined heat and drought stress was investigated in Arabidopsis thaliana and compared to individual stresses to reveal additive effects and interactions. A combination of plant metabolomics and root and rhizosphere bacterial metabarcoding were used to unravel effects at the plant holobiont level. Hierarchical cluster analysis of metabolomics signatures pointed out two main clusters, one including heat and combined heat and drought, and the second cluster that included the control and drought treatments. Overall, phenylpropanoids and nitrogen-containing compounds, hormones and amino acids showed the highest discriminant potential. A decrease in alpha-diversity of Bacteria was observed upon stress, with stress-dependent differences in bacterial microbiota composition. The shift in beta-diversity highlighted the pivotal enrichment of Proteobacteria , including Rhizobiales , Enterobacteriales and Azospirillales. The results corroborate the concept of stress interaction, where the combined heat and drought stress is not the mere combination of the single stresses. Intriguingly, multi-omics interpretations evidenced a good correlation between root metabolomics and root bacterial microbiota, indicating an orchestrated modulation of the whole holobiont. [ABSTRACT FROM AUTHOR] more...

DNA damage response (DDR) contributes to seed quality by guarding genome integrity in the delicate phases of pre- and post-germination. As a key determinant of stress tolerance and resilience, DDR has notable implications on the wider scale of the agroecosystems challenged by harsh climatic events. The present review focuses on the existing and documented links that interconnect DDR efficiency with an array of molecular hallmarks with biochemical, molecular, and physiological valence within the seed metabolic networks. The expression of genes encoding DDR sensors, transducers, mediators, and effectors is interpreted as a source of conserved hallmarks, along with markers of oxidative damage reflecting the seed's ability to germinate. Similarly, the accumulation patterns of proteins and metabolites that contribute to DNA stability are predictive of seed quality traits. While a list of candidates is presented from multiple models and crop species, their interaction with chromatin dynamics, cell cycle progression, and hormonal regulation provides further levels of analysis to investigate the seed stress response holistically. The identification of novel hallmarks of DDR in seeds constitutes a framework to prompt validation with different experimental systems, to refine the current models of pre-germinative metabolism, and to promote targeted approaches for seed quality evaluation. [ABSTRACT FROM AUTHOR] more...

Introduction: The common duckweed (L. minor) is a model organism for investigation of plant physiology, especially stress-related responses. Its two physiological characteristics are of special interest: (1) salt-stressed duckweeds may accumulate starch, a precursor for biofuel; (2) duckweeds are associated with various beneficial (plant-growth promoting, PGP) bacterial strains. In this paper, we analyzed the role of two bacterial strains: Pseudomonas oryzihabitans D1-104/3 and P. gessardii C31-106/3 in regulation of duckweed's growth and antioxidative responses to salt (10 and 100 mM NaCl) and hypothesized that they alleviate salt-induced oxidative stress. Methods: Fresh and dry weight, frond number, photosynthetic pigments, malondialdehyde (MDA) and hydrogen peroxide (H2O2), ascorbic acid (AsA), proline, total polyphenol (TPC) and starch content, as well as antioxidant capacity and antioxidant enzymatic activity were measured after 14 days. Fluorescence microscopy was used to visualize bacterial presence on duckweeds. Results: Fluorescence microscope revealed that Pseudomonas bacteria colonized all duckweed surfaces. The doubling time of duckweeds inoculated with P. gessardii C31-106/3 was significantly longer. Additionally, at 0 and 10 mM NaCl, this strain decreased chlorosis in duckweeds. Moreover, P. gessardii C31-106/3 increased dry-to-fresh-weight ratio, proline, chlorophyll a, b and carotenoid content at 100 mM, as well as AsA content in plants in NaCl-free medium, while P. oryzihabitans D1-104/3 increased AsA at 100 mM NaCl. Both bacterial strains decreased lipid peroxidation, while P. gessardii C31-106/3 increased and P. oryzihabitans D1-104/3 decreased H2O2 content at 100 mM and 0 mM NaCl, respectively. Bacteria significantly increased TPC and antioxidant capacity at 100 mM NaCl, particularly P. oryzihabitans D1-104/3. After 14 days, the SOD and POX activities were at the same level in all samples. At 100 mM NaCl, CAT activity was increased in all plants. Discussion: The results of this study show that two Pseudomonas strains had markedly different effects on duckweed: while P. oryzihabitans D1-104/3 supported growth, P. gessardii C31-106/3 prioritized salt stress tolerance in duckweeds. [ABSTRACT FROM AUTHOR] more...

