ABSTRACT
Water availability influences all aspects of plant growth and development; however, most studies of plant responses to drought have focused on vegetative organs, notably roots and leaves. Far less is known about the molecular bases of drought acclimation responses in fruits, which are complex organs with distinct tissue types. To obtain a more comprehensive picture of the molecular mechanisms governing fruit development under drought, we profiled the transcriptomes of a spectrum of fruit tissues from tomato (Solanum lycopersicum), spanning early growth through ripening and collected from plants grown under varying intensities of water stress. In addition, we compared transcriptional changes in fruit with those in leaves to highlight different and conserved transcriptome signatures in vegetative and reproductive organs. We observed extensive and diverse genetic reprogramming in different fruit tissues and leaves, each associated with a unique response to drought acclimation. These included major transcriptional shifts in the placenta of growing fruit and in the seeds of ripe fruit related to cell growth and epigenetic regulation, respectively. Changes in metabolic and hormonal pathways, such as those related to starch, carotenoids, jasmonic acid, and ethylene metabolism, were associated with distinct fruit tissues and developmental stages. Gene coexpression network analysis provided further insights into the tissue-specific regulation of distinct responses to water stress. Our data highlight the spatiotemporal specificity of drought responses in tomato fruit and indicate known and unrevealed molecular regulatory mechanisms involved in drought acclimation, during both vegetative and reproductive stages of development.
Subject(s)
Solanum lycopersicum , Solanum lycopersicum/metabolism , Fruit/metabolism , Transcriptome/genetics , Gene Expression Regulation, Plant , Dehydration/genetics , Dehydration/metabolism , Plant Proteins/genetics , Plant Proteins/metabolism , Epigenesis, GeneticABSTRACT
Tomato (Solanum lycopersicum) fruit store carbon as starch during early development and mobilize it at the onset of ripening. Starch accumulation has been suggested to buffer fluctuations in carbon supply to the fruit under abiotic stress, and contribute to sugar levels in ripe fruit. However, the role of starch accumulation and metabolism during fruit development is still unclear. Here we show that the tomato mutant adpressa (adp) harbors a mutation in a gene encoding the small subunit of ADP-glucose pyrophosphorylase that abolishes starch synthesis. The disruption of starch biosynthesis causes major transcriptional and metabolic remodeling in adp fruit but only minor effects on fruit size and ripening. Changes in gene expression and metabolite profiles indicate that the lack of carbon flow into starch increases levels of soluble sugars during fruit growth, triggers a readjustment of central carbohydrate and lipid metabolism, and activates growth and stress protection pathways. Accordingly, adp fruits are remarkably resistant to blossom-end rot, a common physiological disorder induced by environmental stress. Our results provide insights into the effects of perturbations of carbohydrate metabolism on tomato fruit development, with potential implications for the enhancement of protective mechanisms against abiotic stress in fleshy fruit.
Subject(s)
Solanum lycopersicum , Solanum lycopersicum/genetics , Fruit/metabolism , Starch/metabolism , Carbohydrate Metabolism , Sugars/metabolism , Carbon/metabolism , Gene Expression Regulation, PlantABSTRACT
SUMMARY: With the development of new high-throughput DNA sequencing technologies and decreasing costs, large gene expression datasets are being generated at an accelerating rate, but can be complex to visualize. New, more interactive and intuitive tools are needed to visualize the spatiotemporal context of expression data and help elucidate gene function. Using tomato fruit as a model, we have developed the Tomato Expression Atlas to facilitate effective data analysis, allowing the simultaneous visualization of groups of genes at a cell/tissue level of resolution within an organ, enhancing hypothesis development and testing in addition to candidate gene identification. This atlas can be adapted to different types of expression data from diverse multicellular species. AVAILABILITY AND IMPLEMENTATION: The Tomato Expression Atlas is available at http://tea.solgenomics.net/ . Source code is available at https://github.com/solgenomics/Tea . CONTACT: jr286@cornell.edu or lam87@cornell.edu. SUPPLEMENTARY INFORMATION: Supplementary data are available at Bioinformatics online.
