851
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Leaf Fructose Content Is Controlled by the Vacuolar Transporter SWEET17 in Arabidopsis. Curr Biol 2013; 23:697-702. [DOI: 10.1016/j.cub.2013.03.021] [Citation(s) in RCA: 163] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2013] [Revised: 02/15/2013] [Accepted: 03/08/2013] [Indexed: 11/16/2022]
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852
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Li W, Chiang YH, Coaker G. The HopQ1 effector's nucleoside hydrolase-like domain is required for bacterial virulence in arabidopsis and tomato, but not host recognition in tobacco. PLoS One 2013; 8:e59684. [PMID: 23555744 PMCID: PMC3608555 DOI: 10.1371/journal.pone.0059684] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2012] [Accepted: 02/16/2013] [Indexed: 12/31/2022] Open
Abstract
Bacterial pathogens deliver multiple effector proteins into host cells to facilitate bacterial growth. HopQ1 is an effector from Pseudomonas syringae pv. tomato DC3000 that is conserved across multiple bacterial pathogens which infect plants. HopQ1's central region possesses some homology to nucleoside hydrolases, but possesses an alternative aspartate motif not found in characterized enzymes. A structural model was generated for HopQ1 based on the E. coli RihB nucleoside hydrolase and the role of HopQ1's potential catalytic residues for promoting bacterial virulence and recognition in Nicotiana tabacum was investigated. Transgenic Arabidopsis plants expressing HopQ1 exhibit enhanced disease susceptibility to DC3000. HopQ1 can also promote bacterial virulence on tomato when naturally delivered from DC3000. HopQ1's nucleoside hydrolase-like domain alone is sufficient to promote bacterial virulence, and putative catalytic residues are required for virulence promotion during bacterial infection of tomato and in transgenic Arabidopsis lines. HopQ1 is recognized and elicits cell death when transiently expressed in N. tabacum. Residues required to promote bacterial virulence were dispensable for HopQ1's cell death promoting activities in N. tabacum. Although HopQ1 has some homology to nucleoside hydrolases, we were unable to detect HopQ1 enzymatic activity or nucleoside binding capability using standard substrates. Thus, it is likely that HopQ1 promotes pathogen virulence by hydrolyzing alternative ribose-containing substrates in planta.
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Affiliation(s)
- Wei Li
- Department of Plant Pathology, University of California Davis, Davis, California, United States of America
| | - Yi-Hsuan Chiang
- Department of Plant Pathology, University of California Davis, Davis, California, United States of America
| | - Gitta Coaker
- Department of Plant Pathology, University of California Davis, Davis, California, United States of America
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853
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Grau J, Wolf A, Reschke M, Bonas U, Posch S, Boch J. Computational predictions provide insights into the biology of TAL effector target sites. PLoS Comput Biol 2013; 9:e1002962. [PMID: 23526890 PMCID: PMC3597551 DOI: 10.1371/journal.pcbi.1002962] [Citation(s) in RCA: 82] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2012] [Accepted: 01/14/2013] [Indexed: 11/19/2022] Open
Abstract
Transcription activator-like (TAL) effectors are injected into host plant cells by Xanthomonas bacteria to function as transcriptional activators for the benefit of the pathogen. The DNA binding domain of TAL effectors is composed of conserved amino acid repeat structures containing repeat-variable diresidues (RVDs) that determine DNA binding specificity. In this paper, we present TALgetter, a new approach for predicting TAL effector target sites based on a statistical model. In contrast to previous approaches, the parameters of TALgetter are estimated from training data computationally. We demonstrate that TALgetter successfully predicts known TAL effector target sites and often yields a greater number of predictions that are consistent with up-regulation in gene expression microarrays than an existing approach, Target Finder of the TALE-NT suite. We study the binding specificities estimated by TALgetter and approve that different RVDs are differently important for transcriptional activation. In subsequent studies, the predictions of TALgetter indicate a previously unreported positional preference of TAL effector target sites relative to the transcription start site. In addition, several TAL effectors are predicted to bind to the TATA-box, which might constitute one general mode of transcriptional activation by TAL effectors. Scrutinizing the predicted target sites of TALgetter, we propose several novel TAL effector virulence targets in rice and sweet orange. TAL-mediated induction of the candidates is supported by gene expression microarrays. Validity of these targets is also supported by functional analogy to known TAL effector targets, by an over-representation of TAL effector targets with similar function, or by a biological function related to pathogen infection. Hence, these predicted TAL effector virulence targets are promising candidates for studying the virulence function of TAL effectors. TALgetter is implemented as part of the open-source Java library Jstacs, and is freely available as a web-application and a command line program.
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Affiliation(s)
- Jan Grau
- Institute of Computer Science, Martin Luther University Halle-Wittenberg, Halle (Saale), Germany.
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854
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Djonović S, Urbach JM, Drenkard E, Bush J, Feinbaum R, Ausubel JL, Traficante D, Risech M, Kocks C, Fischbach MA, Priebe GP, Ausubel FM. Trehalose biosynthesis promotes Pseudomonas aeruginosa pathogenicity in plants. PLoS Pathog 2013; 9:e1003217. [PMID: 23505373 PMCID: PMC3591346 DOI: 10.1371/journal.ppat.1003217] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2012] [Accepted: 01/13/2013] [Indexed: 01/22/2023] Open
Abstract
Pseudomonas aeruginosa strain PA14 is a multi-host pathogen that infects plants, nematodes, insects, and vertebrates. Many PA14 factors are required for virulence in more than one of these hosts. Noting that plants have a fundamentally different cellular architecture from animals, we sought to identify PA14 factors that are specifically required for plant pathogenesis. We show that synthesis by PA14 of the disaccharide trehalose is required for pathogenesis in Arabidopsis, but not in nematodes, insects, or mice. In-frame deletion of two closely-linked predicted trehalose biosynthetic operons, treYZ and treS, decreased growth in Arabidopsis leaves about 50 fold. Exogenously co-inoculated trehalose, ammonium, or nitrate, but not glucose, sulfate, or phosphate suppressed the phenotype of the double ΔtreYZΔtreS mutant. Exogenous trehalose or ammonium nitrate does not suppress the growth defect of the double ΔtreYZΔtreS mutant by suppressing the plant defense response. Trehalose also does not function intracellularly in P. aeruginosa to ameliorate a variety of stresses, but most likely functions extracellularly, because wild-type PA14 rescued the in vivo growth defect of the ΔtreYZΔtreS in trans. Surprisingly, the growth defect of the double ΔtreYZΔtreS double mutant was suppressed by various Arabidopsis cell wall mutants that affect xyloglucan synthesis, including an xxt1xxt2 double mutant that completely lacks xyloglucan, even though xyloglucan mutants are not more susceptible to pathogens and respond like wild-type plants to immune elicitors. An explanation of our data is that trehalose functions to promote the acquisition of nitrogen-containing nutrients in a process that involves the xyloglucan component of the plant cell wall, thereby allowing P. aeruginosa to replicate in the intercellular spaces in a leaf. This work shows how P. aeruginosa, a multi-host opportunistic pathogen, has repurposed a highly conserved "house-keeping" anabolic pathway (trehalose biosynthesis) as a potent virulence factor that allows it to replicate in the intercellular environment of a leaf.
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Affiliation(s)
- Slavica Djonović
- Department of Molecular Biology, Massachusetts General Hospital, Boston, Massachusetts, United States of America
- Department of Genetics, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Jonathan M. Urbach
- Department of Molecular Biology, Massachusetts General Hospital, Boston, Massachusetts, United States of America
| | - Eliana Drenkard
- Department of Molecular Biology, Massachusetts General Hospital, Boston, Massachusetts, United States of America
- Department of Genetics, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Jenifer Bush
- Department of Molecular Biology, Massachusetts General Hospital, Boston, Massachusetts, United States of America
| | - Rhonda Feinbaum
- Department of Molecular Biology, Massachusetts General Hospital, Boston, Massachusetts, United States of America
- Department of Genetics, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Jonathan L. Ausubel
- Department of Molecular Biology, Massachusetts General Hospital, Boston, Massachusetts, United States of America
| | - David Traficante
- Division of Infectious Diseases, Department of Medicine, Brigham and Women's Hospital, Boston, Massachusetts, United States of America
| | - Martina Risech
- Division of Infectious Diseases, Department of Medicine, Brigham and Women's Hospital, Boston, Massachusetts, United States of America
| | - Christine Kocks
- Department of Molecular Biology, Massachusetts General Hospital, Boston, Massachusetts, United States of America
- Department of Genetics, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Michael A. Fischbach
- Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco, San Francisco, California, United States of America
| | - Gregory P. Priebe
- Division of Infectious Diseases, Department of Medicine, Brigham and Women's Hospital, Boston, Massachusetts, United States of America
- Division of Critical Care Medicine, Department of Anesthesiology, Perioperative and Pain Medicine, Boston Children's Hospital, Boston, Massachusetts, United States of America
| | - Frederick M. Ausubel
- Department of Molecular Biology, Massachusetts General Hospital, Boston, Massachusetts, United States of America
- Department of Genetics, Harvard Medical School, Boston, Massachusetts, United States of America
- * E-mail:
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855
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Grant MR, Kazan K, Manners JM. Exploiting pathogens' tricks of the trade for engineering of plant disease resistance: challenges and opportunities. Microb Biotechnol 2013; 6:212-22. [PMID: 23279915 PMCID: PMC3815916 DOI: 10.1111/1751-7915.12017] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2012] [Accepted: 11/17/2012] [Indexed: 12/01/2022] Open
Abstract
With expansion of our understanding of pathogen effector strategies and the multiplicity of their host targets, it is becoming evident that novel approaches to engineering broad-spectrum resistance need to be deployed. The increasing availability of high temporal gene expression data of a range of plant–microbe interactions enables the judicious choices of promoters to fine-tune timing and magnitude of expression under specified stress conditions. We can therefore contemplate engineering a range of transgenic lines designed to interfere with pathogen virulence strategies that target plant hormone signalling or deploy specific disease resistance genes. An advantage of such an approach is that hormonal signalling is generic so if this strategy is effective, it can be easily implemented in a range of crop species. Additionally, multiple re-wired lines can be crossed to develop more effective responses to pathogens.
