title: On the relationship between endoreduplication and collet hair initiation and tip growth, as determined using six Arabidopsis thaliana root-hair mutants.
abstract: A positive correlation between nuclear DNA content and cell size, as postulated by the karyoplasmic theory, has been confirmed in many plant tissues. However, there is also evidence suggesting that there are exceptions. While in previous reports the cell size:ploidy relationship was studied in intact tissues containing cells of different sizes, here simultaneously developing single cells of collet hairs were used to study endoreduplication in Arabidopsis thaliana mutants that produce hairs of variable size and morphology. Endoreduplication in the root and collet zones of six different root-hair mutants was analysed before and after collet hair development using flow cytometry and confocal microscopy. Additionally, the changes in nuclear size (ploidy), shape, and movement in developing collet hairs of a hybrid between Arabidopsis transgenic line NLS-GFP-GUS and the rhd3 (root hair defective3) mutant were followed using time-lapse confocal microscopy. In this hybrid endoreduplication in the collet hairs was disturbed. However, based on the analyses of all mutants, no correlation was found between hair length and the ploidy of the cells in the collet and root regions. The results indicate that the karyoplasmic ratio is maintained at the beginning of collet-hair development, but tip growth proceeds in a DNA-amount-independent manner. The final size of a collet hair appears to be dependent more on genetic modifiers governing general cell physiology than on its DNA content.
authors: Laboratory of Molecular Biology and Cytometry, Department of Plant Genetics, Physiology and Biotechnology, UTP University of Science and Technology, Kaliskiego Ave. 7, 85-789 Bydgoszcz, Poland Department of Molecular and Cellular Biology, University of Guelph, Guelph, ON, N1G 2W1, Canada elwira@utp.edu.pl.
authors: Elwira
authors: E
authors: Sliwinska
authors: Department of Molecular and Cellular Biology, University of Guelph, Guelph, ON, N1G 2W1, Canada.
authors: Jaideep
authors: J
authors: Mathur
authors: Department of Molecular and Cellular Biology, University of Guelph, Guelph, ON, N1G 2W1, Canada.
authors: J Derek
authors: JD
authors: Bewley
mesh_terms: D017360:Arabidopsis / Q000166:cytology / Q000235:genetics* / Q000254:growth & development; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism; D062951:Endoreduplication; D018506:Gene Expression Regulation, Plant; D049452:Green Fluorescent Proteins; D018613:Microscopy, Confocal; D009154:Mutation; D018517:Plant Roots / Q000166:cytology / Q000235:genetics* / Q000254:growth & development; D030821:Plants, Genetically Modified
chemical_list: D029681:Arabidopsis Proteins; D049452:Green Fluorescent Proteins
keywords: Collet-hair length; DNA content; confocal microscopy; endoreduplication; flow cytometry; fluorescent protein; nuclear movement; tip growth.