Abstract

Plant cells are surrounded by cell walls so individual cells do not touch. Besides receptor mediated intercellular signaling, plants have evolved unique channels, called plasmodesmata, that span the cell wall and enable direct cytoplasmic continuity between adjacent cells. We utilize Arabidopsis embryogenesis as a model system to study the structure and function of these channels. Protein and gene silencing signals of differing sizes are transported between cells in particular regions of the developing embryo corresponding to the major organ types. A genetic screen identified several mutants that affect plasmodesmata structure and function. To date, two mutants have been characterized in detail. Both encode RNA helicases that localize to different cellular compartments, mitochondria and cytoplasmic RNA granules. Both genes are essential as null mutants are lethal. These data imply that global cell autonomous homeostasis is critical to regulate the cell-non-autonomous function of plasmodesmata.