Action of gibberellic acid on the mitotic activity of the different zones of the shoot apex ofRudbeckia bicolor andPerilla nankinensis

Planta ◽  
1964 ◽  
Vol 61 (3) ◽  
pp. 236-244 ◽  
Author(s):  
G. Bernier ◽  
R. Bronchart ◽  
A. Jacqmard
Keyword(s):  
Gibberellic Acid ◽  
Mitotic Activity ◽  
Shoot Apex

Further analytical and experimental studies on the shoot apex of Helianthus annuus: variable activity in the central zone

1979 ◽  
Vol 57 (8) ◽  
pp. 971-980 ◽  
Author(s):  
E. L. Davis ◽  
Patricia Rennie ◽  
Taylor A. Steeves
Keyword(s):  
Helianthus Annuus ◽  
Mitotic Activity ◽  
Shoot Apex ◽  
Experimental Studies ◽  
Central Zone ◽  
Peripheral Zone ◽  
Intact Plants ◽  
Cast Doubt ◽  
Young Leaves ◽  
Mitotic Frequency

The cytologically distinctive central zone of the vegetative shoot apex of Helianthus annuus L. cv. Peredovic has a mitotic frequency considerably lower than that of the surrounding peripheral zone in intact plants. Apices excised and grown in culture for 5 days before being supplied with [H3]thymidine reveal a correspondingly low level of DNA synthesis in the central zone when autoradiographed. In similarly cultured apices, mitotic activity in the central zone is less than that recorded for intact plants. Labelling immediately after excision of the apex indicates that the central zone cells are activated by the operation and quiescence returns during the following 5 days. This activation is confirmed by mitotic counts 2 days after excision. The removal of only two young leaves from the apical buds of otherwise intact plants results in a comparable stimulation of mitotic activity in the central zone. These observations cast doubt upon the significance of mitotic activity in living shoot apices when these have been exposed for observation by removal of leaves. They also raise questions about the validity of labelling techniques which involve the partial dissection of the shoot apex.

MITOTIC ACTIVITY AT THE SHOOT APEX OF AZOLLA FILICULOIDES

1981 ◽  
Vol 68 (8) ◽  
pp. 1050-1055 ◽  
Author(s):  
Ernest M. Gifford ◽  
Vito S. Polito
Keyword(s):  
Mitotic Activity ◽  
Shoot Apex ◽  
Azolla Filiculoides

Visualisation des centres générateurs selon la théorie phyllotaxique de Plantefol, dans le point végétatif du grand frêne (Fraxinus excelsior)

1984 ◽  
Vol 62 (12) ◽  
pp. 2636-2643 ◽  
Author(s):  
Alain Cottignies
Keyword(s):  
Cell Proliferation ◽  
Mitotic Activity ◽  
Poisson Distribution ◽  
Shoot Apex ◽  
Unit Area ◽  
Fraxinus Excelsior ◽  
Nearest Neighbour ◽  
Axial Zone ◽  
Cell Cycles ◽  
Mitotic Wave

To visualize the generative center of each foliar helix and its oriented progression, cell proliferation was studied in the ash (Fraxinus excelsior L.) shoot apex. The distribution of mitosis was analysed first with the hypothesis of the multiple foliar helices phyllotactic theory and then without any preliminary hypothesis. The cell cycles were asynchronic and mitotic duration was constant. Therefore, the parameters of both the Poisson distribution of mitosis in each apical zone and of mitotic density, evaluated by the nearest-neighbour method or by the rotation of a unit area, were indicative of the cell proliferation level. The axial zone differed from the initiating ring by virtue of its lower mitotic activity. The initiating ring was heterogeneous and involved two parts which were opposite each other and symmetrical with regard to the axis of the apex. In each half, the cell proliferation increased gradually to a generative center with a maximal mitotic activity, then decreased twice as fast. This heterogeneity showed the necessary rotation of a privileged mitotic wave, which progressed step by step in a single direction. The cartography of the cell proliferation intensity was mapped for one sample meristcm.

Relationship between Shoot Apex and Effect of Gibberellic Acid on Elongation of Pea Stems

Nature ◽  
1957 ◽  
Vol 180 (4580) ◽  
pp. 284-284 ◽  
Author(s):  
A. J. VLITOS ◽  
W. MEUDT
Keyword(s):  
Gibberellic Acid ◽  
Shoot Apex

Influence de la photopériode sur le comportement du méristème caulinaire du Celosia cristata

1977 ◽  
Vol 55 (11) ◽  
pp. 1488-1500
Author(s):  
D. Driss-Ecole
Keyword(s):  
Mitotic Activity ◽  
Shoot Apex ◽  
Unstable State ◽  
Axial Zone ◽  
Histological Studies ◽  
Daily Show ◽  
Differentiated Cells ◽  
Long Day ◽  
Celosia Cristata ◽  
High Level

