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Extracellular DNases of Ralstonia solanacearum modulate biofilms and facilitate bacterial wilt virulence.
Minh Tran, Tuan; MacIntyre, April; Khokhani, Devanshi; Hawes, Martha; Allen, Caitilyn.
Affiliation
  • Minh Tran T; Department of Plant Pathology, University of Wisconsin-Madison, Madison, WI, 53706, USA.
  • MacIntyre A; Department of Plant Pathology, University of Wisconsin-Madison, Madison, WI, 53706, USA.
  • Khokhani D; Microbiology Doctoral Training Program, University of Wisconsin-Madison, Madison, WI, 53706, USA.
  • Hawes M; Department of Plant Pathology, University of Wisconsin-Madison, Madison, WI, 53706, USA.
  • Allen C; Department of Soil, Water and Environmental Science, University of Arizona, Tucson, AZ, 85721, USA.
Environ Microbiol ; 18(11): 4103-4117, 2016 11.
Article in En | MEDLINE | ID: mdl-27387368
ABSTRACT
Ralstonia solanacearum is a soil-borne vascular pathogen that colonizes plant xylem vessels, a flowing, low-nutrient habitat where biofilms could be adaptive. Ralstonia solanacearum forms biofilm in vitro, but it was not known if the pathogen benefits from biofilms during infection. Scanning electron microscopy revealed that during tomato infection, R. solanacearum forms biofilm-like masses in xylem vessels. These aggregates contain bacteria embedded in a matrix including chromatin-like fibres commonly observed in other bacterial biofilms. Chemical and enzymatic assays demonstrated that the bacterium releases extracellular DNA in culture and that DNA is an integral component of the biofilm matrix. An R. solanacearum mutant lacking the pathogen's two extracellular nucleases (exDNases) formed non-spreading colonies and abnormally thick biofilms in vitro. The biofilms formed by the exDNase mutant in planta contained more and thicker fibres. This mutant was also reduced in virulence on tomato plants and did not spread in tomato stems as well as the wild-type strain, suggesting that these exDNases facilitate biofilm maturation and bacterial dispersal. To our knowledge, this is the first demonstration that R. solanacearum forms biofilms in plant xylem vessels, and the first documentation that plant pathogens use DNases to modulate their biofilm structure for systemic spread and virulence.
Subject(s)

Full text: 1 Collection: 01-internacional Database: MEDLINE Main subject: Plant Diseases / Bacterial Proteins / Solanum lycopersicum / Biofilms / Ralstonia solanacearum / Deoxyribonucleases / Extracellular Space Language: En Journal: Environ Microbiol Journal subject: MICROBIOLOGIA / SAUDE AMBIENTAL Year: 2016 Document type: Article Affiliation country: Estados Unidos

Full text: 1 Collection: 01-internacional Database: MEDLINE Main subject: Plant Diseases / Bacterial Proteins / Solanum lycopersicum / Biofilms / Ralstonia solanacearum / Deoxyribonucleases / Extracellular Space Language: En Journal: Environ Microbiol Journal subject: MICROBIOLOGIA / SAUDE AMBIENTAL Year: 2016 Document type: Article Affiliation country: Estados Unidos
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