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Prof. Guido Sessa
Ph.D.: Weizmann Institute of Science, Rehovot, Israel, 1996
Phone:

(Office) +972-3-640-9766

(Lab) +972-3-640-9848
(Fax) +972-3-640-9380

E-mail: guidos@post.tau.ac.il
Room#: Britannia 526
Member's portrait

Research Interests

 

Our research is focused on the study of molecular mechanisms that govern plant immunity and susceptibility to phytopathogenic bacteria. On the plant side, we use molecular biology, functional genomics and proteomics approaches to dissect recognition events and signal transduction pathways that mediate immunity. On the bacterial side, we apply genetic and biochemical strategies to unveil the mode of action of bacterial virulence factors that manipulate host functions. Model systems of our investigation are the interactions of tomato plants with the Gram-negative bacteria Pseudomonas syringae and Xanthomonas campestris, and with the Gram-positive bacterium Clavibacter michiganensis. Our investigation has a direct impact on agriculture by providing targets and biotechnological strategies for the development of disease control strategies against economically important pathogens.

 

Ongoing projects

1. Functional analysis of tomato genes involved in resistance to Xanthomonas campestris pv. vesicatoria (Xcv).

The tomato line Hawaii 7981 expressing the yet-to-be-isolated RxvT3 R gene is resistant to Xcv bacteria carrying the avrXv3 gene. By analyzing gene expression profiles of tomato plants during the onset of resistance, we identified genes that encode possible signaling components involved in tomato disease resistance to Xcv (Gibly et al., 2004; Balaji et al., 2007). We selected a group of differentially expressed genes and genes that are known to be involved in resistance signaling and tested their requirement for resistance to Xcv by virus-induced gene silencing techniques. By this functional screen we identified a plant transcription factor of the GRAS family, SlGRAS6, and a MAP kinase kinase kinase, SlMAP3Kepsilon, as important components of signaling pathways leading to resistance to Xcv (Mayrose et al., 2006; Melech-Bonfil and Sessa, 2011). To follow up this findings, we surveyed the entire tomato GRAS family (18 members) for gene expression changes upon pathogen attack, wounding and treatment with plant hormones. In addition, GRAS family members were characterized in terms of subcellular localization, ability to activate transcription, requirement for disease resistance to phytopathogenic bacteria, and ability to confer broad-spectrum resistance against plant pathogens. This analysis established the first direct link between GRAS transcription factors and disease resistance. We have been also investigating the molecular mechanisms by which SlMAP3Kepsilon regulates host resistance. Results of these activities demonstrated that SlMAP3Kepsilon is a positive regulator of cell death associated with disease resistance, plays a conserved role in different R gene pathways, and is upstream to a known MAP kinase cascade associated with plant immunity. Finally, we characterized molecular and biochemical properties of the MAP kinase LeMPK3, whose gene was induced by Xcv in resistant plants. Our results of gene expression, functional and enzymatic analyses demonstrate that LeMPK3 is a dual-specificity MAP kinase and represents a convergence point for different signaling pathways involved in the activation of immune responses.

 

  1. Mayrose, M., A. Bonshtien and G. Sessa (2004). LeMPK3 is a MAP kinase with dual specificity induced during tomato         defense and wounding responses. J. Biol. Chem. 279: 14819-14827. (PDF)
  2. Gibly, A., A. Bonshtien, V. Balaji, P. Debbie, G.B. Martin and G. Sessa (2004) Identification and expression profiling of tomato genes differentially regulated during a resistance response to Xanthomonas campestris pv. vesicatoria. Mol. Plant-Microbe Interact. 17: 1212-1222. (PDF)
  3. Mayrose, M., S.K. Ekengren, S. Melech-Bonfil, G.B. Martin and G. Sessa (2006). A novel link between tomato GRAS genes, plant disease resistance and mechanical stress response. Mol. Plant Pathol. 7: 593-604. (PDF)
  4. Balaji, V., A. Gibly, P. Debbie and G. Sessa (2007). Transcriptional analysis of the tomato resistance response triggered by recognition of the Xanthomonas type III effector AvrXv3. Functional & Integrative Genomics 7: 205-316. (PDF)
  5. Melech-Bonfil, S. and G. Sessa . Tomato MAPKKKε is a positive regulator of cell-death signaling networks associated with plant immunity (2010). Plant J. 64: 379-391. (PDF)
  6. Melech-Bonfil, S. and G. Sessa (2011). The SlMKK2 and SlMPK2 genes play a role in tomato disease resistance to Xanthomonas campestris pv. vesicatoria. Plant Signaling and Behavior (in press).

