Cell-to-cell communication via plasmodesmata during Arabidopsis embryogenesis.

In Arabidopsis embryogenesis, positional information establishes the overall body plan and lineage-dependent cell fate specifies local patterning. Position-dependent gene expression and responses to the plant hormone auxin are also crucial. Recently, another mechanism that delivers positional information has been uncovered. This pathway utilizes cell-to-cell communication via plasmodesmata. Plasmodesmata span the walls between neighboring plant cells. Groups of cells that allow intercellular transport of biotic and abiotic tracers form symplastic domains of shared communication. Initially, cells of the embryo form one symplast. As development proceeds, symplastic sub-domains that correspond to the major morphological regions of the plant (i.e. shoot apex, cotyledons, hypocotyl, and root) are formed. These sub-domains further resolve into tissue-specific domains of communication (such as protodermal and vascular regions). Cell-to-cell communication via plasmodesmata between embryonic and maternal tissues ceases as development proceeds.