Subject(s)
Databases, Nucleic Acid , Gene Expression Regulation, Plant , Sequence Analysis, RNA/methods , Solanum lycopersicum/genetics , Transcriptome , High-Throughput Nucleotide Sequencing , Organ SpecificityABSTRACT
Fruit formation and early development involve a range of physiological and morphological transformations of the various constituent tissues of the ovary. These developmental changes vary considerably according to tissue type, but molecular analyses at an organ-wide level inevitably obscure many tissue-specific phenomena. We used laser-capture microdissection coupled to high-throughput RNA sequencing to analyze the transcriptome of ovaries and fruit tissues of the wild tomato species Solanum pimpinellifolium. This laser-capture microdissection-high-throughput RNA sequencing approach allowed quantitative global profiling of gene expression at previously unobtainable levels of spatial resolution, revealing numerous contrasting transcriptome profiles and uncovering rare and cell type-specific transcripts. Coexpressed gene clusters linked specific tissues and stages to major transcriptional changes underlying the ovary-to-fruit transition and provided evidence of regulatory modules related to cell division, photosynthesis, and auxin transport in internal fruit tissues, together with parallel specialization of the pericarp transcriptome in stress responses and secondary metabolism. Analysis of transcription factor expression and regulatory motifs indicated putative gene regulatory modules that may regulate the development of different tissues and hormonal processes. Major alterations in the expression of hormone metabolic and signaling components illustrate the complex hormonal control underpinning fruit formation, with intricate spatiotemporal variations suggesting separate regulatory programs.
Subject(s)
Flowers/genetics , Fruit/genetics , Gene Expression Profiling/methods , Gene Expression Regulation, Developmental , Gene Expression Regulation, Plant , Solanum lycopersicum/genetics , Flowers/growth & development , Fruit/growth & development , Gene Regulatory Networks , Genes, Plant/genetics , High-Throughput Nucleotide Sequencing , In Situ Hybridization , Laser Capture Microdissection , Solanum lycopersicum/growth & development , Oligonucleotide Array Sequence Analysis , Plant Proteins/genetics , Reverse Transcriptase Polymerase Chain ReactionABSTRACT
Auxin controls many aspects of fruit development, including fruit set and growth, ripening and abscission. However, the mechanisms by which auxin regulates these processes are still poorly understood. While it is generally agreed that precise spatial and temporal control of auxin distribution and signaling are required for fruit development, the dynamics of auxin biosynthesis and the mechanisms for its transport to different fruit tissues are mostly unknown. Despite major advances in elucidating many aspects of auxin biology in vegetative tissues, until recently, the nature and importance of auxin metabolism, transport and signaling during fruit ontogeny remained obscure. In this review, we summarize recent research that has started to elucidate the molecular mechanisms by which auxin is produced and transported in the fruit and to unravel the complexity of auxin signaling during fruit development. We also discuss recent approaches used to reveal the genes and regulatory networks that mediate cell and tissue-specific control of auxin levels in the developing fruit.
Subject(s)
Fruit/growth & development , Fruit/metabolism , Indoleacetic Acids/metabolism , Fruit/genetics , Gene Expression Regulation, Plant/genetics , Gene Expression Regulation, Plant/physiology , Plant Proteins/genetics , Plant Proteins/metabolismABSTRACT
The temporal and spatial control of auxin distribution has a key role in the regulation of plant growth and development, and much has been learnt about the mechanisms that influence auxin pools and gradients in vegetative tissues, particularly in Arabidopsis. For example polar auxin transport, mediated by PIN and AUX/LAX proteins, is central to the control of auxin distribution. In contrast, very little information is known about the dynamics of auxin distribution and the molecular basis of its transport within and between fruit tissues, despite the fact that auxin regulates many aspects of fruit development, which include fruit formation, expansion, ripening and abscission. In addition, functional information regarding the key regulators of auxin fluxes during both vegetative and reproductive development in species other than Arabidopsis is scarce. To address these issues, we have investigated the spatiotemporal distribution of auxin during tomato (Solanum lycopersicum) fruit development and the function of the PIN and AUX/LAX gene families. Differential concentrations of auxin become apparent during early fruit growth, with auxin levels being higher in internal tissues than in the fruit pericarp and the pattern of auxin accumulation depended on polar transport. Ten tomato PIN (SlPIN1 to 10) and five AUX/LAX (SlLAX1 to 5) genes were identified and found to display heterogeneous expression patterns, with tissue and developmental-stage specificity. RNAi-mediated co-silencing of SlPIN4 and SlPIN3 did not affect fruit development, which suggested functional redundancy of PIN proteins, but did lead to a vegetative phenotype, and revealed a role for these genes in the regulation of tomato shoot architecture.
