The cell plate-associated Arabidopsis dynamin-like protein (ADL1) family is required for cytokinesis and cell expansion

Polarized membrane trafficking during plant cytokinesis and cell expansion is critical for plant morphogenesis. Dynamin and dynamin-related proteins are large GTP binding proteins that are involved in membrane trafficking. ADL1A is an Arabidopsis dynamin-related protein that is associated with the cell plate during cytokinesis. The ADL1 gene family is comprised of five genes that encode highly related ∼68 kDa dynamin-related proteins. I utilized a reverse genetic approach to isolate and characterize Arabidopsis mutant lines containing T-DNA insertions in ADL1 genes. Homozygous adl1A plants exhibited multiple phenotypes including polar cell expansion defects. adl1A-2; adl1E-1 double mutants showed defects in cell plate assembly, cell wall formation and plasma membrane recycling indicating that ADL1A and ADL1E are functionally redundant and are essential for polar cell expansion and cell plate biogenesis.{09}An analysis using a functional ADL1A-GFP fusion protein indicated that the distribution of ADL1A is dynamic, and that the protein is asymmetrically localized in the plasma membrane of newly formed and of mature root cells. The expression profile of ADL1C is distinct from that of ADL1A or ADL1E suggesting unique roles of ADL1C in the Arabidopsis development. Analysis of heterozygous adl1C-1 plants indicated that the mutation specifically affects post-meiotic male gametogenesis. During microspore maturation, adl1C-1 pollen grains displayed defects in the plasma membrane and intine morphology suggesting that ADL1C is essential for the formation and maintenance of the pollen cell surface necessary for viability during desiccation. I propose that ADL1-mediated membrane recycling is essential for plasma membrane formation and maintenance in Arabidopsis.