Award details

Characterisation of a novel type of surface polar attachment induced in Rhizobium leguminosarum by a pea root exudate metabolite

Reference	BBS/E/J/000CA302
Principal Investigator / Supervisor	Professor J Downie
Co-Investigators / Co-Supervisors
Institution	John Innes Centre
Department	John Innes Centre Department
Funding type	Research
Value (£)	133,346
Status	Completed
Type	Institute Project
Start date	18/09/2007
End date	17/09/2010
Duration	36 months

Abstract

Interactions between rhizobia and legumes are usually considered to be initiated by plant-made flavonoids, which induce rhizobial nodulation (nod) genes. Our analysis of biofilm formation by Rhizobium leguminosarum has enabled us to identify a hitherto unrecognised aspect of rhizobial-legume communication totally independent of plant-made flavonoids and rhizobial nod genes. In static culture, R. leguminosarum cells attach to the glass surface side-on along their longitudinal axes in long chains of bacteria lying side-by-side. We have identified and purified a metabolite from pea root exudate which induces R. leguminnosarum to attach end-on (analogous to end-on attachment observed on root hairs) to glass in what appears to be haxagonal close-packed arrays). This proposal aims to chemically identify the factor inducing end-on attachment, understand its mode of action and determine the mechanism of end-on attachment that is induced. This will involve using microarrays to identify induced changes in gene expression and mutating induced genes to identify which are required for end-on attachment. The regulatory mechanism of gene induction will be identified by analysing transcript start sites and identifying mutants defective for gene induction by the factor. The timing and location of gene induction will be measured in situ and the cellular localisation of induced proteins will be analysed using translational GFP fusions. Using the mutants generated, the role of end-on attachment during nodulation, and the effects of pre-induction (and constitutive expression) of the genes will be assessed in competitive nodulation experiments.

Summary

unavailable

Committee	Closed Committee - Plant & Microbial Sciences (PMS)
Research Topics	Crop Science, Microbiology, Plant Science, Soil Science
Research Priority	X – Research Priority information not available
Research Initiative	X - not in an Initiative
Funding Scheme	X – not Funded via a specific Funding Scheme

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