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Affiliation(s)
- Murray R Grant
- College of Life and Environmental Sciences, University of Exeter, Exeter, Stocker Road, Exeter, EX4 4QD, UK.
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856
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Schornack S, Moscou MJ, Ward ER, Horvath DM. Engineering plant disease resistance based on TAL effectors. ANNUAL REVIEW OF PHYTOPATHOLOGY 2013; 51:383-406. [PMID: 23725472 DOI: 10.1146/annurev-phyto-082712-102255] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Transcription activator-like (TAL) effectors are encoded by plant-pathogenic bacteria and induce expression of plant host genes. TAL effectors bind DNA on the basis of a unique code that specifies binding of amino acid residues in repeat units to particular DNA bases in a one-to-one correspondence. This code can be used to predict binding sites of natural TAL effectors and to design novel synthetic DNA-binding domains for targeted genome manipulation. Natural mechanisms of resistance in plants against TAL effector-containing pathogens have given insights into new strategies for disease control.
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Affiliation(s)
- Sebastian Schornack
- Sainsbury Laboratory, University of Cambridge, Cambridge, CB2 1LR, United Kingdom
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857
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Maurino VG, Weber APM. Engineering photosynthesis in plants and synthetic microorganisms. JOURNAL OF EXPERIMENTAL BOTANY 2013; 64:743-51. [PMID: 23028016 DOI: 10.1093/jxb/ers263] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
Photosynthetic organisms, such as cyanobacteria, algae, and plants, sustain life on earth by converting light energy, water, and CO(2) into chemical energy. However, due to global change and a growing human population, arable land is becoming scarce and resources, including water and fertilizers, are becoming exhausted. It will therefore be crucial to design innovative strategies for sustainable plant production to maintain the food and energy bases of human civilization. Several different strategies for engineering improved photosynthesis in crop plants and introducing novel photosynthetic capacity into microorganisms have been reviewed.
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Affiliation(s)
- Veronica G Maurino
- Plant Molecular Physiology and Biotechnology, Institute of Plant Developmental and Molecular Biology, Center of Excellence on Plant Sciences (CEPLAS), Heinrich-Heine-University, Universitätsstrasse 1, D-40225 Düsseldorf, Germany
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858
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Ludewig F, Flügge UI. Role of metabolite transporters in source-sink carbon allocation. FRONTIERS IN PLANT SCIENCE 2013; 4:231. [PMID: 23847636 PMCID: PMC3698459 DOI: 10.3389/fpls.2013.00231] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/08/2013] [Accepted: 06/13/2013] [Indexed: 05/18/2023]
Abstract
Plants assimilate carbon dioxide during photosynthesis in chloroplasts. Assimilated carbon is subsequently allocated throughout the plant. Generally, two types of organs can be distinguished, mature green source leaves as net photoassimilate exporters, and net importers, the sinks, e.g., roots, flowers, small leaves, and storage organs like tubers. Within these organs, different tissue types developed according to their respective function, and cells of either tissue type are highly compartmentalized. Photoassimilates are allocated to distinct compartments of these tissues in all organs, requiring a set of metabolite transporters mediating this intercompartmental transfer. The general route of photoassimilates can be briefly described as follows. Upon fixation of carbon dioxide in chloroplasts of mesophyll cells, triose phosphates either enter the cytosol for mainly sucrose formation or remain in the stroma to form transiently stored starch which is degraded during the night and enters the cytosol as maltose or glucose to be further metabolized to sucrose. In both cases, sucrose enters the phloem for long distance transport or is transiently stored in the vacuole, or can be degraded to hexoses which also can be stored in the vacuole. In the majority of plant species, sucrose is actively loaded into the phloem via the apoplast. Following long distance transport, it is released into sink organs, where it enters cells as source of carbon and energy. In storage organs, sucrose can be stored, or carbon derived from sucrose can be stored as starch in plastids, or as oil in oil bodies, or - in combination with nitrogen - as protein in protein storage vacuoles and protein bodies. Here, we focus on transport proteins known for either of these steps, and discuss the implications for yield increase in plants upon genetic engineering of respective transporters.
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Affiliation(s)
- Frank Ludewig
- *Correspondence: Frank Ludewig, Botanical Institute II, Cologne Biocenter, University of Cologne, Zülpicher Str. 47b, 50674 Cologne, Germany e-mail:
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859
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Fan J, Jiang X, Hu Y, Si Y, Ding L, Wu W. A fluorescent double-network-structured hybrid nanogel as embeddable nanoglucometer for intracellular glucometry. Biomater Sci 2013; 1:421-433. [DOI: 10.1039/c2bm00162d] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
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860
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Senthil-Kumar M, Mysore KS. Nonhost resistance against bacterial pathogens: retrospectives and prospects. ANNUAL REVIEW OF PHYTOPATHOLOGY 2013; 51:407-27. [PMID: 23725473 DOI: 10.1146/annurev-phyto-082712-102319] [Citation(s) in RCA: 95] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Nonhost resistance is a broad-spectrum plant defense that provides immunity to all members of a plant species against all isolates of a microorganism that is pathogenic to other plant species. Upon landing on the surface of a nonhost plant species, a potential bacterial pathogen initially encounters preformed and, later, induced plant defenses. One of the initial defense responses from the plant is pathogen-associated molecular pattern (PAMP)-triggered immunity (PTI). Nonhost plants also have mechanisms to detect nonhost-pathogen effectors and can trigger a defense response referred to as effector-triggered immunity (ETI). This nonhost resistance response often results in a hypersensitive response (HR) at the infection site. This review provides an overview of these plant defense strategies. We enumerate plant genes that impart nonhost resistance and the bacterial counter-defense strategies. In addition, prospects for application of nonhost resistance to achieve broad-spectrum and durable resistance in crop plants are also discussed.
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Affiliation(s)
- Muthappa Senthil-Kumar
- Plant Biology Division, The Samuel Roberts Noble Foundation, Ardmore, Oklahoma 73402, USA.
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861
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Gjetting SK, Schulz A, Fuglsang AT. Perspectives for using genetically encoded fluorescent biosensors in plants. FRONTIERS IN PLANT SCIENCE 2013; 4:234. [PMID: 23874345 PMCID: PMC3709170 DOI: 10.3389/fpls.2013.00234] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/29/2013] [Accepted: 06/13/2013] [Indexed: 05/08/2023]
Abstract
Genetically encoded fluorescent biosensors have long proven to be excellent tools for quantitative live imaging, but sensor applications in plants have been lacking behind those in mammalian systems with respect to the variety of sensors and tissue types used. How can this be improved, and what can be expected for the use of genetically encoded fluorescent biosensors in plants in the future? In this review, we present a table of successful physiological experiments in plant tissue using fluorescent biosensors, and draw some conclusions about the specific challenges plant cell biologists are faced with and some of the ways they have been overcome so far.
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Affiliation(s)
- Sisse K. Gjetting
- Transport Biology Section, Department of Plant and Environmental Sciences, University of CopenhagenCopenhagen, Denmark
| | - Alexander Schulz
- Transport Biology Section, Department of Plant and Environmental Sciences, University of CopenhagenCopenhagen, Denmark
| | - Anja T. Fuglsang
- Transport Biology Section, Department of Plant and Environmental Sciences, University of CopenhagenCopenhagen, Denmark
- Center of Excellence for Membrane Pumps and Disease, PUMPKINAarhus, Denmark
- *Correspondence: Anja T. Fuglsang, Transport Biology Section, Department of Plant and Environmental Sciences, University of Copenhagen, Thorvaldsensvej 40, Copenhagen, DK-1871, Denmark e-mail:
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862
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Heinig U, Gutensohn M, Dudareva N, Aharoni A. The challenges of cellular compartmentalization in plant metabolic engineering. Curr Opin Biotechnol 2012; 24:239-46. [PMID: 23246154 DOI: 10.1016/j.copbio.2012.11.006] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2012] [Revised: 11/13/2012] [Accepted: 11/16/2012] [Indexed: 12/21/2022]
Abstract
The complex metabolic networks in plants are highly compartmentalized and biochemical steps of a single pathway can take place in multiple subcellular locations. Our knowledge regarding reactions and precursor compounds in the various cellular compartments has increased in recent years due to innovations in tracking the spatial distribution of proteins and metabolites. Nevertheless, to date only few studies have integrated subcellular localization criteria in metabolic engineering attempts. Here, we highlight the crucial factors for subcellular-localization-based strategies in plant metabolic engineering including substrate availability, enzyme targeting, the role of transporters, and multigene transfer approaches. The availability of compartmentalized metabolic network models for plants in the near future will greatly advance the integration of localization constraints in metabolic engineering experiments and aid in predicting their outcomes.
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Affiliation(s)
- Uwe Heinig
- Department of Plant Sciences, Weizmann Institute of Science, Rehovot 76100, Israel
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863
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Stitt M. Progress in understanding and engineering primary plant metabolism. Curr Opin Biotechnol 2012; 24:229-38. [PMID: 23219183 DOI: 10.1016/j.copbio.2012.11.002] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2012] [Revised: 10/29/2012] [Accepted: 11/05/2012] [Indexed: 01/07/2023]
Abstract
The maximum yield of crop plants depends on the efficiency of conversion of sunlight into biomass. This review summarises recent models that estimate energy conversion efficiency for successive steps in photosynthesis and metabolism. Photorespiration was identified as a major reason for energy loss during photosynthesis and strategies to modify or suppress photorespiration are presented. Energy loss during the conversion of photosynthate to biomass is also large but cannot be modelled as precisely due to incomplete knowledge about pathways and turnover and maintenance costs. Recent research on pathways involved in metabolite transport and interconversion in different organs, and recent insights into energy requirements linked to the production, maintenance and turnover of the apparatus for cellular growth and repair processes are discussed.