Global climate change poses a significant risk to agricultural productivity due to its diverse impacts on agricultural ecosystems, such as increased temperatures and altered precipitation patterns, all of which can adversely affect crop productivity. To overcome these challenges, plants have evolved intricate mechanisms to regulate stress responses and enhance stress tolerance. The SAL1 gene, which encodes a phosphatase enzyme, has emerged as a key player in plant stress responses. In this review, we provide an overview of the SAL1 gene, its functional significance, and its potential applications for improving stress tolerance in crops. To address the escalating global food demand amidst climate change challenges, it is imperative to pursue innovative strategies aimed at enhancing crop tolerance against abiotic stress. [ABSTRACT FROM AUTHOR] more...

Whereas our knowledge about the diverse pathways aiding DNA repair upon genome damage is steadily increasing, little is known about the molecular players that adjust the plant cell cycle in response to DNA stress. By a meta-analysis of DNA stress microarray data sets, three family members of the SIAMESE/SIAMESE-RELATED (SIM/SMR) class of cyclin-dependent kinase inhibitors were discovered that react strongly to genotoxicity. Transcriptional reporter constructs corroborated specific and strong activation of the three SIM/SMR genes in the meristems upon DNA stress, whereas overexpression analysis confirmed their cell cycle inhibitory potential. In agreement with being checkpoint regulators, SMR5 and SMR7 knockout plants displayed an impaired checkpoint in leaf cells upon treatment with the replication inhibitory drug hydroxyurea (HU). Surprisingly, HU-induced SMR5/SMR7 expression depends on ATAXIA TELANGIECTASIA MUTATED (ATM) and SUPPRESSOR OF GAMMA RESPONSE1, rather than on the anticipated replication stress-activated ATM AND RAD3-RELATED kinase. This apparent discrepancy was explained by demonstrating that, in addition to its effect on replication, HU triggers the formation of reactive oxygen species (ROS). ROS-dependent transcriptional activation of the SMR genes was confirmed by different ROS-inducing conditions, including high-light treatment. We conclude that the identified SMR genes are part of a signaling cascade that induces a cell cycle checkpoint in response to ROS-induced DNA damage. more...

The quiescent center (QC) plays an essential role during root development by creating a microenvironment that preserves the stem cell fate of its surrounding cells. Despite being surrounded by highly mitotic active cells, QC cells self-renew at a low proliferation rate. Here, we identified the ERF115 transcription factor as a rate-limiting factor of QC cell division, acting as a transcriptional activator of the phytosulfokine PSK5 peptide hormone. ERF115 marks QC cell division but is restrained through proteolysis by the APC/C(CCS52A2) ubiquitin ligase, whereas QC proliferation is driven by brassinosteroid-dependent ERF115 expression. Together, these two antagonistic mechanisms delimit ERF115 activity, which is called upon when surrounding stem cells are damaged, revealing a cell cycle regulatory mechanism accounting for stem cell niche longevity. more...

Most of our knowledge on the regulation of photosynthesis originates from studies performed in highly controlled laboratory conditions. However, in their natural habitats plants are simultaneously subjected to a broad range of abiotic and biotic stimuli which influence photosynthetic efficiency; hence there is an emerging need to examine the process of photosynthesis under multivariable field conditions in order to elucidate the mechanisms that underlie its regulation. Such knowledge has potential for providing novel targets that would improve both crop yield and performance. In the present study we compared laboratory- and field-grown Arabidopsis thaliana plants in terms of photosynthetic efficiency in modulated light intensities and CO2 concentrations. We show here that the field-acclimated plants display highly efficient photosynthesis and are more tolerant to variable light intensities and CO2 concentrations than their laboratory-grown counterparts. We also demonstrate that some structural rearrangements of LHCII and PSII, together with altered pigments composition and stomatal density, are responsible for the differences in assimilation and photochemistry. Furthermore, we employ a transcript profiling approach to explain the genetic mechanisms underlying these adaptations and suggest that they are mainly induced by the high and fluctuating light intensities which occur in the natural environment., (Copyright © 2012 Elsevier GmbH. All rights reserved.) more...

