| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
Physiology and Growth |
Departments of Plant Pathology1 and Microbiology2, University of Georgia, Athens, GA 30602, USA
Laboratoire de Biologie Moléculaire des Relations Plantes-Micro-organismes, INRA-CNRS, Toulouse, France3
Author for correspondence: Timothy P. Denny. Tel: +1 706 542 1282. Fax: +1 706 542 1262. e-mail: tdenny{at}arches.uga.edu
Twitching motility is a form of bacterial translocation over firm surfaces that requires retractile type IV pili. Microscopic colonies of Ralstonia solanacearum strains AW1, K60 and GMI1000 growing on the surface of a rich medium solidified with 1·6% agar appeared to exhibit twitching motility, because early on they divided into motile ‘rafts’ of cells and later developed protruding ‘spearheads’ at their margins. Individual motile bacteria were observed only when they were embedded within masses of other cells. Varying degrees of motility were observed for 33 of 35 strains of R. solanacearum in a selected, diverse collection. Timing was more important than culture conditions for observing motility, because by the time wild-type colonies were easily visible by eye (about 48 h) this activity ceased and the spearheads were obscured by continued bacterial multiplication. In contrast, inactivation of PhcA, a transcriptional regulator that is essential for R. solanacearum to cause plant disease, resulted in colonies that continued to expand for at least several additional days. Multiple strains with mutations in regulatory genes important for virulence were tested, but all exhibited wild-type motility. Many of the genes required for production of functional type IV pili, and hence for twitching motility, are conserved among unrelated bacteria, and pilD, pilQ and pilT orthologues were identified in R. solanacearum. Colonies of R. solanacearum pilQ and pilT mutants did not develop spearheads or rafts, confirming that the movement of cells that had been observed was due to twitching motility. Compared to the wild-type parents, both pilQ and pilT mutants caused slower and less severe wilting on susceptible tomato plants. This is the first report of twitching motility by a phytopathogenic bacterium, and the first example where type IV pili appear to contribute significantly to plant pathogenesis.
Keywords: pili, fimbriae, bacterial wilt, bacterial cell movement
Abbreviations: EPS, extracellular polysaccharide; HR, hypersensitive reaction; Tfp, type IV pili
This article has been cited by other articles:
|
|
 |
|
  J. Yao and C. Allen The Plant Pathogen Ralstonia solanacearum Needs Aerotaxis for Normal Biofilm Formation and Interactions with Its Tomato Host J. Bacteriol., September 1, 2007; 189(17): 6415 - 6424. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
P. S. Duggan, P. Gottardello, and D. G. Adams Molecular Analysis of Genes in Nostoc punctiforme Involved in Pilus Biogenesis and Plant Infection J. Bacteriol., June 15, 2007; 189(12): 4547 - 4551. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 Y. Li, G. Hao, C. D. Galvani, Y. Meng, L. D. L. Fuente, H. C. Hoch, and T. J. Burr Type I and type IV pili of Xylella fastidiosa affect twitching motility, biofilm formation and cell-cell aggregation Microbiology, March 1, 2007; 153(3): 719 - 726. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
S. Voisin, J. V. Kus, S. Houliston, F. St-Michael, D. Watson, D. G. Cvitkovitch, J. Kelly, J.-R. Brisson, and L. L. Burrows Glycosylation of Pseudomonas aeruginosa Strain Pa5196 Type IV Pilins with Mycobacterium-Like {alpha}-1,5-Linked D-Araf Oligosaccharides J. Bacteriol., January 1, 2007; 189(1): 151 - 159. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
J. Yao and C. Allen Chemotaxis Is Required for Virulence and Competitive Fitness of the Bacterial Wilt Pathogen Ralstonia solanacearum. J. Bacteriol., May 1, 2006; 188(10): 3697 - 3708. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
Y. Meng, Y. Li, C. D. Galvani, G. Hao, J. N. Turner, T. J. Burr, and H. C. Hoch Upstream Migration of Xylella fastidiosa via Pilus-Driven Twitching Motility J. Bacteriol., August 15, 2005; 187(16): 5560 - 5567. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
G. Bhatt and T. P. Denny Ralstonia solanacearum Iron Scavenging by the Siderophore Staphyloferrin B Is Controlled by PhcA, the Global Virulence Regulator J. Bacteriol., December 1, 2004; 186(23): 7896 - 7904. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
J. V. Kus, E. Tullis, D. G. Cvitkovitch, and L. L. Burrows Significant differences in type IV pilin allele distribution among Pseudomonas aeruginosa isolates from cystic fibrosis (CF) versus non-CF patients Microbiology, May 1, 2004; 150(5): 1315 - 1326. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
C. Aguilar, A. Friscina, G. Devescovi, M. Kojic, and V. Venturi Identification of Quorum-Sensing-Regulated Genes of Burkholderia cepacia J. Bacteriol., November 1, 2003; 185(21): 6456 - 6462. [Abstract] [Full Text] [PDF]
|
|
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
| INT J SYST EVOL MICROBIOL | MICROBIOLOGY | J GEN VIROL |
| J MED MICROBIOL | ALL SGM JOURNALS | |
