MAPK Signaling: Emerging Roles in Lateral Root Formation.

Lateral root (LR) formation is a multi-step developmental process in which auxin and peptide hormones play essential roles. Recent studies in arabidopsis by Huang et al. and Zhu et al. have revealed that the mitogen-activated protein kinase (MAPK) cascade MKK4/MKK5-MPK3/MPK6 functions in both a noncanonical auxin signaling pathway and the IDA peptide signaling pathway to regulate LR morphogenesis and emergence, respectively.