There is growing evidence that for a comprehensive insight into the function of plant genes, it is crucial to assess their functionalities under a wide range of conditions. In this study, we examined the role of lesion simulating disease1 (LSD1), enhanced disease susceptibility1 (EDS1), and phytoalexin deficient4 (PAD4) in the regulation of photosynthesis, water use efficiency, reactive oxygen species/hormonal homeostasis, and seed yield in Arabidopsis (Arabidopsis thaliana) grown in the laboratory and in the field. We demonstrate that the LSD1 null mutant (lsd1), which is known to exhibit a runaway cell death in nonpermissive conditions, proves to be more tolerant to combined drought and high-light stress than the wild type. Moreover, depending on growing conditions, it shows variations in water use efficiency, salicylic acid and hydrogen peroxide concentrations, photosystem II maximum efficiency, and transcription profiles. However, despite these changes, lsd1 demonstrates similar seed yield under all tested conditions. All of these traits depend on EDS1 and PAD4. The differences in the pathways prevailing in the lsd1 in various growing environments are manifested by the significantly smaller number of transcripts deregulated in the field compared with the laboratory, with only 43 commonly regulated genes. Our data indicate that LSD1, EDS1, and PAD4 participate in the regulation of various molecular and physiological processes that influence Arabidopsis fitness. On the basis of these results, we emphasize that the function of such important regulators as LSD1, EDS1, and PAD4 should be studied not only under stable laboratory conditions, but also in the environment abounding in multiple stresses. more...

CYP450 enzymes are versatile catalysts involved in diverse chemical reactions, including xenobiotic metabolism and stress response pathways. Sugarcane, a globally significant energy crop, faces oxidative stress induced by abiotic and biotic stresses impacting plant metabolism and physiology. This study aimed to compare the response of cultivated (Co 86032) and stress-tolerant wild sugarcane species (Erianthus arundinaceus and Saccharum spontaneum) to oxidative stress. Transcriptomic analysis was conducted to identify genes responsive to oxidative stress and CYP450 enzymes, while protein–protein interactions of cytochrome family proteins were explored under oxidative stress conditions. Differential expression patterns of gene transcripts were observed under oxidative stress across different species. In the cultivated variety (Co 86032), two downregulated CYP450 gene transcripts were identified. In contrast, one upregulated CYP450 gene transcript was observed in both Erianthus sp. and S. spontaneum. Additionally, S. spontaneum exhibited eight downregulated transcripts. The gene CYP 450 84A1 was upregulated in all the genotypes; however, the fold change was higher for the wild species than the Co 86032. RT-PCR validation of the CYP450 84A1 gene confirmed the findings from next-generation sequencing data, showing consistent results. Additionally, by designing primers for three individual exons, the study observed varying levels of variant transcripts for the CYP450 84A1. The protein interaction network analysis showed a shared protein, Sh_212F09_p000130, identified as a 4-coumarate-CoA ligase-like 1 protein, present in the networks of both S. spontaneum and Co 86032, suggesting its involvement in combating biotic and abiotic stresses. [ABSTRACT FROM AUTHOR] more...

Environmental stresses adversely affect plant growth and development. A common theme within these adverse conditions is the perturbation of reactive oxygen species (ROS) homeostasis. Here, we demonstrate that the ROS-inducible Arabidopsis thaliana WRKY15 transcription factor (AtWRKY15) modulates plant growth and salt/osmotic stress responses. By transcriptome profiling, a divergent stress response was identified in transgenic WRKY15-overexpressing plants that linked a stimulated endoplasmic reticulum-to-nucleus communication to a disrupted mitochondrial stress response under salt-stress conditions. We show that mitochondrial calcium-flux sensing might be important for regulating an active mitochondrial retrograde signaling and launching an appropriate defense response to confer salt-stress tolerance. more...

