Figure 2.

CK Biosynthesis, Metabolism, and Signaling.

Intensity of signaling output at different developmental stages is depicted based on reporter studies, transcriptome experiments, and signaling mutant phenotypes. Following the perception of rhizobia, CK level and signaling is rapidly induced in the cortex. Cortical CK remains increased during nodule initiation and growth, while surrounding tissue and epidermal responses are restricted. Mature nodules retain CK signaling in the vasculature, with reduced signaling in infected cells. Core biosynthesis, metabolism, and signaling components are depicted at the right, along with species-specific components, where known. NF-induced/repressed components are indicated with a brown arrow (up or down, respectively).