Recently, the octameric vesicle-tethering complex exocyst was found in plants and its importance for Arabidopsis morphogenesis was demonstrated. Exo70 exocyst subunits in plants, unlike in yeasts and mammals, are represented by a multigene family, comprising 23 members in Arabidopsis. For Exo70B2 and Exo70H1 paralogues, transcriptional up-regulation was confirmed on treatment with an elicitor peptide, elf18, derived from the bacterial elongation factor. Their ability to participate in the exocyst complex formation was inferred by the interaction of both the Exo70s with several other exocyst subunits using the yeast two-hybrid system. Arabidopsis plants mutated in these two genes were used to analyse their local reaction upon inoculation with Pseudomonas syringae pv. maculicola and the fungal pathogen Blumeria graminis f. sp. hordei. The Pseudomonas sensitivity test revealed enhanced susceptibility for the two exo70B2 and one H1 mutant lines. After Blumeria inoculation, an increase in the proportion of abnormal papilla formation, with an unusual wide halo made of vesicle-like structures, was found in exo70B2 mutants. Intracellular localization of both Exo70 proteins was studied following a GFP fusion assay and Agrobacterium-mediated transient expression of the constructs in Nicotiana benthamiana leaf epidermis. GFP-Exo70H1 localizes in the vesicle-like structures, while GFP-Exo70B2 is localized mainly in the cytoplasm. It is concluded that both Exo70B2 and Exo70H1 are involved in the response to pathogens, with Exo70B2 having a more important role in cell wall apposition formation related to plant defence.

Institute of Experimental Botany Academy of Sciences of the Czech Republic Rozvojová 263 16502 Praha 6 Czech Republic

Zobrazit více v PubMed

Aist JR. Papillae and related wound plugs of plant cells. Annual Review of Phytopathology. 1976;14:145–163.

Andersen NJ, Yeaman C. Sec3-containing exocyst complex is required for desmosome assembly in mammalian epithelial cells. Molecular Biology of the Cell. 2010;21:152–164. PubMed PMC

Assaad FF, Qiu JL, Youngs H, et al. The PEN1 syntaxin defines a novel cellular compartment upon fungal attack and is required for the timely assembly of papillae. Molecular Biology of the Cell. 2004;15:5118–5129. PubMed PMC

Cao H, Bowling SA, Gordon AS, Dong X. Characterization of an Arabidopsis mutant that is nonresponsive to inducers of systemic acquired resistance. The Plant Cell. 1994;6:1583–1592. PubMed PMC

Cole RA, Synek L, Žárský V, Fowler JE. SEC8, a subunit of the putative Arabidopsis exocyst complex, facilitates pollen germination and competitive pollen tube growth. Plant Physiology. 2005;138:2005–2018. PubMed PMC

Collins NC, Thordal-Christensen H, Lipka V, et al. SNARE-protein-mediated disease resistance at the plant cell wall. Nature. 2003;425:973–977. PubMed

Dangl JL, Ritter C, Gibbon MJ, Mur LA, Wood JR, Goss S, Mansfield J, Tailor JD, Viviant A. Functional homologs of the Arabidopsis RPM1 disease resistance gene in bean and pea. The Plant Cell. 1992;4:1359–1369. PubMed PMC

Davis KR, Schott E, Ausubel FM. Virulence of selected phytopathogenic pseudomonads in. Arabidopsis thaliana. Molecular Plant–Microbe Interaction. 1991;4:477–488.

Eliáš M, Drdová E, Žiak D, Bavlnka B, Hála M, Cvrčková F, Soukupová H, Žárský V. The exocyst complex in plants. Cell Biology International. 2003;27:199–201. PubMed

Fendrych M, Synek L, Pečenková T, et al. The Arabidopsis exocyst complex is involved in cytokinesis and cell plate maturation. The Plant Cell. 2010;22:3053–3065. PubMed PMC

Guo W, Roth D, Walch-Solimena C, Novick P. The exocyst is an effector for Sec4p, targeting secretory vesicles to sites of exocytosis. EMBO Journal. 1999;18:1071–1080. PubMed PMC

Hála M, Cole R, Synek L, et al. An exocyst complex functions in plant cell growth in Arabidopsis and tobacco. The Plant Cell. 2008;20:1330–1345. PubMed PMC

Hsu SC, TerBush D, Abraham M, Guo W. The exocyst complex in polarized exocytosis. International Review of Cytology. 2004;233:243–265. PubMed

Hückelhoven R, Fodor J, Preis C, Kogel KH. Hypersensitive cell death and papilla formation in barley attacked by the powdery mildew fungus are associated with hydrogen peroxide but not with salicylic acid accumulation. Plant Physiology. 1999;119:1251–1260. PubMed PMC