The signal transduction mechanisms of the oxidative stress response in plants remain largely unexplored. Previously, increased levels of cellular hydrogen peroxide (H(2)O(2)) had been shown to drastically affect the plant transcriptome. Genome-wide transcriptome analyses allowed us to build a comprehensive inventory of H(2)O(2)-induced genes in plants. Here, the primary objective was to determine the subcellular localization of these genes and to assess potential trafficking during oxidative stress. After high-throughput cloning in Gateway-derived vectors, the subcellular localization of 49 proteins fused to the green fluorescent protein (GFP) was identified in a transient assay in tobacco (Nicotiana benthamiana) by means of agro-infiltration and confirmed for a selection of genes in transgenic Arabidopsis thaliana plants. Whereas eight of the GFP-tagged proteins are exclusively localized in the nucleus, 23 reside both in the nucleus and cytosol, in which several classes of known transcription factors and proteins of unknown function can be recognized. In this study, the mapping of the subcellular localization of H(2)O(2) -induced proteins paves the way for future research to unravel the H(2)O(2) responses in plants. Furthermore, the effect of increased H(2)O(2) levels on the subcellular localization of a subset of proteins was assessed., (© 2011 Blackwell Publishing Ltd.) more...

Growth day length, CO(2) levels and H(2)O(2) all impact plant function, but interactions between them remain unclear. Using a whole-genome transcriptomics approach, we identified gene expression patterns responding to these three factors in Arabidopsis Col-0 and the conditional catalase-deficient mutant, cat2. Plants grown for 5 weeks at high CO(2) in short days (hCO(2)) were transferred to air in short days (SD air) or long days (LD air), and microarray data produced were subjected to three independent studies. The first two analysed genotype-independent responses. They identified 1549 genes differentially expressed after transfer from hCO(2) to SD air. Almost half of these, including genes modulated by sugars or associated with redox, stress or abscisic acid (ABA) functions, as well as light signalling and clock genes, were no longer significant after transfer to air in LD. In a third study, day length-dependent H(2)O(2)-responsive genes were identified by comparing the two genotypes. Two clearly independent responses were observed in cat2 transferred to air in SD and LD. Most H(2)O(2) -responsive genes were up-regulated more strongly in SD air. Overall, the analysis shows that both CO(2) and H(2)O(2) interact with day length and photoreceptor pathways, indicating close networking between carbon status, light and redox state in environmental responses., (© 2011 Blackwell Publishing Ltd.) more...

Reactive oxygen species (ROS) play a multitude of signaling roles in different organisms from bacteria to mammalian cells. They were initially thought to be toxic byproducts of aerobic metabolism, but have now been acknowledged as central players in the complex signaling network of cells. In this review, we will attempt to address several key questions related to the use of ROS as signaling molecules in cells, including the dynamics and specificity of ROS signaling, networking of ROS with other signaling pathways, ROS signaling within and across different cells, ROS waves and the evolution of the ROS gene network., (Copyright © 2011 Elsevier Ltd. All rights reserved.) more...

Eukaryotic organisms evolved under aerobic conditions subjecting nuclear DNA to damage provoked by reactive oxygen species (ROS). Although ROS are thought to be a major cause of DNA damage, little is known about the molecular mechanisms protecting nuclear DNA from oxidative stress. Here we show that protection of nuclear DNA in plants requires a coordinated function of ROS-scavenging pathways residing in the cytosol and peroxisomes, demonstrating that nuclear ROS scavengers such as peroxiredoxin and glutathione are insufficient to safeguard DNA integrity. Both catalase (CAT2) and cytosolic ascorbate peroxidase (APX1) play a key role in protecting the plant genome against photorespiratory-dependent H(2)O(2)-induced DNA damage. In apx1/cat2 double-mutant plants, a DNA damage response is activated, suppressing growth via a WEE1 kinase-dependent cell-cycle checkpoint. This response is correlated with enhanced tolerance to oxidative stress, DNA stress-causing agents, and inhibited programmed cell death. more...

