Plant Science

Action at the Plate

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Science  26 Oct 2001:
Vol. 294, Issue 5543, pp. 747
DOI: 10.1126/science.294.5543.747b

During the final stage of cell division (cytokinesis) in plants, a cell plate composed of cellular membranes forms between the two nuclei and fuses to separate the daughter cells. In Arabidopsis, KEULE and KNOLLE, two homologs of mammalian SNARE proteins known to be involved in cellular fusion reactions, participate in the fusion events of cytokinesis. Lack of either protein precludes the growth of mutant plant cells in callus culture, as well as the formation of viable plants.

Heese et al. now describe a protein termed AtSNAP33, which is a homolog of another mammalian SNARE, SNAP25. The protein interacts directly with the cytokinesis-specific KNOLLE at the cell plate. When AtSNAP33 function was blocked, the leaves of these mutant plantlets became necrotic, leading to plant death before flowering. Two other SNAP25 homologs may compensate partially for loss of AtSNAP33 in cytokinesis; however, the presence of improperly divided cells eventually weakens plant structures, and death follows.—SMH

J. Cell Biol.155, 239 (2001).

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