2. A chemical-genetic approach for functional analysis of protein kinases involved in plant immunity.

In collaboration with the lab of Prof. Kevan Shokat (UCSF) we developed a chemical-genetic strategy to sensitize plant kinases to specific inhibition by analogs of PP1, an ATP competitive small-molecule inhibitor (Zhang et al., 2005; Salomon et al., 2009b). The same approach also allows the sensitized kinase to use unnatural N6-modified ATP analogs as phosphodonors that can be exploited for tagging direct phosphorylation targets of the kinase of interest. By applying this strategy to the tomato Pto kinase, which confers resistance against Pst bacteria, we resolved the controversial role of Pto kinase activity for effector recognition and signal transduction. Our results strongly suggest a novel form of protein kinase regulation: kinase activity is required to stabilize Pto in the proper conformation for interacting with bacterial effectors but is dispensable for signal transduction (Salomon et al., 2009a).

 

  1. Zhang, C., D.M. Kenski, J. Paulson, A. Bonshtien, G. Sessa , J.V. Cross, D.J. Templeton, K.M. Shokat (2005). A second-site suppressor strategy for chemical genetic analysis of diverse protein kinases. Nature Methods 2: 435-441. (PDF)
  2. Salomon, D., A. Bonshtien, M. Mayrose, C. Zhang, K.M. Shokat and G. Sessa (2009a). Bypassing kinase activity of the tomato Pto resistance protein with small-molecule ligands. J. Biol. Chem. 284: 15289-15298. (PDF)
  3. Salomon, D., A. Bonshtien and G. Sessa (2009b). A chemical-genetic approach for functional analysis of plant protein kinases. Plant Signaling & Behavior 4: 645-647. (PDF)

3. Mode of action of type III secreted effectors from Gram-negative phytopathogenic bacteria.

Gram-negative phytopathogenic bacteria utilize a type III secretion system to inject effector proteins inside plant cells. A line of research the lab concerns the dissection of the molecular and biochemical action of type III effectors as virulence and avirulence factors. Among the effectors secreted by Xcv into tomato cells, we first characterized AvrRxv, which is recognized in tomato lines resistant to Xcv race T1. We analyzed AvrRxv subcellular localization, requirement of its putative catalytic core for recognition by the plant, and trascriptional changes activated by its delivery into resistant plants (Bonshtien et al., 2005). We are currently using yeast as an heterologous system for the expression of the entire repertoire of Xcv effectors (Salomon and Sessa, 2010; Salomon et al., 2011). Expression of certain effectors in yeast resulted in phenotypes that we are exploiting to elucidate the processes they manipulate, gain insight into their enzymatic function, and discover their targets.

 

  1. Bonshtien, A., A. Lev, A. Gibly, P. Debbie, A. Avni and G. Sessa (2005). Molecular properties of the Xanthomonas AvrRxv effector and global transcriptional changes determined by its expression in resistant tomato plants. Mol. Plant-Microbe Interact. 18: 300-310. (PDF)
  2. Salomon, D. and G. Sessa (2010). Identification of growth inhibition phenotypes induced by expression of bacterial type III effectors in yeast. J. Visual. Exp. http://www.jove.com/index/details.stp?id=1865, doi: 10.3791/1865. (Video)
  3. Salomon, D., D. Dar, S. Sreeramulu and G. Sessa (2011). Expression of Xanthomonas campestris pv. vesicatoria type III effectors in yeast affects cell growth and viability. Molecular Plant-Microbe Interactions 24: 305-314. (PDF)

4. Infection strategies of the Gram-positive phytopathogenic bacterium Clavibacter michiganensis subsp. michiganensis (Cmm).

