| 1. |
- Kumar, Manoj, et al.
(författare)
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An update on the nomenclature for the cellulose synthase genes in Populus
- 2009
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Ingår i: Trends in Plant Science. - : Elsevier BV. - 1360-1385 .- 1878-4372. ; 14:5, s. 248-254
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Forskningsöversikt (refereegranskat)abstract
- Cellulose synthase (CesA) is a central catalyst in the generation of the plant cell wall biomass and is, therefore, the focus of intense research. Characterization of individual CesA genes from Populus species has led to the publication of several different naming conventions for CesA gene family members in this model tree. To help reduce the resulting confusion, we propose here a new phylogeny-based CesA nomenclature that aligns the Populus CesA gene family with the established Arabidopsis thaliana CesA family structure.
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| 2. |
- Alvarez, Francisco J., et al.
(författare)
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Diverse Nitrogen Sources in Seminal Fluid Act in Synergy To Induce Filamentous Growth of Candida albicans
- 2015
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Ingår i: Applied and Environmental Microbiology. - 0099-2240 .- 1098-5336. ; 81:8, s. 2770-2780
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Tidskriftsartikel (refereegranskat)abstract
- The pathogenic fungus Candida albicans is the leading cause of vulvovaginal candidiasis (VVC). VVC represents a major quality- of-life issue for women during their reproductive years, a stage of life where the vaginal epithelium is subject to periodic hormonally induced changes associated with menstruation and concomitant exposure to serum as well as potential intermittent contact with seminal fluid. Seminal fluid potently triggers Candida albicans to switch from yeastlike to filamentous modes of growth, a developmental response tightly linked to virulence. Conversely, vaginal fluid inhibits filamentation. Here, we used artificial formulations of seminal and vaginal fluids that faithfully mimic genuine fluids to assess the contribution of individual components within these fluids to filamentation. The high levels of albumin, amino acids, and N-acetylglucosamine in seminal fluid act synergistically as potent inducers of filamentous growth, even at atmospheric levels of CO2 and reduced temperatures (30 degrees C). Using a simplified in vitro model that mimics the natural introduction of seminal fluid into the vulvovaginal environment, a pulse of artificial seminal fluid (ASF) was found to exert an enduring potential to overcome the inhibitory efficacy of artificial vaginal fluid (AVF) on filamentation. These findings suggest that a transient but substantial change in the nutrient levels within the vulvovaginal environment during unprotected coitus can induce resident C. albicans cells to engage developmental programs associated with virulent growth.
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| 3. |
- Bacete, Laura, et al.
(författare)
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Arabidopsis Response Regulator 6 (ARR6) Modulates Plant Cell-Wall Composition and Disease Resistance
- 2020
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Ingår i: Molecular Plant-Microbe Interactions. - : Scientific Societies. - 0894-0282 .- 1943-7706. ; 33:5, s. 767-780
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Tidskriftsartikel (refereegranskat)abstract
- The cytokinin signaling pathway, which is mediated by Arabidopsis response regulator (ARR) proteins, has been involved in the modulation of some disease-resistance responses. Here, we describe novel functions of ARR6 in the control of plant disease-resistance and cell-wall composition. Plants impaired in ARR6 function (arr6) were more resistant and susceptible, respectively, to the necrotrophic fungus Plectosphaerella cucumerina and to the vascular bacterium Ralstonia solanacearum, whereas Arabidopsis plants that overexpress ARR6 showed the opposite phenotypes, which further support a role of ARR6 in the modulation of disease-resistance responses against these pathogens. Transcriptomics and metabolomics analyses revealed that, in arr6 plants, canonical disease-resistance pathways, like those activated by defensive phytohormones, were not altered, whereas immune responses triggered by microbe-associated molecular patterns were slightly enhanced. Cell-wall composition of arr6 plants was found to be severely altered compared with that of wild-type plants. Remarkably, pectin-enriched cell-wall fractions extracted from arr6 walls triggered more intense immune responses than those activated by similar wall fractions from wild-type plants, suggesting that an-6 pectin fraction is enriched in wall-related damage-associated molecular patterns, which trigger immune responses. This work supports a novel function of ARR6 in the control of cell-wall composition and disease resistance and reinforces the role of the plant cell wall in the modulation of specific immune responses.
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| 4. |
- Badreddine, Ilham, et al.
