A study of DNA and mitotic activity in the vegetative apex of Douglas fir during the annual growth cycle

1973 ◽  
Vol 51 (7) ◽  
pp. 1395-1409 ◽  
Author(s):  
John N. Owens ◽  
Marje Molder
Keyword(s):  
Mitotic Activity ◽  
Dna Content ◽  
Peripheral Zone ◽  
Growth Cycle ◽  
Nuclear Volume ◽  
Annual Growth ◽  
Axillary Shoots ◽  
Volume Percentage ◽  
Leaf Initiation ◽  
Mother Cells

Vegetative apices of Pseudotsuga menziesii (Mirb.) Franco were studied throughout the annual growth cycle. When observations based on anatomy, histochemistry, and external morphology are combined, the growth cycle of the vegetative apex should be subdivided into five stages: (1) dormancy, (2) early bud-scale initiation, (3) late bud-scale initiation and rapid apical enlargement, (4) early, rapid leaf initiation, and (5) late, slow leaf initiation. The same cytohistological zonation pattern is present in vegetative apices throughout the growth cycle and usually consists of apical, peripheral, and rib meristem zones. During dormancy, early bud-scale initiation, and early leaf initiation, the apical zone is separated into apical initials and central mother cells based on nuclear characteristics and mitotic activity. Cytohistological zonation is supported by constant differences in nuclear volume, mitotic activity, and DNA content between zones. The peripheral zone is mitotically more active than the apical zone; however, the apical zone is not quiescent. Zones vary in size, prominence, and mitotic activity, which often relates to a particular developmental stage of the apex. The dormant apex has no mitotic activity, and cytohistological zonation is present but not distinct. Zonation increases throughout the first half of the growing season, reaches a maximum during late bud-scale and early leaf initiation, and decreases as dormancy approaches. In general, increases in nuclear volume, percentage of nuclei at 4C, and average DNA content per nucleus correlate with increases in the prominence of zonation. Zonation did not result from different zones being "held" at certain C levels of DNA. Although nuclear volume was used in calculating the DNA content, the DNA level often varied independently of volume. Mitotic activity and dormancy appear to be related to carbohydrate levels within the bud and subtending shoot. The period of most prominent zonation is also the period of most active primordial initiation, largest apical size, and the time when new axillary shoots become determined in their pathway of development.

Bud development in western hemlock. I. Annual growth cycle of vegetative buds

1973 ◽  
Vol 51 (11) ◽  
pp. 2223-2231 ◽  
Author(s):  
John N. Owens ◽  
Marje Molder
Keyword(s):  
Mitotic Activity ◽  
Shoot Elongation ◽  
Growth Cycle ◽  
Leaf Primordia ◽  
Annual Growth ◽  
Western Hemlock ◽  
Bud Burst ◽  
Bud Development ◽  
Vegetative Buds ◽  
Number Of Leaves

Vegetative apices of mature Tsnga heterophylla (Raf.) Sarg. were studied throughout the annual growth cycle. Apices become mitotically active during the last week of March. Leaf primordia elongate, causing the buds to swell, while the apex remains small and produces bud scales. Axillary buds are initiated about mid-April. Little shoot elongation occurs before vegetative buds burst in mid-May. After bud burst, rapid shoot elongation occurs for about 7 weeks, during which time the apex also elongates and the rest of the bud scales are initiated. There is a marked increase in mitotic activity in the apex during the transition from bud-scale initiation to leaf initiation, which occurs early in July when the grand phase of shoot elongation is complete. This is believed to be the time when vegetative apices undergo transition to become reproductive apices. Leaf primordia are initiated in rapid succession until mid-August, when two-thirds of the final number of leaves are initiated and the subtending shoot is fully elongated. From mid-August until mid-November, no shoot elongation occurs, leaf primordia are initiated more slowly, and mitotic activity in the apex gradually decreases. After all of the next season's leaves have been initiated, about mid-November, mitotic activity in the apex stops and the vegetative buds become dormant.

