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  • 1
    Language: English
    In: eLife, 2014-04-08, Vol.3, p.e02131-e02131
    Description: Membrane trafficking is essential to fundamental processes in eukaryotic life, including cell growth and division. In plant cytokinesis, post-Golgi trafficking mediates a massive flow of vesicles that form the partitioning membrane but its regulation remains poorly understood. Here, we identify functionally redundant Arabidopsis ARF guanine-nucleotide exchange factors (ARF-GEFs) BIG1-BIG4 as regulators of post-Golgi trafficking, mediating late secretion from the trans-Golgi network but not recycling of endocytosed proteins to the plasma membrane, although the TGN also functions as an early endosome in plants. In contrast, BIG1-4 are absolutely required for trafficking of both endocytosed and newly synthesized proteins to the cell-division plane during cytokinesis, counteracting recycling to the plasma membrane. This change from recycling to secretory trafficking pathway mediated by ARF-GEFs confers specificity of cargo delivery to the division plane and might thus ensure that the partitioning membrane is completed on time in the absence of a cytokinesis-interphase checkpoint. DOI: http://dx.doi.org/10.7554/eLife.02131.001.
    Subject(s): Arabidopsis Proteins - metabolism ; Endocytosis ; Cell Division ; Golgi Apparatus - metabolism ; Arabidopsis Proteins - secretion ; Arabidopsis - metabolism ; Protein Transport ; Seeds ; Cytokinesis ; Guanine ; Golgi apparatus ; Proteins ; Microscopy ; Phylogenetics ; Membrane trafficking ; Physiology ; Software ; Flowers & plants ; Recycling ; Molecular biology ; Guanine nucleotide exchange factor ; Localization ; Index Medicus ; Plant Biology ; ARF-GEF ; secretion ; Arabidopsis ; cell division ; post-Golgi trafficking ; recycling ; gegulation of vesicle traffic ; Cell Biology
    ISSN: 2050-084X
    E-ISSN: 2050-084X
    Source: PubMed Central
    Source: Directory of Open Access Journals
    Source: © ProQuest LLC All rights reserved〈img src="https://exlibris-pub.s3.amazonaws.com/PQ_Logo.jpg" style="vertical-align:middle;margin-left:7px"〉
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  • 2
    Language: English
    In: Journal of experimental botany, 2018-01-01, Vol.69 (1), p.59-68
    Description: This review highlights current knowledge on membrane trafficking that mediates resistance to powdery mildew fungi and probably involves the release of exosomes. Abstract The ability to ward off filamentous pathogens, such as powdery mildew fungi, is one of the best studied examples of membrane trafficking-dependent disease resistance in plants. Here, papilla formation at the site of attack is essential for the pre-invasive immunity, whereas the encasement can hamper disease post-invasively. Exosomes containing antifungal peptides and small RNAs are thought to play a vital role in forming papillae and encasements that block fungal growth. While exosomes are well described in mammals, and have been shown to play important roles in cell-cell communication regulating development and disease, their function is not well-known in plants. In this review, we focus on some of the recent discoveries on plant exosomes and try to link this information with our current understanding of how plants use this form of unconventional secretion to acquire this durable and effective form of resistance.
