We characterized the molecular function of the Pseudomonas syringae pv. tomato DC3000 (Pto) effector HopQ1. In silico studies suggest that HopQ1 might possess nucleoside hydrolase activity based on the presence of a characteristic aspartate motif. Transgenic Arabidopsis lines expressing HopQ1 or HopQ1 aspartate mutant variants were characterized with respect to flagellin triggered immunity, phenotype and changes in phytohormone content by high-performance liquid chromatography-MS (HPLC-MS). We found that HopQ1, but not its aspartate mutants, suppressed all tested immunity marker assays. Suppression of immunity was the result of a lack of the flagellin receptor FLS2, whose gene expression was abolished by HopQ1 in a promoter-dependent manner. Furthermore, HopQ1 induced cytokinin signaling in Arabidopsis and the elevation in cytokinin signaling appears to be responsible for the attenuation of FLS2 expression. We conclude that HopQ1 can activate cytokinin signaling and that moderate activation of cytokinin signaling leads to suppression of FLS2 accumulation and thus defense signaling.

Forschungsgruppe Pflanzenbiochemie ZMBP Zentrum für Molekularbiologie der Pflanzen Eberhard Karls Universität Tübingen Auf der Morgenstelle 5 72076 Tübingen Germany

Institute of Experimental Botany AS CR Rozvojová 263 165 02 Praha 6 Lysolaje Czech Republic

Section of Plant Physiology Botanical Institute Hebelstrasse 1 CH 4056 Basel Switzerland

The Australian National University The Linnaeus Building Building 134 Linnaeus Way Canberra ACT 0200 Australia

The Sainsbury Laboratory Cambridge University Cambridge CB2 1LR UK

Zobrazit více v PubMed

Akiyoshi DE, Regier DA, Gordon MP. 1987. Cytokinin production by Agrobacterium and Pseudomonas spp. Journal of Bacteriology 169: 4242-4248.

Argueso CT, Ferreira FJ, Epple P, To JP, Hutchison CE, Schaller GE, Dangl JL, Kieber JJ. 2012. Two-component elements mediate interactions between cytokinin and salicylic acid in plant immunity. PLoS Genetics 8: e1002448.

Babosha AV. 2009. Regulation of resistance and susceptibility in wheat-powdery mildew pathosystem with exogenous cytokinins. Journal of Plant Physiology 166: 1892-1903.

Boller T, Felix G. 2009. A renaissance of elicitors: perception of microbe-associated molecular patterns and danger signals by pattern-recognition receptors. Annual Review of Plant Biology 60: 379-406.

Boller T, He SY. 2009. Innate immunity in plants: an arms race between pattern recognition receptors in plants and effectors in microbial pathogens. Science 324: 742-744.

Boutrot F, Segonzac C, Chang KN, Qiao H, Ecker JR, Zipfel C, Rathjen JP. 2010. Direct transcriptional control of the Arabidopsis immune receptor FLS2 by the ethylene-dependent transcription factors EIN3 and EIL1. Proceedings of the National Academy of Sciences, USA 107: 14502-14507.

Bozkurt TO, Schornack S, Banfield MJ, Kamoun S. 2011. Oomycetes, effectors, and all that jazz. Current Opinion in Plant Biology 15: 483-492.

Chinchilla D, Zipfel C, Robatzek S, Kemmerling B, Nurnberger T, Jones JD, Felix G, Boller T. 2007. A flagellin-induced complex of the receptor FLS2 and BAK1 initiates plant defence. Nature 448: 497-500.

Chisholm ST, Coaker G, Day B, Staskawicz BJ. 2006. Host-microbe interactions: shaping the evolution of the plant immune response. Cell 124: 803-814.

Choi J, Choi D, Lee S, Ryu CM, Hwang I. 2011a. Cytokinins and plant immunity: old foes or new friends? Trends in Plant Science 16: 388-394.

Choi J, Huh SU, Kojima M, Sakakibara H, Paek KH, Hwang I. 2011b. The cytokinin-activated transcription factor ARR2 promotes plant immunity via TGA3/NPR1-dependent salicylic acid signaling in Arabidopsis. Developmental Cell 19: 284-295.

Costacurta A, Vanderleyden J. 1995. Synthesis of phytohormones by plant-associated bacteria. Critical Reviews in Microbiology 21: 1-18.

Dawson RMC, Elliott DC, Elliott WH, Jones KM. 1968. Analytical biochemistry, 3rd edn. Oxford, UK: Oxford University Press.

