Response Of Plant Cells Research Articles

Real-time live imaging of cytosolic hydrogen peroxide and Ca2+ of Marchantia polymorpha gemmalings reveal immediate initial responses of plant cells triggered by nonthermal plasma irradiation

Cold atmospheric pressure plasma generators capable of generating plasma under normal pressure and temperature conditions have recently been developed, and their biological applications have been extensively studied. Plasma irradiation has been reported to affect plant germination and growth; however, the molecular mechanism underlying these effects and initial cellular responses to plasma irradiation remains poorly understood. To unravel the molecular and cellular mechanisms underlying the effects of plasma irradiation on plants, we have been establishing novel experimental systems using a model liverwort Marchantia polymorpha. We here focused on the initial responses of plant cells to plasma irradiation. To investigate immediate cellular responses following plasma irradiation, we developed a new plasma device that allows irradiation under a microscope. Through integration with live fluorescence imaging, we established an experimental setup to track, the dynamics of intracellular concentration of H2O2 and Ca2+ as representative initial cellular responses. We revealed that plasma irradiation induced a rapid and transient increase in intracellular concentration of H2O2 and Ca2+ in Marchantia gemmalings. Pharmacological analyses suggested that the long-lived reactive species, H2O2, generated by the plasma generator was directly delivered into the plant cells. Competitive inhibitors of Ca2+ channels abolished the Ca2+ rise, suggesting that plasma irradiation immediately activate plasma membrane Ca2+ channel(s) to induce Ca2+ influx. Importantly, this study marks the inaugural demonstration of real-time monitoring of cytosolic H2O2 and Ca2+ dynamics in plants, triggered by plasma irradiation.

Tradescantia response to air and soil pollution, stamen hair cells dataset and ANN color classification.

Tradescantia plant is a complex system that is sensible to environmental factors such as water supply, pH, temperature, light, radiation, impurities, and nutrient availability. It can be used as a biomonitor for environmental changes; however, the bioassays are time-consuming and have a strong human interference factor that might change the result depending on who is performing the analysis. We have developed computer vision models to study color variations from Tradescantia clone 4430 plant stamen hair cells, which can be stressed due to air pollution and soil contamination. The study introduces a novel dataset, Trad-204, comprising single-cell images from Tradescantia clone 4430, captured during the Tradescantia stamen-hair mutation bioassay (Trad-SHM). The dataset contain images from two experiments, one focusing on air pollution by particulate matter and another based on soil contaminated by diesel oil. Both experiments were carried out in Curitiba, Brazil, between 2020 and 2023. The images represent single cells with different shapes, sizes, and colors, reflecting the plant's responses to environmental stressors. An automatic classification task was developed to distinguishing between blue and pink cells, and the study explores both a baseline model and three artificial neural network (ANN) architectures, namely, TinyVGG, VGG-16, and ResNet34. Tradescantia revealed sensibility to both air particulate matter concentration and diesel oil in soil. The results indicate that Residual Network architecture outperforms the other models in terms of accuracy on both training and testing sets. The dataset and findings contribute to the understanding of plant cell responses to environmental stress and provide valuable resources for further research in automated image analysis of plant cells. Discussion highlights the impact of turgor pressure on cell shape and the potential implications for plant physiology. The comparison between ANN architectures aligns with previous research, emphasizing the superior performance of ResNet models in image classification tasks. Artificial intelligence identification of pink cells improves the counting accuracy, thus avoiding human errors due to different color perceptions, fatigue, or inattention, in addition to facilitating and speeding up the analysis process. Overall, the study offers insights into plant cell dynamics and provides a foundation for future investigations like cells morphology change. This research corroborates that biomonitoring should be considered as an important tool for political actions, being a relevant issue in risk assessment and the development of new public policies relating to the environment.

Protein degradation in auxin response.

The signaling molecule auxin sits at the nexus of plant biology where it coordinates essentially all growth and developmental processes. Auxin molecules are transported throughout plant tissues and are capable of evoking highly specific physiological responses by inducing various molecular pathways. In many of these pathways, proteolysis plays a crucial role for correct physiological responses. This review provides a chronology of the discovery and characterization of the auxin receptor, which is a fascinating example of separate research trajectories ultimately converging on the discovery of a core auxin signaling hub that relies on degradation of a family of transcriptional inhibitor proteins-the Aux/IAAs. Beyond describing the "classical" proteolysis-driven auxin response system, we explore more recent examples of the interconnection of proteolytic systems, which target a range of other auxin signaling proteins, and auxin response. By highlighting these emerging concepts, we provide potential future directions to further investigate the role of protein degradation within the framework of auxin response.

