Quiescent cell populations in apical meristems of Helianthus annuus

1974 ◽  
Vol 52 (10) ◽  
pp. 2195-2201 ◽  
Author(s):  
Haviva D. Langenauer ◽  
Edward L. Davis ◽  
Peter L. Webster
Keyword(s):  
Dna Synthesis ◽  
Helianthus Annuus ◽  
Shoot Apex ◽  
Central Zone ◽  
Quiescent Cell ◽  
Shoot Meristem ◽  
Cell Populations ◽  
Quiescent Center ◽  
Apical Meristems ◽  
Shoot Apical Meristems

Quiescent cell populations in both root and shoot apical meristems of Helianthus annuus are compared. Histoautoradiographs prepared after 12-h provision of [3H]thymidine in the growth medium demonstrate the presence of a quiescent center located subterminally in the apical meristem of cultured and attached Helianthus roots. Similar techniques (using [3H]-thymidine in the medium for 24–48 h) show that while cells of the shoot meristem undergo DNA synthesis, a central zone that does not incorporate the precursor exists at the summit of the cultured vegetative shoot apex. Central zone cells contain larger nuclei than do surrounding cells in the shoot apex, while quiescent-center nuclei are smaller than those in the surrounding meristem of the root apex.Growth of excised roots in medium without carbohydrates causes temporary arrest of proliferative activity in most of the meristem. When sucrose is provided after this treatment, cells of the meristem as well as most cells of the root quiescent center are stimulated into DNA synthesis. In shoots cultured in sucrose-deficient medium, few cells continue to synthesize DNA, but subsequent transfer to medium with carbohydrates stimulates no cells of the central zone into DNA synthesis, although progression through the cycle is resumed by other cells of the meristem. These and other considerations suggest that the quiescent regions in root and shoot apical meristems are not comparable.

Experimental studies on the shoot apex of Helianthus annuus: the effect of surgical bisection on quiescent cells in the apex

1977 ◽  
Vol 55 (5) ◽  
pp. 606-614 ◽  
Author(s):  
E. L. Davis ◽  
T. A. Steeves
Keyword(s):  
Dna Synthesis ◽  
Helianthus Annuus ◽  
Shoot Apex ◽  
Experimental Studies ◽  
Central Zone ◽  
Quiescent Cells ◽  
Cytological Features

When the shoot apex of Helianthus annuus cv. Peredovic is bisected surgically, two new apices are regenerated, each of which, 3 weeks after the operation, contains a quiescent central zone similar to that of the original apex. The operation destroys some cells of the original zone and stimulates others to become active in DNA synthesis. Regenerating apices, supplied with [H3] thymidine and autoradiographed at the end of the 2nd day after the operation, reveal no evidence of a quiescent zone. Evidence for the establishment of quiescence appears by the end of the 3rd day and becomes clearer on the 4th and 5th days after the operation. There is no evidence that the residual zone cells play any particular role in regeneration. It is suggested that quiescence in regard to DNA synthesis and mitosis appears sooner than the cytological features associated with quiescence in the sunflower shoot apex.

Analytical studies on the shoot apex of Helianthus annuus

1969 ◽  
Vol 47 (9) ◽  
pp. 1367-1375 ◽  
Author(s):  
T. A. Steeves ◽  
M. Anne Hicks ◽  
J. M. Naylor ◽  
Patricia Rennie
Keyword(s):  
Helianthus Annuus ◽  
Shoot Apex ◽  
Culture Medium ◽  
Deoxyribonucleic Acid ◽  
Vegetative State ◽  
Central Zone ◽  
Apical Region ◽  
Cell Nuclei ◽  
Liquid Culture Medium ◽  
Vegetative Shoot Apex

The vegetative shoot apex of Helianthus annuus contains a central zone in which the cell nuclei are relatively large and stain faintly in the Feulgen reaction. Excised apices in the vegetative state were supplied with thymidine-H3 through their sterile, liquid culture medium. Autoradiography after 24 or 48 hours of feeding revealed no significant incorporation of the labeled precursor into central zone nuclei, but extensive incorporation in peripheral regions of the apex. It is concluded that during vegetative growth deoxyribonucleic acid (DNA) synthesis and mitosis are arrested in the central zone or reduced to an extremely slow rate. Microspectrophotometry, however, indicates that the central zone nuclei are not held at the 2C level. With the onset of flowering, cytological zonation disappears in the apex and the incorporation of thymidine-H3 is uniformly heavy throughout the apical region.

