Roles of Phosphatidylinositol 3-Kinase in Root Hair Growth
Open Access
- 11 April 2008
- journal article
- Published by Oxford University Press (OUP) in Plant Physiology
- Vol. 147 (2), 624-635
- https://doi.org/10.1104/pp.108.117341
Abstract
The root hair is a model system for understanding plant cell tip growth. As phosphatidylinositol 3-phosphate [PtdIns(3)P] has been shown in other plant cell types to regulate factors that affect root hair growth, including reactive oxygen species (ROS) levels, cytoskeleton, and endosomal movement, we hypothesized that PtdIns(3)P is also important for root hair elongation. The enzyme that generates PtdIns(3)P, phosphatidylinositol 3-kinase (PI3K), was expressed in root hair cells of transgenic plants containing the PI3K promoter:β-glucuronidase reporter construct. To obtain genetic evidence for the role of PtdIns(3)P in root hair elongation, we attempted to isolate Arabidopsis (Arabidopsis thaliana) mutant plants that did not express the gene VPS34 encoding the PI3K enzyme. However, the homozygous mutant was lethal due to gametophytic defects, and heterozygous plants were not discernibly different from wild-type plants. Alternatively, we made transgenic plants expressing the PtdIns(3)P-binding FYVE domain in the root hair cell to block signal transduction downstream of PtdIns(3)P. These transgenic plants had shorter root hairs and a reduced hair growth rate compared with wild-type plants. In addition, LY294002, a PI3K-specific inhibitor, inhibited root hair elongation but not initiation. In LY294002-treated root hair cells, endocytosis at the stage of final fusion of the late endosomes to the tonoplast was inhibited and ROS level decreased in a dose-dependent manner. Surprisingly, the LY294002 effects on ROS and root hair elongation were similar in rhd2 mutant plants, suggesting that RHD2 was not the major ROS generator in the PtdIns(3)P-mediated root hair elongation process. Collectively, these results suggest that PtdIns(3)P is required for maintenance of the processes essential for root hair cell elongation.Keywords
This publication has 59 references indexed in Scilit:
- The Arabidopsis Phosphatidylinositol 3-Kinase Is Important for Pollen DevelopmentPlant Physiology, 2008
- Oscillations in extracellular pH and reactive oxygen species modulate tip growth of Arabidopsis root hairsProceedings of the National Academy of Sciences of the United States of America, 2007
- Suppression of Arabidopsis vesicle-SNARE expression inhibited fusion of H 2 O 2 -containing vesicles with tonoplast and increased salt toleranceProceedings of the National Academy of Sciences of the United States of America, 2006
- Functional Conservation of a Root Hair Cell-Specificcis-Element in Angiosperms with Different Root Hair Distribution PatternsTHE PLANT CELL ONLINE, 2006
- PtdIns3P binding to the PX domain of p40phox is a physiological signal in NADPH oxidase activationThe EMBO Journal, 2006
- PINOID Positively Regulates Auxin Efflux inArabidopsisRoot Hair Cells and Tobacco CellsTHE PLANT CELL ONLINE, 2006
- Endocytosis and vesicle trafficking during tip growth of root hairsProtoplasma, 2005
- Reactive oxygen species produced by NADPH oxidase regulate plant cell growthNature, 2003
- Localization of phosphatidylinositol 3-phosphate in yeast and mammalian cellsThe EMBO Journal, 2000
- Distinct Roles for the p110α and hVPS34 Phosphatidylinositol 3′-Kinases in Vesicular Trafficking, Regulation of the Actin Cytoskeleton, and MitogenesisThe Journal of cell biology, 1998