Subject(s)
Indoleacetic Acids/metabolism , Plant Proteins/genetics , Solanum lycopersicum/genetics , Solanum lycopersicum/metabolism , Biological Transport/drug effects , Fruit/genetics , Fruit/growth & development , Fruit/metabolism , Gene Expression Profiling , Gene Expression Regulation, Developmental/drug effects , Gene Expression Regulation, Plant/drug effects , Glucuronidase/genetics , Glucuronidase/metabolism , Luminescent Proteins/genetics , Luminescent Proteins/metabolism , Solanum lycopersicum/growth & development , Microscopy, Confocal , Molecular Sequence Data , Multigene Family , Phthalimides/pharmacology , Phylogeny , Plant Growth Regulators/pharmacology , Plant Proteins/classification , Plant Proteins/metabolism , Plants, Genetically Modified , RNA Interference , Reverse Transcriptase Polymerase Chain Reaction , Sequence Analysis, DNA , Time Factors , Red Fluorescent ProteinABSTRACT
The isolation and analysis of glycoproteins by coupling lectin affinity chromatography with MS has emerged as a powerful strategy to study the glycoproteome of mammalian cells. However, this approach has not been used extensively for the analysis of plant glycoproteins. As with all eukaryotes, N-glycosylation is a common post-translational modification for plant proteins traveling through the secretory pathway. Many such proteins are destined for the cell wall, or apoplast, where they play important roles in processes such as modifying cell wall structure, sugar metabolism, signaling, and defense against pathogens. Here, we describe a strategy to enrich for and identify secreted plant proteins based on affinity chromatography using the lectin Concanavalin A and two-dimensional liquid chromatography, together with matrix-assisted laser desorption/ionization MS analysis. The value of this approach is illustrated through the characterization of glycoproteins that are expressed in ripe tomato (Solanum lycopersicum) fruit, a developmental stage that is fundamentally linked with significant changes in cell wall structure and composition. This glycoprotein trap strategy allowed the isolation of a sub-proteome with an extremely high proportion of proteins that are predicted to be resident in the cell wall or secretory pathway, and the identification of new putative cell wall proteins.
Subject(s)
Chromatography, Affinity/methods , Glycoproteins/analysis , Plant Proteins/analysis , Proteome/analysis , Solanum lycopersicum/chemistry , Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization/methods , Tandem Mass Spectrometry/methods , Cell Wall/chemistry , Concanavalin A/chemistry , Glycoproteins/chemistry , Glycoproteins/metabolism , Solanum lycopersicum/cytology , Solanum lycopersicum/metabolism , Plant Proteins/chemistry , Plant Proteins/metabolism , Protein Processing, Post-Translational , Proteome/chemistry , Proteome/metabolism , Signal TransductionABSTRACT
BACKGROUND: Access to mental health care is a worldwide public health challenge. In Mexico, an unacceptably high percentage of the population with mental disorders does not receive the necessary treatment, which is mainly due to the lack of access to mental health care. The community mental health care model was created and has been implemented to improve this situation. In order to properly plan and implement this model a precise situational diagnosis of the mental health care network is required, thus this is a first approach to evaluate the community mental health networks in the state of Jalisco. METHODS: Two components from the EvaRedCom-TMS instrument were used including a general description and accessibility of the community mental health care network. A geographic and economic accessibility evaluation was carried out for the different regions of the state ranging from scattered rural to urban communities using information gathered from health institutions, telephone interviews and computer applications. RESULTS: Jalisco's community mental health network includes a total of 31 centers and 0.64 mental health workers for every 10,000 inhabitants > 15 years of age. The mean transportation cost required to access mental health care was 16.25 USD per visit. The time needed to reach the closest mental health center in 7 of the 13 analyzed regions was more than 30 min and the mean time required to reach a prolonged stay center was 172.7 min with transportation cost (taxi, private and public transport) of 22.3 USD. Some marginalized regions in the state have a mean 114 min required to reach the closest mental health care center and 386 min to reach a prolonged stay center. CONCLUSIONS: This first approach to evaluate the mental health networks in Mexico showed that there are multiple barriers to access its care including an unfavorable number of human resources, long distances, and high costs. The identification of Jalisco's mental health network deficiencies is the first step towards establishing a properly planned community mental health care model within the country.
