Figure 7.

Schematic illustration of the signaling networks involving IAA, NO, and cellular messengers that regulate ARF in cucumber. The auxin IAA triggers a transient NO accumulation (Pagnussat et al., 2002). In turn, NO regulates the activation of a MAPK signaling cascade. This pathway could be mediating both mitotic process and the expression of auxin-responsive genes (Mockaitis and Howell, 2000). In parallel, a cGMP-dependent pathway is also present leading to ARF (Pagnussat et al., 2003). NO-mediated signaling pathways that regulate ARF in cucumber: light gray, cGMP-independent; dark gray, cGMP-dependent.