Root cap cells

Although root-cap cells may have some function in the rhizosphere (36) and most cell contents are covered by the term root exudates, it is difficult to see how root debris might have a function that directly benefits the growth of... 

Root debris zymes, siderophores, allelocheini-cals, etc. Root-cap cells, cell contents, etc. 

The permeation of soil at the root-soil interface by mucilage from the root cap may affect structure, and it may oppose the damaging effects of compression and shearing, but little is known. Another suggested role is that the mucilage assists root-cap cells or acts in concert with them to decrease the friction between the growing root tip and soil (51) or, conversely, that the mucilage acts as a lubricant. 

Northcote DH, Pickett-Heaps JD. A function of the Golgi apparatus in polysaccharide synthesis and transport in the root-cap cells of wheat. 5ioc/iem J1966 98 159. 

Sherwood, R. T., 1985, Papilla formation in isolated root-cap cells of maize inoculated with Colletotrichum graminicola, Phytopathol. 75 1313-1314. 

Bennett, R. J., C. M. Bree, and V. H, Bandu, 1990. A role for Ca2+ in the cellular differentiation of root cap cells a re-examination of root growth control mechanisms. Environmental Experimental Botony 30 515-523. 

Fig. 4. Effects of high (10 ppm and 100 ppm) ethylene treatment (24 h) on MTs in cells of cv. LG-11 maize roots. 10 ppm treatment (a-e) has no effects in cells of the quiescent centre (QC) (a) and in meristematic cells of root cap (RC) (a.b), but it depletes MTs from developmentally older root cap cells (b). In addition this ethylene treatment randomizes CMTs in all postmitotic cells of the root proper. For the outer cortex (CXI) and epidermis (EP) cells, this effect is only slight (c). However, cells of the inner cortex (d,e) are strongly affected in this respect and the transverse CMTs are replaced by completely random CMTs. 100 ppm ethylene treatment (f,g) disintegrates MTs from most root cells with the exception of the distal part of meristem and root cap initials and quiescent centre cells (not shown). In the root proper, the epidermis (EP) and outer cortex (OC) cells are the only ones to preserve their MTs which, in the case of epidermis, are still transverse and well-ordered (f). In contrast, the inner cortex cells (IC) are devoid of MTs (g). For more details on ethylene treatments see [157]. Bar represents 10 pm.

Two glycoprotein fractions have been isolated from membranes of the root-cap cells of Zea mays after their incubation with L-[l- H]fucose. The glycoproteins appear to be precursors of the slime polysaccharides their carbohydrate moieties have compositions similar to that of the free slime. For one of the glycoproteins the linkage between carbohydrate and protein was shown to be a D-xylose-threonine bond. 

Treatment with a specific PAO inhibitor attenuates both Spd-induced root cell growth inhibition and Spd-induced cell-cycle arrest. The PAO inhibitor also disrupts differentiation of the secondary wall of meta-xylem elements and xylem parenchymal cells. Overexpression of maize PAO in tobacco plants induces programmed cell death (PCD) in root-cap cells (Tisi et al. 2011). The results suggest that H2O2 produced by Spd oxidation triggers secondary wall deposition and induces PCD. A link between PAs and PCD has been reviewed recently by Moschou and Roubelakis-Angelakis (2014). 

Stephenson, M.B. and Hawes, M.C. (1994) Correlation of Pectin Mcthylesterase Activity in Root Caps of Pea with Root Border Cell Separation. Plant Physiol. 106 739-... 

M. C. Hawes, Living plant cells released from the root cap a regulator of microbial populations in the rhizosphere The Rhizosphere and Plant Growth (D, L. Keister and P. B. Creagan, eds.), Kluwer Academic Publishers. Dordrecht, 1991, p. 51. 

Sedimentation of amyloplasts within the cell has been correlated with the capacity of the plant to perceive gravity. The buoyant mass of amyloplasts present in specialized cells in the center of the root cap and in the stem (depending on the plant species, in the endodermis, the bundle sheath, or in the parenchyma to the inside of the vascular bundle) would allow the amyloplasts to sediment inside the cell, where the cytosol would have a relatively low viscosity. This sedimentation would translate into a signal of an unknown nature, maybe through pressure onto a sensitive part of the cell or acting as a mechano transducer, etc. Whatever the nature of the signal, it eventually results in the asymmetry of the organ and its curvature. The isolation of starchless mutants of Arabidopsis thaliana and Nicotiana sylvestris has made... 

Developing trees contain two major types of meristems (1) terminal or apical meristems and (2) lateral meristems. Apical meristems are located at the tips of all stems and branches (both termed shoots) where they are contained within terminal buds they are also located within the tip regions of all roots. In the tip regions, the meristematic zone is usually protected by another zone of cells called the root cap. Root hairs, or microscopic roots, have no apical meristems, but these minute structures are lateral projections of roots that do have apical meristems. 

Fig. 2. MTs in cells of ev. Alarik maize roots after their treatments either with the auxin transport inhibitor naphthylphthalamic acid (NPA) (100 pM, 6 h) (a-g) and with lAA (100 pM, 24 h) (h-j). After NPA treatment, periclinal divisions were induced in the outer cortex (a, thin arrows indicate young cell walls, thick arrow indicates pre-prophase band of MTs). Cells of the epidermis preserved well-ordered transverse CMTs both near the root apex (b) and in the transition zone (g). On the other hand, cells of the root cap (c), outer cortex (d), inner cortex (e) and of the stele parenchyma (f) showed disturbances to their general appearance and ordering (compare with Figs. 3c, d, g, h). Similarly to NPA treatment, relatively well-ordered transverse CMT arrays are still preserved in postmitotic cells of the epidermis (h) as well as in all cells of the former meristem (i,j) after the auxin treatment. Abbreviations EP, epidermis IC, inner cortex OC, outer cortex RC, root cap.

Orientation of CMTs in ditferent regions of the root cap, as well as the quiescent centre (QC), of in vitro cultured tomato roots which are either wild-type or gib-1 mutant. The root cap probably controls division planes elsewhere in the root these are abnormal in the gib-1 apices [136]. MT orientations were scored as transverse (T), longitudinal (L), oblique (O) or random (R) with respect to the major axis of cell growth. Percentage values are given as pairs (ala), the first value being from wild-type, the second from gib-1 roots, n is the number of ceils scored. Unpublished data of P.W. Barlow and J.S. Parker... 

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