Wandering the Plasmodesmata Field as a Leaf Vein Pattern Finder.

The role of auxin in leaf vein patterning, as expressed through auxin signaling and polar transport, is well established and supported by both experimental and computational data. In contrast, the involvement of plasmodesmata (PDs) in the auxin-driven vein patterning process has only been considered in computational models. Recent experimental data have provided support for the involvement of PDs, specifically their facilitation of auxin movement, in the patterned vein formation process. This review highlights the current model for patterned vein formation in Arabidopsis, examines the various pathways by which PDs enable auxin signal movement, discusses unresolved questions arising from findings on PDs-enabled auxin signal movement (PEASM), and proposes new research questions that may provide potential mechanistic insights into leaf vein patterning mechanisms.