    Subject(s): Index Medicus
    ISSN: 0022-0957
    E-ISSN: 1460-2431
    Source: Alma/SFX Local Collection
    Source: Oxford Journals 2016 Current and Archive A-Z Collection
    Source: © ProQuest LLC All rights reserved〈img src="https://exlibris-pub.s3.amazonaws.com/PQ_Logo.jpg" style="vertical-align:middle;margin-left:7px"〉
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  • 3
    Language: English
    In: Proceedings of the National Academy of Sciences - PNAS, 2012-07-10, Vol.109 (28), p.11443-11448
    Description: Penetration resistance to powdery mildew fungi, conferred by localized cell wall appositions (papillae), is one of the best-studied processes in plant innate immunity. The syntaxin PENETRATION (PEN)1 is required for timely appearance of papillae, which contain callose and extracellular membrane material, as well as PEN1 itself. Appearance of membrane material in papillae suggests secretion of exosomes. These are potentially derived from multivesicular bodies (MVBs), supported by our observation that ARA6-labeled organelles assemble at the fungal attack site. However, the trafficking components that mediate delivery of extracellular membrane material are unknown. Here, we show that the delivery is independent of PEN1 function. Instead, we find that application of brefeldin (BF)A blocks the papillary accumulation of GFP-PEN1-labeled extracellular membrane and callóse, while impeding penetration resistance. We subsequently provide evidence indicating that the responsible BFA-sensitive ADP ribosylation factor-GTP exchange factor (ARF-GEF) is GNOM. Firstly, analysis of the transheterozygote gnom B404a/emb30-1 (gnomB/E) mutant revealed a delay in papilla formation and reduced penetration resistance. Furthermore, a BFA-resistant version of GNOM restored the BFA-sensitive papillary accumulation of GFP-PEN1 and callose. Our data, therefore, provide a link between GNOM and disease resistance. We suggest that papilla formation requires rapid reorganization of material from the plasma membrane mediated by GNOM. The papilla material is subsequently presumed to be sorted into MVBs and directed to the site of fungal attack, rendering the epidermal plant cell inaccessible for the invading powdery mildew fungus.
    Subject(s): Mildews ; Fungi ; Barley ; Leaves ; Secretion ; Cell membranes ; Plants ; Exosomes ; Papillae ; Plant cells ; Exosomes - metabolism ; Gene Expression Regulation, Fungal ; Arabidopsis Proteins - physiology ; Guanine Nucleotide Exchange Factors - physiology ; Brefeldin A - pharmacology ; Immunity, Innate ; Microscopy, Confocal - methods ; Arabidopsis - genetics ; Arabidopsis Proteins - metabolism ; GTP Phosphohydrolases - metabolism ; Biological Transport ; Microscopy, Fluorescence - methods ; Models, Biological ; Qa-SNARE Proteins - metabolism ; Heterozygote ; Glucans - chemistry ; Arabidopsis thaliana ; Plant proteins ; Plant defenses ; Physiological aspects ; Research ; Properties ; Guanosine triphosphatase ; Index Medicus ; Biological Sciences ; pathogen ; vesicle transport ; fungal penetration ; defense ; GTPase
    ISSN: 0027-8424
    E-ISSN: 1091-6490
    Source: HighWire Press (Free Journals)
    Source: Hellenic Academic Libraries Link
    Source: PubMed Central
    Source: © ProQuest LLC All rights reserved〈img src="https://exlibris-pub.s3.amazonaws.com/PQ_Logo.jpg" style="vertical-align:middle;margin-left:7px"〉
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  • 4
    Language: English
    In: PloS one, 2017, Vol.12 (1), p.e0170118-e0170118
    Description: To understand the function of membrane proteins, it is imperative to know their topology. For such studies, a split green fluorescent protein (GFP) method is useful. GFP is barrel-shaped, consisting of 11 β-sheets. When the first ten β-sheets (GFP1-10) and the 11th β-sheet (GFP11) are expressed from separate genes they will self-assembly and reconstitute a fluorescent GFP protein. However, this will only occur when the two domains co-localize in the same cellular compartment. We have developed an easy-to-use Gateway vector set for determining on which side of the membrane the N- and C-termini are located. Two vectors were designed for making N- and C-terminal fusions between the membrane proteins-of-interest and GFP11, while another three plasmids were designed to express GFP1-10 in either the cytosol, the endoplasmic reticulum (ER) lumen or the apoplast. We tested functionality of the system by applying the vector set for the transmembrane domain, CNXTM, of the ER membrane protein, calnexin, after transient expression in Nicotiana benthamiana leaves. We observed GFP signal from the ER when we reciprocally co-expressed GFP11-CNXTM with GFP1-10-HDEL and CNXTM-GFP with cytosolic GFP1-10. The opposite combinations did not result in GFP signal emission. This test using the calnexin ER-membrane domain demonstrated its C-terminus to be in the cytosol and its N-terminus in the ER lumen. This result confirmed the known topology of calnexin, and we therefore consider this split-GFP system highly useful for ER membrane topology studies. Furthermore, the vector set provided is useful for detecting the topology of proteins on other membranes in the cell, which we confirmed for a plasma membrane syntaxin. The set of five Ti-plasmids are easily and efficiently used for Gateway cloning and transient transformation of N. benthamiana leaves.
