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Taxonomy of Plant Pathogenic Bacteria News:

Retirement Announcements

The ISPP Committee on the Taxonomy of Plant Pathogenic Bacteria (CTPPB) announces the retirement of two esteemed committee members, Drs. David Stead and Timothy Denny. The committee took nominations and added two new members (T. Coutinho and X. Li) in 2013 in anticipation of these retirements. The ISPP-CTPPB asks readers to join them in thanking Drs. David Stead and Timothy Denny for their combined 35 years of meaningful service to the ISPP

Dr. David Stead was born in Yorkshire, UK and from about the age of 9 he had a dilemma, as he wanted to become a plant biochemist and work in an African National Park. Plant pathology became the vehicle for his dreams. He received his B.Sc. in Microbiology at the then Chelsea College of Science and Technology, followed by a Ph.D. for work on potato blackleg and soft rot with Prof. RKS Wood at Imperial College. Both degrees had their “fair share of biochemistry.” He took a break from biochemistry to teach crop pathology and microbiology at the University of Malawi for eight years.  His plant pathology expertise extended to studying elephant damage in woodlands in a local National Park. He returned to the UK as Plant Bacteriologist at the Plant Pathology Laboratory in Harpenden where he provided diagnostic services for bacterial plant pathogens, curated the National Collection of Plant Pathogenic Bacteria (NCPPB) and conducted research relevant to controlling diseases and to improve diagnostic methods. David worked much of his career on potato ring rot and brown rot and he particularly enjoyed working with colleagues in the European Union to develop Control Directives for both of these economically important diseases. His research into improved diagnostics resulted in pioneering the use of fatty acid profiling and real time PCR for routine use and his broad experience from running the diagnostic clinic enabled him to write a book on diagnosis of bacterial diseases with his predecessor, Ron Lelliott.  In 2009, Dr. Stead retired as the Head of Microbiology at the Central Science Laboratory in York, UK.  David actively served as a member of the ISPP - CTPPB for 22 years (since 1992). His leadership during the transition between conveners of the committee (2001 and 2007) was invaluable to the smooth running of the committee and accuracy of our publications. The committee is grateful that David maintained his membership on the ISPP – CTPPB for an additional five years during his retirement. Additionally, David reports that he has metamorphosed into an amateur entomologist, specialising in moth identification and confesses “Once a taxonomist, always a taxonomist”.

Dr. Timothy Denny retired from the Department of Plant Pathology of the University of Georgia on April 1, 2014. His early training was in botany, receiving a B.S. degree in 1975 from Duke University. He received a Ph.D. in plant pathology from Cornell University in 1983 under the direction of Hans Van Etten where he was the first to characterize non-degradative tolerance of phytoalexins by fungi. Tim joined the University of Georgia faculty in 1984 was and promoted to Professor in 1998.  He made significant contributions to molecular diversity of Pseudomonas syringae before focusing his research on genetic and biochemical mechanisms that enable Ralstonia solanacearum to cause lethal wilting diseases. His laboratory explored factors influencing the pathogen’s ability to colonize plants including motility, the role of extracellular enzymes and polysaccharides, and the role of the type II system to secrete extracellular proteins important to colonization. Studies on the pathogen’s modulation of gene expression for survival and pathogenesis lead to discovery of the reversible phenotype conversion of R. solanacearum, whereby the pathogen uses a complex regulatory cascade to coordinately control many traits for virulence and survival in response to 3-hydroxy palmitic acid methyl ester, a unique autoinducer. He served phytobacterologists worldwide as both an associate and senior editor for Phytopathology, an associate editor for Molecular Plant Microbe Interactions. In conjunction with his long time collaborator, Dr. Mark Schell, he was awarded the UGA Creative Research Medal in 1998 and was selected as an APS Fellow in 2002. Tim used his expertise to monitor changes in Pseudomonas and Ralstonia nomenclature for the ISPP – CTPPB since 2005. He always raised insightful questions, found obscure proposals for new names, and was a great help in finalizing the formatting for the Lists of Names published during his tenure.



