Li, Xiang (Sean)

Image Li, Sean (Xiang)
Research Scientist

Canadian Food Inspection Agency, Charlottetown Laboratory; coordinates and conducts research and technology development for the detection, identification, and classification of plant pathogenic bacteria of regulatory importance. Specialises in potato brown rot, ring rot, blackleg/soft rot, zebra chip, and phytoplasma diseases, and root and butt rot diseases of conifers employing comparative genomics and metegenomics, phylogenetics and phylogeographics, and conventional and molecular diagnostic technologies.

Current research and/or projects

Detection/identification of plant pathogenic bacteria of regulatory importance: Ralstonia solanacearum, Clavibacter sepedonicus,  'Candidatus Liberibacter solanacearum', 'Candidatus Phytoplasma spp.'

Classification/taxonomy of plant pathogenic bacteria: Clavibacter spp. Pectobacterium spp., Dickeya spp.  

Development of on-the-spot diagnostic techniques: Handheld device on the basis of loop-mediated isothermal amplification and qPCR technologies

Phylogentic and phylogeographics of root and butt rot diseases of conifers: Heterobasidion spp. 

Other research activities: Potato common scab and powdery scab, Stewartii's wilt of corn, bacterial leaf streak, virus and viroid diseases of potato.

Comparative genomics and metagenomics technologies

Professional activities / interests

  • Member of the ISPP-CTPPB (Committee on Taxonomy of Plant Pathogenic Bacteria of International Society for Plant Pathology)

  • Member of the ISPP-CPQB (Committee on Plant Quarantine and Biosecurity)

  • Editorial Board Member of Acta Microbiologica Sinica

  • Member of the American Phytopathology Society, Diagnostics Committee member, and Bacteriology Committee member.

  • Member of the Canadian Phytopathological Society.

  • Invited speaker at many conferences and Universities.

  • Supervision of postdoctoral fellows, PhD, Master's and co-op students.

  • Review of scientific manuscripts for international journals

  • Review of proposal applications for research grants.

Education and awards

1993-1995 Canadian Government Laboratory Visiting Fellowship (Postdoc Fellow), AAFC Vancouver Research Station, Vancouver, BC, Canada

1993. Ph.D. in Department of Microbiology, the University of Queensland, QLD, Australia, Award: University of Queensland Postgraduate Scholorship