    Subject(s): Arabidopsis Proteins - physiology ; Green Fluorescent Proteins - analysis ; Recombinant Fusion Proteins - analysis ; Agrobacterium tumefaciens - genetics ; Green Fluorescent Proteins - genetics ; Recombinant Fusion Proteins - chemistry ; Membrane Proteins - analysis ; Arabidopsis Proteins - chemistry ; Membrane Proteins - chemistry ; Membrane Proteins - physiology ; Tobacco - genetics ; Cloning, Molecular - methods ; Protein Domains ; Arabidopsis Proteins - analysis ; Green Fluorescent Proteins - chemistry ; Physiological aspects ; Genetic aspects ; Research ; Structure ; Green fluorescent protein ; Membrane proteins ; Index Medicus ; Research and analysis methods ; Biology and Life Sciences ; Plasma ; Self assembly ; Membranes ; Transformation ; Peptides ; Emission analysis ; Fluorescence ; Cytosol ; Proteins ; Leaves ; Deoxyribonucleic acid ; Sheets ; Cloning ; Topology ; C-Terminus ; Apoplast ; Calnexin ; Studies ; Syntaxin ; Self-assembly ; Environmental science ; Plasmids ; DNA ; N-Terminus ; Proteomics ; Endoplasmic reticulum
    ISSN: 1932-6203
    E-ISSN: 1932-6203
    Source: Academic Search Ultimate
    Source: PubMed Central
    Source: Directory of Open Access Journals
    Source: © ProQuest LLC All rights reserved〈img src="https://exlibris-pub.s3.amazonaws.com/PQ_Logo.jpg" style="vertical-align:middle;margin-left:7px"〉
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  • 5
    Language: English
    In: Plant molecular biology, 2006-07, Vol.61 (4), p.589-601
    Description: Proper embryo development is crucial for normal growth and development of barley. Numerous related aspects of this process—for example how the embryo establishes and sustains disease resistance for extended periods during dormancy—remain largely unknown. Here we report the results of microarray analyses of 〉22,000 genes, which together with measurements of jasmonic acid and salicylic acid during embryo development provide new information on the initiation in the developing barley embryo of at least two distinct types of developmental defense activation (DDA). Early DDA is characterized by the up-regulation of a specific set of genes around 20 days after flowering, including co-regulation of those for encoding 9-lipoxygenase and several oxylipin-generating enzymes, possibly leading to the formation of α-ketols. The same developmental phase includes an up-regulation of several defense genes, and indications of co-regulation of those for enzymes involved in the generation of phenylpropanoid phytoalexins. Late DDA is initiated prior to grain desiccation, around 37 days after flowering, with up-regulation of several genes encoding proteins with roles in antioxidant responses as well as a simultaneous up-regulation of several PR genes is notable. Throughout barley embryo development, there are no indications of an increased biosynthesis of either jasmonic acid or salicylic acid. Collectively, the results help explain how the proposed DDA enables protection of the developing barley embryo and grain for purposes of disease resistance.