Djilianov DD, Dobrev PI, Moyankova DP, Vankova R, Georgieva DT, Gajdosova S, Motyka V. 2013. Dynamics of endogenous phytohormones during desiccation and recovery of the resurrection plant species Haberlea rhodopensis. Journal of Plant Growth Regulation 32: 564-574.

Dobrev PI, Kaminek M. 2002. Fast and efficient separation of cytokinins from auxin and abscisic acid and their purification using mixed-mode solid-phase extraction. Journal of Chromatography A 950: 21-29.

Dobrev PI, Vankova R. 2012. Quantification of abscisic Acid, cytokinin, and auxin content in salt-stressed plant tissues. Methods in Molecular Biology 913: 251-261.

Feng F, Zhou JM. 2012. Plant-bacterial pathogen interactions mediated by type III effectors. Current Opinion in Plant Biology 15: 469-476.

Ferrante P, Clarke CR, Cavanaugh KA, Michelmore RW, Buonaurio R, Vinatzer BA. 2009. Contributions of the effector gene hopQ1-1 to differences in host range between Pseudomonas syringae pv. phaseolicola and P. syringae pv. tabaci. Molecular Plant Pathology 10: 837-842.

Gajdosova S, Spichal L, Kaminek M, Hoyerova K, Novak O, Dobrev PI, Galuszka P, Klima P, Gaudinova A, Zizkova E et al. 2011. Distribution, biological activities, metabolism, and the conceivable function of cis-zeatin-type cytokinins in plants. Journal of Experimental Botany 62: 2827-2840.

Gimenez-Ibanez S, Hann DR, Ntoukakis V, Petutschnig E, Lipka V, Rathjen JP. 2009. AvrPtoB targets the LysM receptor kinase CERK1 to promote bacterial virulence on plants. Current Biology 19: 423-429.

Giska F, Lichocka M, Piechocki M, Dadlez M, Schmelzer E, Hennig J, Krzymowska M. 2013. Phosphorylation of HopQ1, a Type III Effector from Pseudomonas syringae, creates a binding site for host 14-3-3 proteins. Plant Physiology 161: 2049-2061.

Glockner FO, Kube M, Bauer M, Teeling H, Lombardot T, Ludwig W, Gade D, Beck A, Borzym K, Heitmann K et al. 2003. Complete genome sequence of the marine planctomycete Pirellula sp strain 1. Proceedings of the National Academy of Sciences, USA 100: 8298-8303.

Gohre V, Spallek T, Haweker H, Mersmann S, Mentzel T, Boller T, de Torres M, Mansfield JW, Robatzek S. 2008. Plant pattern-recognition receptor FLS2 is directed for degradation by the bacterial ubiquitin ligase AvrPtoB. Current Biology 18: 1824-1832.

Grosskinsky DK, Naseem M, Abdelmohsen UR, Plickert N, Engelke T, Griebel T, Zeier J, Novak O, Strnad M, Pfeifhofer H et al. 2011. Cytokinins mediate resistance against Pseudomonas syringae in tobacco through increased antimicrobial phytoalexin synthesis independent of salicylic acid signaling. Plant Physiology 157: 815-830.

Hann DR, Gimenez-Ibanez S, Rathjen JP. 2011. Bacterial virulence effectors and their activities. Current Opinion in Plant Biology 13: 388-393.

Hann DR, Rathjen JP. 2007. Early events in the pathogenicity of Pseudomonas syringae on Nicotiana benthamiana. Plant Journal 49: 607-618.

Hann DR, Rathjen JP. 2011. The long and winding road: virulence effector proteins of plant pathogenic bacteria. Cellular and Molecular Life Sciences 67: 3425-3434.

Heese A, Hann DR, Gimenez-Ibanez S, Jones AM, He K, Li J, Schroeder JI, Peck SC, Rathjen JP. 2007. The receptor-like kinase SERK3/BAK1 is a central regulator of innate immunity in plants. Proceedings of the National Academy of Sciences, USA 104: 12217-12222.

Jones JD, Dangl JL. 2006. The plant immune system. Nature 444: 323-329.

de Jonge R, Bolton MD, Thomma BP. 2011. How filamentous pathogens co-opt plants: the ins and outs of fungal effectors. Current Opinion in Plant Biology 14: 400-406.

