Giles Oldroyd |
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Genetic dissection of Nod factor SignallingThe initial stages of the legume/rhizobial symbiosis involve a complex array of signalling events between the plant and bacteria. The first signals are plant derived phenolics, such as flavanoids, which are released from the roots of the host plant and perceived by compatible bacteria in the rhizosphere. Perception of the phenolic signal results in the transcriptional activation of bacterial nod genes through the transcription factor NodD. Nod genes are predominantly involved in the production of Nod factor, an extremely potent signal that is active on the plant at concentrations as low as 10-12M. Nod factors consist of a chitin backbone (3-5 N-acetylglucosamine residues) with a N-acyl group attached to the non-reducing sugar and a variety of additional substituents attached to the glucosamine residues. Isolated Nod factor can induce many of the plant responses seen in the early stages of this interaction. We are interested in understanding how the plant perceives and transduces the Nod factor signal to establish this symbiosis. We are using genetics to identify the proteins involved in this signal transduction pathway. Work here and in other laboratories have led to the identification of a signal transduction pathway for Nod factor perception. We are currently characterising the mechanisms of Nod factor signal transduction.
The symbiosis signalling pathway
The structure of Sinorhizobium meliloti Nod factor
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