The ISPP-CTPPB has published an up-date of the "List of Names of Plant Pathogenic Bacteria. The citation for this publication is   Bull, C.T., Coutinho, T.A., Denny, T.P., Firrao, G., Fischer-Le Saux, M., Li, X., Saddler, G.S., Scortichini, M., Stead, D.E., Takikawa, Y. List Of New Names Of Plant Pathogenic Bacteria (2011-2012) Journal of Plant Pathology 96:223-226 (2014) and is available at http://sipav.org/main/jpp/index.php/jpp/article/view/3127  

Please contact the convener Carolee.Bull@ars.usda.gov with questions about this or other lists (below). 

Bull, C. T., S.H. De Boer, T.P. Denny, G. Firrao, M. Fischer-Le Saux, G.S. Saddler, M. Scortichini, D.E. Stead, Y. Takikawa. 2012. List of New Names of Plant Pathogenic Bacteria (2008-2010). Journal of Plant Pathology 94 (1), 21-27. doi: 10.4454/jpp.fa.2011.003.  

Bull, C. T., S.H. De Boer, T.P. Denny, G. Firrao, M. Fischer-Le Saux,   G.S. Saddler, M. Scortichini, D.E. Stead, Y. Takikawa, 2010.    COMPREHENSIVE LIST OF NAMES OF PLANT PATHOGENIC BACTERIA, 1980-2007.    Journal of Plant Pathology 92:551-592.
Download PDF <http://www.isppweb.org/SMC_Files/Bull%20et%20al.%202010%20JPP%20List.pdf>  
Bull, C. T., S.H. De Boer, T.P. Denny, G. Firrao, M. Fischer-Le Saux,   G.S. Saddler, M. Scortichini, D.E. Stead, Y. Takikawa,. 2008.     Demystifying Nomenclature of Bacterial Plant Pathogens Journal of Plant   Pathology 90:403-417. 
Download PDF <http://www.isppweb.org/SMC_Files/Bull%20et%20al%202008%20InvitedReview_403.pdf>    

Taxonomy of Plant Pathogenic Bacteria - Committee members:

C.T. Bull (Convener), US Department of Agriculture, 1636 E Alisal Street, Salinas, CA 93905, USA  e-mail:  

T.A. Coutinho, Department of Microbiology and Plant Pathology Forestry and Agricultural Biotechnology Institute (FABI), University of Pretoria, Pretoria 0002, South Africa  email:

T.P. Denny, University of Georgia, Plant Pathology Department, Plant Science Building, Athens, GA 30602-7274, USA  e-mail: 

G. Firrao, Dipartimento di Biologia Applicata alla Difesa delle Piante, Universita, via Scienze 208, 33100 Udine, Italy  e-mail: 

M. Fischer-Le Saux, UMR de Pathologie Vegetale, INRA, BP 60057, 49071 Beaucouze Cedex, France  e-mail:

X. Li, Canadian Food Inspection Agency, Charlottetown Laboratory, 93 Mount Edward Road, Charlottetown, PE C1A 5T1, Canada  email:

G.E. Saddler, Scottish Agricultural Science Agency, 1 Roddinglaw Road, Edinburgh, EH12 9FJ, Scotland, United Kingdom  e-mail: 

M. Scortichini, C.R.A. - Istituto Sperimentale per la Frutticoltura, Via di Fioranello, 52, 00134  Roma, Italy  e-mail: 

D.E. Stead, Central Science Laboratory, Department for Environment, Food and Rural Affairs, Sand Hutton, York, YO41 1LZ, United Kingdom  e-mail:. 

Y. Takikawa, Faculty of Agriculture, Shizuoka University, 836 Ohya, Shizuoka 422-8529, Japan  e-mail: