The Role of Axillary Meristems in Coppice and Epicormic Bud Initiation in Araucaria cunninghamii

1990 ◽  
Vol 151 (3) ◽  
pp. 293-301 ◽  
Author(s):  
G. E. Burrows
Keyword(s):  
Axillary Meristems ◽  
Araucaria Cunninghamii ◽  
Bud Initiation

An altered body plan is conferred on Arabidopsis plants carrying dominant alleles of two genes

Development ◽  
1996 ◽  
Vol 122 (8) ◽  
pp. 2395-2403 ◽  
Author(s):  
B. Grbic ◽  
A.B. Bleecker
Keyword(s):  
Shoot Apical Meristem ◽  
Apical Meristem ◽  
Reproductive Development ◽  
Body Plan ◽  
Chromosome 4 ◽  
Chromosome 5 ◽  
Present Evidence ◽  
Primary Shoot ◽  
Axillary Meristems

In this paper, we describe a late-flowering ecotype of Arabidopsis, Sy-0, in which the axillary meristems maintain a prolonged vegetative phase, even though the primary shoot apical meristem has already converted to reproductive development. This novel heterochronic shift in the development of axillary meristems results in the formation of aerial rosettes of leaves at the nodes of the primary shoot axis. We present evidence that the aerial-rosette phenotype arises due to the interaction between dominant alleles of two genes: ART, aerial rosette gene (on chromosome 5) and EAR, enhancer of aerial rosette (on chromosome 4): EAR has been tentatively identified as a new allele of the FRI locus. The possible role of these two genes in the conversion of shoot apical meristems to reproductive development is discussed.

A Scanning and Transmission Electron Microscope Study of Leaf Axil Structure in Araucaria cunninghamii

1991 ◽  
Vol 39 (1) ◽  
pp. 67 ◽  
Author(s):  
GE Burrows
Keyword(s):  
Smooth Endoplasmic Reticulum ◽  
Leaf Axil ◽  
Thin Walls ◽  
Hoop Pine ◽  
Axillary Meristems ◽  
Full Complement ◽  
Plasmodesmatal Frequency ◽  
Transmission Electron Microscope Study ◽  
Storage Products ◽  
Araucaria Cunninghamii

The cells of active plant meristems are characterised by their small size, thin walls and a full complement of organelles, most noticeably a large nucleus surrounded by densely staining, little-vacuolated cytoplasm. The axillary meristems of Araucaria cunninghamii Aiton ex D. Don (hoop pine) possess a similar ultrastructure, even though they quickly assume a near complete, potentially permanent quiescence following their detachment from the flanks of the actively dividing apical meristem. However, they differ from metabolically active cells in that those organelles and structures associated with cytokinesis and cell wall formation are either absent (microtubules) or infrequent and in an apparently inactive state (smooth endoplasmic reticulum, non-vesiculating dictyosomes, nuclei with a low heterochromatin to euchromatin ratio). In addition, storage products (starch, lipid globules), usually not present in metabolically active cells, are well developed. In addition to not developing a bud-like organisation, the meristems are also unlike typical axillary buds in that they have no vascular or provascular connections with the axial vascular tissues and are bounded adaxially by a group of thick-walled cells. While these cells constitute a physical barrier around the axillary meristems, they are nucleated and possess numerous simple pits that have a high plasmodesmatal frequency. Thus it appears that the meristems are not physiologically isolated, but are in cytoplasmic continuity with the remainder of the plant.

Budding in hydra: the role of cell multiplication and cell movement in bud initiation

Development ◽  
1972 ◽  
Vol 27 (2) ◽  
pp. 301-316
Author(s):  
Gerald Webster ◽  
Susan Hamilton
Keyword(s):  
Cell Division ◽  
Mitotic Index ◽  
Cell Population ◽  
Cell Movement ◽  
Growth Zone ◽  
Cell Multiplication ◽  
Rapid Rise ◽  
The Mean ◽  
Bud Initiation

The work described in this paper is concerned with the role of cell multiplication and cell movement in relation to the initiation of buds in hydra. Hydra starved for 6 days do not initiate new buds; in such animals the mean mitotic index is only 10% of that in well-fed animals. When starved animals are re-fed, there is a rapid rise in mitotic index which reaches a maximum 12 h after feeding and thereafter declines. This cell division causes an increase in the cell population of about 30% in the 24 h following the meal. New buds are initiated at 24–72 h, i.e. at some time after the major part of the cell multiplication. Cell division occurs in all parts of the axis to more or less the same extent and there is no sign of a growth zone in the budding region. However, the cell population in the budding zone of re-fed animals shows a significantly greater increase than in other parts of the axis and this can only be accounted for if it is assumed that cells have moved into this region from other parts of the axis. Some cell multiplication is a necessary prerequisite for bud initiation, but grafting experiments with starved animals suggest that division per se is not necessary; the important factor seems to be the increase in size resulting from division. The mechanics and causes of the cell movement which results in bud initiation are briefly discussed. It is suggested that changes in intercellular adhesion may be important.