Perfluorobutanoic acid triggers metabolic and transcriptional reprogramming in wheat seedlings

The environmental risks of fluorinated alternatives are of great concern with the phasing out of perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate. Here, multi-omics (i.e., metabolomics and transcriptomics) coupled with physiological and biochemical analyses were employed to investigate the stress responses of wheat seedings (Triticum aestivum L.) to perfluorobutanoic acid (PFBA), one of the short-chain per- and polyfluoroalkyl substances (PFAS) and PFOA alternatives, at environmentally relevant concentrations (0.1–100 ng/g). After 28 days of soil exposure, PFBA boosted the generation of OH and O2− in wheat seedlings, resulting in lipid peroxidation, protein perturbation and impaired photosynthesis. Non-enzymatic antioxidant defense systems (e.g., glutathione, phenolics, and vitamin C) and enzymatic antioxidant copper/zinc superoxide dismutase were strikingly activated (p < 0.05). PFBA-triggered oxidative stress induced metabolic and transcriptional reprogramming, including carbon and nitrogen metabolisms, lipid metabolisms, immune responses, signal transduction processes, and antioxidant defense-related pathways. Down-regulation of genes related to plant-pathogen interaction suggested suppression of the immune-response, offering a novel understanding on the production of reactive oxygen species in plants under the exposure to PFAS. The identified MAPK signaling pathway illuminated a novel signal transduction mechanism in plant cells in response to PFAS. These findings provide comprehensive understandings on the phytotoxicity of PFBA to wheat seedlings and new insights into the impacts of PFAS on plants.

Resource allocation modeling for autonomous prediction of plant cell phenotypes

Predicting the plant cell response in complex environmental conditions is a challenge in plant biology. Here we developed a resource allocation model of cellular and molecular scale for the leaf photosynthetic cell of Arabidopsis thaliana, based on the Resource Balance Analysis (RBA) constraint-based modeling framework. The RBA model contains the metabolic network and the major macromolecular processes involved in the plant cell growth and survival and localized in cellular compartments. We simulated the model for varying environmental conditions of temperature, irradiance, partial pressure of CO2 and O2, and compared RBA predictions to known resource distributions and quantitative phenotypic traits such as the relative growth rate, the C:N ratio, and finally to the empirical characteristics of CO2 fixation given by the well-established Farquhar model. In comparison to other standard constraint-based modeling methods like Flux Balance Analysis, the RBA model makes accurate quantitative predictions without the need for empirical constraints. Altogether, we show that RBA significantly improves the autonomous prediction of plant cell phenotypes in complex environmental conditions, and provides mechanistic links between the genotype and the phenotype of the plant cell.

Genome-wide analysis of LOG family genes in castor and RcLOG5 enhances drought, salt, and cold stress tolerance in Arabidopsis thaliana

The gene encoding the specific phosphohydrolase LONELY GUY (LOG) plays an important role in the activation of cytokinin and the stress response in plant cells. However, the role of LOG genes in castor bean (Ricinus communis) has not been reported. In this study, we identified a total of nine members of the LOG gene family in the castor bean genome and investigated the upregulated expression of the RcLOG5 gene using transcriptome data analysis. We found that the RcLOG5 gene exhibited tissue-specific expression and was activated by polyethylene glycol, NaCl, low temperature, and abscisic acid stress. The subcellular localization results showed that the RcLOG5 gene is mainly located in the cytoplasm. Based on phenotypic and physiological indicators, namely root length, peroxidase activity, and malondialdehyde content, overexpression of the RcLOG5 gene not only improved the drought resistance, salt tolerance, and cold tolerance of transgenic Arabidopsis, but also shortened the dormancy period of the transgenic plants. Transcriptomic sequencing revealed that the overexpression of the RcLOG5 gene led to the enrichment of differentially expressed genes in the glutathione metabolism pathway in transgenic Arabidopsis. Moreover, the overexpression plants had higher levels of glutathione and a higher GSH/GSSG ratio under stress compared to the wild type. Therefore, we inferred that the RcLOG5 gene may be responsible for regulating cell membrane homeostasis by reducing the accumulation of reactive oxygen species through the glutathione pathway. Overall, the overexpression of the RcLOG5 gene positively regulated the stress resistance of transgenic Arabidopsis. This study provides valuable gene resources for breeding stress-tolerant castor bean varieties.