1983. Bachelor of Agricultural Science. Department of Pland Protection, Huazhong Agricultural University, Wuhan, China

Key publications

Selected publications

  1. Li X., Tambong J.,  Yuan X., Chen W., Xu H., Levesque C.A. and De Boer, S.H. 2018. Re-classification of Clavibacter michiganensis subspecies on the basis of whole-genome and multi-locus sequence analyses. International Journal of Systematics and Evolutionary Microbiology 68:234–240. DOI 10.1099/ijsem.0.002492
  2. Li X., Yuan X. 2017. Genome sequences for multiple Clavibacter strains from different subspecies. Genome Announc 5:e00721-17.
  3. Tian, Y., Zhao, Y., Yuan X., Yi, J., Fan, J., Xu, Z., Hu, B.*, De Boer, S.H., and Li, X.* 2016. Dickeya fangzhongdai sp. nov., a plant-pathogenic bacterium isolated from pear trees (Pyrus pyrifolia). International Journal of Systematic and Evolutional Microbiology.  66(8):2831-2835.
  4. Gagnon, M.C., van der Lee, T., Bonants, P., Smith, D.S., Li, X., Levesque, C.A., Bilodeau, G.J. 2016. Development of polymorphic microsatellite loci for potato wart from next-generation sequence data. Phytopathology 106(6):636-644.
  5. Li, X., De Boer, S.H., Alvarez, A.M., and Schaad, N.W. 2016. Detection of Ralstonia solanacearum in potato and geranium. Chapter 30 in APS manual on detection of plant pathogenic bacteria in seed and planting material (Ed. M'Barek Fatmis)
  6. Yuan, K., Cullis, J., Lévesque, C.A., Tambong, J., Chen, W., Lewis, C.T., De Boer, S.H., Li, X. 2015. Draft genome sequences of Ralstonia solanacearum race 3 biovar 2 strains with different temperature adaptations. Genome Announcements 3(4):e00815-15. doi: 10.1128/genomeA.00815-15.
  7. Li, X., Yuan, K., Cullis, J., Lévesque, A.C., Chen, W., Lewis, C.T. and De Boer, S.H. 2015. Draft genome sequences for Canadian isolates of Pectobacterium carotovorum subsp. brasiliense with weak virulence on potato. Genome Announcement 3(2):e00240-15, doi:10.1128/genomeA.00240-15
  8. Yuan, K., Adam, L., Tambong, J., Lévesque, C.A., Chen, W., Lewis, C.T. De Boer, S.H. , and Li, X.* 2013. Draft genome sequence of Pectobacterium wasabiae strain CFIA1002. Genome Announcement 15:2(3). pii: e00214-14. doi: 10.1128/genomeA.00214-14.
  9. Li, X.*, Nie, J., Hammill, D.L., Smith, D., Xu, H., and De Boer, S.H. 2014 A comprehensive comparison of assays for detection and identification of Ralstonia solanacearum race 3 biovar 2. Journal of Applied Microbiology 117(4):1132-43. doi: 10.1111/jam.12585
  10. Bull, C.T., Coutinho, T.A., Denny, T.P., Firrao, G., Saux, M.F. Li, X., Saddler, G.S., Scortichini, M. Stead, D.E., Takikawa, Y. 2014. List of new names of plant pathogenic bacteria 2011-2012. Journal of Plant Pathology 96: 223-226
  11. Yuan, K., Li, X.*, Adam, L., Tambong, J., Lévesque, C.A., Chen, W., Lewis, C.T. De Boer, S.H. 2014. Draft genome sequence of Pectobacterium wasabiae strain CFIA1002. Genome Announcement 2(3):e00214-14. doi:10.1128/genomeA.00214-14.
  12. Li, X., Nie, J. Arsenault, H. Hammill, D.L., Xu, H., and S.H. De Boer 2013 Tomato as a latent carrier of ‘Candidatus Liberibacter solanacearum’, the causal agent of potato zebra chip disease EPPO Bulletin 43 (2): 229-237
  13. De Boer, S.H., Li, X., and Ward, L. 2012 Pectobacterium spp. associated with bacterial stem rot syndrome of potato in Canada. Phytopathology 102: 937-947
  14. Xu, M., Chen, X., Qiu, M., Zeng, X., Xu, J., Deng, D., Sun, G., Li, X., Guo, J. 2012. Bar-coded pyrosequencing reveals the responses of PBDE-degrading microbial communities to electron donor amendments. PLOS One 7(1): e30439
  15. Li, X., Nie, J., Ward, L. Nickerson, J., De Boer, S.H. 2011 Development and evaluation of a loop-mediated isothermal amplification assay for rapid detection and identification of Pectobacterium atrosepticum. Can J Plant Pathol 33: 447-457
  16. Li, X., Levy, L., Olivas, A.F, and De Boer, S.H., Detection and Identification of Ralstonia solanacearum Phylotype II Sequevar 1 (Race 3 Biovar 2), Annex 19 in NAPPO RSPM 3.
  17. Madani, M., Subbotin, S.A., Ward, L.J. Li, X., and De Boer, S.H. 2010 Molecular characterization of Canadian populations of potato cyst nematodes, Globodera rostochiensis and G. pallida using ribosomal nuclear RNA and cytochrome b genes Can J Plant Pathol 32: 252-263.
  18. Li, X., Nie, J., Ward, L., Madani, M., Hsiang, T., Zhao, Y., De Boer, S.H. 2009. Comparative genomics-guided loop-mediated isothermal amplification for characterization of Pseudomonas syringae pv. phaseolicola.  Journal of Applied Microbiology 107(3): 717-726
  19. Secor, G.A. V.V. Rivera, J.A. Abad, G.R.G. Clover, L.W. Liefting, X. Li, S.H. De Boer. 2009. Association of ‘Candidatus Liberibacter’ sp. with the Zebra Chip Disease of Potato Established by Grafting, Psyllid Transmission and Electron Microscopy. Plant Disease 93(6): 574-583
  20. Li X.*, Guo J, Dai S, Ouyang Y, Wu H, Sun W, Wang G. 2009 Exploring and exploiting microbial diversity through metagenomics for natural product drug discovery. Current Topics in Medicinal Chemistry 9 (16): 1525-1535.
  21. Xie, LW, Jiang, SM, Zhu, HH, Sun, W, Ouyang, YC, Dai, SK, and Li, X.*, 2008. Potential inhibitors against Sclerotinia sclerotiorum, produced by fungus Myrothecium sp. associated with marine sponge Axinella sp. European Journal of Plant Pathology 122(4): 571-578
  22. Li, X.* and Qin, L. 2005 Metagenome-Based Drug Discovery and Marine Microbial Diversity. Trends in Biotechnology 23 (11): 539-543.
  23. Li, X.* and De Boer, S.H. 2005 First Report of Burkholderia andropogonis causing leaf spots of Bougainvillea sp. in Hong Kong and clover in Canada. Plant Disease 89: 1132.


Research facility

93 Mount Edward Road
Charlottetown, PE C1A5T1


Agence canadienne d’inspection des aliments, Laboratoire de Charlottetown, Charlottetown (Île‑du-Prince-Édouard)



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