​​Habitat Manipulation: An Important Component of IPM in the Management of Webbing Caterpillar, Maruca vitrata (Geyer) in Pigeonpea

2021 ◽  
Author(s):  
Zadda Kavitha ◽  
C. Vijayaraghavan
Keyword(s):  
Tamil Nadu ◽  
Insect Pest ◽  
Maruca Vitrata ◽  
Habitat Manipulation ◽  
Pod Borer ◽  
Initiation Stage ◽  
The One ◽  
Bud Initiation ◽  
Crop Environment

Background: Maruca vitrata is an economically important cryptic insect pest in pigeonpea. Caterpillar, the damaging stage hides in the webs thus escapes the contact with insecticides thus making an effective insecticide also ineffective. Hence, the role of some tall statured intercrops in the manipulation of pigeonpea crop environment for reducing the incidence of this webbing caterpillar was studied. Methods: Studies were conducted at NPRC, Vamban, Pudukottai dt., Tamil Nadu to study the effect of different intercrops in reducing the incidence of Maruca vitrata. During kharif 2016-17 and 2017-18, M. vitrata incidence was compared among the intercropping systems (pigeonpea with pearlmillet, sorghum and maize in 1:6 ratio) and sole pigeonpea crop. IPM modules were formulated in which botanical spray (NSKE 5% at bud initiation stage) and spray of recommended insecticide (indoxacarb 15.8 EC-0.7 ml/lt at flowering and 15 days later) were integrated with intercropping practice and tested for efficacy against this borer pest. Result: Intercropping of pigeonpea with pearlmillet was effective in managing the spotted pod borer. Coccinellids and spiders were more in intercropped pigeonpea than the sole pigeonpea crop. Synchronized flowering times of short duration pigeonpea and intercrops would have facilitated the transfer of natural enemies from intercrops to pigeonpea and this may be the one of the reasons for the lower insect population. IPM module I (pigeonpea intercropped with pearlmillet, NSKE and indoxacarb sprays) was effective in reducing the spotted pod borer damage. In IPM module I, yield of 770 kg/ha was obtained as against 550 kg/ha in sole pigeonpea crop. Among the IPM modules, high B:C ratio of 1:1.66 was recorded with IPM module I.

GRAS transcription factor LOSS OF AXILLARY MERISTEMS is essential for stamen and runner formation in wild strawberry

2021 ◽  
Author(s):  
Jia Feng ◽  
Laichao Cheng ◽  
Zhenying Zhu ◽  
Feiqi Yu ◽  
Cheng Dai ◽  
...  
Keyword(s):  
Transcription Factor ◽  
Gibberellic Acid ◽  
Complementation Test ◽  
Causative Mutation ◽  
Gras Transcription Factor ◽  
Axillary Meristems ◽  
Wild Strawberry ◽  
Acid Pathway ◽  
Bud Initiation ◽  
Branch Crown

Abstract Axillary bud development is a major factor that impacts plant architecture. A runner is an elongated shoot that develops from axillary buds and is frequently used for clonal propagation of strawberry. However, the genetic control underlying runner production is largely unknown. Here, we identified and characterized loss of axillary meristems (lam), an EMS-induced mutant of the diploid woodland strawberry (Fragaria vesca) that lacked stamens in flowers and had reduced numbers of branch crowns and runners. The reduced branch crown and runner phenotypes were caused by a failure of axillary meristem initiation. The causative mutation of lam was located in FvH4_3g41310, which encodes a GRAS transcription factor, and was validated by a complementation test. lamCR mutants generated by CRISPR/Cas9 produced flowers without stamens and had fewer runners than the wild type. LAM was broadly expressed in meristematic tissues. Gibberellic acid (GA) application induced runner outgrowth from the remaining buds in lam, but failed to do so at the empty axils of lam. In contrast, treatment with the GA biosynthesis inhibitor paclobutrazol (PBZ) converted the runners into branch crowns. Moreover, genetic studies indicated that lam is epistatic to suppressor of runnerless (srl), a mutant of FveRGA1 in the gibberellic acid pathway, during runner formation. Our results demonstrate that LAM is required for stamen and runner formation and acts sequentially with GA from bud initiation to runner outgrowth, providing insights into the molecular regulation of these economically important organs in strawberry.

