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Systemic regulation of nodulation and root development

Team SILEG / Florian Frugier


Forward genetic screens allowed us to identify mutants affected both in root and nodule development, referred to as compact root architecture (cra ; Laffont et al., 2010).

One of these mutants, cra2 , affects antagonistically nodule and lateral root development and is defective in a CLAVATA1-like LRR-RLK (Huault et al., 2014). Graft experiments showed that the regulation of symbiotic nodulation was determined by the activity of the receptor in shoots, implying a systemic regulation of root nodulation. More recently, we have showed that the MtCEP1 peptide positive effect on nodulation and negative effect on lateral root formation relies on the MtCRA2 receptor (Mohd-Radzman et al., 2016). We are currently analyzing how this new regulatory pathway integrates with the previously reported systemic Super Numeric Nodules (SUNN)-dependent “Autoregulation of Nodulation” pathway and the cytokinin/CRE1 pathway.

A working model for a dynamic fine tuning of nodulation by SUNN and CRA2 systemic pathways. CRA2, Compact Root Architecture 2 LRR-RLK ; SUNN, Super Numeric Nodules LRR-RLK ; CLE12, CLE13 : CLAVATA3-like peptides 12 and 13 ; CEP1, C-terminally Encoded Peptides 1 ; AON, Autoregulation Of Nodulation.