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 ultrastructure of the central zone cells of the shoot apex of Helianthus annuus

1981 ◽  
Vol 59 (11) ◽  
pp. 2009-2015 ◽  
Author(s):  
V. K. Sawhney ◽  
P. J. Rennie ◽  
T. A. Steeves
Keyword(s):  
Endoplasmic Reticulum ◽  
Helianthus Annuus ◽  
Shoot Apex ◽  
Ultrastructural Study ◽  
Central Zone ◽  
Peripheral Zone ◽  
Striking Difference ◽  
Vegetative Shoot ◽  
Helianthus Annuus L ◽  
Vegetative Shoot Apex

An ultrastructural study of the vegetative shoot apex of Helianthus annuus L. cv. Peredovic has shown that in most respects the cytoplasmic components of the central zone cells were similar to those of the mitotically active peripheral zone cells. For example, the mitochondria, dictyosomes, endoplasmic reticulum, ribosomes, and microtubules were not different either in their structure or in distribution in the two types of cells. The only striking difference found was the presence of starch-containing plastids in the central zone, primarily in the two tunica layers in this region, and their absence from peripheral and immediately subjacent regions of the meristem. Starch-containing plastids were observed in the differentiating pith cells. Plasmodesmata were observed in the central zone and in walls between central and peripheral zone cells.

scholarly journals Studies of genes and mutants in the shoot apex and shoot apical meristems

1993 ◽  
Vol 140 (6) ◽  
pp. 721-721
Author(s):  
June Medford
Keyword(s):  
Shoot Apex ◽  
Apical Meristems ◽  
Shoot Apical Meristems

The aba dynamics in leaves and shoot apical meristems (sam) of isogenic by E genes soybean lines under different photoperiod

2016 ◽  
Vol 48 (2) ◽  
pp. 167-177
Author(s):  
Yu.Yu. Yuhno ◽  
◽  
V.V. Zhmurko ◽  
Keyword(s):  
Apical Meristems ◽  
Shoot Apical Meristems

Differentiation of Multiple Shoot Apical Meristems in Mutant Rice with One Embryo Causing Multiple Plumuples

2012 ◽  
Vol 37 (12) ◽  
pp. 2251-2260
Author(s):  
Jing-Yu GUO ◽  
Zhi-Xiong CHEN ◽  
Bing-Yao YANG ◽  
Xin-Fen CHEN ◽  
Xiang-Dong LIU ◽  
...  
Keyword(s):  
Multiple Shoot ◽  
Apical Meristems ◽  
Shoot Apical Meristems

The effect of cadmium on shoot apical meristems of barley

2006 ◽  
Vol 37 (6) ◽  
pp. 371-374 ◽  
Author(s):  
N. M. Kaznina ◽  
G. F. Laidinen ◽  
A. F. Titov
Keyword(s):  
Apical Meristems ◽  
Shoot Apical Meristems

The PINHEAD/ZWILLE gene acts pleiotropically in Arabidopsis development and has overlapping functions with the ARGONAUTE1 gene

Development ◽  
1999 ◽  
Vol 126 (3) ◽  
pp. 469-481 ◽  
Author(s):  
K. Lynn ◽  
A. Fernandez ◽  
M. Aida ◽  
J. Sedbrook ◽  
M. Tasaka ◽  
...  
Keyword(s):  
Expression Patterns ◽  
Bilateral Symmetry ◽  
Floral Organ ◽  
Axillary Shoot ◽  
Apical Meristems ◽  
Shoot Apical Meristems ◽  
Positional Identity ◽  
Competence Factor ◽  
High Level

Several lines of evidence indicate that the adaxial leaf domain possesses a unique competence to form shoot apical meristems. Factors required for this competence are expected to cause a defect in shoot apical meristem formation when inactivated and to be expressed or active preferentially in the adaxial leaf domain. PINHEAD, a member of a family of proteins that includes the translation factor eIF2C, is required for reliable formation of primary and axillary shoot apical meristems. In addition to high-level expression in the vasculature, we find that low-level PINHEAD expression defines a novel domain of positional identity in the plant. This domain consists of adaxial leaf primordia and the meristem. These findings suggest that the PINHEAD gene product may be a component of a hypothetical meristem forming competence factor. We also describe defects in floral organ number and shape, as well as aberrant embryo and ovule development associated with pinhead mutants, thus elaborating on the role of PINHEAD in Arabidopsis development. In addition, we find that embryos doubly mutant for PINHEAD and ARGONAUTE1, a related, ubiquitously expressed family member, fail to progress to bilateral symmetry and do not accumulate the SHOOT MERISTEMLESS protein. Therefore PINHEAD and ARGONAUTE1 together act to allow wild-type growth and gene expression patterns during embryogenesis.

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