Root Cap


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root cap

[′rüt ‚kap]
(botany)
A thick, protective mass of parenchymal cells covering the meristematic tip of the root.

Root Cap

 

the protective formation (effective primarily against mechanical damage) on the growing tip of a root.

The root cap is a small (about 0.2 mm, or, rarely, in aerial roots, up to several mm) conical cap covering the tender cells of the root apex and part of the root’s growth zone. It differentiates in the earliest stages of root development from cells composing the calyptrogen (for example, in grasses and other monocotyledons) or from the apical meristem of the root (in many dicotyledons and gymnosperms). The root cap is composed of a complex of living parenchyma cells with thin mucilaginous membranes and mobile starch grains (statoliths) that are important in the geotropical reaction of the root. The outer layers of cells of the cap separate easily, and during friction with soil particles they are sloughed off, easing the root’s passage through the soil. In water plants the root cap may be reduced and be replaced by a root pocket (as in duckweed, frogbit, and water chestnut).

R. P. BARYKINA

References in periodicals archive ?
In many species, strong asymmetrical growth in the lower scutellum and coleoptile region of the proembryo displaces the root cap and plumule away from their original basal and lateral position (Goetghebeur 1986).
Nagahashi G, Douds DD Jr (2004) Isolated root caps, border cells, and mucilage from host roots stimulate hyphal branching of the arbuscular mycorrhizal fungus, Gigaspora gigantea.
Aluminium toxicity in roots: an investigation of spatial sensitivity and the role of the root cap. J.
However, the growth of root part was more inhibited by the extract, showing root cap necrosis, early secondary root formation, gravitropic inversion and atrophy in all weeds.
In general, root caps of many plants are not colonized by bacteria (Foster & Bowen, 1982).
In the root cap cells, Golgi bodies are sensitive to aluminum.
Under field drying, alignment of LB followed a trend similar to PC drying, that is, from the periphery (root cap) toward inner QC cells.
Elmore and Bayer (1992) described the root apical meristem in perennial ryegrass as having three groups of initials: one giving rise to the root cap; one producing the cells of the epidermis and cortex; and the third, innermost set, forming the vascular cylinder.
Mucilage layers in general on root surfaces have been studied extensively (e.g., Greaves & Darbyshire, 1972; Oades, 1978; Foster, 1982) as has the secretion from root cap cells (see Rougier, 1981; Rougier & Chaboud, 1985).
"We developed a bioassay that has allowed us to determine that chemical compounds exuding from the host's roots, root caps, and root border cells induce fungal hyphal branching," Nagahashi explains.
Moreover the presence of nutritive compounds in the rhizosphere as root exudates, mucilage from root caps and sloughed-off dead root cells [16] will enhance bacterial growth than in the non- rhizosphere soil where such compounds are absent; and as a rule there is always a general increase in the microorganisms in the rhizosphere [19].