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The WD40 Repeat Protein NEDD1 Functions in Microtubule Organization during Cell Division in Arabidopsis thaliana
C. J. Tracy Zeng, Y.-R. Julie Lee and Bo Liu
The Plant Cell
Vol. 21, No. 4 (Apr., 2009), pp. 1129-1140
Published by: American Society of Plant Biologists (ASPB)
Stable URL: http://www.jstor.org/stable/40536869
Page Count: 12
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Although cells of flowering plants lack a structurally defined microtubule-organizing center like the centrosome, organization of the spindles and phragmoplasts in mitosis is known to involve the evolutionarily conserved γ-tubulin complex. We have investigated the function of Arabidopsis thaliana NEDD1, a WD40 repeat protein related to the animal NEDD1/GCP-WD protein, which interacts with the γ-tubulin complex. The NEDD1 protein decorates spindle microtubules (MTs) preferentially toward spindle poles and phragmoplast MTs toward their minus ends. A T-DNA insertional allele of the single NEDD1 gene was isolated and maintained in heterozygous sporophytes, and NEDDI's function in cell division was analyzed in haploid microspores produced by the heterozygote. In approximately half of the dividing microspores exhibiting aberrant MT organization, spindles were no longer restricted to the cell periphery and became abnormally elongated. After mitosis, MTs aggregated between reforming nuclei but failed to appear in a bipolar configuration. Consequently, defective microspores did not form a continuous cell plate, and two identical nuclei were produced with no differentiation into generative and vegetative cells. Our results support the notion that the plant NEDD1 homolog plays a critical role in MT organization during mitosis, and its function is likely linked to that of the γ-tubulin complex.
The Plant Cell © 2009 American Society of Plant Biologists (ASPB)