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Affiliation(s)
- Mark Stitt
- Max Planck Institute of Molecular Plant Physiology, Am Muehlenberg 1, 14474 Potsdam-Golm, Germany.
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864
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Faulkner C, Robatzek S. Plants and pathogens: putting infection strategies and defence mechanisms on the map. CURRENT OPINION IN PLANT BIOLOGY 2012; 15:699-707. [PMID: 22981427 DOI: 10.1016/j.pbi.2012.08.009] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/09/2012] [Revised: 08/20/2012] [Accepted: 08/22/2012] [Indexed: 06/01/2023]
Abstract
All plant organs are vulnerable to colonisation and molecular manipulation by microbes. When this interaction allows proliferation of the microbe at the expense of the host, the microbe can be described as a pathogen. In our attempts to understand the full nature of the interactions that occur between a potential pathogen and its host, various aspects of the molecular mechanisms of infection and defence have begun to be characterised. There is significant variation in these mechanisms. While previous research has examined plant-pathogen interactions with whole plant/organ resolution, the specificity of infection strategies and changes in both gene expression and protein localisation of immune receptors upon infection suggest there is much to be gained from examination of plant-microbe interactions at the cellular level.
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865
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Verdier V, Triplett LR, Hummel AW, Corral R, Cernadas RA, Schmidt CL, Bogdanove AJ, Leach JE. Transcription activator-like (TAL) effectors targeting OsSWEET genes enhance virulence on diverse rice (Oryza sativa) varieties when expressed individually in a TAL effector-deficient strain of Xanthomonas oryzae. THE NEW PHYTOLOGIST 2012; 196:1197-1207. [PMID: 23078195 DOI: 10.1111/j.1469-8137.2012.04367.x] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/03/2012] [Accepted: 08/31/2012] [Indexed: 05/24/2023]
Abstract
Genomes of the rice (Oryza sativa) xylem and mesophyll pathogens Xanthomonas oryzae pv. oryzae (Xoo) and pv. oryzicola (Xoc) encode numerous secreted transcription factors called transcription activator-like (TAL) effectors. In a few studied rice varieties, some of these contribute to virulence by activating corresponding host susceptibility genes. Some activate disease resistance genes. The roles of X. oryzae TAL effectors in diverse rice backgrounds, however, are poorly understood. Xoo TAL effectors that promote infection by activating SWEET sucrose transporter genes were expressed in TAL effector-deficient X. oryzae strain X11-5A, and assessed in 21 rice varieties. Some were also tested in Xoc on variety Nipponbare. Several Xoc TAL effectors were tested in X11-5A on four rice varieties. Xoo TAL effectors enhanced X11-5A virulence on most varieties, but to varying extents depending on the effector and variety. SWEET genes were activated in all tested varieties, but increased virulence did not correlate with activation level. SWEET activators also enhanced Xoc virulence on Nipponbare. Xoc TAL effectors did not alter X11-5A virulence. SWEET-targeting TAL effectors contribute broadly and non-tissue-specifically to virulence in rice, and their function is affected by host differences besides target sequences. Further, the utility of X11-5A for characterizing individual TAL effectors in rice was established.
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Affiliation(s)
- Valérie Verdier
- Department of Bioagricultural Sciences and Pest Management and Program in Plant Molecular Biology, Colorado State University, Fort Collins, CO, 80523-1177, USA
- Institut de Recherche pour le Développement, UMR Résistance des Plantes aux Bioagresseurs, IRD-CIRAD-UM2, 911 Avenue Agropolis BP 64501, 34394, Montpellier Cedex 5, France
| | - Lindsay R Triplett
- Department of Bioagricultural Sciences and Pest Management and Program in Plant Molecular Biology, Colorado State University, Fort Collins, CO, 80523-1177, USA
| | - Aaron W Hummel
- Department of Plant Pathology and Microbiology, Iowa State University, Ames, IA, 50011, USA
| | - Rene Corral
- Department of Bioagricultural Sciences and Pest Management and Program in Plant Molecular Biology, Colorado State University, Fort Collins, CO, 80523-1177, USA
| | - R Andres Cernadas
- Department of Plant Pathology and Microbiology, Iowa State University, Ames, IA, 50011, USA
- Department of Plant Pathology and Plant-Microbe Biology, Cornell University, Ithaca, NY, 14850, USA
| | - Clarice L Schmidt
- Department of Plant Pathology and Microbiology, Iowa State University, Ames, IA, 50011, USA
| | - Adam J Bogdanove
- Department of Plant Pathology and Microbiology, Iowa State University, Ames, IA, 50011, USA
- Department of Plant Pathology and Plant-Microbe Biology, Cornell University, Ithaca, NY, 14850, USA
| | - Jan E Leach
- Department of Bioagricultural Sciences and Pest Management and Program in Plant Molecular Biology, Colorado State University, Fort Collins, CO, 80523-1177, USA
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866
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Lapin D, Meyer RC, Takahashi H, Bechtold U, Van den Ackerveken G. Broad-spectrum resistance of Arabidopsis C24 to downy mildew is mediated by different combinations of isolate-specific loci. THE NEW PHYTOLOGIST 2012; 196:1171-1181. [PMID: 23025493 DOI: 10.1111/j.1469-8137.2012.04344.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/28/2012] [Accepted: 08/17/2012] [Indexed: 05/09/2023]
Abstract
Most natural Arabidopsis thaliana accessions are susceptible to one or more isolates of the downy mildew pathogen Hyaloperonospora arabidopsidis (Hpa). However, Arabidopsis C24 has proved resistant to all Hpa isolates tested so far. Here we describe the complex genetic basis of broad-spectrum resistance in C24. The genetics of C24 resistance to three Hpa isolates was analyzed by segregation analysis and quantitative trait locus (QTL) mapping on recombinant inbred and introgression lines. Resistance of C24 to downy mildew was found to be a multigenic trait with complex inheritance. Many identified resistance loci were isolate-specific and located on different chromosomes. Among the C24 resistance QTLs, we found dominant, codominant and recessive loci. Interestingly, none of the identified loci significantly contributed to resistance against all three tested Hpa isolates. Our study demonstrates that broad-spectrum resistance of Arabidopsis C24 to Hpa is based on different combinations of multiple isolate-specific loci. The identified quantitative resistance loci are particularly promising as they provide an important basis for the cloning of susceptibility- and immunity-related genes.
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Affiliation(s)
- Dmitry Lapin
- Plant-Microbe Interactions, Department of Biology, Utrecht University, Padualaan 8, 3584, CH, Utrecht, the Netherlands
| | - Rhonda C Meyer
- Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), Corrensstraße 3, 06466, Gatersleben, Germany
| | - Hideki Takahashi
- Graduate School of Agricultural Science, Tohoku University, 1-1 Tsutsumidori-Amamiyamachi Aoba-ku, 987-8555, Sendai, Miyagi, Japan
| | - Ulrike Bechtold
- School of Biological Sciences, University of Essex, Wivenhoe Park, Colchester, CO4 3SQ, UK
| | - Guido Van den Ackerveken
- Plant-Microbe Interactions, Department of Biology, Utrecht University, Padualaan 8, 3584, CH, Utrecht, the Netherlands
- Centre for BioSystems Genomics, Wageningen, the Netherlands
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867
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Heptahelical protein PQLC2 is a lysosomal cationic amino acid exporter underlying the action of cysteamine in cystinosis therapy. Proc Natl Acad Sci U S A 2012; 109:E3434-43. [PMID: 23169667 DOI: 10.1073/pnas.1211198109] [Citation(s) in RCA: 126] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Cystinosin, the lysosomal cystine exporter defective in cystinosis, is the founding member of a family of heptahelical membrane proteins related to bacteriorhodopsin and characterized by a duplicated motif termed the PQ loop. PQ-loop proteins are more frequent in eukaryotes than in prokaryotes; except for cystinosin, their molecular function remains elusive. In this study, we report that three yeast PQ-loop proteins of unknown function, Ypq1, Ypq2, and Ypq3, localize to the vacuolar membrane and are involved in homeostasis of cationic amino acids (CAAs). We also show that PQLC2, a mammalian PQ-loop protein closely related to yeast Ypq proteins, localizes to lysosomes and catalyzes a robust, electrogenic transport that is selective for CAAs and strongly activated at low extracytosolic pH. Heterologous expression of PQLC2 at the yeast vacuole rescues the resistance phenotype of an ypq2 mutant to canavanine, a toxic analog of arginine efficiently transported by PQLC2. Finally, PQLC2 transports a lysine-like mixed disulfide that serves as a chemical intermediate in cysteamine therapy of cystinosis, and PQLC2 gene silencing trapped this intermediate in cystinotic cells. We conclude that PQLC2 and Ypq1-3 proteins are lysosomal/vacuolar exporters of CAAs and suggest that small-molecule transport is a conserved feature of the PQ-loop protein family, in agreement with its distant similarity to SWEET sugar transporters and to the mitochondrial pyruvate carrier. The elucidation of PQLC2 function may help improve cysteamine therapy. It may also clarify the origin of CAA abnormalities in Batten disease.
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868
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Deslandes L, Rivas S. Catch me if you can: bacterial effectors and plant targets. TRENDS IN PLANT SCIENCE 2012; 17:644-55. [PMID: 22796464 DOI: 10.1016/j.tplants.2012.06.011] [Citation(s) in RCA: 199] [Impact Index Per Article: 16.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/06/2012] [Revised: 06/18/2012] [Accepted: 06/20/2012] [Indexed: 05/18/2023]
Abstract
To suppress plant defense responses and favor the establishment of disease, phytopathogenic bacteria have gained the ability to deliver effector molecules inside host cells through the type III secretion system. Inside plant cells, bacterial effector proteins may be addressed to different subcellular compartments where they are able to manipulate a variety of host cellular components and molecular functions. Here we review how the recent identification and functional characterization of plant components targeted by bacterial effectors, as well as the discovery of new pathogen recognition capabilities evolved in turn by plant cells, have significantly contributed to further our knowledge about the intricate molecular interactions that are established between plants and their invading bacteria.