(författare)
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Cell Wall Chitosaccharides Are Essential Components and Exposed Patterns of the Phytopathogenic Oomycete Aphanomyces euteiches
- 2008
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Ingår i: Eukaryotic Cell. - : American Society for Microbiology. - 1535-9778 .- 1535-9786. ; 7:11, s. 1980-1993
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Tidskriftsartikel (refereegranskat)abstract
- Chitin is an essential component of fungal cell walls, where it forms a crystalline scaffold, and chitooligosaccharides derived from it are signaling molecules recognized by the hosts of pathogenic fungi. Oomycetes are cellulosic fungus-like microorganisms which most often lack chitin in their cell walls. Here we present the first study of the cell wall of the oomycete Aphanomyces euteiches, a major parasite of legume plants. Biochemical analyses demonstrated the presence of ca. 10% N-acetyl-D-glucosamine (GlcNAc) in the cell wall. Further characterization of the GlcNAc-containing material revealed that it corresponds to noncrystalline chitosaccharides associated with glucans, rather than to chitin per se. Two putative chitin synthase (CHS) genes were identified by data mining of an A. euteiches expressed sequence tag collection and Southern blot analysis, and full-length cDNA sequences of both genes were obtained. Phylogeny analysis indicated that oomycete CHS diversification occurred before the divergence of the major oomycete lineages. Remarkably, lectin labeling showed that the Aphanomyces euteiches chitosaccharides are exposed at the cell wall surface, and study of the effect of the CHS inhibitor nikkomycin Z demonstrated that they are involved in cell wall function. These data open new perspectives for the development of antioomycete drugs and further studies of the molecular mechanisms involved in the recognition of pathogenic oomycetes by the host plants.
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| 5. |
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| 6. |
- Belmonte, Rodrigo, et al.
(författare)
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Role of Pathogen-Derived Cell Wall Carbohydrates and Prostaglandin E-2 in Immune Response and Suppression of Fish Immunity by the Oomycete Saprolegnia parasitica
- 2014
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Ingår i: Infection and Immunity. - 0019-9567 .- 1098-5522. ; 82:11, s. 4518-4529
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Tidskriftsartikel (refereegranskat)abstract
- Saprolegnia parasitica is a freshwater oomycete that is capable of infecting several species of fin fish. Saprolegniosis, the disease caused by this microbe, has a substantial impact on Atlantic salmon aquaculture. No sustainable treatment against saprolegniosis is available, and little is known regarding the host response. In this study, we examined the immune response of Atlantic salmon to S. parasitica infection and to its cell wall carbohydrates. Saprolegnia triggers a strong inflammatory response in its host (i. e., induction of interleukin-1 beta(1) [IL-1 beta(1)], IL-6, and tumor necrosis factor alpha), while severely suppressing the expression of genes associated with adaptive immunity in fish, through downregulation of T-helper cell cytokines, antigen presentation machinery, and immunoglobulins. Oomycete cell wall carbohydrates were recognized by fish leukocytes, triggering upregulation of genes involved in the inflammatory response, similar to what is observed during infection. Our data suggest that S. parasitica is capable of producing prostaglanding E-2 (PGE(2)) in vitro, a metabolite not previously shown to be produced by oomycetes, and two proteins with homology to vertebrate enzymes known to play a role in prostaglandin biosynthesis have been identified in the oomycete genome. Exogenous PGE(2) was shown to increase the inflammatory response in fish leukocytes incubated with cell wall carbohydrates while suppressing genes involved in cellular immunity (gamma interferon [IFN-gamma] and the IFN-gamma-inducible protein [gamma-IP]). Inhibition of S. parasitica zoospore germination and mycelial growth by two cyclooxygenase inhibitors (aspirin and indomethacin) also suggests that prostaglandins may be involved in oomycete development.
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| 7. |
- Bessueille, Laurence, et al.