ABSTRACT
Solanum pimpinellifolium (SP) is the wild progenitor of cultivated tomato. Because of its remarkable stress tolerance and intense flavor, SP has been used as an important germplasm donor in modern tomato breeding. Here, we present a high-quality chromosome-scale genome sequence of SP LA2093. Genome comparison identifies more than 92,000 structural variants (SVs) between LA2093 and the modern cultivar, Heinz 1706. Genotyping these SVs in ~600 representative tomato accessions identifies alleles under selection during tomato domestication, improvement and modern breeding, and discovers numerous SVs overlapping genes known to regulate important breeding traits such as fruit weight and lycopene content. Expression quantitative trait locus (eQTL) analysis detects hotspots harboring master regulators controlling important fruit quality traits, including cuticular wax accumulation and flavonoid biosynthesis, and SVs contributing to these complex regulatory networks. The LA2093 genome sequence and the identified SVs provide rich resources for future research and biodiversity-based breeding.
Subject(s)
Genome, Plant , Plant Breeding , Solanum lycopersicum/genetics , Solanum/genetics , Domestication , Gene Expression Regulation, Plant , Genotype , Lycopene/metabolism , Quantitative Trait Loci/genetics , Selection, Genetic , Sequence Analysis, DNAABSTRACT
Tomato (Solanum lycopersicum) is an established model for studying fruit biology; however, most studies of tomato fruit growth and ripening are based on homogenized pericarp, and do not consider the internal tissues, or the expression signatures of individual cell and tissue types. We present a spatiotemporally resolved transcriptome analysis of tomato fruit ontogeny, using laser microdissection (LM) or hand dissection coupled with RNA-Seq analysis. Regulatory and structural gene networks, including families of transcription factors and hormone synthesis and signaling pathways, are defined across tissue and developmental spectra. The ripening program is revealed as comprising gradients of gene expression, initiating in internal tissues then radiating outward, and basipetally along a latitudinal axis. We also identify spatial variations in the patterns of epigenetic control superimposed on ripening gradients. Functional studies elucidate previously masked regulatory phenomena and relationships, including those associated with fruit quality traits, such as texture, color, aroma, and metabolite profiles.
Subject(s)
Fruit/genetics , Gene Expression Regulation, Developmental , Gene Expression Regulation, Plant , Solanum lycopersicum/genetics , Transcriptome , Fruit/growth & development , Fruit/ultrastructure , Gene Expression Profiling/methods , Gene Regulatory Networks , Solanum lycopersicum/growth & development , Microscopy, Electron, Transmission , Plant Proteins/genetics , Plants, Genetically ModifiedABSTRACT
Recent studies have further confirmed the ubiquity of cell wall restructuring during plant growth and development, and have emphasized the fact that our understanding of the breadth of molecular processes that mediate wall modification is still rudimentary. In the past few years, both enzymatic and non-enzymatic agents that apparently contribute to wall disassembly have been identified, and it is likely that additional mechanisms will continue to be revealed. These discoveries are being propelled by the development of new biochemical and biophysical assays, by database mining in the wake of the explosion of plant sequence information from genome sequencing and expressed sequence tags, and by a variety of strategies used to catalog the cell wall proteome. The daunting question of how these mechanistically diverse and complex processes are coordinated remains unresolved.
Subject(s)
Cell Wall/metabolism , Plants/metabolism , Arabidopsis/enzymology , Arabidopsis/genetics , Arabidopsis/metabolism , Expressed Sequence Tags , Genome, Plant , Multigene Family , Oryza/enzymology , Oryza/genetics , Oryza/metabolism , Polysaccharides/biosynthesis , Signal TransductionABSTRACT
This protocol enables transcriptome profiling of specific cell or tissue types that are isolated from tomato using laser microdissection (LM). To prepare tissue for LM, fruit samples are first fixed in optimal cutting temperature (OCT) medium and frozen in molds. The tissue is then sectioned using a cryostat before being dissected using an LM instrument. The RNAs contained in the harvested cells are purified and subjected to two rounds of amplification to yield sufficient quantities of RNA to generate cDNA libraries. Unlike several other techniques that are used to isolate specific cell types, LM has the advantage of being readily applied to any plant species without having to generate transgenic plants. Using the protocols described here, LM-mediated cell-type transcriptomic analysis of two samples requires â¼8 d from tissue harvest to RNA sequencing (RNA-seq), whereas each additional sample, up to a total of 12 samples, requires â¼1 additional day for the LM step. RNA obtained using this method has been successfully used for deep-coverage transcriptome profiling, which is a particularly effective strategy for identifying genes that are differentially expressed between cell or tissue types.
