The arabidopsis cell plate-associated dynamin-like protein, ADL1Ap, is required for multiple stages of plant growth and development

Dynamin and dynamin-like proteins are GTP-binding proteins involved in vesi cle trafficking. In soybean, a 68-kD dynamin-like protein called phragmopla stin has been shown to be associated with the cell plate in dividing cells (Cu and Verma, 1996). Five ADL1 genes encoding dynamin-like proteins relate d to phragmoplastin have been identified in the completed Arabidopsis genom e. Here we report that ADL1Ap is associated with punctate subcellular struc tures and with the cell plate in dividing cells. To assess the function of ADL1Ap we utilized a reverse genetic approach to isolate three separate Ara bidoysis mutant lines containing T-DNA insertions in ADL1A. Homozygous adl1 A seeds were shriveled and mutant seedlings arrested soon after germination , producing only two leaf primordia and severely stunted roots. Immunoblott ing revealed that ADL1Ap expression was not detectable in the mutants. Desp ite the loss of ADL1Ap, the mutants did not display any defects in cytokine sis, and growth of the mutant seedlings could be rescued in tissue culture by the addition of sucrose. Although these sucrose-rescued plants displayed normal vegetative growth and flowered, they set very few seeds. Thus, ADL1 Ap is critical for several stages of plant development, including embryogen esis, seedling development, and reproduction. We discuss the putative role of ADL1Ap in vesicular trafficking, cytokinesis, and other aspects of plant growth.