Figure 2. Bidirectional signaling pathway between the stele and the ground-tissue. SHR transcription occurs in the stele (1), after which the protein moves outwards from the stele to the endodermis to activate miRNA transcription together with SCR (2). The miRNAs move to the stele periphery (3) and downregulate PHB expression by targeting its mRNA transcripts for cleavage (4). Stele is highlighted in pink, endodermis in blue and cortex in yellow.