A coherent feed forward loop drives vascular regeneration in damaged aerial organs growing in normal developmental-context

Abstract

Aerial organs of plants being highly prone to local injuries, require tissue restoration to ensure their survival. However, knowledge of the underlying mechanism is sparse. In this study, we mimicked natural injuries in growing leaf and stem to study the reunion between mechanically disconnected tissues. We show that PLETHORA(PLT)/ AINTEGUMENTA(ANT) genes, which encodes stem cell promoting factors, are activated and contribute to vascular regeneration in response to these injuries. PLT proteins bind to and activate the CUC2 promoter. Both PLT and CUC2 regulate the transcription of the local auxin biosynthesis gene YUC4 in a coherent feed forward loop, and this process is necessary to drive vascular regeneration. In the absence of this PLT mediated regeneration response, leaf ground tissue cells can neither acquire early vascular identity marker ATHB8, nor properly polarize auxin transporters to specify new venation paths. The PLT-CUC2 module is required for vascular regeneration, but is dispensable for midvein formation in leaf. We reveal the mechanisms of vascular regeneration in plants and distinguishes the wound repair ability of the tissue from its formation during normal development.