Subject(s)
Fruit/cytology , Fruit/genetics , Gene Expression Profiling/methods , Lasers , Microdissection/methods , Solanum lycopersicum/cytology , Solanum lycopersicum/genetics , Paraffin Embedding , RNA, Plant/geneticsABSTRACT
Lectins are proteins that bind to sugars with varying specificities and several have been identified that show differential binding to structurally variable glycans attached to glycoproteins. Consequently, lectin affinity chromatography represents a valuable tool for glycoproteome studies, allowing enrichment of glycoproteins in samples prior to their identification by mass spectrometry (MS). From the perspective of plant scientists, lectin enrichment has proven useful for studies of the proteomes of the secretory pathways and cell wall, due to the high proportion of constituent proteins that are glycosylated. This chapter outlines a strategy to generate samples enriched with glycoproteins from bulk plant tissues prior to further characterization by MS, or other techniques.
Subject(s)
Chromatography, Affinity/methods , Glycoproteins/isolation & purification , Lectins/metabolism , Plant Proteins/isolation & purification , Dialysis , Glycopeptides/isolation & purification , Graphite/chemistry , Spectrophotometry, UltravioletABSTRACT
Las fístulas vesicovaginales están entre las complicaciones más angustiantes de los procedimientos ginecológicos y obstétricos. El manejo de estas fístulas se ha definido mejor y estandarizado en la última década. La reparación de la fístula vesico-vaginal frecuentemente se lleva a cabo a través de un abordaje transvaginal en el caso de las fístulas infratrigonales y mediante un abordaje abdominal transvesical para las fístulas supratrigonales. Presentamos un caso de fístula vesico-vaginal tras histerectomía que fue reparada mediante una abordaje laparoscópico. Vamos a describir una técnica novedosa para el tratamiento de fístula vesico-vaginal de ubicación supratrigonal por vía laparoscópica intraperitoneal (AU)
Vesicovaginal fístula is among the most distressing complications of gynaecological and obstetrical procedures. Management of these fístulas has been better defined and standardised over the last decade. Vesicovaginal fístula repair is most commonly repaired with transvaginal approach in cases of supratrigonal fístula and with abdominal approach in cases of supratrigonal fístula. We report a case of a vesicovaginal fístula after abdominal hysterectomy, which was repaired using a laparoscopic approach. The fístula followed a hysterectomy. We will describe a novel technique for the treatment of vesicovaginal fístula of supratrigonal location by intraperitoneal laparoscopic approach (AU)
Subject(s)
Humans , Female , Middle Aged , Vesicovaginal Fistula/complications , Vesicovaginal Fistula/surgery , Vesicovaginal Fistula , Laparoscopy/methods , Hysterectomy/methods , Gynecologic Surgical Procedures/methods , Cystoscopy/methods , Vagina/surgeryABSTRACT
Objetivo: El objetivo del presente trabajo es describir de forma retrospectiva la técnica, eficacia y seguridad de la colposacropexia laparoscópica con malla en Y de macroporo y anclajes helicoidales de titanio para el tratamiento del prolapso de cúpula vaginal. Método: Catorce pacientes, desde enero de 2011 a enero de 2013, fueron intervenidas en el Servicio de Ginecología del Hospital General Universitario de Castellón. La técnica consistía en la fijación de la vagina al sacro con la ayuda de una malla de polipropileno y anclajes helicoidales de titanio. La paridad de las pacientes fue entre 1 y 3 partos vaginales con un rango de edad entre 49 y 78 años. Resultados: La técnica quirúrgica logró la corrección del defecto en las 14 pacientes. No se reportaron complicaciones intraoperatorias, ni postoperatorias, con rápida recuperación e incorporación a las actividades diarias. Conclusiones: La colposacropexia laparoscópica con malla de polipropileno es una técnica segura, efectiva y reproducible con excelentes resultados (AU)
Objective: To retrospectively analyze the technical feasibility, effectiveness and safety of laparoscopic sacrocolpopexy with Y wide-pore mesh and helical titanium anchorages for the treatment of vaginal vault prolapse. Method: Between January 2011 and January 2013, 14 laparoscopic colposacropexies were performed in the Gynecology Service of the General University Hospital of Castellón. The technique consisted of mesh joined to the sacropromontory with helical titanium anchorages. Parity was between one and three births. The age of the patients was between 49 and 78 years. Results: The surgical technique successfully corrected the defect in 14 patients. There were no interoperative or postoperative complications, with prompt recovery and reintegration to usual activities. Conclusions: Laparoscopic colposacropexy with polypropylene mesh is a safe, effective and reproducible technique with excellent results (AU)
