Download mbpp_abstract_example

Pseudomonas fluorescens SBW25 secretes a biosurfactant that facilitates sliding
motility and plant growth promotion
Alsohim, A.1, Gallie, J.2, Zhang, X.-X.2, Rainey, P.B.2,3 and Jackson, R.W.1
1
School of Biological Sciences, University of Reading, Whiteknights, Reading, RG6 6AJ, UK
New Zealand Institute for Advanced Study, Massey University at Albany, New Zealand
3
Max Planck Institute for Evolutionary Biology, Ploen, Germany
2
Pseudomonas fluorescens bacteria are common soil inhabitants that favour colonisation of
plants, especially the root environment (rhizosphere). P. fluorescens strain SBW25 has been
studied to understand the genetic basis of its ecological success in the rhizosphere. The
flagellum master regulator, FleQ, is important for negatively regulating wss genes (encoding
cellulose extracellular polysaccharide (EPS)) and positively regulating flagellar genes. This
indicates that FleQ is probably important for transitional switching of the bacterial lifecycle from
the motile planktonic form (in the soil) to the non-motile EPS-producing biofilm form on and
within plant tissues. It was discovered that FleQ plays a role in bacterial surface-spreading:
mutation of fleQ in SBW25 (SBW25fleQ) revealed a flagellum-independent surface-spreading
motility phenotype. Mutagenesis of SBW25fleQ identified several non-motile mutants. PCR
analysis identified the mutations to two non-ribosomal synthetase genes known to be involved
in production of the biosurfactant viscosin. Complementation of these mutants with fleQ
restored surface motility despite a lack of viscosin production. This indicates that SBW25 can
move over surfaces by flagellum-dependent swarming and viscosin-dependent sliding motility.
Plant growth promotion assays using SBW25fleQ viscosin mutants showed that viscosin is the
key bacterial product responsible for suppression of root pathogen effects on plant seedling
emergence and development.