We are involved in a comprehensive research to investigate the interaction between tomato plants and the Gram-positive bacterium Cmm . We study the interplay between Cmm virulence determinants and basal defense responses that tomato plants mount upon Cmm infection. After the initial analysis of Cmm strains present in Israel (Kleitman et., 2008), we analyzed gene expression profiles of tomato stems infected with Cmm (Balaji et al., 2009; Balaji and Sessa, 2009). This analysis led us to the finding that the plant hormone ethylene is involved in development of disease symptoms. Moreover, by functional analysis of tomato genes differential expressed during Cmm infection we identified genes that are involved in plant basal defense responses (Balaji et al., 2011). Current efforts are aimed at the identification, molecular and biochemical characterization of Cmm virulence factors, and molecular strategies used by the plant to recognize Cmm infection.

Symptoms of bacterial wilt caused by Cmm in tomato plants

 

  1. Kleitman, F., I. Barash, A. Burger, N. Iraki, Y. Falah, G. Sessa , D. Weinthal, L. Chalupowicz, K. Gartemann, R. Eichenlaub and S. Manulis-Sasson (2008). Characterization of Clavibacter michiganensis subsp. michiganensis population in Israel. Eur. J. Plant Pathol. 121: 463-475. (PDF)
  2. Balaji, V., M. Mayrose, O. Sherf, J. Jacob-Hirsch, R. Eichenlaub, N. Iraki, S. Manulis-Sasson, G. Rechavi, I. Barash and G. Sessa (2008). Tomato transcriptional changes in response to Clavibacter michiganensis subsp. michiganensis reveal a role for ethylene in disease development. Plant Physiol. 4: 1797-1809. (PDF)
  3. Balaji, V. and G. Sessa (2008). Activation and manipulation of host responses by a Gram-positive bacterium. Plant Signaling & Behavior 3: 839-841. (PDF)
  4. Balaji V., G. Sessa and C.D. Smart (2011). Silencing of host basal defense response-related gene expression increases susceptibility of Nicotiana benthamiana to Clavibacter michiganensis subsp. michiganensis . Phytopathology 101: 349-357. (PDF)

 

Selected Publications
  1. Mayrose, M., A. Bonshtien and G. Sessa (2004). LeMPK3 is a MAP kinase with dual specificity induced during tomato defense and wounding responses. J. Biol. Chem. 279: 14819-14827. (PDF)
  2. Gibly, A., A. Bonshtien, V. Balaji, P. Debbie, G.B. Martin and G. Sessa (2004) Identification and expression profiling of tomato genes differentially regulated during a resistance response to Xanthomonas campestris pv. vesicatoria. Mol. Plant-Microbe Interact. 17: 1212-1222. (PDF)
  3. Bonshtien, A., A. Lev, A. Gibly, P. Debbie, A. Avni and G. Sessa (2005). Molecular properties of the Xanthomonas AvrRxv effector and global transcriptional changes determined by its expression in resistant tomato plants. Mol. Plant-Microbe Interact. 18: 300-310. (PDF)
  4. Mayrose, M., S.K. Ekengren, S. Melech-Bonfil, G.B. Martin and G. Sessa (2006). A novel link between tomato GRAS genes, plant disease resistance and mechanical stress response. Mol. Plant Pathol. 7: 593-604. (PDF)
  5. Balaji, V., M. Mayrose, O. Sherf, J. Jacob-Hirsch, R. Eichenlaub, N. Iraki, S. Manulis-Sasson, G. Rechavi, I. Barash and G. Sessa (2008). Tomato transcriptional changes in response to Clavibacter michiganensis subsp. michiganensis reveal a role for ethylene in disease development. Plant Physiol. 4: 1797-1809. (PDF)
  6. Salomon, D., A. Bonshtien, M. Mayrose, C. Zhang, K.M. Shokat and G. Sessa (2009). Bypassing kinase activity of the tomato Pto resistance protein with small-molecule ligands. J. Biol. Chem. 284: 15289-15298. (PDF)
  7. Melech-Bonfil S. and G. Sessa. Tomato MAPKKKε is a positive regulator of cell-death signaling networks associated with plant immunity (2010). Plant J. 64: 379-391. (PDF)
  8. Salomon, D., D. Dar, S. Sreeramulu and G. Sessa (2011). Expression of Xanthomonas campestris pv. vesicatoria type III effectors in yeast affects cell growth and viability. Molecular Plant-Microbe Interactions 24: 305-314. (PDF)

