Добірка наукової літератури з теми "Pectin remodeling enzyme"

Pectin is an abundant cell wall polysaccharide with essential roles in various biological processes. The structural diversity of pectins, along with the numerous combinations of the enzymes responsible for pectin biosynthesis and modification, plays key roles in ensuring the specificity and plasticity of cell wall remodeling in different cell types and under different environmental conditions. This review focuses on recent progress in understanding various aspects of pectin, from its biosynthetic and modification processes to its biological roles in different cell types. In particular, we describe recent findings that cell wall modifications serve not only as final outputs of internally determined pathways, but also as key components of intercellular communication, with pectin as a major contributor to this process. The comprehensive view of the diverse roles of pectin presented here provides an important basis for understanding how cell wall-enclosed plant cells develop, differentiate, and interact.

There is considerable interest in engineering plant cell wall components, particularly lignin, to improve forage quality and biomass properties for processing to fuels and bioproducts. However, modifying lignin content and/or composition in transgenic plants through down-regulation of lignin biosynthetic enzymes can induce expression of defense response genes in the absence of biotic or abiotic stress. Arabidopsis thaliana lines with altered lignin through down-regulation of hydroxycinnamoyl CoA:shikimate/quinate hydroxycinnamoyl transferase (HCT) or loss of function of cinnamoyl CoA reductase 1 (CCR1) express a suite of pathogenesis-related (PR) protein genes. The plants also exhibit extensive cell wall remodeling associated with induction of multiple cell wall-degrading enzymes, a process which renders the corresponding biomass a substrate for growth of the cellulolytic thermophile Caldicellulosiruptor bescii lacking a functional pectinase gene cluster. The cell wall remodeling also results in the release of size- and charge-heterogeneous pectic oligosaccharide elicitors of PR gene expression. Genetic analysis shows that both in planta PR gene expression and release of elicitors are the result of ectopic expression in xylem of the gene ARABIDOPSIS DEHISCENCE ZONE POLYGALACTURONASE 1 (ADPG1), which is normally expressed during anther and silique dehiscence. These data highlight the importance of pectin in cell wall integrity and the value of lignin modification as a tool to interrogate the informational content of plant cell walls.

Drought causes the excessive abscission of flowers in yellow lupine, leading to yield loss and serious economic consequences in agriculture. The structure that determines the time of flower shedding is the abscission zone (AZ). Its functioning depends on the undisturbed auxin movement from the flower to the stem. However, little is known about the mechanism guiding cell–cell adhesion directly in an AZ under water deficit. Therefore, here, we seek a fuller understanding of drought-dependent reactions and check the hypothesis that water limitation in soil disturbs the natural auxin balance within the AZ and, in this way, modifies the cell wall structure, leading to flower separation. Our strategy combined microscopic, biochemical, and chromatography approaches. We show that drought affects indole-3-acetic acid (IAA) distribution and evokes cellular changes, indicating AZ activation and flower abortion. Drought action was manifested by the accumulation of proline in the AZ. Moreover, cell wall-related modifications in response to drought are associated with reorganization of methylated homogalacturonans (HG) in the AZ, and upregulation of pectin methylesterase (PME) and polygalacturonase (PG)—enzymes responsible for pectin remodeling. Another symptom of stress action is the accumulation of hemicelluloses. Our data provide new insights into cell wall remodeling events during drought-induced flower abscission, which is relevant to control plant production.

Filamentous fungi, such asNeurospora crassa, are very efficient in deconstructing plant biomass by the secretion of an arsenal of plant cell wall-degrading enzymes, by remodeling metabolism to accommodate production of secreted enzymes, and by enabling transport and intracellular utilization of plant biomass components. Although a number of enzymes and transcriptional regulators involved in plant biomass utilization have been identified, how filamentous fungi sense and integrate nutritional information encoded in the plant cell wall into a regulatory hierarchy for optimal utilization of complex carbon sources is not understood. Here, we performed transcriptional profiling ofN. crassaon 40 different carbon sources, including plant biomass, to provide data on how fungi sense simple to complex carbohydrates. From these data, we identified regulatory factors inN. crassaand characterized one (PDR-2) associated with pectin utilization and one with pectin/hemicellulose utilization (ARA-1). Using in vitro DNA affinity purification sequencing (DAP-seq), we identified direct targets of transcription factors involved in regulating genes encoding plant cell wall-degrading enzymes. In particular, our data clarified the role of the transcription factor VIB-1 in the regulation of genes encoding plant cell wall-degrading enzymes and nutrient scavenging and revealed a major role of the carbon catabolite repressor CRE-1 in regulating the expression of major facilitator transporter genes. These data contribute to a more complete understanding of cross talk between transcription factors and their target genes, which are involved in regulating nutrient sensing and plant biomass utilization on a global level.

