Abstract text: Building on the seminal discovery by the Demura lab that inducible expression of specific transcription factors can reprogram photosynthetic mesophyll cells into xylem vessel elements and thereby trigger secondary cell wall formation in planta (Yamaguchi et al., 2010, Plant Physiology), we sought to overcome the lack of spatial control inherent to chemical induction systems.

Here, we report the development of an optogenetic platform that enables light-directed activation of these key developmental regulators, allowing predefined vascular architectures to be “drawn” within living leaf tissue. Using monochromatic visible light in combination with a simple and cost-effective photolithography approach, patterned xylem vessel networks were generated with high spatial precision. The newly formed xylem elements became functionally integrated into the endogenous vasculature and contributed to water transport, establishing this system as a proof-of-concept for true tissue engineering in plants.

The results demonstrate that optogenetic regulation provides sophisticated spatial control of gene expression, enabling rapid prototyping of complex biological patterns including secondary wall deposition, targeted synthesis of specific wall polymers, and the study of signaling interactions between neighboring cells.