Students and Lab Members

Dr. Shivakumar Sreeramulu

Postdoctoral Associate

Email: sskumar_ag@yahoo.com

Dr. Alon Savidor

Postdoctoral Associate

Email: asavidor@post.tau.ac.il

Dr. Adiel Cohen

Postdoctoral Associate

Email: adic@post.tau.ac.il

Dor Salomon

Ph.D. Student

Email: dorsalomon@gmail.com

Shiri Melech-Bonfil

Ph.D. Student

Email: melechsh@post.tau.ac.il

Doron Teper

Ph.D. Student

Email: doron.teper@gmail.com

Yana Mostizky

Ph.D. Student

Email: ymostizky@gmail.com


Full Publications

     

  1. Ori, N., G. Sessa , T. Lotan, S. Himmelhoch and R. Fluhr (1990). A major stylar matrix polypeptide (sp41) is a member of the pathogenesis-related proteins superclass. EMBO J. 9: 3429-3436. (PDF)
  2. Jansen, M.A.K., G. Sessa, S. Malkin and R. Fluhr (1992). PEPC-mediated carbon fixation in transmitting tract cells reflects style-pollen tube interactions. Plant J. 2: 507-515. (PDF)
  3. Meller, Y., G. Sessa , Y. Eyal and R. Fluhr (1993). DNA-protein interactions on a cis -DNA element essential for ethylene regulation. Plant Mol. Biol. 23: 453-463. (PDF)
  4. Sessa, G. and R. Fluhr. (1995). The expression of an abundant transmitting tract-specific endoglucanase (Sp41) is promoter-dependent and not essential in the reproductive physiology of tobacco. Plant Mol. Biol. 29: 969-982. (PDF)
  5. Sessa, G., Yang, X-Q., Raz, V., Eyal, Y. and R. Fluhr. (1995). Dark induction and subcellular localization of the pathogenesis-related PRB-1b protein. Plant Mol. Biol. 28: 537-547. (PDF)
  6. Sessa, G., Meller, Y. and Fluhr, R. (1995). A GCC element and a G-box motif participate in ethylene-induced expression of the PRB-1b gene. Plant Mol. Biol. 28: 145-153. (PDF)
  7. Sessa, G., Raz, V., Savaldi, S. and Fluhr, R. (1996). PK12, a plant dual-specificity protein kinase of the LAMMER family, is regulated by the hormone ethylene. Plant Cell 8: 2223-2234. (PDF)
  8. Sessa, G., D'Ascenzo, M., Loh, Y.-T. and Martin, G.B. (1998). Biochemical properties of two protein kinases involved in disease resistance signaling in tomato. J. Biol. Chem. 273: 15860-15865. (PDF)
  9. Frederick, R.D., R.L. Thilmony, G. Sessa, and Martin, G.B. (1998). Recognition specificity for the bacterial avirulence protein AvrPto is determined by Thr-204 in the activation loop of the tomato Pto kinase. Mol. Cell 2: 241-245. (PDF)
  10. Savaldi-Goldstein, S., G. Sessa and R. Fluhr (2000). The ethylene-inducible PK12 kinase mediates the phosphorylation of SR splicing factors . Plant J. 21: 91-96. (PDF)
  11. Sessa, G., M. D'Ascenzo and G.B. Martin (2000). The major site of the Pti1 kinase phosphorylated by the Pto kinase is located in the activation domain and is required for Pto-Pti1 physical interaction. Eur. J. Biochem. 267: 171-178. (PDF)
  12. Sessa, G. and G.B. Martin (2000). Signal recognition and transduction mediated by the tomato Pto kinase: a paradigm of innate immunity in plants . Microbes and Infection 2: 1591-1597. (PDF)