Bud development in Sitka spruce. I. Annual growth cycle of vegetative buds and shoots

1976 ◽  
Vol 54 (3-4) ◽  
pp. 313-325 ◽  
Author(s):  
John N. Owens ◽  
Marje Molder
Keyword(s):  
Early Period ◽  
Shoot Elongation ◽  
Growth Cycle ◽  
Picea Sitchensis ◽  
Leaf Primordia ◽  
Annual Growth ◽  
Bud Burst ◽  
Leaf Initiation ◽  
Number Of Leaves ◽  
Vegetative Bud

Vegetative apices of Picea sitchensis (Bong.) Carr. were studied throughout the annual growth cycle. Apices became mitotically active late in March and the shoot axis and leaf primordia elongated causing the bud to swell. New axillary apices were initiated in mid-April and the terminal apex and new axillary apices initiated bud scales until early in July. Vegetative bud burst occurred early in June and shoot elongation was completed by mid-July. The end of shoot elongation coincided with the onset of leaf initiation. The change from bud-scale to leaf initiation was characterized by a period of increased mitotic activity and rapid apical growth. About half of the final number of leaves were initiated during the early period of rapid leaf initiation. The remaining leaf primordia were initiated more slowly over the next 3 months. Buds became dormant by mid-November.

Bud development in Picea glauca. I. Annual growth cycle of vegetative buds and shoot elongation as they relate to date and temperature sums

1977 ◽  
Vol 55 (21) ◽  
pp. 2728-2745 ◽  
Author(s):  
John N. Owens ◽  
Marje Molder ◽  
Hilary Langer
Keyword(s):  
Picea Glauca ◽  
Shoot Growth ◽  
Shoot Elongation ◽  
Growth Cycle ◽  
Bud Dormancy ◽  
Annual Growth ◽  
Bud Development ◽  
Leaf Initiation ◽  
Vegetative Buds ◽  
Vegetative Bud

Vegetative buds of Picea glauca (Moench) Voss were studied throughout the annual growth cycle in several trees in 1975 and 1976 and bud development was related to lateral vegetative shoot growth, date, and temperature sums.Vegetative buds became mitotically active in mid-April at lower elevations and about 6 weeks later at higher elevations. Shoot elongation was characterized by similar smooth sigmoid curves in both years. Shoot growth was slow for the 1st month, rapid during the 2nd month, and slow again for the 3rd month and ended by early August. Temperature sums related best to percentage of shoot elongation if the end of vegetative bud dormancy was used as the starting date and 5 °C was used as the threshold temperature. Arbitrarily chosen starting dates and threshold temperatures gave temperature sums which were related to shoot elongation only when shoot elongation was nearly completed. Generally, if the end of vegetative bud dormancy is known, the number of days from that time is nearly as accurate as the more complex use of temperature sums in predicting the percentage of shoot elongation or the stage of vegetative bud development.Bud-scale initiation occurred during shoot elongation. Axillary buds were initiated in mid-May and flushing occurred when shoots had elongated to about 30% of their final length in late May or early June. The end of shoot elongation coincided with the onset of leaf initiation on all trees in both years. The change from bud-scale initiation to leaf initiation was preceded by a marked increase in apical width and a slight increase in apical height and mitotic frequency. Leaf initiation was rapid for 6 weeks then slower for the last 4 weeks. Vegetative buds became dormant in mid-October.Vegetative bud development is closely related to shoot elongation. Breaking of vegetative bud dormancy was not affected by temperature but shoot elongation and flushing were affected by temperatures which occurred after dormancy was broken.

Changes in chromosome structure, mitotic activity and nuclear DNA content from cells of Allium Test induced by bark water extract of Uncaria tomentosa (Willd.) DC

2006 ◽  
Vol 107 (2) ◽  
pp. 211-221 ◽  
Author(s):  
Mieczysław Kuraś ◽  
Julita Nowakowska ◽  
Elwira Śliwińska ◽  
Radosław Pilarski ◽  
Renata Ilasz ◽  
...  
Keyword(s):  
Mitotic Activity ◽  
Dna Content ◽  
Nuclear Dna ◽  
Chromosome Structure ◽  
Water Extract ◽  
Nuclear Dna Content ◽  
Allium Test ◽  
Uncaria Tomentosa

scholarly journals Transcriptional profiles of the annual growth cycle in Populus deltoides