Katagiri F, Thilmony R, He SY. The Arabidopsis thaliana–Pseudomonas syringae interaction. In: Somerville CR, Meyerowitz EM, editors. The Arabidopsis book. Rockville, MD: American Society of Plant Biologists; 2002. PubMed PMC

Kunkel BN, Bent AF, Dahlbeck D, Innes RW, Staskawicz BJ. RPS2, an Arabidopsis disease resistance locus specifying recognition of Pseudomonas syringae strains expressing the avirulence gene avrRpt2. The Plant Cell. 1993;5:865–875. PubMed PMC

Kunze G, Zipfel C, Robatzek S, Niehaus K, Boller T, Felix G. The N terminus of bacterial elongation factor Tu elicits innate immunity in Arabidopsis plants. The Plant Cell. 2004;16:3496–3507. PubMed PMC

Kwon C, Neu C, Pajonk S, et al. Co-option of a default secretory pathway for plant immune responses. Nature. 2008;451:835–840. PubMed

Lavy M, Bloch D, Hazak O, Gutman I, Poraty L, Sorek N, Sternberg H, Yalovsky S. A Novel ROP/RAC effector links cell polarity, root-meristem maintenance, and vesicle trafficking. Current Biology. 2007;17:947–952. PubMed

Levine A, Tenhaken R, Dixon R, Lamb C. H2O2 from the oxidative burst orchestrates the plant hypersensitive disease resistance response. Cell. 1994;79:583–593. PubMed

Littleton JT, Chapman ER, Kreber R, Garment MB, Carlson SD, Ganetzky B. Temperature-sensitive paralytic mutations demonstrate that synaptic exocytosis requires SNARE complex assembly and disassembly. Neuron. 1998;21:401–413. PubMed

McLusky SR, Bennett MH, Beale MH, Lewis MJ, Gaskin P, Mansfield JW. Cell wall alterations and localized accumulation of feruloyl-3′-methoxytyramine in onion epidermis at sites of attempted penetration by Botrytis allii are associated with actin polarization, peroxidase activity and suppression of flavonoid biosynthesis. The Plant Journal. 1999;17:523–534.

Mehta SQ, Hiesinger PR, Betonka S, et al. Mutations in Drosophila sec15 reveal a function in neuronal targeting for a subset of exocyst components. Neuron. 2005;46:219–232. PubMed

Nakagawa T, Kurose T, Hino T, Tanaka K, Kawamukai M, Niwa Y, Toyooka K, Matsuoka K, Jinbo T, Kimura T. Development of series of gateway binary vectors, pGWBs, for realizing efficient construction of fusion genes for plant transformation. Journal of Bioscience and Bioengineering. 2007;104:34–41. PubMed

Novick P, Field C, Schekman R. Identification of 23 complementation groups required for post-translational events in the yeast secretory pathway. Cell. 1980;21:205–215. PubMed

Novick P, Zerial M. The diversity of Rab proteins in vesicle transport. Current Opinion in Cell Biology. 1997;9:496–504. PubMed

Ridley AJ. Rho GTPases and actin dynamics in membrane protrusions and vesicle trafficking. Trends in Cell Biology. 2006;16:522–529. PubMed

Ringelmann A, Riedel M, Riederer M, Hildebrandt U. Two sides of a leaf blade: Blumeria graminis needs chemical cues in cuticular waxes of Lolium perenne for germination and differentiation. Planta. 2009;230:95–105. PubMed

Robatzek S. Vesicle trafficking in plant immune responses. Cell Microbiology. 2007;9:1–8. PubMed

Rothman JE. Intracellular membrane fusion. Advances in Second Messenger and Phosphoprotein Research. 1994;29:81–96. PubMed

Sanderfoot AA, Assaad FF, Raikhel NV. The Arabidopsis genome. an abundance of soluble N-ethylmaleimide-sensitive factor adaptor protein receptors. Plant Physiology. 2000;124:1558–1569. PubMed PMC

Schmelzer E. Cell polarization, a crucial process in fungal defence. Trends in Plant Science. 2002;7:411–415. PubMed

Sharifmoghadam MR, de Leon N, Hoya M, Curto MA, Valdivieso MH. Different steps of sexual development are differentially regulated by the Sec8p and Exo70p exocyst subunits. FEMS Microbiology Letters. 2010;305:71–80. PubMed

Sivaram MV, Saporita JA, Furgason ML, Boettcher AJ, Munson M. Dimerization of the exocyst protein Sec6p and its interaction with the t-SNARE Sec9p. Biochemistry. 2005;44:6302–6311. PubMed