    Subject(s): Life Sciences ; Biochemistry, general ; Plant Pathology ; Disease resistance ; Lipoxygenase pathway ; Defense activation ; Microarray ; Plant Sciences ; Embryo development ; Oxylipins ; Seeds - metabolism ; Oxidative Stress ; Signal Transduction ; Seeds - genetics ; Gene Expression Regulation, Plant - genetics ; Gene Expression Profiling ; DNA, Plant ; Plant Proteins - genetics ; Cell Cycle ; Gene Expression Regulation, Developmental ; Hordeum - embryology ; Cyclopentanes - metabolism ; Hordeum - genetics ; Fatty Acids - metabolism ; Cluster Analysis ; Physiological aspects ; Barley ; Index Medicus
    ISSN: 0167-4412
    E-ISSN: 1573-5028
    Source: Alma/SFX Local Collection
    Source: © ProQuest LLC All rights reserved〈img src="https://exlibris-pub.s3.amazonaws.com/PQ_Logo.jpg" style="vertical-align:middle;margin-left:7px"〉
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  • 6
    Article
    Article
    2018
    ISSN: 1559-2316  ISSN: 1559-2324 
    Language: English
    In: Plant signaling & behavior, 2018-04-03, Vol.13 (4), p.e1445950-e1445950
    Description: Plant innate immunity enables plants to defend themselves against infectious pathogens. While membrane trafficking and release of exosomes are considered vital for correct execution of innate immunity, the mechanisms behind remain elusive. Recently, we have shown that VPS9a, the general guanine-nucleotide exchange factor activating Rab5 GTPases, is required for both pre- and post-invasive immunity against powdery mildew fungi in Arabidopsis thaliana. Yet, the Arabidopsis genome contains a close homologue of VPS9a, which potentially plays specific roles in innate immunity. Here we show that this gene, VPS9b, while weakly expressed, contributes to regulating development and disease resistance, which is predominantly regulated by VPS9a. Based on these observations, we suggest that VPS9b has no specialized functionality, but rather is becoming a non-expressed pseudogene.
    Subject(s): VPS9 ; Rab GTPase ; powdery mildew ; Arabidopsis - genetics ; Arabidopsis Proteins - metabolism ; Arabidopsis Proteins - genetics ; Guanine Nucleotide Exchange Factors - genetics ; Genome, Plant - genetics ; Guanine Nucleotide Exchange Factors - metabolism ; Immunity, Innate - physiology ; Immunity, Innate - genetics ; Arabidopsis - metabolism ; Index Medicus
    ISSN: 1559-2316
    ISSN: 1559-2324
    E-ISSN: 1559-2324
    Source: PubMed Central
    Source: © ProQuest LLC All rights reserved〈img src="https://exlibris-pub.s3.amazonaws.com/PQ_Logo.jpg" style="vertical-align:middle;margin-left:7px"〉
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  • 7
    Language: English
    In: Journal of experimental botany, 2017-12-16, Vol.68 (21-22), p.5731-5743
    Description: Many filamentous plant pathogens place specialized feeding structures, called haustoria, inside living host cells. As haustoria grow, they are believed to manipulate plant cells to generate a specialized, still enigmatic extrahaustorial membrane (EHM) around them. Here, we focused on revealing properties of the EHM. With the help of membrane-specific dyes and transient expression of membrane-associated proteins fused to fluorescent tags, we studied the nature of the EHM generated by barley leaf epidermal cells around powdery mildew haustoria. Observations suggesting that endoplasmic reticulum (ER) membrane-specific dyes labelled the EHM led us to find that Sar1 and RabD2a GTPases bind this membrane. These proteins are usually associated with the ER and the ER/cis-Golgi membrane, respectively. In contrast, transmembrane and luminal ER and Golgi markers failed to label the EHM, suggesting that it is not a continuum of the ER. Furthermore, GDP-locked Sar1 and a nucleotide-free RabD2a, which block ER to Golgi exit, did not hamper haustorium formation. These results indicated that the EHM shares features with the plant ER membrane, but that the EHM membrane is not dependent on conventional secretion. This raises the prospect that an unconventional secretory pathway from the ER may provide this membrane's material. Understanding these processes will assist future approaches to providing resistance by preventing EHM generation.