Potato (Solanum tuberosum L.) exhibits broad variations in cultivar resistance to tuber and root infections by the soilborne, obligate biotrophic pathogen Spongospora subterranea. Host resistance has been recognised as an important approach in potato disease management, whereas zoospore root attachment has been identified as an effective indicator for the host resistance to Spongospora root infection. However, the mechanism of host resistance to zoospore root attachment is currently not well understood. To identify the potential basis for host resistance to S. subterranea at the molecular level, twelve potato cultivars differing in host resistance to zoospore root attachment were used for comparative proteomic analysis. In total, 3723 proteins were quantified from root samples across the twelve cultivars using a data-independent acquisition mass spectrometry approach. Statistical analysis identified 454 proteins that were significantly more abundant in the resistant cultivars; 626 proteins were more abundant in the susceptible cultivars. In resistant cultivars, functional annotation of the proteomic data indicated that Gene Ontology terms related to the oxidative stress and metabolic processes were significantly over-represented. KEGG pathway analysis identified that the phenylpropanoid biosynthesis pathway was associated with the resistant cultivars, suggesting the potential role of lignin biosynthesis in the host resistance to S. subterranea. Several enzymes involved in pectin biosynthesis and remodelling, such as pectinesterase and pectin acetylesterase, were more abundant in the resistant cultivars. Further investigation of the potential role of root cell wall pectin revealed that the pectinase treatment of roots resulted in a significant reduction in zoospore root attachment in both resistant and susceptible cultivars. This study provides a comprehensive proteome-level overview of resistance to S. subterranea zoospore root attachment across twelve potato cultivars and has identified a potential role for cell wall pectin in regulating zoospore root attachment.

Floral patterning is a complex task. Various organs and tissues must be formed to fulfill reproductive functions. Flower development has been studied, mainly looking for master regulators. However, downstream changes such as the cell wall composition are relevant since they allow cells to divide, differentiate, and grow. In this review, we focus on the main components of the primary cell wall—cellulose, hemicellulose, and pectins—to describe how enzymes involved in the biosynthesis, modifications, and degradation of cell wall components are related to the formation of the floral organs. Additionally, internal and external stimuli participate in the genetic regulation that modulates the activity of cell wall remodeling proteins.

The resurrection plant Ramonda serbica Panc. survives long desiccation periods and fully recovers metabolic functions within one day upon watering. This study aimed to identify key candidates and pathways involved in desiccation tolerance in R. serbica. We combined differential transcriptomics and proteomics, phenolic and sugar analysis, FTIR analysis of the cell wall polymers, and detailed analysis of the photosynthetic electron transport (PET) chain. The proteomic analysis allowed the relative quantification of 1192 different protein groups, of which 408 were differentially abundant between hydrated (HL) and desiccated leaves (DL). Almost all differentially abundant proteins related to photosynthetic processes were less abundant, while chlorophyll fluorescence measurements implied shifting from linear PET to cyclic electron transport (CET). The levels of H2O2 scavenging enzymes, ascorbate-glutathione cycle components, catalases, peroxiredoxins, Fe-, and Mn superoxide dismutase (SOD) were reduced in DL. However, six germin-like proteins (GLPs), four Cu/ZnSOD isoforms, three polyphenol oxidases, and 22 late embryogenesis abundant proteins (LEAPs; mainly LEA4 and dehydrins), were desiccation-inducible. Desiccation provoked cell wall remodeling related to GLP-derived H2O2/HO● activity and pectin demethylesterification. This comprehensive study contributes to understanding the role and regulation of the main metabolic pathways during desiccation aiming at crop drought tolerance improvement.

Abstract Background Pectin methylesterase (PME) is a hydrolytic enzyme that catalyzes the demethylesterification of homogalacturonans and controls pectin reconstruction, being essential in regulation of cell wall modification. During fruit ripening stage, PME-mediated cell wall remodeling is an important process to determine fruit firmness and softening. Strawberry fruit is a soft fruit with a short postharvest life, due to a rapid loss of firm texture. Hence, preharvest improvement of strawberry fruit rigidity is a prerequisite for extension of fruit refreshing time. Although PME has been well characterized in model plants, knowledge regarding the functionality and evolutionary property of PME gene family in strawberry remain limited. Results A total of 54 PME genes (FvPMEs) were identified in woodland strawberry (Fragaria vesca ‘Hawaii 4’). Phylogeny and gene structure analysis divided these FvPME genes into four groups (Group 1–4). Duplicate events analysis suggested that tandem and dispersed duplications effectively contributed to the expansion of the PME family in strawberry. Through transcriptome analysis, we identified FvPME38 and FvPME39 as the most abundant-expressed PMEs at fruit ripening stages, and they were positively regulated by abscisic acid. Genetic manipulation of FvPME38 and FvPME39 by overexpression and RNAi-silencing significantly influences the fruit firmness, pectin content and cell wall structure, indicating a requirement of PME for strawberry fruit softening. Conclusion Our study globally analyzed strawberry pectin methylesterases by the approaches of phylogenetics, evolutionary prediction and genetic analysis. We verified the essential role of FvPME38 and FvPME39 in regulation of strawberry fruit softening process, which provided a guide for improving strawberry fruit firmness by modifying PME level.