Shoot ontogeny in Fraxinus pennsylvanica (green ash). I. Seasonal cycle of terminal meristem activity

1989 ◽  
Vol 67 (6) ◽  
pp. 1624-1632 ◽  
Author(s):  
W. R. Remphrey
Keyword(s):  
Seasonal Cycle ◽  
Histological Analysis ◽  
Leaf Primordia ◽  
Leaf Primordium ◽  
Fraxinus Pennsylvanica ◽  
Green Ash ◽  
Heat Unit ◽  
Foliage Leaf ◽  
Axillary Meristems ◽  
Bud Initiation

Terminal meristem ontogeny of mature Fraxinus pennsylvanica var. subintegerrima (Vahl) Fern, (green ash) was investigated by bud dissection, histological analysis, and scanning electron microscopy. The shoots were completely preformed and bud-scale initiation for the next bud began in the spring shortly before any visible sign of swell. Foliage-leaf initiation began in May and ceased in late June or early July, but there were certain differences in primordium production patterns between the two trees investigated and between the years of the study. Although temperature, as measured by heat-unit accumulation, played a significant role in the onset of shoot expansion and primordium initiation, its importance in controlling these processes diminished as the season progressed. Buds formed in the axil of every leaf primordium, but those in the axils of scales remained small. There was evidence of axillary bud initiation as early as the P1, stage. By P2 or P3 there was a clearly discernable shell zone of elongated cells. Such cells had relatively large vacuoles concentrated at each end, in contrast with the essentially nonvacuolate cells of the incipient bud meristem. In the terminal resting bud, there were well-developed scale-axil buds and protruding axillary meristems associated with foliage-leaf primordia.

170. THE ROLE OF MEGALIN IN PROSTATE DEVELOPMENT OF THE MOUSE

2010 ◽  
Vol 22 (9) ◽  
pp. 88 ◽  
Author(s):  
M. Gamat ◽  
G. Shaw ◽  
M. B. Renfree
Keyword(s):  
Cell Membrane ◽  
Knockout Mice ◽  
Sex Steroids ◽  
Urogenital Sinus ◽  
Sex Steroid ◽  
Testicular Descent ◽  
Mouse Prostate ◽  
Bud Induction ◽  
Bud Initiation

Prostatic development is dependent on androgens; but the precise mechanism by which androgens mediate their effect is still unclear. Megalin, a cell membrane transporter, may shuttle sex steroids into cells to regulate androgen-responsive genes responsible for prostatic bud induction in the urogenital sinus (UGS). In megalin knockout mice, testicular descent fails and the vagina fails to open in females, both of which are dependent on sex steroid signalling (Hammes et al. 2005) . In this megalin-mediated pathway, SHBG-bound sex steroids bind to megalin, which is internalised. The SHBG-sex steroid complex is released, and the sex steroid is released from SHBG where it can bind to the androgen receptor to regulate androgen responsive genes. Receptor-Associated Protein (RAP) is a molecular chaperone protein that protects newly synthesised megalin from binding to potential ligands in the cytoplasm prior to insertion into the cell membrane. We hypothesised that megalin may shuttle SHBG-bound androgens across the cell membrane. This study characterised the expression and evaluated a possible role for megalin in the development of the mouse prostate. Megalin, SHBG and RAP transcripts were detected in the developing male and female UGS of the mouse from day E14.5 to day E18.5 (when prostatic buds start to form) and in the adult prostate. Megalin, SHBG and RAP protein were localised in the urogenital epithelium. To assess the role of megalin in prostatic development, UGS tissues were incubated with androgens in the presence and absence of RAP. Incubating UGS tissues with RAP did NOT inhibit prostatic bud initiation. Furthermore, in the UGS of megalin knockout mice, prostatic bud formation appeared to be identical to those of wild-type littermates. These results demonstrate that megalin is not involved in prostatic bud initiation. However, the ubiquitous expression of megalin suggests that its role is redundant in the prostate. (1) Hammes A et al. (2005) Role of endocytosis in cellular uptake of sex steroids. Cell 122(5), 751–62.

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