Subject(s)
Humans , Female , Middle Aged , Aged , Colposcopy/methods , Laparoscopy/methods , Uterine Prolapse/surgery , Surgical Mesh , Suture Anchors , Titanium , Retrospective Studies , Pelvic Organ Prolapse/surgeryABSTRACT
Objetivo. El objetivo del presente trabajo fue describir de forma retrospectiva los resultados de nuestro centro, de una serie de pacientes a quienes se realizó histerectomía total laparoscópica. Material y métodos. Se realizó un estudio retrospectivo tras la revisión de las 120 pacientes a las que se les sometió a una histerectomía laparoscópica en el periodo comprendido entre enero de 2012 y diciembre de 2014. La edad media fue de 54 años (23-94), con un IMC medio de 27,6. Se analizaron las características generales, indicaciones, presencia de intervenciones previas, complicaciones intraoperatorias y postoperatorias, duración del procedimiento y tasa de conversión a laparotomía. Resultados. Las complicaciones intraoperatorias fueron: lesiones en la vejiga (0,8%) y lesión ureteral (1,7%). Hubo complicaciones postoperatorias en 6 pacientes (tres con síndrome febril, fístula ureterovaginal, dos dehiscencias de cúpula vaginal, dos sangrados vaginales y un hemoperitoneo). La tasa de conversión a histerectomía abdominal fue de 1,6%. Conclusión. La histerectomía laparoscópica es un proceso reproducible, con una tasa de complicaciones baja, aceptado por las pacientes por su calidad de vida, y con una recuperación postoperatoria rápida (AU)
Objective. To describe complications and clinical evolution of patients underwent to total laparoscopic hysterectomy. Material and method. A retrospective study was performed after reviewing 120 patients who were subjected to laparoscopic hysterectomy in the period between January 2012 and December 2014. Medium age was 54 years (23-94) and BMI 27.6. The general characteristics, indications, presence of previous surgery, perioperative complications were analyzed and postoperative duration of the procedure and rate of conversion to laparotomy. Results. The intraoperative complications were bladder injury (0.8%) and ureteral injury (1.7%). There were postoperative complications in 6 patients (three febrile syndrome, fistula ureterovaginal, two vaginal cuff dehiscence, two vaginal bleeding and hemoperitoneum). The conversion rate to abdominal hysterectomy was 1.6%. Conclusion. Laparoscopic hysterectomy is a reproducible process with a low complication rate accepted by the patients quality of life, and with rapid postoperative recovery (AU)
Subject(s)
Adult , Aged, 80 and over , Aged , Female , Humans , Middle Aged , Hysterectomy/methods , Laparoscopy/methods , Intraoperative Complications/prevention & control , Intraoperative Complications/therapy , Postoperative Complications/epidemiology , Postoperative Complications/prevention & control , Postoperative Complications/therapy , Retrospective Studies , Urinary Bladder/injuries , Urethra/injuries , Fistula/complications , Fistula/surgery , Hemorrhage/complications , Hemoperitoneum/complications , Hemoperitoneum/diagnosisABSTRACT
A critical structural feature of many microbial endo-beta-1,4-glucanases (EGases, or cellulases) is a carbohydrate binding module (CBM), which is required for effective crystalline cellulose degradation. However, CBMs are absent from plant EGases that have been biochemically characterized to date, and accordingly, plant EGases are not generally thought to have the capacity to degrade crystalline cellulose. We report the biochemical characterization of a tomato EGase, Solanum lycopersicum Cel8 (SlCel9C1), with a distinct C-terminal noncatalytic module that represents a previously uncharacterized family of CBMs. In vitro binding studies demonstrated that this module indeed binds to crystalline cellulose and can similarly bind as part of a recombinant chimeric fusion protein containing an EGase catalytic domain from the bacterium Thermobifida fusca. Site-directed mutagenesis studies show that tryptophans 559 and 573 play a role in crystalline cellulose binding. The SlCel9C1 CBM, which represents a new CBM family (CBM49), is a defining feature of a new structural subclass (Class C) of plant EGases, with members present throughout the plant kingdom. In addition, the SlCel9C1 catalytic domain was shown to hydrolyze artificial cellulosic polymers, cellulose oligosaccharides, and a variety of plant cell wall polysaccharides.