Abstract Segment drying is a severe physiological disorder of citrus fruit, and vesicles become granulated or collapsed. Aside from the hypothesis that alteration of cell wall metabolism is the main factor of citrus granulation, little is known about vesicle collapse. This study aimed to elucidate the changes in pectin metabolism during vesicle collapse in blood orange. Vesicle collapse was characterized by decreased nutrients while increased chelate- and sodium carbonate-soluble pectin and calcium content. The nanostructure of chelate-soluble pectin got complex and developed multi-branching upon collapse. The activity of pectin methylesterase increased, while that of polygalacturonase and pectate lyase decreased upon collapse. Genome-wide transcriptional analysis revealed an increasing pattern of genes encoding pectin methylesterase and other enzymes involved in pectin synthesis and de-acetylation upon collapse. Drying vesicles were characterized by increased abscisic acid content and relevant gene expressions. In conclusion, we discovered alteration of pectin metabolism underlying citrus vesicle collapse, mainly promoting pectin demethylesterification, remodeling pectin structures, and further inhibiting pectin degradation, which was hypothesized to be a main factor for the citrus collapse. This is the first to disclose the potential intrinsic mechanism underlying vesicle collapse in orange fruit.

The plant growth-promoting rhizobacterium Delftia acidovorans RAY209 is capable of establishing strong root attachment during early plant development at 7 days post-inoculation. The transcriptional response of RAY209 was measured using RNA-seq during early (day 2) and sustained (day 7) root colonization of canola plants, capturing RAY209 differentiation from a medium-suspended cell state to a strongly root-attached cell state. Transcriptomic data was collected in an identical manner during RAY209 interaction with soybean roots to explore the putative root colonization response to this globally relevant crop. Analysis indicated there is an increased number of significantly differentially expressed genes between medium-suspended and root-attached cells during early soybean root colonization relative to sustained colonization, while the opposite temporal pattern was observed for canola root colonization. Regardless of the plant host, root-attached RAY209 cells exhibited the least amount of differential gene expression between early and sustained root colonization. Root-attached cells of either canola or soybean roots expressed high levels of a fasciclin gene homolog encoding an adhesion protein, as well as genes encoding hydrolases, multiple biosynthetic processes, and membrane transport. Notably, while RAY209 ABC transporter genes of similar function were transcribed during attachment to either canola or soybean roots, several transporter genes were uniquely differentially expressed during colonization of the respective plant hosts. In turn, both canola and soybean plants expressed genes encoding pectin lyase and hydrolases – enzymes with purported function in remodelling extracellular matrices in response to RAY209 colonization. RAY209 exhibited both a core regulatory response and a planthost-specific regulatory response to root colonization, indicating that RAY209 specifically adjusts its cellular activities to adapt to the canola and soybean root environments. This transcriptomic data defines the basic RAY209 response as both a canola and soybean commercial crop and seed inoculant.