Three groups of plants of Celosia cristata were grown in a 8-h, 12-h, or 16-h day. Histological studies of the shoot apex were performed during the vegetative and the prefloral phases.The apical meristems of the plants subjected to long-day conditions (16 h) flatten (fasciation). At the beginning of the fasciation, an activation of the corpus and a restructuration of the meristem are observed. The transformed meristem shows four superficial layers which cover a group of differentiated cells. The zonation is always recognizable and the apex initiates numerous leaves. The broadening of the meristem is due to the high level of mitotic activity of two opposite regions in the ‘anneau initial’ which takes an elliptical shape and to the peculiar orientation of the mitoses. During this transformation the volumes of the lateral and medullary zones increase while the volume of the axial zone remains almost identical. The long vegetative phase ceases with the homogeneization of the meristematic state of the four superficial layers and with the edification of a prefloral crest.The apex of plants grown under an 8-h photoperiod remains small sized. They never undergo fasciation and reach the prefloral phase very quickly.The meristems of the plants cultivated under 12 h of light daily show an unstable state and sometimes evolve tardily towards fasciation.

scholarly journals Effects of gibberellic acid and AMO-1618 on the development of vegetative systems in generatively matured thalli of Chara vulgaris L.

2014 ◽  
Vol 49 (4) ◽  
pp. 445-458 ◽  
Author(s):  
Maria Kwiatkowska ◽  
Mirosław Godlewski
Keyword(s):  
Gibberellic Acid ◽  
Mitotic Activity ◽  
Main Axis ◽  
Chara Vulgaris ◽  
Cell Divisions ◽  
Lateral Buds ◽  
Apical Cells ◽  
Axenic Conditions ◽  
High Level ◽  
Amo 1618

Effects of GA<sub>3</sub> (10<sup>-11</sup>-10<sup>-4</sup> M) and AMO-1618 (10<sup>-6</sup>-10<sup>-4</sup> M) on the development of generatively matured thalli of <em>Chara vulgaris</em> were investigated during 21-day culture of plants in axenic conditions. It has been found that in the main bud the divisions of apical cells of the thalli are not stimulated by GA<sub>3</sub>, whereas in the lateral buds the cell divisions are stimulated by higher GA<sub>3</sub> concentrations. Subsequent mitotic activity of the apical cells in the branches of the main axis is not stimulated by GA<sub>3</sub>, whereas the lateral buds of these branches are activated. The development of rhizoids in younger nodes is accelerated by high GA<sub>3</sub> concentrations. The elongation of the polynuclear, internodal cells of the main axis and that of pleuridia are inhibited proportionally to the GA<sub>3</sub> concentration. AMO-1618 stimulates the development of new nodes, elongation of internodes and delays the activation of lateral buds as well as the formation of rhizoids. These results suggest that the GA<sub>3</sub>-induced inhibition of elongation of the thalli and diminution of the apical domination is connected with a high level of endogenous gibberellins in the generatively matured thallus.

The relationship between the mitotic activity and moisture content of recalcitrant seeds ofAcer saccharinum(L.) during maturation, post-maturation drying and germination

2000 ◽  
Vol 10 (3) ◽  
pp. 225-232 ◽  
Author(s):  
L.E. Kozeko ◽  
V.M. Troyan
Keyword(s):  
Cell Cycle ◽  
Cell Division ◽  
Moisture Content ◽  
Mitotic Activity ◽  
Shoot Apex ◽  
Root Apex ◽  
Recalcitrant Seeds ◽  
Orthodox Seeds ◽  
The Relationship ◽  
Mature Seeds

AbstractThe decline of embryo moisture content from approx. 82 to 53% in 1997 and 56% in 1998 in recalcitrant seeds ofAcer saccharinumduring maturation was accompanied by decreased mitotic activity in the meristems and an increase in the percentage of cells in the G1phase of the cell cycle. DNA synthesis and mitosis in the root apex ceased at approx. 53% embryo moisture content, and 67% of the cells were arrested in the G1phase. During post-maturation drying, cell division in the shoot apex and embryonic leaves continued as long as the embryo moisture content was higher than 50 and 45%, respectively. Mitotic activity in the drying embryo may be controlled by its moisture level. Increased proliferation of the root, shoot and leaf meristems of the mature seeds was already recorded at 24 h of germination, before the root protruded through the seed coat. However, the increase in the embryo moisture content was small – from 56 to 59%. In the 3 d seedlings (10–15 mm long) the mitotic index reached 8% in the root apex and 12% in the shoot apex with leaves. Placing mature seeds in moist conditions might be necessary for the switch from proliferation decline towards its activation. Thus, in contrast with orthodox seeds, the preservation of cell division capacity and increased mitotic activity may be essential for rapid germination immediately after shedding in matureAcerseeds.

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