Department of Your Department

Student of the Month (February 2009)


Name: Shuangchun Yan (yansc at vt.edu)

Research project: Unraveling non-host resistance of Arabidopsis to the tomato pathogen Pseudomonas syringae pv. tomato T1

Advisor: Boris Vinatzer

Departmental affiliation: PPWS

Anticipated defense date: 2010

Project description:

The bacterial plant pathogen Pseudomonas syringae is a widespread species that causes damage to agricultural crops around the world. We have selected a group of closely related isolates within the P. syringae species for investigating host range and virulence evolution and plant non-host resistance. The selected group of strains includes the completely sequenced Arabidopsis and tomato pathogen Pto DC3000 and additional strains that are able to cause disease on Arabidopsis. DC3000 has long been used as a model probe for understanding the Arabidopsis immune system. DC3000 injects over 30 type III effectors into Arabidopsis cells via a type III secretion system to subvert defense and hijack plant cells in favor of pathogen growth. However, other members of this group, such as Pto T1 and Pto JL1065, do not cause disease on Arabidopsis. Despite of distinctive host range and virulence, these isolates have been confirmed to share over 99% DNA identity with Pto DC3000 in housekeeping genes. By comparing this group of strains, we expect to uncover the mystery of what makes a P. syringae strain a successful pathogen on Arabidopsis. Genome sequencing of T1 have revealed unexpected diversity in some genomic regions, which are believed to be the primary contributors to the observed virulence and host range differences between isolates. Thus, these isolates represent a perfect combination of closeness in phylogeny combined with divergence in host range and virulence. My goal for the rest of my PhD study is to uncover the genetic basis of the inability of T1-like isolates to cause disease on A. thaliana. Additionally, over 10 DC3000 relatives have recently been sequenced in our lab. Comparative genomics of these strains will greatly facilitate the dissection of virulence and host range evolution in P. syringae and the uncovering of the genetic basis of A. thaliana - P. syringae host and non-host interactions, which will shed more light on A. thaliana defense signaling pathways.

Publications:

  • lmeida, N. F.*, Yan, S.*, Lindeberg, M.*, D. J. Studholme, D. J. Schneider, B. Condon, H. Liu, C. J. Viana, A. Warren, C. Evans, E. Kemen, D. Maclean, A. Angot, G. B. Martin, J. D. Jones, A. Collmer, J. C. Setubal & B. A. Vinatzer, (2009) A draft genome sequence of Pseudomonas syringae pv. tomato T1 reveals a type III effector repertoire significantly divergent from that of Pseudomonas syringae pv. tomato DC3000. Mol Plant Microbe Interact 22: 52-62. *These authors contributed equally to this work.
  • Yan, S., Liu, H., Mohr, T., Jenrette, J., Chiodini, R., Zaccardelli, M., Setubal, J. C., Vinazter, B. A. The Role of Recombination in the Evolution of The Model Plant Pathogen Pseudomonas syringae pv. tomato DC3000, a Very Atypical Tomato Strain. Appl Environ Microbiol 74: 3171-3181.
  • Mohr, T. J., Liu, H., Yan, S., Morris, C. E., Castillo, J. A., Jelenska, J., & Vinatzer, B. A. Naturally Occurring Non-pathogenic Isolates of the Plant Pathogen Species Pseudomonas syringae Lack a Type III Secretion System and Effector Gene Orthologues. J Bacteriol 190: 2858-2870.
  • Morris, C. E., Sands, D. C., Vinatzer, B. A., Glaux, C., Guilbaud, C., Buffiere, A., Yan, S., Dominguez, H., & Thompson, B. M. The life history of the plant pathogen Pseudomonas syringae is linked to the water cycle. (2008) ISME J 2, 321-334.
  • Vinatzer, B. A. & Yan, S. Mining the genomes of plant pathogenic bacteria: how not to drown in gigabases of sequence. (2008) Molecular Plant Pathology 9, 105-118.

Posters at international meetings:

  • Conference for Genomes, Evolution, and Bioinformatics, May 24-28, 2006, Tempe, Arizona, USA: Yan, S., Chiodini, R., Cai, Z., Mohr, T., Jenrette, J., Zaccardelli, M., Williams, L., Zhang, L., Setubal, J. C., Vinatzer, B. A. Closely Related Strains of the Plant Pathogen Pseudomonas syringae: Clonal or Freely Recombining? Cai, Z., Yan, S., Vinatzer, B. A., Setubal, J. C.. Bacterial Genome Alignments and Genomic Islands: A Pseudomonas syringae Case Study.
  • 8th Conference of the European Foundation for Plant Pathology, August 13-17, 2006, Copenhagen, Denmark: Vinatzer, B. A., Yan, S., Chiodini, R., Mohr, T. J., Jenrette, J., Williams, L., Setubal, J. C., Zaccardelli, M. Pseudomonas syringae pv. tomato DC3000: is it pathovar tomato, maculicola, or what else?
  • XIII International Congress on Molecular Plant-Microbe Interactions, July 21-27, 2007, Sorrento, Italy: Yan, S., Chiodini, R., Jenrette, J., Mohr, T. J., Zaccardelli, M., Vinatzer, B. A. Contribution of Recombination to Virulence and Host Range Evolution in Pseudomonas syringae
  • 19th International Conference on Arabidopsis Research, July 23 - 27, 2008, Montreal, Canada: Yan, S., Vinatzer BA, et. al. Dissecting Arabidopsis host and nonhost interactions with Pseudomonas syringae-- taking advantage of comparative and evolutionary genomics

Talks and Presentations:

  • PMBDG seminar, August 27th, 2008, Virginia Tech, Blacksburg: Why is Arabidopsis Immune to the Tomato Pathogen Pseudomonas syringae pv. T1?
  • PPWS seminar given on Sept. 29th, 2007, Virginia Tech, Blacksburg: Host Range Evolution in Bacterial Plant Pathogen Pseudmonas syringae.
  • American Phytopathological Society (APS) Potomac Division Annual Meeting, March 21-23, 2007 Blacksburg, Virginia, USA: Yan, S., Chiodini, R., Jenrette, J., Mohr, T., Vinatzer, B. A. (2007) Pathogenicity Evolution by Recombination in Pseudomonas syringae.
  • 7th International Conference on Pseudomonas syringae and Related Pathogens, November 12-16, 2006 Agadir, Morocco (Talk was presented by Boris A. Vinatzer): Yan, S., Chiodini R, Mohr TJ, Jenrette J, Cai, Z, Zaccardelli, M., Setubal JC, Vinatzer BA. Pseudomonas syringae pv. tomato DC3000 is a Member of a Frequently Recombining Worldwide Population Found on Wild and Cultivated Solanaceous and Brassicaceous Plants.

Awards:

  • GSA Graduate Research and Development Project (GRDP) Grant, Spring 2008 from Virginia Tech

Membership:

  • Gamma Sigma Delta, The Honor Society of Agriculture
  • The American Society For Microbiology
  • International Society of Plant-Microbe Interaction (IS-MPMI)
  • Phi Sigma Biological Honor Society

Services and Positions:

  • 2008-2009, Department delegate for Graduate Student Assembly of Virginia Tech
  • 2008-2009, Registered Student Organization Budget Board
  • 2008-2009, Panelist for Graduate Honor System