Meristem apical

Crevecoeur M. Pinedo M. Greppin H. Penel C. (1997) Peroxodase activity in shoot apical meristem from Spimcia / / Acta Histochem. V. 99(2). P. 177-186. 

Barlow, E.W.R., Munns, R.E. Brady, C.J. (1980). Drought responses of apical meristems. In Adaptation of Plants to Water and High Temperature Stress, ed. N.C. Turner and P.J. Kramer, pp. 191-206. New York Wiley Interscience. 

Most plants exhibit "apical dominance" which means that the presence of a terminal (distal) meristem tends to suppress lateral shoot initiation (11). Since lateral shoot production is an important characteristic to assess in hydrilla, the frequency of shoot production was determined in sequentially cut (distal to proximal) explants (Table VI). Even though the 4 cm apical meristem contained several nodes, almost none of these produced new shoots. However, nearly half the 2-node explants subtending the cut apical meristem produced new shoots. There was no apparent difference in percent of new shoots produced once the apical meristem was removed. 

FIG. 1. Shoot apical meristem structure. The shoot apical meristem consists of three clonally distinct cell layers (LI, L2, L3). LI and L2 represent tunica layers, L3 represents the corpus. Cell divisions in LI and L2 are exclusively anticlinal, cell divisions in the L3 occur in all planes. The central zone harbours the stem cells and is surrounded by the peripheral zone where organ primordia are initiated. 

Atrazine enters plants primarily by way of the roots and secondarily by way of the foliage, passively translocated in the xylem with the transpiration stream, and accumulates in the apical meristems and leaves (Hull 1967 Forney 1980 Reed 1982 Wolf and Jackson 1982). The main phytotoxic effect is the inhibition of photosynthesis by blocking the electron transport during Hill reaction of photosystem II. This blockage leads to inhibitory effects on the synthesis of carbohydrate, a reduction in the carbon pool, and a buildup of carbon dioxide within the leaf, which subsequently causes closure of the stomates, thus inhibiting transpiration (Stevenson et al. 1982 Jachetta et al. 1986 Shabana 1987). 

ZONDLO, S.C., IRISH, V.F., CYP78A5 encodes a cytochrome P450 that marks the shoot apical meristem boundary in Arabidopsis, Plant J., 1999,19,259-268. 

The plant species Phragmites australis and Typha latifolia were obtained from surface-sterilized seeds whereas Carex gracillis and Juncus glaucus were initiated from apical meristem. The seeds were treated by a... 

Secondary Growth Growth by the activity of the cambium, resulting in an increase in diameter and responsible for the bulk of the plant body of long lived vascular plants, as contrasted to growth in length due to the activity of the apical meristem. 

Each mitotic figure indicated by dot. Pith tissue bounded by apical meristem at top and vascular tissue on sides. Observations for cortical tissue confined to area bounded by outer edge of vascular tissue and line connecting leaf bases. Boundaries for vascular tissue and lower limit of apical meristem. . . indicated by dashed lines. 

Apparently there exists in plants in general a rather clear-cut division of labor in the growth of the stem the apical meristem is the site of shoot organogenesis (leaf initiation and tissue pattern determination) but its direct contribution to stem growth is small the great majority of cells that actually constitute the mature... 

Figure 2 shows the effect of the inoculated root tip part on the growth of P. ginseng hairy roots. The end part, whose apical meristem of root tip had been excised prior to inoculation, was grown to a total biomass 1.6 times greater than that of the center parts, which are the root tip part after being excised about 10 mm from the end part. In all experiments, new lateral branch formation was observed on the inoculated main root tip. 

The root tip with apical meristem showed length enhancement with lateral root formation. However, the center root tip formed lateral roots without length enhancement of the original root tip (Fig. 3). Some researchers have reported the effect of the apical dominance on growth, which was observed as an increase in specific growth rate for inocula formed by branched roots (12,14). 

The root apex is covered with a calyptra extending proximally up to about 600 pm from the tip. The apical meristem is of the closed type, with each of the three root tissue systems, i.e. the vascular cylinder, the cortex, and the calyptra/epidermis, arising from its own independent groups of initials.16 Cellular differentiation had already started at a distance of about 600 pm from the tip in the 16 h-control while very little differentiation could be seen in roots from treated seeds. 

Plant Growth Regulator taken up into xylem through the leaves, stems or roots and translocated to the growing sub-apical meristems. Produces more compact plants and enhances flowering and fruiting... 

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