  13. Sessa, G., M. D'Ascenzo, and G.B. Martin (2000). Thr-38 and Ser-198 are Pto autophosphorylation sites required for the AvrPto-Pto mediated hypersensitive response. EMBO J. 19: 2257-2269. (PDF)
  14. Cohn, J., G. Sessa , and G.B. Martin (2001). Innate immunity in plants. Curr. Opin. Immunol. 13: 55-62. (PDF)
  15. Martin, G.B., A.J. Bogdanove and G. Sessa (2003). Understanding the functions of plant disease resistance proteins. Annu. Rev. Plant Biol. 54: 23-61. (PDF)
  16. Mayrose, M., A. Bonshtien and G. Sessa (2004). LeMPK3 is a MAP kinase with dual specificity induced during tomato defense and wounding responses. J. Biol. Chem. 279: 14819-14827. (PDF)
  17. Gibly, A., A. Bonshtien, V. Balaji, P. Debbie, G.B. Martin and G. Sessa (2004) Identification and expression profiling of tomato genes differentially regulated during a resistance response to Xanthomonas campestris pv. vesicatoria. Mol. Plant-Microbe Interact. 17: 1212-1222. (PDF)
  18. Bonshtien, A., A. Lev, A. Gibly, P. Debbie, A. Avni and G. Sessa (2005). Molecular properties of the Xanthomonas AvrRxv effector and global transcriptional changes determined by its expression in resistant tomato plants. Mol. Plant-Microbe Interact. 18: 300-310. (PDF)
  19. Nissan, G., S. Manulis, D. M. Weinthal, G. Sessa and I. Barash (2005). Analysis of promoters recognized by HrpL, an alternative sigma factor protein from Pantoea agglomerans pv. gypsophilae. Mol. Plant-Microbe Interact. 18: 634-643. (PDF)
  20. Zhang, C., D.M. Kenski, J. Paulson, A. Bonshtien, G. Sessa, J.V. Cross, D.J. Templeton, K.M. Shokat (2005). A second-site suppressor strategy for chemical genetic analysis of diverse protein kinases. Nature Methods 2: 435-441. (PDF)
  21. Anderson, J.C., P.E. Pascuzzi, F. Xiao, G. Sessa and G. B. Martin (2006). Host-mediated phosphorylation of type III effector AvrPto promotes Pseudomonas virulence and avirulence in tomato. Plant Cell 18: 502-514. (PDF)
  22. Nissan, G., S. Manulis-Sasson, D. Weinthal, H. Mor, G. Sessa and I. Barash (2006). The type III effectors HsvG and HsvB of gall forming Pantoea agglomerans determine host specificity and function as transcriptional activators. Mol. Microbiol. 61: 1118-1131.  (PDF)
  23. Mayrose, M., S.K. Ekengren, S. Melech-Bonfil, G.B. Martin and G. Sessa (2006). A novel link between tomato GRAS genes, plant disease resistance and mechanical stress response. Mol. Plant Pathol. 7: 593-604. (PDF)
  24. Balaji, V., A. Gibly, P. Debbie and G. Sessa (2007). Transcriptional analysis of the tomato resistance response triggered by recognition of the Xanthomonas type III effector AvrXv3. Functional & Integrative Genomics 7: 205-316. (PDF)
  25. Kleitman, F., I. Barash, A. Burger, N. Iraki, Y. Falah, G. Sessa, D. Weinthal, L. Chalupowicz, K. Gartemann, R. Eichenlaub and S. Manulis-Sasson (2008). Characterization of Clavibacter michiganensis subsp. michiganensis population in Israel. Eur. J. Plant Pathol. 121: 463-475. (PDF)
