The role of ROP GTPases in Nod factor signalling
A. AKAMATSU (1), G. Oldroyd (2) (1) John Innes Centre, United Kingdom; (2) John Innes Centre, United Kingdom

The establishment of the legume-rhizobial association is initiated by a molecular communication between the plant root and the free-living rhizobial bacteria in the soil. Plants release flavonoids that are recognized by the rhizobial bacteria, which in turn produce Nod factors (NFs). NFs perception by lysin motif (LysM)-containing receptor like kinases, LYK3 and NFP in Medicago truncatula, activates the symbiosis signalling pathway. This signalling pathway is required for root hair responses to rhizobial bacteria and for the activation of nodule organogenesis. The ROP small GTPases constitute a plant-specific Rho subfamily and participate in diverse signal transduction processes including root hair development, defense signalling, pollen tube growth and hormone responses. ROPs can transmit information immediately downstream of receptor kinases to coordinate cellular processes. In this work, we aim to identify ROP activation and inactivation pathway induced by rhizobial bacteria infection. We have found that overexpression of the MtROPa dominant negative form causes the reduction of the expression level of the nodulation-associated transcription factor Nodule Inception (NIN) at 3 weeks after inoculation with rhizobia Sinorhizobium meliloti and nodule formation. Yeast Two-Hybrid indicates a specific interaction with MtROPa and symbiotic receptors. These studies indicate that MtROPa function during Nod factor signalling associated with rhizobial infection.

Abstract Number: P2-14
Session Type: Poster