Root hairs

Overview

Root hairs provide an interface between the primary plant roots, and the soil. Aside from the larger more commonly known system, root hairs are smaller cylindrical extensions of larger roots that are important for nutrient acquisition, microbial interactions below-ground, and for plant anchorage in the soil. Root hairs are able to be beneficial to the health of a plant and its root systems because it effectively increases the surface area and diameter of the roots [1]. Root hairs can be 10μm in diameter or up to 1mm in diameter. The study of root hairs is important for ecology, cell biology, and plant physiology because of their unique cell makeup and cell growth. Root hairs are often players in the formation of root nodules on legume plants; these facilitate symbiotic mycorrhizal interactions.

Growth and Development

Root hairs are excellent specimens to study in the field of cell biology. Root hairs are tip growing extensions from root epidermal cells; in most angiosperms root hairs develop on epidermal cells in the differentiation zones of younger roots [2]. In most eudicots, the first sign of root hair development is a bulge on the outer radial wall (periclinal wall) of the epidermal cell [2]. Cells of the plant epidermis in the differentiation zone can either become a root hair or non root hair cell. After the basic understanding that the root epidermis consists of root hair cells and non root hair cells, it is important to understand that there are three different types patterns of differentiation that have been seen to occur in the development of root hairs [3].

Type 1:

Root hairs can emerge from any kind of cell and can be considered a random type.

Type 2:

Root hairs develop from a specific population of root epidermal cells composed of vertically alternating short and long cells; root hairs will emerge from the short cells.

Type 3:

Root hairs grow from cells that are localized between two cortical cells (cell in the cortex) in which non hair cells contact only one cortical cell. This makes for adequate spacing between root hair growths.

Citations

[1]Grierson, C., E. Nielsen, T. Ketelaarc, and J. Schiefelbein. 2014. Root Hairs. The Arabidopsis Book / American Society of Plant Biologists 12.

[2]Datta, S., C. M. Kim, M. Pernas, N. D. Pires, H. Proust, T. Tam, P. Vijayakumar, and L. Dolan. 2011. Root hairs: development, growth and evolution at the plant-soil interface. Plant and Soil 346:1–14.

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