Hydrogen peroxide (H(2)O(2)) is an important signal molecule involved in plant development and environmental responses. Changes in H(2)O(2) availability can result from increased production or decreased metabolism. While plants contain several types of H(2)O(2)-metabolizing proteins, catalases are highly active enzymes that do not require cellular reductants as they primarily catalyse a dismutase reaction. This review provides an update on plant catalase genes, function, and subcellular localization, with a focus on recent information generated from studies on Arabidopsis. Original data are presented on Arabidopsis catalase single and double mutants, and the use of some of these lines as model systems to investigate the outcome of increases in intracellular H(2)O(2) are discussed. Particular attention is paid to interactions with cell thiol-disulphide status; the use of catalase-deficient plants to probe the apparent redundancy of reductive H(2)O(2)-metabolizing pathways; the importance of irradiance and growth daylength in determining the outcomes of catalase deficiency; and the induction of pathogenesis-related responses in catalase-deficient lines. Within the context of strategies aimed at understanding and engineering plant stress responses, the review also considers whether changes in catalase activities in wild-type plants are likely to be a significant part of plant responses to changes in environmental conditions or biotic challenge. more...

While it is well established that reactive oxygen species can induce cell death, intracellularly generated oxidative stress does not induce lesions in the Arabidopsis (Arabidopsis thaliana) photorespiratory mutant cat2 when plants are grown in short days (SD). One interpretation of this observation is that a function necessary to couple peroxisomal hydrogen peroxide (H(2)O(2))-triggered oxidative stress to cell death is only operative in long days (LD). Like lesion formation, pathogenesis-related genes and camalexin were only induced in cat2 in LD, despite less severe intracellular redox perturbation compared with SD. Lesion formation triggered by peroxisomal H(2)O(2) was modified by introducing secondary mutations into the cat2 background and was completely absent in cat2 sid2 double mutants, in which ISOCHORISMATE SYNTHASE1 (ICS1) activity is defective. In addition to H(2)O(2)-induced salicylic acid (SA) accumulation, the sid2 mutation in ICS1 abolished a range of LD-dependent pathogen responses in cat2, while supplementation of cat2 with SA in SD activated these responses. Nontargeted transcript and metabolite profiling identified clusters of genes and small molecules associated with the daylength-dependent ICS1-mediated relay of H(2)O(2) signaling. The effect of oxidative stress in cat2 on resistance to biotic challenge was dependent on both growth daylength and ICS1. We conclude that (1) lesions induced by intracellular oxidative stress originating in the peroxisomes can be genetically reverted; (2) the isochorismate pathway of SA synthesis couples intracellular oxidative stress to cell death and associated disease resistance responses; and (3) camalexin accumulation was strictly dependent on the simultaneous presence of both H(2)O(2) and SA signals. more...

Transgenic plants with reduced poly(ADP-ribose) polymerase (PARP) levels have broad-spectrum stress-resistant phenotypes. Both Arabidopsis thaliana and oilseed rape (Brassica napus) lines overexpressing RNA interference-PARP constructs were more resistant to various abiotic stress treatments in laboratory and greenhouse experiments without negative effects on growth, development, and seed production. This outperforming stress tolerance was initially attributed solely to a maintained energy homeostasis due to reduced NAD(+) consumption. We show that in PARP2-deficient Arabidopsis plants, the observed abiotic stress resistance can also be explained by alterations in abscisic acid levels that facilitate the induction of a wide set of defense-related genes. more...

Sclerotinia sclerotiorum as a necrotrophic fungus causes the devastating diseases in many important oilseed crops worldwide. The preferred strategy for controlling S. sclerotiorum is to develop resistant varieties, but the molecular mechanisms underlying S. sclerotiorum resistance remain poorly defined in sunflower (Helianthus annuus). Here, a comparative transcriptomic analysis was performed in leaves of two contrasting sunflower genotypes, disease susceptible (DS) B728 and disease resistant (DR) C6 after S. sclerotiorum inoculation. At 24 h post-inoculation, the DR genotype exhibited no visible growth of the hyphae as well as greater activity of superoxide dismutase activity (SOD), peroxidase (POD), catalase (CAT), glutathione-S-transferase (GST), ascorbate peroxidase (APX) and monodehydroascorbate reductase (MDAR) than DS genotype. A total of 10151 and 7439 differentially expressed genes (DEGs) were detected in DS and DR genotypes, respectively. Most of DEGs were enriched in cell wall organisation, protein kinase activity, hormone, transcription factor activities, redox homeostasis, immune response, and secondary metabolism. Differential expression of genes involved in expansins, pectate lyase activities, ethylene biosynthesis and signaling and antioxidant activity after S. sclerotiorum infection could potentially be responsible for the differential resistance among two genotypes. In summary, these finding provide additional insights into the potential molecular mechanisms of S. sclerotiorum's defense response and facilitate the breeding of Sclerotinia-resistant sunflower varieties. [ABSTRACT FROM AUTHOR] more...