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Affiliation(s)
- Laurent Deslandes
- INRA, Laboratoire des Interactions Plantes-Microorganismes, UMR441, F-31326 Castanet-Tolosan, France
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869
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Bapaume L, Reinhardt D. How membranes shape plant symbioses: signaling and transport in nodulation and arbuscular mycorrhiza. FRONTIERS IN PLANT SCIENCE 2012; 3:223. [PMID: 23060892 PMCID: PMC3464683 DOI: 10.3389/fpls.2012.00223] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/03/2012] [Accepted: 09/14/2012] [Indexed: 05/19/2023]
Abstract
As sessile organisms that cannot evade adverse environmental conditions, plants have evolved various adaptive strategies to cope with environmental stresses. One of the most successful adaptations is the formation of symbiotic associations with beneficial microbes. In these mutualistic interactions the partners exchange essential nutrients and improve their resistance to biotic and abiotic stresses. In arbuscular mycorrhiza (AM) and in root nodule symbiosis (RNS), AM fungi and rhizobia, respectively, penetrate roots and accommodate within the cells of the plant host. In these endosymbiotic associations, both partners keep their plasma membranes intact and use them to control the bidirectional exchange of signaling molecules and nutrients. Intracellular accommodation requires the exchange of symbiotic signals and the reprogramming of both interacting partners. This involves fundamental changes at the level of gene expression and of the cytoskeleton, as well as of organelles such as plastids, endoplasmic reticulum (ER), and the central vacuole. Symbiotic cells are highly compartmentalized and have a complex membrane system specialized for the diverse functions in molecular communication and nutrient exchange. Here, we discuss the roles of the different cellular membrane systems and their symbiosis-related proteins in AM and RNS, and we review recent progress in the analysis of membrane proteins involved in endosymbiosis.
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Affiliation(s)
| | - Didier Reinhardt
- Department of Biology, University of FribourgFribourg, Switzerland
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870
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Weber APM, Bräutigam A. The role of membrane transport in metabolic engineering of plant primary metabolism. Curr Opin Biotechnol 2012; 24:256-62. [PMID: 23040411 DOI: 10.1016/j.copbio.2012.09.010] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2012] [Revised: 09/18/2012] [Accepted: 09/18/2012] [Indexed: 11/29/2022]
Abstract
Plant cells are highly compartmentalized and so is their metabolism. Most metabolic pathways are distributed across several cellular compartments, which requires the activities of membrane transporters to catalyze the flux of precursors, intermediates, and end products between compartments. Metabolites such as sucrose and amino acids have to be transported between cells and tissues to supply, for example, metabolism in developing seeds or fruits with precursors and energy. Thus, rational engineering of plant primary metabolism requires a detailed and molecular understanding of the membrane transporters. This knowledge however still lags behind that of soluble enzymes. Recent advances include the molecular identification of pyruvate transporters at the chloroplast and mitochondrial membranes and of a new class of transporters called SWEET that are involved in the release of sugars to the apoplast.
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Affiliation(s)
- Andreas P M Weber
- Institute for Plant Biochemistry and Center of Excellence on Plant Sciences (CEPLAS), Heinrich-Heine-University, Geb. 26.03.01, Universitätsstrasse 1, D-40225 Düsseldorf, Germany.
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871
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The emerging field of transport engineering of plant specialized metabolites. Curr Opin Biotechnol 2012; 24:263-70. [PMID: 23040969 DOI: 10.1016/j.copbio.2012.09.006] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2012] [Revised: 09/05/2012] [Accepted: 09/05/2012] [Indexed: 01/30/2023]
Abstract
From a biotechnological perspective transport processes represent attractive targets for modulation of metabolite levels and are the foundation for the emerging field of transport engineering. Potential applications of transport engineering include control of metabolite accumulation in a tissue-specific manner in crop plants as well as increased yields of commercially valuable compounds produced in synthetic biology approaches. Within specialized metabolism, recent advances include identification of not only vacuolar but now also plasma membrane-localized transporters and neo-functionalization of members of primary metabolite transporter families to include specific roles in transport of specialized metabolites. As glucosinolates are specialized metabolites of the model plant Arabidopsis, glucosinolate transport processes emerge as a model system for studying transport of specialized metabolites.
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872
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Haferkamp I, Linka N. Functional expression and characterisation of membrane transport proteins. PLANT BIOLOGY (STUTTGART, GERMANY) 2012; 14:675-90. [PMID: 22639981 DOI: 10.1111/j.1438-8677.2012.00591.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Membrane transporters set the framework organising the complexity of plant metabolism in cells, tissues and organisms. Their substrate specificity and controlled activity in different cells is a crucial part for plant metabolism to run pathways in concert. Transport proteins catalyse the uptake and exchange of ions, substrates, intermediates, products and cofactors across membranes. Given the large number of metabolites, a wide spectrum of transporters is required. The vast majority of in silico annotated membrane transporters in plant genomes, however, has not yet been functionally characterised. Hence, to understand the metabolic network as a whole, it is important to understand how transporters connect and control the metabolic pathways of plant cells. Heterologous expression and in vitro activity studies of recombinant transport proteins have highly improved their functional analysis in the last two decades. This review provides a comprehensive overview of the recent advances in membrane protein expression and functional characterisation using various host systems and transport assays.
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Affiliation(s)
- I Haferkamp
- Plant Physiology, Technical University of Kaiserslautern, Kaiserslautern, Germany Plant Biochemistry, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
| | - N Linka
- Plant Physiology, Technical University of Kaiserslautern, Kaiserslautern, Germany Plant Biochemistry, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
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873
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The in planta transcriptome of Ralstonia solanacearum: conserved physiological and virulence strategies during bacterial wilt of tomato. mBio 2012; 3:mBio.00114-12. [PMID: 22807564 PMCID: PMC3413399 DOI: 10.1128/mbio.00114-12] [Citation(s) in RCA: 115] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Plant xylem fluid is considered a nutrient-poor environment, but the bacterial wilt pathogen Ralstonia solanacearum is well adapted to it, growing to 108 to 109 CFU/g tomato stem. To better understand how R. solanacearum succeeds in this habitat, we analyzed the transcriptomes of two phylogenetically distinct R. solanacearum strains that both wilt tomato, strains UW551 (phylotype II) and GMI1000 (phylotype I). We profiled bacterial gene expression at ~6 × 108 CFU/ml in culture or in plant xylem during early tomato bacterial wilt pathogenesis. Despite phylogenetic differences, these two strains expressed their 3,477 common orthologous genes in generally similar patterns, with about 12% of their transcriptomes significantly altered in planta versus in rich medium. Several primary metabolic pathways were highly expressed during pathogenesis. These pathways included sucrose uptake and catabolism, and components of these pathways were encoded by genes in the scrABY cluster. A UW551 scrA mutant was significantly reduced in virulence on resistant and susceptible tomato as well as on potato and the epidemiologically important weed host Solanum dulcamara. Functional scrA contributed to pathogen competitive fitness during colonization of tomato xylem, which contained ~300 µM sucrose. scrA expression was induced by sucrose, but to a much greater degree by growth in planta. Unexpectedly, 45% of the genes directly regulated by HrpB, the transcriptional activator of the type 3 secretion system (T3SS), were upregulated in planta at high cell densities. This result modifies a regulatory model based on bacterial behavior in culture, where this key virulence factor is repressed at high cell densities. The active transcription of these genes in wilting plants suggests that T3SS has a biological role throughout the disease cycle. Ralstonia solanacearum is a widespread plant pathogen that causes bacterial wilt disease. It inflicts serious crop losses on tropical farmers, with major economic and human consequences. It is also a model for the many destructive microbes that colonize the water-conducting plant xylem tissue, which is low in nutrients and oxygen. We extracted bacteria from infected tomato plants and globally identified the biological functions that R. solanacearum expresses during plant pathogenesis. This revealed the unexpected presence of sucrose in tomato xylem fluid and the pathogen’s dependence on host sucrose for virulence on tomato, potato, and the common weed bittersweet nightshade. Further, R. solanacearum was highly responsive to the plant environment, expressing several metabolic and virulence functions quite differently in the plant than in pure culture. These results reinforce the utility of studying pathogens in interaction with hosts and suggest that selecting for reduced sucrose levels could generate wilt-resistant crops.
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874
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Petre B, Morin E, Tisserant E, Hacquard S, Da Silva C, Poulain J, Delaruelle C, Martin F, Rouhier N, Kohler A, Duplessis S. RNA-Seq of early-infected poplar leaves by the rust pathogen Melampsora larici-populina uncovers PtSultr3;5, a fungal-induced host sulfate transporter. PLoS One 2012; 7:e44408. [PMID: 22952974 PMCID: PMC3431362 DOI: 10.1371/journal.pone.0044408] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2012] [Accepted: 08/02/2012] [Indexed: 02/03/2023] Open
Abstract
Biotroph pathogens establish intimate interactions with their hosts that are conditioned by the successful secretion of effectors in infected tissues and subsequent manipulation of host physiology. The identification of early-expressed pathogen effectors and early-modulated host functions is currently a major goal to understand the molecular basis of biotrophy. Here, we report the 454-pyrosequencing transcriptome analysis of early stages of poplar leaf colonization by the rust fungus Melampsora larici-populina. Among the 841,301 reads considered for analysis, 616,879 and 649 were successfully mapped to Populus trichocarpa and M. larici-populina genome sequences, respectively. From a methodological aspect, these results indicate that this single approach is not appropriate to saturate poplar transcriptome and to follow transcript accumulation of the pathogen. We identified 19 pathogen transcripts encoding early-expressed small-secreted proteins representing candidate effectors of interest for forthcoming studies. Poplar RNA-Seq data were validated by oligoarrays and quantitatively analysed, which revealed a highly stable transcriptome with a single transcript encoding a sulfate transporter (herein named PtSultr3;5, POPTR_0006s16150) showing a dramatic increase upon colonization by either virulent or avirulent M. larici-populina strains. Perspectives connecting host sulfate transport and biotrophic lifestyle are discussed.