(författare)
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A survey of cellulose biosynthesis in higher plants
- 2008
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Ingår i: PLANT BIOTECHNOLOGY. - : Japanese Society for Plant Cell and Molecular Biology. - 1342-4580 .- 1347-6114. ; 25:3, s. 315-322
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Tidskriftsartikel (refereegranskat)abstract
- Cellulose plays a central role in plant development and its biosynthesis represents one of the most important biochemical processes in plant biology. However, the corresponding molecular mechanisms are not well understood, despite the progress made in the past years in the identification of genes that code for the catalytic subunits of the cellulose synthases and other proteins potentially involved in cellulose formation. A major bottleneck is the high instability of the cellulose synthase complexes and their location in the plasma membrane. Additional efforts are currently being made to unravel the mechanisms of cellulose biosynthesis. Indeed, understanding how cellulose is formed and how its crystallinity is achieved is relevant not only for studying plant development, but also for improving the digestibility of the plant biomass, which is foreseen as an alternative to fossil fuels for the production of energy. This review summarizes the major unanswered questions related to the process of cellulose biosynthesis, and describes the recent progress that has been made in the area through the combination of biochemical approaches and molecular genetics.
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| 8. |
- Bessueille, Laurence, et al.
(författare)
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Plasma membrane microdomains from hybrid aspen cells are involved in cell wall polysaccharide biosynthesis
- 2009
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Ingår i: Biochemical Journal. - : Portland Press Ltd.. - 0264-6021 .- 1470-8728. ; 420, s. 93-103
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Tidskriftsartikel (refereegranskat)abstract
- Detergent-resistant plasma membrane microdomains [DRMs (detergent-resistant membranes)] were isolated recently from several plant species. As for animal cells, a large range of cellular functions, such as signal transduction, endocytosis and protein trafficking, have been attributed to plant lipid rafts and DRMs. The data available are essentially based on protcomics and more approaches need to be undertaken to elucidate the precise function of individual populations of DRMs in plants. We report here the first isolation of DRMs from purified plasma membranes of a tree species, the hybrid aspen Populus tremula x tremuloides, and their biochemical characterization. Plasma membranes were solubilized with Triton X-100 and the resulting DRMs were isolated by flotation in sucrose density gradients. The DRMs were enriched in sterols, sphingolipids and glycosylphosphatidylinositol-anchored proteins and thus exhibited similar properties to DRMs from other species. However, they contained key carbohydrate synthases involved in cell wall polysaccharide biosynthesis, namely callose [(1 -> 3)-beta-D-glucan] and cellulose synthases. The association of these enzymes with DRMs was demonstrated using specific glucan synthase assays and antibodies, as well as biochemical and chemical approaches for the characterization of the polysaccharides synthesized in vitro by the isolated DRMs. More than 70% of the total glucan synthase activities present in the original plasma membranes was associated with the DRM fraction. In addition to shedding light on the lipid environment of callose and cellulose synthases, our results demonstrate the involvement of DRMs in the biosynthesis of important cell wall polysaccharides. This novel concept suggests a function of plant membrane microdomains in cell growth and morphogenesis.
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| 9. |
- Betts, Natalie S., et al.
(författare)
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Identification and spatio-temporal expression analysis of barley genes that encode putative modular xylanolytic enzymes
- 2021
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Ingår i: Plant Science. - : Elsevier BV. - 0168-9452 .- 1873-2259. ; 308
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Tidskriftsartikel (refereegranskat)abstract
- Arabinoxylans are cell wall polysaccharides whose re-modelling and degradation during plant development are mediated by several classes of xylanolytic enzymes. Here, we present the identification and new annotation of twelve putative (1,4)-13-xylanase and six 13-xylosidase genes, and their spatio-temporal expression patterns during vegetative and reproductive growth of barley (Hordeum vulgare cv. Navigator). The encoded xylanase proteins are all predicted to contain a conserved carbohydrate-binding module (CBM) and a catalytic glycoside hydrolase (GH) 10 domain. Additional domains in some xylanases define three discrete phylogenetic clades: one clade contains proteins with an additional N-terminal signal sequence, while another clade contains proteins with multiple CBMs. Homology modelling revealed that all fifteen xylanases likely contain a third domain, a 13-sandwich folded from two non-contiguous sequence segments that bracket the catalytic GH domain, which may explain why the full length protein is required for correct folding of the active enzyme. Similarly, predicted xylosidase proteins share a highly conserved domain structure, each with an N-terminal signal peptide, a split GH 3 domain, and a C-terminal fibronectin-like domain. Several genes appear to be ubiquitously expressed during barley growth and development, while four newly annotated xylanase and xylosidase genes are expressed at extremely high levels, which may be of broader interest for industrial applications where cell wall degradation is necessary.
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| 10. |
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