Subject(s)
Carbohydrates/chemistry , Cellulase/physiology , Solanum lycopersicum/enzymology , Amino Acid Sequence , Catalytic Domain , Cell Wall/metabolism , Cellulase/chemistry , Cellulase/genetics , Cellulase/metabolism , Cellulose/chemistry , Glutathione Transferase/metabolism , Models, Molecular , Molecular Sequence Data , Mutagenesis, Site-Directed , Protein Binding , Recombinant Fusion Proteins/chemistry , Sequence Homology, Amino Acid , Tryptophan/chemistryABSTRACT
Xyloglucan endotransglucosylase/hydrolases (XTHs) are cell wall-modifying enzymes that align within three or four distinct phylogenetic subgroups. One explanation for this grouping is association with different enzymic modes of action, as XTHs can have xyloglucan endotransglucosylase (XET) or endohydrolase (XEH) activities. While Group 1 and 2 XTHs predominantly exhibit XET activity, to date the activity of only one member of Group 3 has been reported: nasturtium TmXH1, which has a highly specialized function and hydrolyses seed-storage xyloglucan rather than modifying cell wall structure. Tomato fruit ripening was selected as a model to test the hypothesis that preferential XEH activity might be a defining characteristic of Group 3 XTHs, which would be expressed during processes where net xyloglucan depolymerization occurs. Database searches identified 25 tomato XTHs, and one gene (SlXTH5) was of particular interest as it aligned within Group 3 and was expressed abundantly during ripening. Recombinant SlXTH5 protein acted primarily as a transglucosylase in vitro and depolymerized xyloglucan more rapidly in the presence than in the absence of xyloglucan oligosaccharides (XGOs), indicative of XET activity. Thus, there is no correlation between the XTH phylogenetic grouping and the preferential enzymic activities (XET or XEH) of the proteins in those groups. Similar analyses of SlXTH2, a Group 2 tomato XTH, and nasturtium seed TmXTH1 revealed a spectrum of modes of action, suggesting that all XTHs have the capacity to function in both modes. The biomechanical properties of plant walls were unaffected by incubation with SlXTH5, with or without XGOs, suggesting that XTHs do not represent primary cell wall-loosening agents. The possible roles of SlXTH5 in vivo are discussed.
Subject(s)
Fruit/enzymology , Glycosyltransferases/metabolism , Plant Proteins/metabolism , Solanum lycopersicum/enzymology , Cell Wall/physiology , Fruit/genetics , Fruit/growth & development , Glycosyltransferases/classification , Glycosyltransferases/genetics , Solanum lycopersicum/genetics , Solanum lycopersicum/growth & development , Phylogeny , Plant Proteins/classification , Plant Proteins/genetics , RNA, Messenger/metabolism , Sequence Analysis, ProteinABSTRACT
Major improvements in proteomic techniques in recent years have led to an increase in their application in all biological fields, including plant sciences. For all proteomic approaches, protein extraction and sample preparation are of utmost importance for optimal results; however, extraction of proteins from plant tissues represents a great challenge. Plant tissues usually contain relatively low amounts of proteins and high concentrations of proteases and compounds that potentially can limit tissue disintegration and interfere with subsequent protein separation and identification. An effective protein extraction protocol must also be adaptable to the great variation in the sets of secondary metabolites and potentially contaminating compounds that occurs between tissues (e.g., leaves, roots, fruit, seeds and stems) and between species. Here we present two basic protein extraction protocols that have successfully been used with diverse plant tissues, including recalcitrant tissues. The first method is based on phenol extraction coupled with ammonium acetate precipitation, and the second is based on trichloroacetic acid (TCA) precipitation. Both extraction protocols can be completed within 2 d.