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Affiliation(s)
- Benjamin Petre
- Unité Mixte de Recherche 1136 ‘Interactions Arbres/Microorganismes’, INRA (Institut National de la Recherche Agronomique)/Université de Lorraine, Centre INRA de Nancy, Champenoux, France
| | - Emmanuelle Morin
- Unité Mixte de Recherche 1136 ‘Interactions Arbres/Microorganismes’, INRA (Institut National de la Recherche Agronomique)/Université de Lorraine, Centre INRA de Nancy, Champenoux, France
| | - Emilie Tisserant
- Unité Mixte de Recherche 1136 ‘Interactions Arbres/Microorganismes’, INRA (Institut National de la Recherche Agronomique)/Université de Lorraine, Centre INRA de Nancy, Champenoux, France
| | - Stéphane Hacquard
- Unité Mixte de Recherche 1136 ‘Interactions Arbres/Microorganismes’, INRA (Institut National de la Recherche Agronomique)/Université de Lorraine, Centre INRA de Nancy, Champenoux, France
| | | | - Julie Poulain
- CEA-Genoscope, Centre National de Séquençage, Evry, France
| | - Christine Delaruelle
- Unité Mixte de Recherche 1136 ‘Interactions Arbres/Microorganismes’, INRA (Institut National de la Recherche Agronomique)/Université de Lorraine, Centre INRA de Nancy, Champenoux, France
| | - Francis Martin
- Unité Mixte de Recherche 1136 ‘Interactions Arbres/Microorganismes’, INRA (Institut National de la Recherche Agronomique)/Université de Lorraine, Centre INRA de Nancy, Champenoux, France
| | - Nicolas Rouhier
- Unité Mixte de Recherche 1136 ‘Interactions Arbres/Microorganismes’, INRA (Institut National de la Recherche Agronomique)/Université de Lorraine, Centre INRA de Nancy, Champenoux, France
| | - Annegret Kohler
- Unité Mixte de Recherche 1136 ‘Interactions Arbres/Microorganismes’, INRA (Institut National de la Recherche Agronomique)/Université de Lorraine, Centre INRA de Nancy, Champenoux, France
| | - Sébastien Duplessis
- Unité Mixte de Recherche 1136 ‘Interactions Arbres/Microorganismes’, INRA (Institut National de la Recherche Agronomique)/Université de Lorraine, Centre INRA de Nancy, Champenoux, France
- * E-mail:
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875
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Göhre V, Jones AME, Sklenář J, Robatzek S, Weber APM. Molecular crosstalk between PAMP-triggered immunity and photosynthesis. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2012; 25:1083-92. [PMID: 22550958 DOI: 10.1094/mpmi-11-11-0301] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
The innate immune system allows plants to respond to potential pathogens in an appropriate manner while minimizing damage and energy costs. Photosynthesis provides a sustained energy supply and, therefore, has to be integrated into the defense against pathogens. Although changes in photosynthetic activity during infection have been described, a detailed and conclusive characterization is lacking. Here, we addressed whether activation of early defense responses by pathogen-associated molecular patterns (PAMPs) triggers changes in photosynthesis. Using proteomics and chlorophyll fluorescence measurements, we show that activation of defense by PAMPs leads to a rapid decrease in nonphotochemical quenching (NPQ). Conversely, NPQ also influences several responses of PAMP-triggered immunity. In a mutant impaired in NPQ, apoplastic reactive oxygen species production is enhanced and defense gene expression is differentially affected. Although induction of the early defense markers WRKY22 and WRKY29 is enhanced, induction of the late markers PR1 and PR5 is completely abolished. We propose that regulation of NPQ is an intrinsic component of the plant's defense program.
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Affiliation(s)
- Vera Göhre
- Heinrich-Heine University, Dusseldorf, Germany.
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876
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Fan J, Doerner P. Genetic and molecular basis of nonhost disease resistance: complex, yes; silver bullet, no. CURRENT OPINION IN PLANT BIOLOGY 2012; 15:400-6. [PMID: 22445191 DOI: 10.1016/j.pbi.2012.03.001] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/02/2012] [Revised: 02/24/2012] [Accepted: 03/01/2012] [Indexed: 05/20/2023]
Abstract
Nonhost resistance (NHR), in which a successful pathogen on some plants fails to overcome host barriers on others, has attracted much attention owing to its potential for robust crop improvement. Recent advances reveal that a multitude of underlying mechanisms contribute to NHR, ranging from components shared with recognition-based defenses up to recessive susceptibility factors involved in plant primary metabolism. Most NHR appears multi-factorial and quantitative. This implies that there is no single, 'silver bullet' NHR mechanism that can be used to broadly restrict pathogens in many or all crops.
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Affiliation(s)
- Jun Fan
- Department of Plant Pathology, China Agricultural University, Beijing 100193, China.
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877
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Feng F, Zhou JM. Plant-bacterial pathogen interactions mediated by type III effectors. CURRENT OPINION IN PLANT BIOLOGY 2012; 15:469-76. [PMID: 22465133 DOI: 10.1016/j.pbi.2012.03.004] [Citation(s) in RCA: 151] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/21/2012] [Accepted: 03/06/2012] [Indexed: 05/06/2023]
Abstract
Effectors secreted by the bacterial type III system play a central role in the interaction between Gram-negative bacterial pathogens and their host plants. Recent advances in the effector studies have helped cementing several key concepts concerning bacterial pathogenesis, plant immunity, and plant-pathogen co-evolution. Type III effectors use a variety of biochemical mechanisms to target specific host proteins or DNA for pathogenesis. The identifications of their host targets led to the identification of novel components of plant innate immune system. Key modules of plant immune signaling pathways such as immune receptor complexes and MAPK cascades have emerged as a major battle ground for host-pathogen adaptation. These modules are attacked by multiple type III effectors, and some components of these modules have evolved to actively sense the effectors and trigger immunity.
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Affiliation(s)
- Feng Feng
- State Key Laboratory of Plant Genomics and National Center for Plant Gene Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China
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878
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Rafiqi M, Ellis JG, Ludowici VA, Hardham AR, Dodds PN. Challenges and progress towards understanding the role of effectors in plant-fungal interactions. CURRENT OPINION IN PLANT BIOLOGY 2012; 15:477-82. [PMID: 22658704 DOI: 10.1016/j.pbi.2012.05.003] [Citation(s) in RCA: 78] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/15/2012] [Revised: 05/07/2012] [Accepted: 05/07/2012] [Indexed: 05/04/2023]
Abstract
Both mutualistic and biotrophic pathogenic fungi rely on living host plants for growth and reproduction and must modify host cell structure and function for successful infection. The deployment of a diverse set of secreted virulence determinants referred to as 'effectors', many of which are directly delivered into the host cell, is postulated to be the key to host infection. This review provides a snapshot of the current progress in fungal effector biology. Recent genome sequencing of rust and powdery mildew obligate biotrophs has provided insight into the repertoires of potential effectors of these highly specialised pathogens. Identification of the first host-translocated effectors from mutualistic fungi has revealed that these fungi also manipulate host cells through effectors. The biological activities of some fungal effectors are just beginning to be revealed, while much uncertainty still surrounds the mechanisms of transport into host cells.
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Affiliation(s)
- Maryam Rafiqi
- Institute of Phytopathology and Applied Zoology, Research Centre for BioSystems, LandUse, and Nutrition, Justus Liebig University, Giessen, Germany
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879
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Wu J, Yu H, Dai H, Mei W, Huang X, Zhu S, Peng M. Metabolite profiles of rice cultivars containing bacterial blight-resistant genes are distinctive from susceptible rice. Acta Biochim Biophys Sin (Shanghai) 2012; 44:650-9. [PMID: 22687573 DOI: 10.1093/abbs/gms043] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The metabolic changes of bacterial blight-resistant line C418/Xa23 generated by molecular marker-assisted selection (n= 12), transgenic variety C418-Xa21 generated by using the Agrobacterium-mediated system (n= 12), and progenitor cultivar C418 (n= 12) were monitored using gas chromatography/mass spectrometry. The validation, discrimination, and establishment of correlative relationships between metabolite signals were performed by cluster analysis, principal component analysis, and partial least squares-discriminant analysis. Significant and unintended changes were observed in 154 components in C418/Xa23 and 48 components in C418-Xa21 compared with C418 (P< 0.05, Fold change > 2.0). The most significant decreases detected (P< 0.001) in both C418/Xa23 and C418-Xa21 were in three amino acids: glycine, tyrosine, and alanine, and four identified metabolites: malic acid, ferulic acid, succinic acid, and glycerol. Linoleic acid was increased specifically in C418/Xa23 which was derived from traditional breeding. This line, possessing a distinctive metabolite profile as a positive control, shows more differences vs. the parental than the transgenic line. Only succinic acid that falls outside the boundaries of natural variability between the two non-transgenic varieties C418 and C418/Xa23 should be further investigated with respect to safety or nutritional impact.
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Affiliation(s)
- Jiao Wu
- Institute of Tropic Bioscience and Biotechnology, Chinese Academy of Tropic Agricultural Sciences, Haikou 571101, China
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880
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Baker RF, Leach KA, Braun DM. SWEET as sugar: new sucrose effluxers in plants. MOLECULAR PLANT 2012; 5:766-8. [PMID: 22815540 DOI: 10.1093/mp/sss054] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Affiliation(s)
- R Frank Baker
- Division of Biological Sciences, Missouri Maize Center, University of Missouri, Columbia, MO 65211, USA
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881
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Doidy J, Grace E, Kühn C, Simon-Plas F, Casieri L, Wipf D. Sugar transporters in plants and in their interactions with fungi. TRENDS IN PLANT SCIENCE 2012; 17:413-22. [PMID: 22513109 DOI: 10.1016/j.tplants.2012.03.009] [Citation(s) in RCA: 174] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/16/2011] [Revised: 03/06/2012] [Accepted: 03/17/2012] [Indexed: 05/18/2023]
Abstract
Sucrose and monosaccharide transporters mediate long distance transport of sugar from source to sink organs and constitute key components for carbon partitioning at the whole plant level and in interactions with fungi. Even if numerous families of plant sugar transporters are defined; efflux capacities, subcellular localization and association to membrane rafts have only been recently reported. On the fungal side, the investigation of sugar transport mechanisms in mutualistic and pathogenic interactions is now emerging. Here, we review the essential role of sugar transporters for distribution of carbohydrates inside plant cells, as well as for plant-fungal interaction functioning. Altogether these data highlight the need for a better comprehension of the mechanisms underlying sugar exchanges between fungi and their host plants.
