PT  - JOURNAL ARTICLE
AU  - Stenzel, Irene
AU  - Ischebeck, Till
AU  - König, Sabine
AU  - Hołubowska, Anna
AU  - Sporysz, Marta
AU  - Hause, Bettina
AU  - Heilmann, Ingo
TI  - The Type B Phosphatidylinositol-4-Phosphate 5-Kinase 3 Is Essential for Root Hair Formation in <em>Arabidopsis thaliana</em>
AID  - 10.1105/tpc.107.052852
DP  - 2008 Jan 01
TA  - The Plant Cell
PG  - 124--141
VI  - 20
IP  - 1
4099  - http://www.plantcell.org/content/20/1/124.short
4100  - http://www.plantcell.org/content/20/1/124.full
SO  - Plant Cell2008 Jan 01; 20
AB  - Root hairs are extensions of root epidermal cells and a model system for directional tip growth of plant cells. A previously uncharacterized Arabidopsis thaliana phosphatidylinositol-4-phosphate 5-kinase gene (PIP5K3) was identified and found to be expressed in the root cortex, epidermal cells, and root hairs. Recombinant PIP5K3 protein was catalytically active and converted phosphatidylinositol-4-phosphate to phosphatidylinositol-4,5-bisphosphate [PtdIns(4,5)P2]. Arabidopsis mutant plants homozygous for T-DNA–disrupted PIP5K3 alleles were compromised in root hair formation, a phenotype complemented by expression of wild-type PIP5K3 cDNA under the control of a 1500-bp PIP5K3 promoter fragment. Root hair–specific PIP5K3 overexpression resulted in root hair deformation and loss of cell polarity with increasing accumulation of PIP5K3 transcript. Using reestablishment of root hair formation in T-DNA mutants as a bioassay for physiological functionality of engineered PIP5K3 variants, catalytic activity was found to be essential for physiological function, indicating that PtdIns(4,5)P2 formation is required for root hair development. An N-terminal domain containing membrane occupation and recognition nexus repeats, which is not required for catalytic activity, was found to be essential for the establishment of root hair growth. Fluorescence-tagged PIP5K3 localized to the periphery of the apical region of root hair cells, possibly associating with the plasma membrane and/or exocytotic vesicles. Transient heterologous expression of full-length PIP5K3 in tobacco (Nicotiana tabacum) pollen tubes increased plasma membrane association of a PtdIns(4,5)P2-specific reporter in these tip-growing cells. The data demonstrate that root hair development requires PIP5K3-dependent PtdIns(4,5)P2 production in the apical region of root hair cells.