Figure 7.

Model for Cell Death Regulation Controlled by CPK1 and ORE1.

Senescence- and stress-related cell death in plants is governed by interconnected gene networks converging on ORE1, which acts as a master switch that is positively and negatively regulated by upstream transcription factors and miR164, respectively. The ORE1 protein undergoes an additional layer of control by posttranslational modification via phosphorylation by CPK1, a member of the calcium-regulatory network. This leads to high ORE1 activity and subsequent induction of expression of target gene(s) such as BFN1. The linkage between the reversible calcium-dependent signaling network via CPK1 and the irreversible gene-regulatory network via ORE1 guarantees a highly coordinated response, enabling, for example, a maximal retrieval of nutrients from the dying cells.