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Affiliation(s)
- Joan Doidy
- UMR INRA 1347, Agrosup, Université de Bourgogne, Agroécologie, Pôle Interactions Plantes Microorganismes ERL CNRS 6300, BP 86510, 21065 Dijon Cedex, France
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882
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Yin H, Yan B, Sun J, Jia P, Zhang Z, Yan X, Chai J, Ren Z, Zheng G, Liu H. Graft-union development: a delicate process that involves cell-cell communication between scion and stock for local auxin accumulation. JOURNAL OF EXPERIMENTAL BOTANY 2012; 63:4219-32. [PMID: 22511803 PMCID: PMC3398452 DOI: 10.1093/jxb/ers109] [Citation(s) in RCA: 89] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/05/2011] [Revised: 03/15/2012] [Accepted: 03/19/2012] [Indexed: 05/18/2023]
Abstract
Grafting is an ancient cloning method that has been used widely for thousands of years in agricultural practices. Graft-union development is also an intricate process that involves substantial changes such as organ regeneration and genetic material exchange. However, the molecular mechanisms for graft-union development are still largely unknown. Here, a micrografting method that has been used widely in Arabidopsis was improved to adapt it a smooth procedure to facilitate sample analysis and to allow it to easily be applied to various dicotyledonous plants. The developmental stage of the graft union was characterized based on this method. Histological analysis suggested that the transport activities of vasculature were recovered at 3 days after grafting (dag) and that auxin modulated the vascular reconnection at 2 dag. Microarray data revealed a signal-exchange process between cells of the scion and stock at 1 dag, which re-established the communication network in the graft union. This process was concomitant with the clearing of cell debris, and both processes were initiated by a wound-induced programme. The results demonstrate the feasibility and potential power of investigating various plant developmental processes by this method, and represent a primary and significant step in interpretation of the molecular mechanisms underlying graft-union development.
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Affiliation(s)
| | | | | | | | | | | | | | | | | | - Heng Liu
- To whom correspondence should be addressed. E-mail:
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883
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Eom JS, Choi SB, Ward JM, Jeon JS. The mechanism of phloem loading in rice (Oryza sativa). Mol Cells 2012; 33:431-8. [PMID: 22453778 PMCID: PMC3887736 DOI: 10.1007/s10059-012-0071-9] [Citation(s) in RCA: 72] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2012] [Accepted: 03/09/2012] [Indexed: 01/03/2023] Open
Abstract
Carbohydrates, mainly sucrose, that are synthesized in source organs are transported to sink organs to support growth and development. Phloem loading of sucrose is a crucial step that drives long-distance transport by elevating hydrostatic pressure in the phloem. Three phloem loading strategies have been identified, two active mechanisms, apoplastic loading via sucrose transporters and symplastic polymer trapping, and one passive mechanism. The first two active loading mechanisms require metabolic energy, carbohydrate is loaded into the phloem against a concentration gradient. The passive process, diffusion, involves equilibration of sucrose and other metabolites between cells through plasmodesmata. Many higher plant species including Arabidopsis utilize the active loading mechanisms to increase carbohydrate in the phloem to higher concentrations than that in mesophyll cells. In contrast, recent data revealed that a large number of plants, especially woody species, load sucrose passively by maintaining a high concentration in mesophyll cells. However, it still remains to be determined how the worldwide important cereal crop, rice, loads sucrose into the phloem in source organs. Based on the literature and our results, we propose a potential strategy of phloem loading in rice. Elucidation of the phloem loading mechanism should improve our understanding of rice development and facilitate its manipulation towards the increase of crop productivity.
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Affiliation(s)
- Joon-Seob Eom
- Graduate School of Biotechnology and Crop Biotech Institute, Kyung Hee University, Yongin 446-701,
Korea
| | | | | | - Jong-Seong Jeon
- Graduate School of Biotechnology and Crop Biotech Institute, Kyung Hee University, Yongin 446-701,
Korea
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884
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Li C, Wei J, Lin Y, Chen H. Gene silencing using the recessive rice bacterial blight resistance gene xa13 as a new paradigm in plant breeding. PLANT CELL REPORTS 2012; 31:851-62. [PMID: 22218673 DOI: 10.1007/s00299-011-1206-8] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/09/2011] [Revised: 12/01/2011] [Accepted: 12/06/2011] [Indexed: 05/03/2023]
Abstract
Resistant germplasm resources are valuable for developing resistant varieties in agricultural production. However, recessive resistance genes are usually overlooked in hybrid breeding. Compared with dominant traits, however, they may confer resistance to different pathogenic races or pest biotypes with different mechanisms of action. The recessive rice bacterial blight resistance gene xa13, also involved in pollen development, has been cloned and its resistance mechanism has been recently characterized. This report describes the conversion of bacterial blight resistance mediated by the recessive xa13 gene into a dominant trait to facilitate its use in a breeding program. This was achieved by knockdown of the corresponding dominant allele Xa13 in transgenic rice using recently developed artificial microRNA technology. Tissue-specific promoters were used to exclude most of the expression of artificial microRNA in the anther to ensure that Xa13 functioned normally during pollen development. A battery of highly bacterial blight resistant transgenic plants with normal seed setting rates were acquired, indicating that highly specific gene silencing had been achieved. Our success with xa13 provides a paradigm that can be adapted to other recessive resistance genes.
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Affiliation(s)
- Changyan Li
- National Key Laboratory of Crop Genetic Improvement and National Centre of Plant Gene Research (Wuhan), Huazhong Agricultural University, Wuhan 430070, China
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885
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Okumoto S. Quantitative imaging using genetically encoded sensors for small molecules in plants. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2012; 70:108-17. [PMID: 22449046 DOI: 10.1111/j.1365-313x.2012.04910.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Quantitative imaging in live cells is a powerful method for monitoring the dynamics of biomolecules at an excellent spatio-temporal resolution. Such an approach, initially limited to a small number of substrates for which specific dyes were available, has become possible for a large number of biomolecules due to the development of genetically encoded, protein-based sensors. These sensors, which can be introduced into live cells through a transgenic approach, offer the benefits of quantitative imaging, with an extra advantage of non-invasiveness. In the past decade there has been a drastic expansion in the number of biomolecules for which genetically encoded sensors are available, and the functional properties of existing sensors are being improved at a dramatic pace. A number of technical improvements have now made the application of genetically encoded sensors in plants rather straightforward, and some of the sensors such as calcium indicator proteins have become standard analytical tools in many plant laboratories. The use of a handful of probes has already revealed an amazing specificity of cellular biomolecule dynamics in plants, which leads us to believe that there are many more discoveries to be made using genetically encoded sensors. In this short review, we will summarize the progress made in the past 15 years in the development in genetically encoded sensors, and highlight significant discoveries made in plant biology.
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Affiliation(s)
- Sakiko Okumoto
- Department of Plant Pathology, Physiology and Weed Science, Virginia Tech, Blacksburg, VA 24061, USA.
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886
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Shechner T, Britton JC, Pérez-Edgar K, Bar-Haim Y, Ernst M, Fox NA, Leibenluft E, Pine DS. Attention biases, anxiety, and development: toward or away from threats or rewards? Depress Anxiety 2012; 29:282-94. [PMID: 22170764 PMCID: PMC3489173 DOI: 10.1002/da.20914] [Citation(s) in RCA: 158] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/24/2011] [Revised: 09/13/2011] [Accepted: 09/16/2011] [Indexed: 01/06/2023] Open
Abstract
Research on attention provides a promising framework for studying anxiety pathophysiology and treatment. The study of attention biases appears particularly pertinent to developmental research, as attention affects learning and has down-stream effects on behavior. This review summarizes recent findings about attention orienting in anxiety, drawing on findings in recent developmental psychopathology and affective neuroscience research. These findings generate specific insights about both development and therapeutics. The review goes beyond a traditional focus on biased processing of threats and considers biased processing of rewards. Building on this work, we then turn to the treatment of pediatric anxiety, where manipulation of attention to threat and/or reward may serve a therapeutic role as a component of Attention Bias Modification Therapy.
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Affiliation(s)
- Tomer Shechner
- Section on Developmental Affective Neuroscience, The National Institute of Mental Health, Bethesda, Maryland 20892, USA.
| | | | | | - Yair Bar-Haim
- Department of Psychology, Tel Aviv University, Israel
| | - Monique Ernst
- The National Institute of Mental Health, Bethesda, MD, USA
| | - Nathan A. Fox
- Department of Human Development, University of Maryland, College Park, MD, USA
| | | | - Daniel S. Pine
- The National Institute of Mental Health, Bethesda, MD, USA
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887
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Albrecht U, Bowman KD. Transcriptional response of susceptible and tolerant citrus to infection with Candidatus Liberibacter asiaticus. PLANT SCIENCE : AN INTERNATIONAL JOURNAL OF EXPERIMENTAL PLANT BIOLOGY 2012; 185-186:118-30. [PMID: 22325873 DOI: 10.1016/j.plantsci.2011.09.008] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/21/2011] [Revised: 09/26/2011] [Accepted: 09/27/2011] [Indexed: 05/06/2023]
Abstract
Candidatus Liberibacter asiaticus (Las), a non-culturable phloem-limited bacterium, is the suspected causal agent of huanglongbing (HLB) in Florida. HLB is one of the most devastating diseases of citrus and no resistant cultivars have been identified to date, though tolerance has been observed in the genus Poncirus and some of its hybrids. This study compares transcriptional changes in tolerant US-897 (Citrus reticulata Blanco×Poncirus trifoliata L. Raf.) and susceptible 'Cleopatra' mandarin (C. reticulata) seedlings in response to infection with Las using the Affymetrix GeneChip citrus array, with the main objective of identifying genes associated with tolerance to HLB. Microarray analysis identified 326 genes which were significantly upregulated by at least 4-fold in the susceptible genotype, compared with only 17 genes in US-897. Exclusively upregulated in US-897 was a gene for a 2-oxoglutarate (2OG) and Fe(II)-dependant oxygenase, an important enzyme involved in the biosynthesis of plant secondary metabolites. More than eight hundred genes were expressed at much higher levels in US-897 independent of infection with Las. Among these, genes for a constitutive disease resistance protein (CDR1) were notable. The possible involvement of these and other detected genes in tolerance to HLB and their possible use for biotechnology are discussed.
