Gradient Expression of Transcription Factor Imposes a Boundary on Organ Regenerative Potential in Plant

A wide variety of multicellular organisms across the kingdoms display remarkable ability to restore their tissues or organs when they suffer damage, but the regenerative capacity varies widely along the organ axis. Here we provide a deeper understanding into the elusive mechanistic basis of what imposes a boundary on regeneration potential of cells in a growing root and show that gradient expression of PLT2 protein is the underlying cause. While transient downregulation of PLT2 in distinct set of plt mutant backgrounds renders meristematic cells incapable of regeneration, forced expression of PLT2 acts through auto activation to confer regenerative potential to the cells undergoing differentiation. Furthermore, we show that PLT2 activates root tip regeneration in a dosage dependent manner. Surprisingly, sustained high levels of PLT2, beyond a threshold, abolishes regeneration despite giving rise to longer meristem. Our studies reveal previously unidentified dosage dependent role of gradient expressed PLT2 in root tip regeneration and uncouple the size of organ from its regenerative potential.