Phosphorylation-dependent activation of the bHLH transcription factor ICE1/SCRM promotes polarization of the Arabidopsis zygote.

In Arabidopsis thaliana, the asymmetric cell division (ACD) of the zygote gives rise to the embryo proper and an extraembryonic suspensor, respectively. This process is controlled by the ERECTA-YODA-MPK3/6 receptor kinase-MAP kinase-signaling pathway, which also orchestrates ACDs in the epidermis. In this context, the bHLH transcription factor ICE1/SCRM is negatively controlled by MPK3/6-directed phosphorylation.

A multifaceted kinase axis regulates plant organ abscission through conserved signaling mechanisms.

Plants have evolved mechanisms to abscise organs as they develop or when exposed to unfavorable conditions. Uncontrolled abscission of petals, fruits, or leaves can impair agricultural productivity. Despite its importance for abscission progression, our understanding of the IDA signaling pathway and its regulation remains incomplete.