Independent regulation of symbiotic nodulation by the SUNN negative and CRA2 positive systemic pathways (Plant Physiol) ($)

Autoregulation of nodule development (AON) is a process by which leguminous plants control nodule development. SUNN, a LRR-RLK, and a systemic CLE peptide play a negative role in nodulation through systemic signaling. In this paper Laffont et al. showed the another systemic regulation of nodulation in Medicago by CRA2 (COMPACT ROOR ARCHITECTURE 2), a leucine-rich receptor-like kinase (LRR-RLK). Moreover, the nodulation inhibitory effect of MtCLE13 peptide is unaltered in cra2 mutants suggesting an independent pathway of the SUNN-CLE mechanism. It has been demonstrated using grafting studies with different combinations of Wt, sunn, cra2 mutants that a balance in nodulation, maintained by positive systemic regulation by CRA2 and negative systemic regulation by SUNN, is necessary to achieve proper nodulation. (Summary by Suresh Damodaran) @sureshdamod  Plant Physiol.  10.1104/pp.18.01588