La salinisation des sols est une situation préoccupante rencontrée dans plusieurs régions du monde où la pression sur l'eau devient de plus en plus forte, notamment en raison des changements climatiques et de la nécessité d'augmenter le rendement des cultures face à une population mondiale croissante. La présence d'un excès de sels dans le sol affecte les mécanismes physiologiques de la plante réduisant ainsi la production végétale. Une meilleure connaissance des mécanismes de défense des plantes en réponse au stress salin s'avère indispensable pour fournir des stratégies efficaces dans l'amélioration des cultures. La paroi végétale, première barrière physique entre le compartiment cellulaire végétal et l'environnement, a un rôle essentiel dans les mécanismes de croissance et de différentiation cellulaire et aussi en réponse à différents stress, dont le stress salin. La paroi végétale est une structure complexe et dynamique constituée principalement de polysaccharides (cellulose, hémicelluloses et pectines). Les pectines peuvent être méthylestérifiées et acétylées, les degrés de méthylestérification (DM) et d'acétylation (DA) sont contrôlés in muro par des enzymes spécifiques, les pectine méthylestérases (PME, EC 3.1.1.11) et acétylestérases (PAE, EC 3.1.1.6). Quelques données de la littérature montrent l'implication des pectines et du degré de méthylestérification de ces dernières, dans la tolérance au stress salin. Ces travaux avaient pour objectif d'incrémenter les données parcellaires actuelles sur le rôle de la paroi en réponse au stress salin. Trois stratégies d'étude distinctes ont été mises en place en choisissant comme modèle d'étude la plante glycophyte Arabidopsis thaliana. D'une part, la variabilité naturelle entre deux écotypes communs d'Arabidopsis thaliana (Wassilewskija, Ws et Columbia, Col-0) en réponse au stress salin a été caractérisée par une approche intégrative établissant une corrélation entre les résultats obtenus via des analyses physiologiques, biochimiques, métabolomiques et protéomiques. Les résultats ont montré une meilleure tolérance du stress salin associée au fond génétique Ws, avec un stade de développement plus avancé, une meilleure détoxification des espèces réactives à l'oxygène et une paroi plus riche en hémicelluloses et lignines. D'autre part, une approche de génétique inverse a été développée afin de déterminer les rôles fonctionnels des enzymes de modification des pectines AtPME3 et AtPAE7 dans la réponse au stress salin. Les résultats ont mis en évidence une perturbation du remodelage de la paroi par le stress salin. En effet, le stress salin induit une modulation des activités des enzymes de modification des pectines associée à une altération du patron de méthylestérification des pectines mais également à une réduction plus importante des homogalacturonanes et une augmentation des arabinanes par rapport aux plantes témoins. Enfin, une approche plus informative associant le métabolisme pariétal, la voie de détoxification des ions sodium, et l'impact des ions calcium sur la paroi a été menée afin de caractériser le remodelage pariétal induit par le stress salin chez le mutant hypersensible Atsos1 dont le gène SOS1 code un antiport Na+/H+ responsable de l'exclusion du Na+ à l'extérieur de la cellule. Les résultats préliminaires montrent une activité PME et PAE plus faibles que chez les plantes témoins en réponse au stress salin. Cela s'accompagne d'une réduction des acides galacturoniques et des résidus mannose. Ces résultats montrent que le remodelage des pectines et le mannose, semblent jouer un rôle prépondérant dans la tolérance au stress salin. L'ensemble des données confirme le rôle essentiel de la paroi et l'implication du calcium dans la tolérance au stress salin chez ce mutant
Soil salinization is a alarming situation encountered in several regions of the world where the pressure on water is becoming increasingly strong, especially due to climate change and the need to increase crop yields to face a global growing population. Excess of salt in soil affects plant physiological mechanism thus reducing plant production. A better knowledge of plant defense mechanism in response to salt stress is crucial to provide efficient strategies in crop yield. The plant cell wall is the first physical barrier between the plant cell compartment and the environment and plays an essential role in cell growth and development but also in response to various stresses, including salt stress. The cell wall is a highly complex and dynamic structure, mainly composed of polysaccharides (cellulose, hemicelluloses and pectins). Pectins can be methylesterified and acetylated, and their degree of methylesterification (DM) and acetylation (DA) can be modulated in muro by specific enzymes, pectin methylesterases (PMEs, EC 3.1.1.11) and acetylesterases (PAEs, EC 3.1. 1.6). Some parcelar data from the literature showed the role of pectins and their degree of methylesterification in tolerance to salt stress. The aim of this work was to provide new insights on the role of the cell wall in response to salt stress in the glycophyte Arabidopsis thaliana. Three distinct strategies were developed. Firstly, the natural variation between two common accessions of Arabidopsis thaliana (Wassilewskija, Ws and Columbia, Col-0) in response to salt stress has been characterized using an integrative approach establishing a correlation between physiological, biochemical, metabolomics and proteomics analyses. The results showed a better tolerance to salt stress associated with the genetic background Ws with an older developmental stage, a more efficient detoxification of reactive oxygen species and a higher content of xylan, mannan and lignin within the wall. Secondly, a reverse genetics approach has been developed to determine the contribution of two pectin remodeling enzymes, AtPME3 and AtPAE7 in salt tolerance. The results showed changes in the cell wall sugar composition as a reduction in homogalacturonan and an increase in arabinan in both atpme3 and atpae7 mutants after a long exposure to salt. Additionaly, salt stress induces a modulation of the PRE activities with an alteration of the pectin methylesterification pattern indicating a role of PME and PAE in cell wall integrity under salinity. Finally, a more informative approach combining cell wall metabolism, pectin remodeling enzymes, sodium ion detoxification pathway, and impact of calcium ions on cell wall integrity was carried out to characterize the role of the cell wall in the sodium hypersensitive mutant Atsos1. The SOS1 gene encodes a Na+/H+ antiporter which is involved in Na + exclusion. Preliminary results revealed that PME and PAE activities remained unchanged in atsos1 unlike the wild-type where the activites increased. That was associated with a reduction in pectin and mannan in atsos1, which was recovered by Ca2+ supply. All these data suggest the key role of atsos1 to maintain cell wall integrity under salt stress