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. 2010 May 11;63(1):141–154. doi: 10.1111/j.1365-313X.2010.04228.x

Figure 5.

Figure 5

A model for regulation pathways responsible for RN and AM symbioses. (a) In response to Nod factors, the signal generated by NFR1/NFR5 splits into two pathways, one of these flows into the common symbiosis pathway (pink line). The input of another pathway (deep pink line) is prerequisite for successful infection of rhizobia. Epistasis between CYCLOPS and NSP2 on the pathway remains unclear. ITs were rarely, but initiated in cyclops (Yano et al., 2006, 2008), while no micro-colonies were observed in nsp2 (Murakami et al., 2006). Therefore, CYCLOPS appears to be downstream of NSP2 on the pathway leading to IT formation. One possible explanation is that NSP2 may be positioned on another pathway that originates from NFR1/NFR5. For nodule organogenesis, only one signal is sufficient for activation of the downstream pathway, in which LHK1, NSP1/2 and NIN are involved. CYCLOPS is not involved in nodule organogenesis. (b) In the AM symbiosis, a plausible AM pathway that bifurcates after putative receptors (grey arrow) might be converged with common symbiosis pathway (blue arrows).