Growth and ultrastructure ofArabidopsis root hairs: therhd3 mutation alters vacuole enlargement and tip growth |
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Authors: | M. E. Galway J. W. Heckman Jr. J. W. Schiefelbein |
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Affiliation: | (1) Department of Biology, The University of Michigan, 48109-1048 Ann Arbor, MI, USA;(2) Center for Electron Optics, Michigan State University, 48824-1311 East Lansing, MI, USA;(3) Present address: Department of Biology, St. Francis Xavier University, B2G 2W5 Antigonish, Nova Scotia, Canada |
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Abstract: | The root hairs of plants are tubular projections of root epidermal cells and are suitable for investigating the control of cellular morphogenesis. In wild-typeArabidopsis thaliana (L.) Heynh, growing root hairs were found to exhibit cellular expansion limited to the apical end of the cell, a polarized distribution of organelles in the cytoplasm, and vesicles of several types located near the growing tip. Therhd3 mutant produces short and wavy root hairs with an average volume less than one-third of the wild-type hairs, indicating abnormal cell expansion. The mutant hairs display a striking reduction in vacuole size and a corresponding increase in the relative proportion of cytoplasm throughout hair development. Bead-labeling experiments and ultrastructural analyses indicate that the wavy-hair phenotype of the mutant is caused by asymmetric tip growth, possibly due to abnormally distributed vesicles in cortical areas flanking the hair tips. It is suggested that a major effect of therhd3 mutation is to inhibit vacuole enlargement which normally accompanies root hair cell expansion. |
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Keywords: | Arabidopsis (mutant, root hairs) Mutant (Arabidopsis rhd3) Root hair (ultrastructure) Tip growth Vacuole |
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