Deletion of the sugar importer gene OsSWEET1b accelerates sugar starvation-promoted leaf senescence in rice.

Leaf senescence is a combined response of plant cells stimulated by internal and external signals. Sugars acting as signaling molecules or energy metabolites can influence the progression of leaf senescence. Both sugar starvation and accumulation can promote leaf senescence with diverse mechanisms that are reported in different species. Sugars Will Eventually be Exported Transporters (SWEETs) are proposed to play essential roles in sugar transport, but whether they have roles in senescence and the corresponding mechanism are unclear. Here, we functionally characterized a sugar transporter, OsSWEET1b, which transports sugar and promotes senescence in rice (Oryza sativa L.). OsSWEET1b could import glucose and galactose when heterologously expressed in Xenopus oocytes and translocate glucose and galactose from the extracellular apoplast into the intracellular cytosol in rice. Loss of function of OsSWEET1b decreased glucose and galactose accumulation in leaves. ossweet1b mutants showed accelerated leaf senescence under natural and dark-induced conditions. Exogenous application of glucose and galactose complemented the defect of OsSWEET1b deletion-promoted senescence. Moreover, the senescence-activated transcription factor OsWRKY53, acting as a transcriptional repressor, genetically functions upstream of OsSWEET1b to suppress its expression. OsWRKY53-overexpressing plants had attenuated sugar accumulation, exhibiting a similar phenotype as the ossweet1b mutants. Our findings demonstrate that OsWRKY53 downregulates OsSWEET1b to impair its influx transport activity, leading to compromised sugar accumulation in the cytosol of rice leaves where sugar starvation promotes leaf senescence.

Visualizing spatial and temporal responses of plant cells to the environment

Visualizing spatial and temporal responses of plant cells to the environment

Pathogen perception and signaling in plant immunity.

Plant diseases are a constant and serious threat to agriculture and ecological biodiversity. Plants possess a sophisticated innate immunity system capable of detecting and responding to pathogen infection to prevent disease. Our understanding of this system has grown enormously over the past century. Early genetic descriptions of plant disease resistance and pathogen virulence were embodied in the gene-for-gene hypothesis, while physiological studies identified pathogen-derived elicitors that could trigger defense responses in plant cells and tissues. Molecular studies of these phenomena have now coalesced into an integrated model of plant immunity involving cell surface and intracellular detection of specific pathogen-derived molecules and proteins culminating in the induction of various cellular responses. Extracellular and intracellular receptors engage distinct signaling processes but converge on many similar outputs with substantial evidence now for integration of these pathways into interdependent networks controlling disease outcomes. Many of the molecular details of pathogen recognition and signaling processes are now known, providing opportunities for bioengineering to enhance plant protection from disease. Here we provide an overview of the current understanding of the main principles of plant immunity, with an emphasis on the key scientific milestones leading to these insights.

Less Frequently Used Growth Regulators in Plant Tissue Culture.

Plant growth regulators are routinely added to in vitro culture media to foster the growth and differentiation of the cells, tissues, and organs. However, while the literature on usage of the more common auxins, cytokinins, gibberellins, abscisic acid, and ethylene is vast, other compounds that also have shown a growth-regulating activity have not been studied as frequently. Such substances are also capable of modulating the responses of plant cells and tissues in vitro by regulating their growth, differentiation, and regeneration competence, but also by enhancing their responses toward biotic and abiotic stress agents and improving the production of secondary metabolites of interest. This chapter will discuss the in vitro effects of several of such less frequently added plant growth regulators, including brassinosteroids (BRS), strigolactones (SLs), phytosulfokines (PSKs), methyl jasmonate, salicylic acid (SA), sodium nitroprusside (SNP), hydrogen sulfite, various plant growth retardants and inhibitors (e.g., ancymidol, uniconazole, flurprimidol, paclobutrazol), and polyamines.