2008 ◽  
Vol 28 (3) ◽  
pp. 321-329 ◽  
Author(s):  
Sunchung Park ◽  
Daniel E. Keathley ◽  
Kyung-Hwan Han
Keyword(s):  
Populus Deltoides ◽  
Growth Cycle ◽  
Annual Growth ◽  
Transcriptional Profiles

scholarly journals DNA CONTENT OF PLACENTAL NUCLEI

1962 ◽  
Vol 13 (2) ◽  
pp. 183-191 ◽  
Author(s):  
Michael Galton
Keyword(s):  
Cell Proliferation ◽  
Dna Synthesis ◽  
Mitotic Activity ◽  
Dna Content ◽  
Reproductive Capacity ◽  
Interphase Nuclei ◽  
Daughter Cells ◽  
Reproductive Ability ◽  
Dna Values ◽  
Rapid Accumulation

The DNA content of individual nuclei in four immature human placentas was determined by microspectrophotometric analysis of Feulgen-stained sections. The absence of mitosis in the syncytiotrophoblast, taken together with the finding of a diploid unimodal distribution, at a time of rapid placental growth, indicated that the syncytiotrophoblast possessed little or no intrinsic reproductive capacity. In contrast, the cytotrophoblast displayed considerable mitotic activity and was found to contain a high proportion of nuclei with DNA values in excess of the diploid amount, corresponding to DNA synthesis in interphase nuclei preparatory to division. From the complementary behavior of the two layers of trophoblast, with respect to evidence of reproductive ability, it is concluded that the rapid accumulation of nuclei in the syncytiotrophoblast, during the early development of the placenta, is accounted for by cell proliferation within the cytotrophoblast followed by alignment and coalescence of some daughter cells in the syncytiotrophoblast.

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.

The shoot apex and the ontogeny of axillary buds in Cuminum cyminum L

1969 ◽  
Vol 17 (2) ◽  
pp. 241 ◽  
Author(s):  
JJ Shah ◽  
K Unnikrishnan
Keyword(s):  
Shoot Apex ◽  
Peripheral Zone ◽  
Axillary Bud ◽  
Vegetative Shoot ◽  
Apical Position ◽  
Leaf Initiation ◽  
Axillant Leaf ◽  
Meristematic Activity ◽  
Vegetative Shoot Apex ◽  
The One

The structure and plastochronic changes of the shoot apex, and the origin, development, procambialization, and vascular relationships of the axillary bud in Cuminum cyminium were investigated. Pre-leaf initiation, leaf initiation, and post-leaf initiation phases of the shoot apex are identified. The inflorescence is axillary. During flowering the main vegetative shoot apex is semispherical, stratified, and devoid of any distinction between the central and peripheral zones. The vegetative axillary bud is differentiated from the peripheral zone of the shoot apex at the second node. It is delimited by an arcuate shell zone which helps in changing the apical position of the bud to foliar. The emergence of the bud is effected by the meristematic activity of tunica and corpus cells. A single prophyll is formed at right angles to the axillant leaf. Usually the bud trace procambium is differentiated during prophyll initiation. Occasionally it may be seen earlier, but not in connection with the earliest visible bud meristem. There are four to six strands of the bud trace directly interconnecting not only the strands of the prophyll and axillant leaf traces but also those of the second or sometimes even the third bud leaf and the axillant leaf. The bud trace procambial connection is formed by basipetal and acropetal differentiation of procambium in which the bud meristem cells and vacuolated ground meristem cells below the bud are involved. The cells of the peripheral zone of the bud apex below the prophyll primordium procambialize in a basipetal direction. As a continuation from the strand of the axillant leaf trace, the adjacent vacuolated ground meristem cells below the bud acropetally differentiate into procambial cells in the direction of the basipetal procambium and they make connection with it. All the strands of the bud trace are not simultaneously developed. The vegetative and inflorescence buds show varying vascular relationships between the strands of the leaf traces and those of the bud traces. The node differentiated during the vegetative phase of the plant is trilacunar and the one formed at flowering time is tetra- or pentalacunar. The nature and number of bud trace strands, however, suggest fundamental similarities between vegetative and inflorescence buds.

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