    Subject(s): Host-Pathogen Interactions ; Ascomycota - physiology ; Plant Diseases - microbiology ; Membrane Proteins - metabolism ; Plant Proteins - metabolism ; Endoplasmic Reticulum ; Hordeum - microbiology ; Index Medicus ; Barley organelle markers ; Rab GTPase ; Research Papers ; powdery mildew ; Sar1 GTPase ; secretion ; endoplasmic reticulum (ER) ; extrahaustorial membrane (EHM)
    ISSN: 0022-0957
    E-ISSN: 1460-2431
    Source: Alma/SFX Local Collection
    Source: Oxford Journals 2016 Current and Archive A-Z Collection
    Source: © ProQuest LLC All rights reserved〈img src="https://exlibris-pub.s3.amazonaws.com/PQ_Logo.jpg" style="vertical-align:middle;margin-left:7px"〉
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  • 8
    Language: English
    In: The Plant cell, 2017-08-01, Vol.29 (8), p.1927-1937
    Description: Plant innate immunity can effectively prevent the proliferation of filamentous pathogens. Papilla formation at the site of attack is essential for preinvasive immunity; in postinvasive immunity, the encasement of pathogen structures inside host cells can hamper disease. Whereas papillae are highly dependent on transcytosis of premade material, little is known about encasement formation. Here, we show that endosome-associated VPS9a, the conserved guanine-nucleotide exchange factor activating Rab5 GTPases, is required for both pre- and postinvasive immunity against a nonadapted powdery mildew fungus ( f. sp ) in . Surprisingly, VPS9a acts in addition to two previously well-described innate immunity components and thus represents an additional step in the regulation of how plants resist pathogens. We found VPS9a to be important for delivering membrane material to the encasement and VPS9a also plays a predominant role in postinvasive immunity. GTP-bound Rab5 GTPases accumulate in the encasement, but not the papillae, suggesting that two independent pathways form these defense structures. VPS9a also mediates defense to an adapted powdery mildew fungus, thus regulating a durable type of defense that works in both host and nonhost resistance. We propose that VPS9a plays a conserved role in organizing cellular endomembrane trafficking, required for delivery of defense components in response to powdery mildew fungi.
    Subject(s): RESEARCH ARTICLES ; rab GTP-Binding Proteins - metabolism ; Plant Immunity ; Ascomycota - physiology ; Plant Diseases - immunology ; Arabidopsis - immunology ; Plant Diseases - microbiology ; Guanosine Triphosphate - metabolism ; Immunity, Innate ; Mutation - genetics ; Arabidopsis - metabolism ; Arabidopsis Proteins - metabolism ; Arabidopsis - microbiology ; Guanine Nucleotide Exchange Factors - metabolism ; Models, Biological ; Cell Membrane - metabolism ; Arabidopsis thaliana ; Drug resistance in microorganisms ; G proteins ; Index Medicus ; s
    ISSN: 1040-4651
    E-ISSN: 1532-298X
    Source: American Society of Plant Biologists
    Source: HighWire Press (Free Journals)
    Source: Elektronische Zeitschriftenbibliothek - Frei zugängliche E-Journals
    Source: PubMed Central
    Source: © ProQuest LLC All rights reserved〈img src="https://exlibris-pub.s3.amazonaws.com/PQ_Logo.jpg" style="vertical-align:middle;margin-left:7px"〉
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  • 9
    Language: English
    In: The Plant cell, 2020-08, Vol.32 (8), p.2491-2507