Jung B, Florchinger M, Kunz HH, Traub M, Wartenberg R, Jeblick W, Neuhaus HE, Mohlmann T. 2009. Uridine-Ribohydrolase is a key regulator in the uridine degradation pathway of Arabidopsis. Plant Cell 21: 876-891.

Kamínek M, Březinová A, Gaudinová A, Motyka V, Vaňková R, Zažímalová E. 2000. Purine cytokinins: a proposal of abbreviations. Plant Growth Regulation 32: 253-256.

Kurakawa T, Ueda N, Maekawa M, Kobayashi K, Kojima M, Nagato Y, Sakakibara H, Kyozuka J. 2007. Direct control of shoot meristem activity by a cytokinin-activating enzyme. Nature 445: 652-655.

Kuroha T, Tokunaga H, Kojima M, Ueda N, Ishida T, Nagawa S, Fukuda H, Sugimoto K, Sakakibara H. 2009. Functional analyses of LONELY GUY cytokinin-activating enzymes reveal the importance of the direct activation pathway in Arabidopsis. Plant Cell 21: 3152-3169.

Li J, Wen JQ, Lease KA, Doke JT, Tax FE, Walker JC. 2002. BAK1, an Arabidopsis LRR receptor-like protein kinase, interacts with BRI1 and modulates brassinosteroid signaling. Cell 110: 213-222.

Li W, Chiang YH, Coaker G. 2013a. 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 8: e59684.

Li W, Yadeta KA, Elmore JM, Coaker G. 2013b. The Pseudomonas effector HopQ1 promotes bacterial virulence and interacts with tomato 14-3-3 proteins in a phosphorylation dependent manner. Plant Physiology 161: 2062-2074.

Mersmann S, Bourdais G, Rietz S, Robatzek S. 2010. Ethylene signaling regulates accumulation of the FLS2 receptor and is required for the oxidative burst contributing to plant immunity. Plant Physiology 154: 391-400.

Navarro L, Dunoyer P, Jay F, Arnold B, Dharmasiri N, Estelle M, Voinnet O, Jones JD. 2006. A plant miRNA contributes to antibacterial resistance by repressing auxin signaling. Science 312: 436-439.

Ntoukakis V, Mucyn TS, Gimenez-Ibanez S, Chapman HC, Gutierrez JR, Balmuth AL, Jones AM, Rathjen JP. 2009. Host inhibition of a bacterial virulence effector triggers immunity to infection. Science 324: 784-787.

Ortiz-Castro R, Contreras-Cornejo HA, Macias-Rodriguez L, Lopez-Bucio J. 2009. The role of microbial signals in plant growth and development. Plant Signaling & Behavior 4: 701-712.

Parkin DW, Horenstein BA, Abdulah DR, Estupinan B, Schramm VL. 1991. Nucleoside hydrolase from Crithidia fasciculata. Metabolic role, purification, specificity, and kinetic mechanism. Journal of Biological Chemistry 266: 20658-20665.

Peng ZY, Zhou X, Li L, Yu X, Li H, Jiang Z, Cao G, Bai M, Wang X, Jiang C et al. 2009. Arabidopsis hormone database: a comprehensive genetic and phenotypic information database for plant hormone research in Arabidopsis. Nucleic Acids Research 37: D975-D982.

Robatzek S, Bittel P, Chinchilla D, Kochner P, Felix G, Shiu SH, Boller T. 2007. Molecular identification and characterization of the tomato flagellin receptor LeFLS2, an orthologue of Arabidopsis FLS2 exhibiting characteristically different perception specificities. Plant Molecular Biology 64: 539-547.

Robert-Seilaniantz A, Navarro L, Bari R, Jones JD. 2007. Pathological hormone imbalances. Current Opinion in Plant Biology 10: 372-379.

Romanov GA, Lomin SN, Schmulling T. 2006. Biochemical characteristics and ligand-binding properties of Arabidopsis cytokinin receptor AHK3 compared to CRE1/AHK4 as revealed by a direct binding assay. Journal of Experimental Botany 57: 4051-4058.

Roux M, Schwessinger B, Albrecht C, Chinchilla D, Jones A, Holton N, Malinovsky FG, Tor M, de Vries S, Zipfel C. 2011. The Arabidopsis leucine-rich repeat receptor-like kinases BAK1/SERK3 and BKK1/SERK4 are required for innate immunity to hemibiotrophic and biotrophic pathogens. Plant Cell 23: 2440-2455.