RETINOBLASTOMA-RELATED (RBR) proteins orchestrate cell division, differentiation, and survival in response to environmental and developmental cues through protein–protein interactions that are governed by multisite phosphorylation. Here we explore, using a large collection of transgenic RBR phosphovariants to complement protein function in Arabidopsis thaliana, whether differences in the number and position of RBR phosphorylation events cause a diversification of the protein's function. While the number of point mutations influence phenotypic strength, phosphosites contribute differentially to distinct phenotypes. RBR pocket domain mutations associate primarily with cell proliferation, while mutations in the C-region are linked to stem cell maintenance. Both phospho-mimetic and a phospho-defective variants promote cell death, suggesting that distinct mechanisms can lead to similar cell fates. We observed combinatorial effects between phosphorylated T406 and phosphosites in different protein domains, suggesting that specific, additive, and combinatorial phosphorylation events fine-tune RBR function. Suppression of dominant phospho-defective RBR phenotypes with a mutation that inhibits RBR interacting with LXCXE motifs, and an exhaustive protein–protein interaction assay, not only revealed the importance of DREAM complex members in phosphorylation-regulated RBR function but also pointed to phosphorylation-independent RBR roles in environmental responses. Thus, combinatorial phosphorylation defined and separated developmental, but not environmental, functions of RBR. Synopsis: RETINOBLASTOMA-RELATED (RBR) proteins orchestrate diverse cellular processes through multiple phosphorylation-regulated protein interactions with transcriptional regulators. Here, functional analysis of an A. thaliana RBR phosphorylation-variant collection reveals that combinatorial phosphorylation partially separates RBR roles in plant growth. RBR phospho-sites contribute differentially and additively to distinct phenotypes. Phospho-sites in the pocket-domain are primarily associated with cell proliferation, and phospho-sites in the C-region with stem cell maintenance. Both a phospho-mimetic RBR variant as well as a specific phospho-defective variant result in cell death as a common cell fate. Cell death is prevented by the T406 phospho-site in combination with C-terminal phosphor-sites, but not pocket-domain sites. Embryo lethality and growth repression in phospho-defective RBR variants can be suppressed by disrupting interactions with DREAM complex members and other RBR interactors. RBR complementation assays in plants reveal that an intricate phosphorylation landscape regulates the balance between cell proliferation and stem cell maintenance. [ABSTRACT FROM AUTHOR] more...

Selenicereus undatus L., (pitaya) is an important tropical fruit crop, and faces significant challenges from soil salinity and heavy metal toxicity. This study explores the role of melatonin (M) in enhancing stress tolerance in pitaya against salinity (S) and copper (Cu) toxicity, both individually and in combination (SCu). SCu stress reduced plant biomass by ~54%, while melatonin application mitigated stress effects and increased plant growth by ~73.26% under SCuM compared to SCu treatment. Antioxidant activities were also modulated by stress. Transcriptomic analysis revealed 21 differentially expressed genes (DEGs) common across stress treatments and 13 DEGs specific to combined melatonin with stress treatments involved in stress signaling, secondary metabolite biosynthesis, and photosynthesis. A weighted gene co-expression network analysis (WGCNA) identified four gene modules (brown, dark green, dark grey, and grey) significantly associated with phenotypic traits. A protein–protein interaction (PPI) network analysis highlighted 14 hub genes per module, including GH3, JAZ, PAL, CCR, and POD, implicated in MAPK signaling, phenylpropanoid biosynthesis, and hormone signaling pathways. Integration of DESeq2 and WGCNA identified 12 key stress-responsive genes strongly correlated with phenotypic traits. This study provides insights into regulatory mechanisms underlying stress responses and highlights candidate genes for developing stress-resilient S. undatus through breeding programs. [ABSTRACT FROM AUTHOR] more...

Copyright of Guihaia is the property of Guihaia Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.) more...