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Affiliation(s)
- Ute Albrecht
- US Horticultural Research Laboratory, US Department of Agriculture, Agricultural Research Service, Fort Pierce, FL 34945, USA.
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888
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Wang K, Senthil-Kumar M, Ryu CM, Kang L, Mysore KS. Phytosterols play a key role in plant innate immunity against bacterial pathogens by regulating nutrient efflux into the apoplast. PLANT PHYSIOLOGY 2012; 158:1789-802. [PMID: 22298683 PMCID: PMC3320186 DOI: 10.1104/pp.111.189217] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/14/2011] [Accepted: 01/30/2012] [Indexed: 05/15/2023]
Abstract
Bacterial pathogens colonize a host plant by growing between the cells by utilizing the nutrients present in apoplastic space. While successful pathogens manipulate the plant cell membrane to retrieve more nutrients from the cell, the counteracting plant defense mechanism against nonhost pathogens to restrict the nutrient efflux into the apoplast is not clear. To identify the genes involved in nonhost resistance against bacterial pathogens, we developed a virus-induced gene-silencing-based fast-forward genetics screen in Nicotiana benthamiana. Silencing of N. benthamiana SQUALENE SYNTHASE, a key gene in phytosterol biosynthesis, not only compromised nonhost resistance to few pathovars of Pseudomonas syringae and Xanthomonas campestris, but also enhanced the growth of the host pathogen P. syringae pv tabaci by increasing nutrient efflux into the apoplast. An Arabidopsis (Arabidopsis thaliana) sterol methyltransferase mutant (sterol methyltransferase2) involved in sterol biosynthesis also compromised plant innate immunity against bacterial pathogens. The Arabidopsis cytochrome P450 CYP710A1, which encodes C22-sterol desaturase that converts β-sitosterol to stigmasterol, was dramatically induced upon inoculation with nonhost pathogens. An Arabidopsis Atcyp710A1 null mutant compromised both nonhost and basal resistance while overexpressors of AtCYP710A1 enhanced resistance to host pathogens. Our data implicate the involvement of sterols in plant innate immunity against bacterial infections by regulating nutrient efflux into the apoplast.
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Affiliation(s)
| | | | | | | | - Kirankumar S. Mysore
- Plant Biology Division, Samuel Roberts Noble Foundation, Ardmore, Oklahoma 73402
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889
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Moreau M, Degrave A, Vedel R, Bitton F, Patrit O, Renou JP, Barny MA, Fagard M. EDS1 contributes to nonhost resistance of Arabidopsis thaliana against Erwinia amylovora. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2012; 25:421-430. [PMID: 22316300 DOI: 10.1094/mpmi-05-11-0111] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Erwinia amylovora causes fire blight in rosaceous plants. In nonhost Arabidopsis thaliana, E. amylovora triggers necrotic symptoms associated with transient bacterial multiplication, suggesting either that A. thaliana lacks a susceptibility factor or that it actively restricts E. amylovora growth. Inhibiting plant protein synthesis at the time of infection led to an increase in necrosis and bacterial multiplication and reduced callose deposition, indicating that A. thaliana requires active protein synthesis to restrict E. amylovora growth. Analysis of the callose synthase-deficient pmr4-1 mutant indicated that lack of callose deposition alone did not lead to increased sensitivity to E. amylovora. Transcriptome analysis revealed that approximately 20% of the genes induced following E. amylovora infection are related to defense and signaling. Analysis of mutants affected in NDR1 and EDS1, two main components of the defense-gene activation observed, revealed that E. amylovora multiplied ten times more in the eds1-2 mutant than in the wild type but not in the ndr1-1 mutant. Analysis of mutants affected in three WRKY transcription factors showing EDS1-dependent activation identified WRKY46 and WRKY54 as positive regulators and WRKY70 as a negative regulator of defense against E. amylovora. Altogether, we show that EDS1 is a positive regulator of nonhost resistance against E. amylovora in A. thaliana and hypothesize that it controls the production of several effective defenses against E. amylovora through the action of WRKY46 and WRKY54, while WRKY70 acts as a negative regulator.
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890
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891
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Saudek V. Cystinosin, MPDU1, SWEETs and KDELR belong to a well-defined protein family with putative function of cargo receptors involved in vesicle trafficking. PLoS One 2012; 7:e30876. [PMID: 22363504 PMCID: PMC3281891 DOI: 10.1371/journal.pone.0030876] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2011] [Accepted: 12/22/2011] [Indexed: 12/26/2022] Open
Abstract
Classification of proteins into families based on remote homology often helps prediction of their biological function. Here we describe prediction of protein cargo receptors involved in vesicle formation and protein trafficking. Hidden Markov model profile-to-profile searches in protein databases using endoplasmic reticulum lumen protein retaining receptors (KDEL, Erd2) as query reveal a large and diverse family of proteins with seven transmembrane helices and common topology and, most likely, similar function. Their coding genes exist in all eukaryota and in several prokaryota. Some are responsible for metabolic diseases (cystinosis, congenital disorder of glycosylation), others are candidate genes for genetic disorders (cleft lip and palate, certain forms of cancer) or solute uptake and efflux (SWEETs) and many have not yet been assigned a function. Comparison with the properties of KDEL receptors suggests that the family members could be involved in protein trafficking and serve as cargo receptors. This prediction sheds new light on a range of biologically, medically and agronomically important proteins and could open the way to discovering the function of many genes not yet annotated. Experimental testing is suggested.
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Affiliation(s)
- Vladimir Saudek
- University of Cambridge Metabolic Research Labs, Institute of Metabolic Science, Addenbrooke's Hospital, Cambridge, United Kingdom.
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892
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Pseudomonas syringae type III effector repertoires: last words in endless arguments. Trends Microbiol 2012; 20:199-208. [PMID: 22341410 DOI: 10.1016/j.tim.2012.01.003] [Citation(s) in RCA: 157] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2011] [Revised: 12/20/2011] [Accepted: 01/04/2012] [Indexed: 01/10/2023]
Abstract
Many plant pathogens subvert host immunity by injecting compositionally diverse but functionally similar repertoires of cytoplasmic effector proteins. The bacterial pathogen Pseudomonas syringae is a model for exploring the functional structure of such repertoires. The pangenome of P. syringae encodes 57 families of effectors injected by the type III secretion system. Distribution of effector genes among phylogenetically diverse strains reveals a small set of core effectors targeting antimicrobial vesicle trafficking and a much larger set of variable effectors targeting kinase-based recognition processes. Complete disassembly of the 28-effector repertoire of a model strain and reassembly of a minimal functional repertoire reveals the importance of simultaneously attacking both processes. These observations, coupled with growing knowledge of effector targets in plants, support a model for coevolving molecular dialogs between effector repertoires and plant immune systems that emphasizes mutually-driven expansion of the components governing recognition.
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893
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Reeves PH, Ellis CM, Ploense SE, Wu MF, Yadav V, Tholl D, Chételat A, Haupt I, Kennerley BJ, Hodgens C, Farmer EE, Nagpal P, Reed JW. A regulatory network for coordinated flower maturation. PLoS Genet 2012; 8:e1002506. [PMID: 22346763 PMCID: PMC3276552 DOI: 10.1371/journal.pgen.1002506] [Citation(s) in RCA: 167] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2011] [Accepted: 12/11/2011] [Indexed: 11/19/2022] Open
Abstract
For self-pollinating plants to reproduce, male and female organ development must be coordinated as flowers mature. The Arabidopsis transcription factors AUXIN RESPONSE FACTOR 6 (ARF6) and ARF8 regulate this complex process by promoting petal expansion, stamen filament elongation, anther dehiscence, and gynoecium maturation, thereby ensuring that pollen released from the anthers is deposited on the stigma of a receptive gynoecium. ARF6 and ARF8 induce jasmonate production, which in turn triggers expression of MYB21 and MYB24, encoding R2R3 MYB transcription factors that promote petal and stamen growth. To understand the dynamics of this flower maturation regulatory network, we have characterized morphological, chemical, and global gene expression phenotypes of arf, myb, and jasmonate pathway mutant flowers. We found that MYB21 and MYB24 promoted not only petal and stamen development but also gynoecium growth. As well as regulating reproductive competence, both the ARF and MYB factors promoted nectary development or function and volatile sesquiterpene production, which may attract insect pollinators and/or repel pathogens. Mutants lacking jasmonate synthesis or response had decreased MYB21 expression and stamen and petal growth at the stage when flowers normally open, but had increased MYB21 expression in petals of older flowers, resulting in renewed and persistent petal expansion at later stages. Both auxin response and jasmonate synthesis promoted positive feedbacks that may ensure rapid petal and stamen growth as flowers open. MYB21 also fed back negatively on expression of jasmonate biosynthesis pathway genes to decrease flower jasmonate level, which correlated with termination of growth after flowers have opened. These dynamic feedbacks may promote timely, coordinated, and transient growth of flower organs.