The role of plant proteases in the response of plants to abiotic stress factors

The primary function of proteolytic enzymes is the hydrolysis of peptide bonds. Enzymes responsible for catalyzing this reaction are commonly referred to as proteases. The vast majority of these enzymes belong to the class of hydrolases and operate in aqueous environments. However, there is a distinct group of proteases known as intramembrane proteases, which are integral membrane proteins capable of cleaving peptide bonds in the hydrophobic environment of biological membranes. Proteolysis serves several essential functions in plant cells, ranging from the degradation of damaged and unnecessary proteins to the removal of non-functional protein aggregates. It plays a role in the quality control system for proteins and even releases transcription factors from membrane proteins. Proteolytic processes are indispensable at every stage of plant development and allow for the modification of the cell’s protein composition based on developmental needs and environmental requirements. Proteases are also enzymatic components of the cell that facilitate the efficient regeneration of many key metabolic pathways, such as photosynthesis and respiration. The response of plant cells and the entire plant organism to various biotic and abiotic stresses often requires the remodeling of metabolic pathways, the regeneration of key enzymatic complexes, or changes in the protein profile. By participating in all these processes, proteases constitute a crucial element of the cellular response to environmental stresses. The aim of this work is to review the role that individual proteases play in the response of plant cells to abiotic stress factors, such as drought, salinity, cold, temperature, and light.

Origin, evolution, and diversification of the wall-associated kinase gene family in plants.

The study of the origin, evolution, and diversification of the wall-associated kinase gene family in plants facilitates their functional investigations in the future. Wall-associated kinases (WAKs) make up one subfamily of receptor-like kinases (RLKs), and function directly in plant cell elongation and responses to biotic and abiotic stresses. The biological functions of WAKs have been extensively characterized in angiosperms; however, the origin and evolutionary history of the WAK family in green plants remain unclear. Here, we performed a comprehensive analysis of the WAK family to reveal its origin, evolution, and diversification in green plants. In total, 1061 WAK genes were identified in 37 species from unicellular algae to multicellular plants, and the results showed that WAK genes probably originated before bryophyte differentiation and were widely distributed in land plants, especially angiosperms. The phylogeny indicated that the land plant WAKs gave rise to five clades and underwent lineage-specific expansion after species differentiation. Cis-acting elements and expression patterns analyses of WAK genes in Arabidopsis and rice demonstrated the functional diversity of WAK genes in these two species. Many gene gains and losses have occurred in angiosperms, leading to an increase in the number of gene copies. The evolutionary trajectory of the WAK family during polyploidization was uncovered using Gossypium species. Our results provide insights into the evolution of WAK genes in green plants, facilitating their functional investigations in the future.

Cell specialization and coordination in Arabidopsis leaves upon pathogenic attack revealed by scRNA-seq

Plant defense responses involve several biological processes that allow plants to fight against pathogenic attacks. How these different processes are orchestrated within organs and depend on specific cell types is poorly known. Here, using single-cell RNA sequencing (scRNA-seq) technology on three independent biological replicates, we identified several cell populations representing the core transcriptional responses of wild-type Arabidopsis leaves inoculated with the bacterial pathogen Pseudomonas syringae DC3000. Among these populations, we retrieved major cell types of the leaves (mesophyll, guard, epidermal, companion, and vascular S cells) with which we could associate characteristic transcriptional reprogramming and regulators, thereby specifying different cell-type responses to the pathogen. Further analyses of transcriptional dynamics, on the basis of inference of cell trajectories, indicated that the different cell types, in addition to their characteristic defense responses, can also share similar modules of gene reprogramming, uncovering a ubiquitous antagonism between immune and susceptible processes. Moreover, it appears that the defense responses of vascular S cells, epidermal cells, and mesophyll cells can evolve along two separate paths, one converging toward an identical cell fate, characterized mostly by lignification and detoxification functions. As this divergence does not correspond to the differentiation between immune and susceptible cells, we speculate that this might reflect the discrimination between cell-autonomous and non-cell-autonomous responses. Altogether our data provide an upgraded framework to describe, explore, and explain the specialization and the coordination of plant cell responses upon pathogenic challenge.

Drought and heat stress mediated activation of lipid signaling in plants: a critical review.