Synek L, Schlager N, Eliáš M, Quentin M, Hauser MT, Žárský V. AtEXO70A1, a member of a family of putative exocyst subunits specifically expanded in land plants, is important for polar growth and plant development. The Plant Journal. 2006;48:54–72. PubMed PMC

TerBush DR, Maurice T, Roth D, Novick P. The exocyst is a multiprotein complex required for exocytosis in. Saccharomyces cerevisiae. EMBO Journal. 1996;15:6483–6494. PubMed PMC

Thilmony R, Underwood W, He SY. Genome-wide transcriptional analysis of the Arabidopsis thaliana interaction with the plant pathogen Pseudomonas syringae pv. tomato DC3000 and the human pathogen Escherichia coli O157:H7. The Plant Journal. 2006;46:34–53. PubMed

Wen TJ, Hochholdinger F, Sauer M, Bruce W, Schnable PS. The roothairless1 gene of maize encodes a homolog of sec3, which is involved in polar exocytosis. Plant Physiology. 2005;138:1637–1643. PubMed PMC

Wick P, Gansel X, Oulevey C, Page V, Studer I, Dürst M, Sticher L. The expression of the t-SNARE AtSNAP33 is induced by pathogens and mechanical stimulation. Plant Physiology. 2003;132:343–351. PubMed PMC

Yu GL, Katagiri F, Ausubel FM. Arabidopsis mutations at the RPS2 locus result in loss of resistance to Pseudomonas syringae strains expressing the avirulence gene. avrRpt2. Molecular Plant–Microbe Interaction. 1993;6:434–443. PubMed

Zeyen RJ, Bushnell WR. Papilla response of barley epidermal cells caused by Erysiphe graminis. Rate and method of deposition determined by microcinematography and transmission microscopy. Canadian Journal of Botany. 1979;57:898–913.

Zimmermann P, Hirsch-Hoffmann M, Hennig L, Gruissem W. GENEVESTIGATOR: Arabidopsis microarray database and analysis toolbox. Plant Physiology. 2004;136:2621–2632. PubMed PMC

Zipfel C, Robatzek S, Navarro L, Oakeley EJ, Jones JD, Felix G, Boller T. Bacterial disease resistance in Arabidopsis through flagellin perception. Nature. 2004;428:764–767. PubMed

Žárský V, Cvrčková F, Potocký M, Hála M. Exocytosis and cell polarity in plants: exocyst and recycling domains. New Phytologist. 2009;183:255–272. PubMed

Interplay of EXO70 and MLO proteins modulates trichome cell wall composition and susceptibility to powdery mildew

A lineage-specific Exo70 is required for receptor kinase-mediated immunity in barley

Plasma membrane phospholipid signature recruits the plant exocyst complex via the EXO70A1 subunit

Functional Specialization within the EXO70 Gene Family in Arabidopsis

EXO70A2 Is Critical for Exocyst Complex Function in Pollen Development

Synergy among Exocyst and SNARE Interactions Identifies a Functional Hierarchy in Secretion during Vegetative Growth

Redundant and Diversified Roles Among Selected Arabidopsis thaliana EXO70 Paralogs During Biotic Stress Responses

Regulation of Exocyst Function in Pollen Tube Growth by Phosphorylation of Exocyst Subunit EXO70C2

Exocyst Subunit EXO70H4 Has a Specific Role in Callose Synthase Secretion and Silica Accumulation

Early Arabidopsis root hair growth stimulation by pathogenic strains of Pseudomonas syringae

RIN4 recruits the exocyst subunit EXO70B1 to the plasma membrane

EXO70C2 Is a Key Regulatory Factor for Optimal Tip Growth of Pollen

Unconventional Transport Routes of Soluble and Membrane Proteins and Their Role in Developmental Biology

Analysis of Exocyst Subunit EXO70 Family Reveals Distinct Membrane Polar Domains in Tobacco Pollen Tubes

Exocyst SEC3 and Phosphoinositides Define Sites of Exocytosis in Pollen Tube Initiation and Growth

Tethering Complexes in the Arabidopsis Endomembrane System

Endosidin2 targets conserved exocyst complex subunit EXO70 to inhibit exocytosis

Cell wall maturation of Arabidopsis trichomes is dependent on exocyst subunit EXO70H4 and involves callose deposition

The exocyst at the interface between cytoskeleton and membranes in eukaryotic cells

Old AIMs of the exocyst: evidence for an ancestral association of exocyst subunits with autophagy-associated Atg8 proteins