Figure 7.

Schematic of the Interplay between SPY and the STOMAGEN–ERECTA Signaling Pathway in ROS Sensing and Redox-Mediated Cortex Proliferation in the Arabidopsis Root.

Under stress, plants accumulate ROS, which oxidize and activate STOMAGEN. STOMAGEN in turn activates ERECTA, which exerts its effect on mitosis in the endodermis through intercellular signaling. ROS also oxidizes and inactivates SPY, which normally represses middle-cortex formation by maintaining the expression of peroxidases and thus cellular redox. SPY acts downstream of ERECTA, but how SPY is affected by the ERECTA signaling pathway remains unknown.