Lipids are a principal component of plasma membrane, acting as a protective barrier between the cell and its surroundings. Abiotic stresses such as drought and temperature induce various lipid-dependent signaling responses, and the membrane lipids respond differently to environmental challenges. Recent studies have revealed that lipids serve as signal mediators forreducing stress responses in plant cells and activating defense systems. Signaling lipids, such as phosphatidic acid, phosphoinositides, sphingolipids, lysophospholipids, oxylipins, and N-acylethanolamines, are generated in response to stress. Membrane lipids are essential for maintaining the lamellar stack of chloroplasts and stabilizing chloroplast membranes under stress. However, the effects of lipid signaling targets in plants are not fully understood. This review focuses on the synthesis of various signaling lipids and their roles in abiotic stress tolerance responses, providing an essential perspective for further investigation into the interactions between plant lipids and abiotic stress.

Tissue-specific modulation of functional stress responsive proteins and organic osmolytes by a single or dual short-term high CO2 treatment during long-term cold storage Autumn Royal table grapes

Plant cell response to damage from environmental stressors that cause dehydration involves stress-related proteins and osmotically active compounds whose constitutive levels increase in association with the tolerance response mechanism. In table grape postharvest scope, the application of a second 3 d 20 kPa CO2 treatment significantly reduced the incidence and severity of long-term cold postharvest storage disorders in Autumn Royal cv. counteracting ultrastructural cell damage and restraining intracellular and membrane oxidative stress. In this sense, it may be of relevance to postharvest quality to know how this dual short-term high CO2 treatment modulates the cell stress responsive defense strategies, and whether these are tissue-dependent and timing-regulated. In this work, we studied the differential profile of protective osmolytes proline, glycine betaine, γ-aminobutyric acid and trehalose in the berry tissues. Likewise, we assessed the temporal and spatial expression and accumulation patterns of the thaumatin-like protein (VviTL1, VviOsmo) and dehydrin (VviDHN1a, VviDHN4, VviDHN2, VviDHN2D) isoforms in the whole berry tissues and rachis of cv. Autumn Royal table grapes during long-term cold storage period and evaluated the profile-shift by CO2 treatments. Their subcellular localization in the pericarp tissues was also determined by immunocytochemical transmission electron microscopy (TEM). The results showed that the cold-drought defense strategies activated by the short-term high CO2 are dose-dependent, tissue-specific and transcriptionally timing-regulated during long-term postharvest cold storage period in table grapes. The results also showed that the more short-term high CO2 treatment is applied to Autumn Royal grapes, the more microstructural evidence there is of enhanced tolerance to storage disorders in terms of thicker and denser cell wall that could contribute to restrain swelling, dehydration and osmotic stress.

Yet uninfected? Resolving cell states of plants under pathogen attack

Although we have made significant strides in unraveling plant responses to pathogen attacks at the tissue or major cell type scale, a comprehensive understanding of individual cell responses still needs to be achieved. Addressing this gap, Zhu etal. employed single-cell transcriptome analysis to unveil the heterogeneous responses of plant cells when confronted with bacterial pathogens.

Differential plant cell responses to Acidovorax citrulli T3SS and T6SS reveal an effective strategy for controlling plant-associated pathogens.

Acidovorax citrulli is a gram-negative plant pathogen that employs the type Ⅲ secretion system (T3SS) to infect cucurbit crops and cause bacterial fruit blotch. This bacterium also possesses an active type Ⅵ secretion system (T6SS) with strong antibacterial and antifungal activities. However, how plant cells respond to these two secretion systems and whether there is any cross talk between T3SS and T6SS during infection remain unknown. Here, we employ transcriptomic analysis to compare cellular responses to the T3SS and the T6SS during in planta infection and report distinctive effects on multiple pathways. The T3SS-mediated differentially expressed genes were enriched in the pathways of phenylpropanoid biosynthesis, plant-pathogen interaction, MAPK signaling pathway, and glutathione metabolism, while the T6SS uniquely affected genes were related to photosynthesis. The T6SS does not contribute to the in planta virulence of A. citrulli but is critical for the survival of the bacterium when mixed with watermelon phyllosphere bacteria. In addition, T3SS-mediated virulence is independent of the T6SS, and the inactivation of the T3SS does not affect the T6SS-mediated competition against a diverse set of bacterial pathogens that commonly contaminate edible plants or directly infect plants. A T6SS-active T3SS-null mutant (Acav) could inhibit the growth of Xanthomonas oryzae pv. oryzae significantly both in vitro and in vivo and also reduce symptoms of rice bacterial blight. In conclusion, our data demonstrate the T6SS in A. citrulli is nonpathogenic to the plant host and can be harnessed as a pathogen killer against plant-associated bacteria. IMPORTANCE Chemical pesticides are widely used to protect crops from various pathogens. Still, their extensive use has led to severe consequences, including drug resistance and environmental contamination. Here, we show that an engineered T6SS-active, but avirulent mutant of Acidovorax citrulli has strong inhibition capabilities against several pathogenic bacteria, demonstrating an effective strategy that is an alternative to chemical pesticides for sustainable agricultural practices.

