A Model Analysis of Mechanisms for Radial Microtubular Patterns at Root Hair Initiation Sites

AbstractUltrastructure was investigated along the files of developing epidermal cells in the root tip of a model plant Medicago sativa, in which all rhizodermal cells are potential hair-forming trichoblasts. Differentiation at subcellular level was observed up to the stage of bulge initiation in the trichoblasts. Root hair initiation indicated by the emergence of bulges from trichoblasts was detected at various distances from the root tip and, it was independent of the trichoblast size.During rhizodermal cell differentiation, starch grains accumulated in the plastids. Nuclei located in the central part of the young, meristematic cells moved towards the inner periclinal wall as the central vacuole enlarged. The bulging region of the trichoblasts located opposite the nucleus and was rich in mitochondria, ER, ribosomes, and Golgi bodies, and contained also vesicles enclosing fibrillar material. This material responded positively to phosphotungstic acid, which was used for detection of cell wall polysaccharides. The cell wall thickness within the bulging domain was significantly lower than in other parts of trichoblasts. We suggest that internalization of cell wall polysaccharides occurs within the bulging area, contributing to local thinning of the cell wall and providing a source of osmotically active compounds for maintaining turgor in the trichoblast. Thus, the internalization process might be necessary for root hair outgrowth.

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Spot Dynamics in a Reaction-Diffusion Model of Plant Root Hair Initiation

SIAM Journal on Applied Mathematics ◽

10.1137/17m1120932 ◽

2018 ◽

Vol 78 (1) ◽

pp. 291-319 ◽

Cited By ~ 10

Author(s):

Daniele Avitabile ◽

Victor F. Bren͂a ◽

Michael J. Ward

Keyword(s):

Diffusion Model ◽

Root Hair ◽

Plant Root ◽

Reaction Diffusion ◽

Reaction Diffusion Model ◽

Root Hair Initiation

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Effects of glucose and ethylene on root hair initiation and elongation in lettuce (Lactuca sativa L.) seedlings

Journal of Plant Research ◽

10.1007/s10265-017-1003-8 ◽

2017 ◽

Vol 131 (3) ◽

pp. 543-554 ◽

Cited By ~ 1

Author(s):

Wakana Harigaya ◽

Hidenori Takahashi

Keyword(s):

Lactuca Sativa ◽

Root Hair ◽

Lactuca Sativa L ◽

Root Hair Initiation

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Mathematical Modeling of Plant Root Hair Initiation: Dynamics of Localized Patches

SIAM Journal on Applied Dynamical Systems ◽

10.1137/120902264 ◽

2014 ◽

Vol 13 (1) ◽

pp. 210-248 ◽

Cited By ~ 14

Author(s):

V. Bren͂a--Medina ◽

A. R. Champneys ◽

C. Grierson ◽

M. J. Ward

Keyword(s):

Mathematical Modeling ◽

Root Hair ◽

Plant Root ◽

Root Hair Initiation

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Regulation of Root Hair Initiation and Expansin Gene Expression in Arabidopsis

The Plant Cell ◽

10.1105/tpc.006437 ◽

2002 ◽

Vol 14 (12) ◽

pp. 3237-3253 ◽

Cited By ~ 266

Author(s):

Hyung-Taeg Cho ◽

Daniel J. Cosgrove

Keyword(s):

Gene Expression ◽

Root Hair ◽

Expansin Gene ◽

Root Hair Initiation

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AtRBOHC/RHD2 vesicular delivery to the apical plasma membrane domain during root hair development

10.1101/2021.09.13.460100 ◽

2021 ◽

Author(s):

Lenka Kuběnová ◽

Michaela Tichá ◽

Jozef Šamaj ◽

Miroslav Ovečka

Keyword(s):

Plasma Membrane ◽

Quantitative Analysis ◽

Root Hair ◽

Tip Growth ◽

Root Hairs ◽

Apical Plasma Membrane ◽

Loss Of Function ◽

Short Root ◽

Early Endosomes ◽

Root Hair Initiation

AbstractArabidopsis root hairs develop as long tubular extensions from the rootward pole of trichoblasts and exert polarized tip growth. The establishment and maintenance of root hair polarity is a complex process involving the local apical production of reactive oxygen species (ROS) generated by NADPH oxidase RESPIRATORY BURST OXIDASE HOMOLOG PROTEIN C/ROOT HAIR DEFECTIVE 2 (AtRBOHC/RHD2). It has been shown that loss-of-function rhd2 mutants have short root hairs that are unable to elongate by tip growth, and this phenotype was fully complemented by GFP-RHD2 expressed under the RHD2 promoter. However, the spatiotemporal mechanism of AtRBOHC/RHD2 subcellular redistribution and delivery to the plasma membrane (PM) during root hair initiation and tip growth are still unclear. Here, we used advanced microscopy for detailed qualitative and quantitative analysis of vesicular compartments containing GFP-RHD2 and characterization of their movements in developing bulges and growing root hairs. These compartments, identified by an independent marker such as the trans-Golgi network (TGN), deliver GFP-RHD2 to the apical PM domain, the extent of which correlates with the stage of root hair formation. Movements of TGN/early endosomes, but not late endosomes, were affected in the bulging domains of the rhd2-1 mutant. Finally, we reveal that accumulation in the growing tip, docking, and incorporation of TGN compartments containing GFP-RHD2 to the apical PM of root hairs requires structural sterols. These results help clarify the mechanism of polarized AtRBOHC/RHD2 targeting, maintenance, and recycling at the apical PM domain, coordinated with different developmental stages of root hair initiation and growth.One-sentence summaryAdvanced microscopy and quantitative analysis of vesicular TGN compartments revealed that delivering GFP-RHD2 to the apical plasma membrane domains of developing bulges and growing root hairs requires structural sterols.

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