    Description: Membrane trafficking maintains the organization of the eukaryotic cell and delivers cargo proteins to their subcellular destinations, such as sites of action or degradation. The formation of membrane vesicles requires the activation of the ADP-ribosylation factor ARF GTPase by the SEC7 domain of ARF guanine-nucleotide exchange factors (ARF-GEFs), resulting in the recruitment of coat proteins by GTP-bound ARFs. In vitro exchange assays were done with monomeric proteins, although ARF-GEFs form dimers in vivo. This feature is conserved across eukaryotes, although its biological significance is unknown. Here, we demonstrate the proximity of ARF1•GTPs in vivo by fluorescence resonance energy transfer-fluorescence lifetime imaging microscopy, mediated through coordinated activation by dimers of Arabidopsis ( ) ARF-GEF GNOM, which is involved in polar recycling of the auxin transporter PIN-FORMED1. Mutational disruption of ARF1 spacing interfered with ARF1-dependent trafficking but not with coat protein recruitment. A mutation impairing the interaction of one of the two SEC7 domains of the GNOM ARF-GEF dimer with its ARF1 substrate reduced the efficiency of coordinated ARF1 activation. Our results suggest a model of coordinated activation-dependent membrane insertion of ARF1•GTP molecules required for coated membrane vesicle formation. Considering the evolutionary conservation of ARFs and ARF-GEFs, this initial regulatory step of membrane trafficking might well occur in eukaryotes in general.
    Subject(s): Arabidopsis Proteins - metabolism ; DNA-Binding Proteins - metabolism ; Transcription Factors - metabolism ; Phenotype ; Guanine Nucleotide Exchange Factors - metabolism ; Models, Biological ; Transport Vesicles - metabolism ; Plants, Genetically Modified ; Protein Multimerization ; Protein Binding ; Cell Membrane - metabolism ; Arabidopsis - metabolism ; Index Medicus
    ISSN: 1040-4651
    E-ISSN: 1532-298X
    Source: American Society of Plant Biologists
    Source: Elektronische Zeitschriftenbibliothek - Frei zugängliche E-Journals
    Source: © ProQuest LLC All rights reserved〈img src="https://exlibris-pub.s3.amazonaws.com/PQ_Logo.jpg" style="vertical-align:middle;margin-left:7px"〉
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  • 10
    Article
    Article
    2012
    ISSN: 1559-2316  ISSN: 1559-2324 
    Language: English
    In: Plant signaling & behavior, 2012-12-01, Vol.7 (12), p.1541-1543
    Description: Penetration resistance against powdery mildews is one of the best-studied processes of plant innate immunity. One vital component is the plant syntaxin, PEN1, which is required for timely deposition of callose and extracellular membrane material, as well as PEN1 itself, at the attack sites. Recently, we reported that the ARF-GEF GNOM also is required for penetration resistance, mediating transport of recycled material, including PEN1, to the site of attack. The close relative of PEN1, SYP122, does not accumulate at the sites of attack nor does it affect penetration resistance. In support of this, we show here that in contrast to PEN1, SYP122 does not continuously recycle. Furthermore, by using a PEN1 transgene that is only transcribed in dividing cells, we show that papillary PEN1 accumulation is not dependent on de-novo protein synthesis. This emphasizes the involvement of recycling in penetration resistance, which possibly relates to the differences in function of the two syntaxins.
    Subject(s): pathogen ; vesicle transport ; fungal penetration ; defense ; syntaxin ; Arabidopsis - genetics ; Arabidopsis Proteins - metabolism ; Qa-SNARE Proteins - genetics ; Arabidopsis Proteins - genetics ; Qa-SNARE Proteins - metabolism ; Arabidopsis - metabolism ; Index Medicus ; Short Communication
    ISSN: 1559-2316
    ISSN: 1559-2324
    E-ISSN: 1559-2324
    Source: PubMed Central
    Source: © ProQuest LLC All rights reserved〈img src="https://exlibris-pub.s3.amazonaws.com/PQ_Logo.jpg" style="vertical-align:middle;margin-left:7px"〉
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