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Affiliation(s)
- Paul H. Reeves
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
| | - Christine M. Ellis
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
| | - Sara E. Ploense
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
| | - Miin-Feng Wu
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
| | - Vandana Yadav
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
| | - Dorothea Tholl
- Department of Biological Sciences, Virginia Tech University, Blacksburg, Virginia, United States of America
| | - Aurore Chételat
- Department of Plant Molecular Biology, Biophore, University of Lausanne, Lausanne, Switzerland
| | - Ina Haupt
- Max-Planck Institute for Chemical Ecology, Jena, Germany
| | - Brian J. Kennerley
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
| | - Charles Hodgens
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
| | - Edward E. Farmer
- Department of Plant Molecular Biology, Biophore, University of Lausanne, Lausanne, Switzerland
- College of Science, King Saud University, Riyadh, Saudi Arabia
| | - Punita Nagpal
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
| | - Jason W. Reed
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
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894
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895
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Nerveless and gutsy: intestinal nutrient sensing from invertebrates to humans. Semin Cell Dev Biol 2012; 23:614-20. [PMID: 22248674 PMCID: PMC3712190 DOI: 10.1016/j.semcdb.2012.01.002] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2011] [Revised: 12/27/2011] [Accepted: 01/04/2012] [Indexed: 12/22/2022]
Abstract
The increasingly recognized role of gastrointestinal signals in the regulation of food intake, insulin production and peripheral nutrient storage has prompted a surge of interest in studying how the gastrointestinal tract senses and responds to nutritional information. Identification of metabolically important intestinal nutrient sensors could provide potential new drug targets for the treatment of diabetes, obesity and gastrointestinal disorders. From a more fundamental perspective, the study of intestinal chemosensation is revealing novel, non-neuronal modes of communication involving differentiated epithelial cells. It is also identifying signalling mechanisms downstream of not only canonical receptors but also nutrient transporters, thereby supporting a chemosensory role for “transceptors” in the intestine. This review describes known and proposed mechanisms of intestinal carbohydrate, protein and lipid sensing, best characterized in mammalian systems. It also highlights the potential of invertebrate model systems such as C. elegans and Drosophila melanogaster by summarizing known examples of molecular evolutionary conservation. Recently developed genetic tools in Drosophila, an emerging model system for the study of physiology and metabolism, allow the temporal, spatial and high-throughput manipulation of putative intestinal sensors. Hence, fruit flies may prove particularly suited to the study of the link between intestinal nutrient sensing and metabolic homeostasis.
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896
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Martinoia E, Meyer S, De Angeli A, Nagy R. Vacuolar transporters in their physiological context. ANNUAL REVIEW OF PLANT BIOLOGY 2012; 63:183-213. [PMID: 22404463 DOI: 10.1146/annurev-arplant-042811-105608] [Citation(s) in RCA: 152] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Vacuoles in vegetative tissues allow the plant surface to expand by accumulating energetically cheap inorganic osmolytes, and thereby optimize the plant for absorption of sunlight and production of energy by photosynthesis. Some specialized cells, such as guard cells and pulvini motor cells, exhibit rapid volume changes. These changes require the rapid release and uptake of ions and water by the vacuole and are a prerequisite for plant survival. Furthermore, seed vacuoles are important storage units for the nutrients required for early plant development. All of these fundamental processes rely on numerous vacuolar transporters. During the past 15 years, the transporters implicated in most aspects of vacuolar function have been identified and characterized. Vacuolar transporters appear to be integrated into a regulatory network that controls plant metabolism. However, little is known about the mode of action of these fundamental processes, and deciphering the underlying mechanisms remains a challenge for the future.
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Affiliation(s)
- Enrico Martinoia
- Institute of Plant Biology, University of Zurich, Zurich, Switzerland.
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897
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Okumoto S, Jones A, Frommer WB. Quantitative imaging with fluorescent biosensors. ANNUAL REVIEW OF PLANT BIOLOGY 2012; 63:663-706. [PMID: 22404462 DOI: 10.1146/annurev-arplant-042110-103745] [Citation(s) in RCA: 158] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Molecular activities are highly dynamic and can occur locally in subcellular domains or compartments. Neighboring cells in the same tissue can exist in different states. Therefore, quantitative information on the cellular and subcellular dynamics of ions, signaling molecules, and metabolites is critical for functional understanding of organisms. Mass spectrometry is generally used for monitoring ions and metabolites; however, its temporal and spatial resolution are limited. Fluorescent proteins have revolutionized many areas of biology-e.g., fluorescent proteins can report on gene expression or protein localization in real time-yet promoter-based reporters are often slow to report physiologically relevant changes such as calcium oscillations. Therefore, novel tools are required that can be deployed in specific cells and targeted to subcellular compartments in order to quantify target molecule dynamics directly. We require tools that can measure enzyme activities, protein dynamics, and biophysical processes (e.g., membrane potential or molecular tension) with subcellular resolution. Today, we have an extensive suite of tools at our disposal to address these challenges, including translocation sensors, fluorescence-intensity sensors, and Förster resonance energy transfer sensors. This review summarizes sensor design principles, provides a database of sensors for more than 70 different analytes/processes, and gives examples of applications in quantitative live cell imaging.
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Affiliation(s)
- Sakiko Okumoto
- Department of Plant Pathology, Physiology, and Weed Science, Virginia Tech, Blacksburg, VA 24061, USA
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898
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Abstract
Genetical genomics combines acquired high-throughput genomic data with genetic analysis. In this chapter, we discuss the application of genetical genomics for evolutionary studies, where new high-throughput molecular technologies are combined with mapping quantitative trait loci (QTL) on the genome in segregating populations.The recent explosion of high-throughput data--measuring thousands of proteins and metabolites, deep sequencing, chromatin, and methyl-DNA immunoprecipitation--allows the study of the genetic variation underlying quantitative phenotypes, together termed xQTL. At the same time, mining information is not getting easier. To deal with the sheer amount of information, powerful statistical tools are needed to analyze multidimensional relationships. In the context of evolutionary computational biology, a well-designed experiment may help dissect a complex evolutionary trait using proven statistical methods for associating phenotypical variation with genomic locations.Evolutionary expression QTL (eQTL) studies of the last years focus on gene expression adaptations, mapping the gene expression landscape, and, tentatively, eQTL networks. Here, we discuss the possibility of introducing an evolutionary prior, in the form of gene families displaying evidence of positive selection, and using that in the context of an eQTL experiment for elucidating host-pathogen protein-protein interactions. Through the example of an experimental design, we discuss the choice of xQTL platform, analysis methods, and scope of results. The resulting eQTL can be matched, resulting in putative interacting genes and their regulators. In addition, a prior may help distinguish QTL causality from reactivity, or independence of traits, by creating QTL networks.
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Affiliation(s)
- Pjotr Prins
- Laboratory of Nematology, Wageningen University, Wageningen, The Netherlands.
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899
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Wolfenstetter S, Wirsching P, Dotzauer D, Schneider S, Sauer N. Routes to the tonoplast: the sorting of tonoplast transporters in Arabidopsis mesophyll protoplasts. THE PLANT CELL 2012; 24:215-32. [PMID: 22253225 PMCID: PMC3289566 DOI: 10.1105/tpc.111.090415] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/12/2011] [Revised: 12/22/2011] [Accepted: 12/28/2011] [Indexed: 05/05/2023]
Abstract
Vacuoles perform a multitude of functions in plant cells, including the storage of amino acids and sugars. Tonoplast-localized transporters catalyze the import and release of these molecules. The mechanisms determining the targeting of these transporters to the tonoplast are largely unknown. Using the paralogous Arabidopsis thaliana inositol transporters INT1 (tonoplast) and INT4 (plasma membrane), we performed domain swapping and mutational analyses and identified a C-terminal di-leucine motif responsible for the sorting of higher plant INT1-type transporters to the tonoplast in Arabidopsis mesophyll protoplasts. We demonstrate that this motif can reroute other proteins, such as INT4, SUCROSE TRANSPORTER2 (SUC2), or SWEET1, to the tonoplast and that the position of the motif relative to the transmembrane helix is critical. Rerouted INT4 is functionally active in the tonoplast and complements the growth phenotype of an int1 mutant. In Arabidopsis plants defective in the β-subunit of the AP-3 adaptor complex, INT1 is correctly localized to the tonoplast, while sorting of the vacuolar sucrose transporter SUC4 is blocked in cis-Golgi stacks. Moreover, we demonstrate that both INT1 and SUC4 trafficking to the tonoplast is sensitive to brefeldin A. Our data show that plants possess at least two different Golgi-dependent targeting mechanisms for newly synthesized transporters to the tonoplast.
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Affiliation(s)
| | | | | | | | - Norbert Sauer
- Friedrich-Alexander-Universität Erlangen-Nürnberg, Molecular Plant Physiology and ECROPS (Erlangen Center of Plant Science), D-91058 Erlangen, Germany
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900
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Chang HS, Zhang C, Chang YH, Zhu J, Xu XF, Shi ZH, Zhang XL, Xu L, Huang H, Zhang S, Yang ZN. No primexine and plasma membrane undulation is essential for primexine deposition and plasma membrane undulation during microsporogenesis in Arabidopsis. PLANT PHYSIOLOGY 2012; 158:264-72. [PMID: 22100644 PMCID: PMC3252091 DOI: 10.1104/pp.111.184853] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
Primexine deposition and plasma membrane undulation are the initial steps of pollen wall formation. However, little is known about the genes involved in this important biological process. Here, we report a novel gene, NO PRIMEXINE AND PLASMA MEMBRANE UNDULATION (NPU), which functions in the early stage of pollen wall development in Arabidopsis (Arabidopsis thaliana). Loss of NPU function causes male sterility due to a defect in callose synthesis and sporopollenin deposition, resulting in disrupted pollen in npu mutants. Transmission electronic microscopy observation demonstrated that primexine deposition and plasma membrane undulation are completely absent in the npu mutants. NPU encodes a membrane protein with two transmembrane domains and one intracellular domain. In situ hybridization analysis revealed that NPU is strongly expressed in microspores and the tapetum during the tetrad stage. All these results together indicate that NPU plays a vital role in primexine deposition and plasma membrane undulation during early pollen wall development.
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