Upstream open reading frame-mediated upregulation of ANAC082 expression in response to nucleolar stress in Arabidopsis.

Perturbations in ribosome biogenesis cause a type of cellular stress called nucleolar or ribosomal stress, which triggers adaptive responses in both animal and plant cells. The Arabidopsis ANAC082 transcription factor has been identified as a key mediator of the plant nucleolar stress response. The 5'-untranslated region (5'-UTR) of ANAC082 mRNA contains an upstream ORF (uORF) encoding an evolutionarily conserved amino acid sequence. Here, we report that this uORF mediates the upregulation of ANAC082 expression in response to nucleolar stress. When transgenic Arabidopsis plants containing a luciferase reporter gene under the control of the ANAC082 promoter and 5'-UTR were treated with reagents that induced nucleolar stress, expression of the reporter gene was enhanced in a uORF sequence-dependent manner. Additionally, we examined the effect of an endoplasmic reticulum (ER) stress-inducing reagent on reporter gene expression because the closest homolog of ANAC082 in Arabidopsis, ANAC103, is involved in the ER stress response. However, the ANAC082 uORF did not respond to ER stress. Interestingly, although ANAC103 has a uORF with an amino acid sequence similar to that of the ANAC082 uORF, the C-terminal sequence critical for regulation is not well conserved among ANAC103 homologs in Brassicaceae. Transient expression assays revealed that unlike the ANAC082 uORF, the ANAC103 uORF does not exert a sequence-dependent repressive effect. Altogether, our findings suggest that the ANAC082 uORF is important for the nucleolar stress response but not for the ER stress response, and that for this reason, the uORF sequence-dependent regulation was lost in ANAC103 during evolution.

Detection and Evaluation of Environmental Stress in Winter Wheat Using Remote and Proximal Sensing Methods and Vegetation Indices—A Review

Climate change has a significant impact on winter wheat (Triticum aestivum L.) cultivation due to the occurrence of various environmental stress parameters. It destabilizes wheat production mainly through abiotic stresses (heat waves, drought, floods, frost, salinity, and nutrient deficiency) and improved conditions for pest and disease development and infestation as biotic parameters. The impact of these parameters can be reduced by timely and appropriate management measures such as irrigation, fertilization, or pesticide application. However, this requires the early diagnosis and quantification of the various stressors. Since they induce specific physiological responses in plant cells, structures, and tissues, environmental stress parameters can be monitored by different sensing methods, taking into account that these responses affect the signal in different regions of the electromagnetic spectrum (EM), especially visible (VIS), near infrared (NIR), and shortwave infrared (SWIR). This study reviews recent findings in the application of remote and proximal sensing methods for early detection and evaluation of abiotic and biotic stress parameters in crops, with an emphasis on winter wheat. The study first provides an overview of climate-change-induced stress parameters in winter wheat and their physiological responses. Second, the most promising non-invasive remote sensing methods are presented, such as airborne and satellite multispectral (VIS and NIR) and hyperspectral imaging, as well as proximal sensing methods using VNIR-SWIR spectroscopy. Third, data analysis methods using vegetation indices (VI), chemometrics, and various machine learning techniques are presented, as well as the main application areas of sensor-based analysis, namely, decision-making processes in precision agriculture.

Bioelectricity in Plants: From So Simple a Beginning

Bioelectricity in Plants: From So Simple a Beginning