Sakakibara H. 2006. Cytokinins: activity, biosynthesis, and translocation. Annual Review of Plant Biology 57: 431-449.

Schulze B, Mentzel T, Jehle AK, Mueller K, Beeler S, Boller T, Felix G, Chinchilla D. 2010. Rapid heteromerization and phosphorylation of ligand-activated plant transmembrane receptors and their associated kinase BAK1. Journal of Biological Chemistry 285: 9444-9451.

Shan L, He P, Li J, Heese A, Peck SC, Nurnberger T, Martin GB, Sheen J. 2008. Bacterial effectors target the common signaling partner BAK1 to disrupt multiple MAMP receptor-signaling complexes and impede plant immunity. Cell Host & Microbe 4: 17-27.

Shi W, Schramm VL, Almo SC. 1999. Nucleoside hydrolase from Leishmania major. Cloning, expression, catalytic properties, transition state inhibitors, and the 2.5-a crystal structure. Journal of Biological Chemistry 274: 21114-21120.

Soylu SB, Brown I, Mansfield JW. 2005. Cellular reactions in Arabidopsis following challenge by strains of Pseudomonas syringae: from basal resistance to compatibility. Physiological and Molecular Plant Pathology 66: 232-243.

Stolz A, Riefler M, Lomin SN, Achazi K, Romanov GA, Schmulling T. 2011. The specificity of cytokinin signalling in Arabidopsis thaliana is mediated by differing ligand affinities and expression profiles of the receptors. Plant Journal 67: 157-168.

Tokunaga H, Kojima M, Kuroha T, Ishida T, Sugimoto K, Kiba T, Sakakibara H. 2012. Arabidopsis lonely guy (LOG) multiple mutants reveal a central role of the LOG-dependent pathway in cytokinin activation. Plant Journal 69: 355-365.

Versees W, Steyaert J. 2003. Catalysis by nucleoside hydrolases. Current Opinion in Structural Biology 13: 731-738.

Walters DR, McRoberts N. 2006. Plants and biotrophs: a pivotal role for cytokinins? Trends in Plant Science 11: 581-586.

Walters DR, McRoberts N, Fitt BD. 2008. Are green islands red herrings? Significance of green islands in plant interactions with pathogens and pests. Biological Reviews of the Cambridge Philosophical Society 83: 79-102.

Wang X, Kota U, He K, Blackburn K, Li J, Goshe MB, Huber SC, Clouse SD. 2008. Sequential transphosphorylation of the BRI1/BAK1 receptor kinase complex impacts early events in brassinosteroid signaling. Developmental Cell 15: 220-235.

Wei CF, Kvitko BH, Shimizu R, Crabill E, Alfano JR, Lin NC, Martin GB, Huang HC, Collmer A. 2007. A Pseudomonas syringae pv. tomato DC3000 mutant lacking the type III effector HopQ1-1 is able to cause disease in the model plant Nicotiana benthamiana. Plant Journal 51: 32-46.

Wulfetange K, Lomin SN, Romanov GA, Stolz A, Heyl A, Schmulling T. 2011. The cytokinin receptors of Arabidopsis are located mainly to the endoplasmic reticulum. Plant Physiology 156: 1808-1818.

Xiang T, Zong N, Zou Y, Wu Y, Zhang J, Xing W, Li Y, Tang X, Zhu L, Chai J et al. 2008. Pseudomonas syringae effector AvrPto blocks innate immunity by targeting receptor kinases. Current Biology 18: 74-80.

Zong N, Xiang T, Zou Y, Chai J, Zhou JM. 2008. Blocking and triggering of plant immunity by Pseudomonas syringae effector AvrPto. Plant Signaling & Behavior 3: 583-585.

Zuo J, Niu QW, Chua NH. 2000. Technical advance: an estrogen receptor-based transactivator XVE mediates highly inducible gene expression in transgenic plants. Plant Journal 24: 265-273.

Structure-function relation of cytokinins determines their differential efficiency in mediating tobacco resistance against Pseudomonas syringae

Manipulation of cytokinin level in the ergot fungus Claviceps purpurea emphasizes its contribution to virulence

Cytokinin Metabolism of Pathogenic Fungus Leptosphaeria maculans Involves Isopentenyltransferase, Adenosine Kinase and Cytokinin Oxidase/Dehydrogenase

Cytokinin production by Pseudomonas fluorescens G20-18 determines biocontrol activity against Pseudomonas syringae in Arabidopsis