  26. Balaji, V., M. Mayrose, O. Sherf, J. Jacob-Hirsch, R. Eichenlaub, N. Iraki, S. Manulis-Sasson, G. Rechavi, I. Barash and G. Sessa (2008). Tomato transcriptional changes in response to Clavibacter michiganensis subsp. michiganensis reveal a role for ethylene in disease development. Plant Physiol. 4: 1797-1809. (PDF)
  27. Chalupowicz, L., S. Manulis-Sasson, M. Itkin, A. Sacher, G. Sessa and I. Barash (2008). Quorum sensing system affects gall development incited by Pantoea agglomerans pv. gypsophilae. Mol Plant-Microbe Interact. 21: 1094-1105. (PDF)
  28. Balaji, V. and G. Sessa (2008). Activation and manipulation of host responses by a Gram-positive bacterium. Plant Signaling & Behavior 3: 839-841. (PDF)
  29. Chalupowicz, L., I. Barash, M. Panijel, G. Sessa and S. Manulis-Sasson (2009). Regulatory interactions between quorum-sensing, auxin, cytokinin and the Hrp regulon in relation to gall formation and epiphytic fitness of Pantoea agglomerans pv. gypsophilae . Mol Plant-Microbe Interact. 22: 849-856. (PDF)
  30. Salomon, D., A. Bonshtien, M. Mayrose, C. Zhang, K.M. Shokat and G. Sessa (2009). Bypassing kinase activity of the tomato Pto resistance protein with small-molecule ligands. J. Biol. Chem. 284: 15289-15298. (PDF)
  31. Salomon, D., A. Bonshtien and G. Sessa (2009). A chemical-genetic approach for functional analysis of plant protein kinases. Plant Signaling & Behavior 4: 645-647. (PDF)
  32. Chalupowicz, L., M. Cohen-Kandli, O. Dror, R. Eichenlaub, K-H. Gartemann, G. Sessa, I. Barash and S. Manulis-Sasson (2010). Sequential expression of bacterial virulence and plant defense genes during infection of tomato with Clavibacter michiganensis subsp. michiganensis. Phytopathology 100: 252-261. (PDF)
  33. Salomon, D. and G. Sessa (2010). Identification of growth inhibition phenotypes induced by expression of bacterial type III effectors in yeast. J. Visual. Exp. http://www.jove.com/index/details.stp?id=1865, doi: 10.3791/1865. (Video)
  34. Melech-Bonfil S. and G. Sessa. Tomato MAPKKKε is a positive regulator of cell-death signaling networks associated with plant immunity (2010). Plant J. 64: 379-391. (PDF)
  35. Balaji V., G. Sessa and C.D. Smart (2011). Silencing of host basal defense response-related gene expression increases susceptibility of Nicotiana benthamiana to Clavibacter michiganensis subsp. michiganensis. Phytopathology 101: 349-357. (PDF)
  36. Salomon, D., D. Dar, S. Sreeramulu and G. Sessa (2011). Expression of Xanthomonas campestris pv. vesicatoria type III effectors in yeast affects cell growth and viability. Molecular Plant-Microbe Interactions 24: 305-314. (PDF)
  37. S. Melech-Bonfil and G. Sessa (2011). The SlMKK2 and SlMPK2 genes play a role in tomato disease resistance to Xanthomonas campestris pv. vesicatoria . Plant Signaling and Behavior (in press).
  38. D.M. Weinthal, S. Manulis-Sasson, T. Tzfira, G. Sessa and I. Barash (2011). Nuclear localization signals of the type III effectors HsvG and HsvB: characterization and role in pathogenicity of the gall-forming bacterium Pantoea agglomerans. Microbiology (in press).
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