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Mechanism of action of Rhizobium nod factors

Reference	BBS/E/J/00001222
Principal Investigator / Supervisor	Professor J Downie
Co-Investigators / Co-Supervisors
Institution	John Innes Centre
Department	John Innes Centre Department
Funding type	Research
Value (£)	5,151
Status	Completed
Type	Institute Project
Start date	01/05/1998
End date	30/04/2002
Duration	48 months

Abstract

Rhizobia are able to invade the roots of their leguminous host plants, where they trigger the formation of root nodules. In these nodules, the bacterial are able to reduce atmospheric nitrogen into ammonia. The rhizobial genes that play a crucial role in the induction of the plant responses are the nodulation (nod) genes. Upon induction of the nod genes all rhizobia secrete specific lipochitooligosaccharides named Nod factors. The substitutions of these molecules determine on which host plant they are active as well as the type of response that can be induced. It is now clearly established that purified Rhizobium Nod factors are able to elicit many of the key events involved in early stages of the nodulation process, including root hair deformation, pre-infection thread formation and nodule organogenesis. Therefore, Rhizobium Nod factors are potent plant signalling molecules, capable of eliciting a variety of morphogenic and mitogenic responses in the host legume. At present we have an extensive knowledge on the biosynthetic pathways of Nod factors and the structures of these molecules made by different rhizobia. From the host plant, several genes that are specifically activated have been cloned and analysed. However, our knowledge on the mode of action of Nod factors - in other words; how do these signal molecules induce the various host responses - is very scanty. Major questions now to be solved concern the molecular mechanism of Nod factor-perception and -signal transduction by the host and how these result in the activation of specific genes and morphogenetic responses. To answer such questions it is essential to integrate approaches involving a variety of complementary disciplines. Thus, within an EU collaborative project experts on legume and Rhizobium genetics will collaborate with colleagues with electro physiology, cell cycle expertise, micro spectroscopy, ballistic targeting methods, and cell biological approaches to study signal transduction . The combined efforts and expertise present within the network will provide major new insights into the mode of action of Nod factors and how they induce morphogenetic responses.

Summary

unavailable

Committee	Closed Committee - Plant & Microbial Sciences (PMS)
Research Topics	X – not assigned to a current Research Topic
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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