Gibberellin-induced reorganization of spatial relationships of emerging leaf primordia at the shoot apical meristem in Hedera helix L.

Planta ◽  
1991 ◽  
Vol 185 (2) ◽  
Author(s):  
Jan Marc ◽  
WesleyP. Hackett
Keyword(s):  
Shoot Apical Meristem ◽  
Apical Meristem ◽  
Leaf Primordia ◽  
Spatial Relationships ◽  
Hedera Helix

Phyllotaxis of the palm Euterpe oleracea Mart. at the level of the shoot apical meristem

Botany ◽  
2010 ◽  
Vol 88 (5) ◽  
pp. 528-536 ◽  
Author(s):  
Denis Barabé ◽  
Laura Bourque ◽  
Xiaofeng Yin ◽  
Christian Lacroix
Keyword(s):  
Shoot Apical Meristem ◽  
Fundamental Theorem ◽  
Apical Meristem ◽  
Leaf Primordia ◽  
Leaf Primordium ◽  
Divergence Angle ◽  
Euterpe Oleracea ◽  
The Mean ◽  
The Relationship ◽  
Euterpe Oleracea Mart

Previous studies on palm phyllotaxis deal mainly with the mature trunk. The goals of this study are (i) to determine the relationship between the number of parastichies, the divergence angle, and the plastochrone ratio at the level of the shoot apical meristem; (ii) to examine whether there are fluctuations in the divergence angle; (iii) to interpret the significance of phyllotactic parameters with respect to the mode of growth of the apex. The tubular base of the leaf primordium is more or less asymmetrical, and completely surrounds the shoot apical meristem. The phyllotactic system corresponds to a (2, 3) conspicuous parastichy pair. The mean divergence angle per apex varies between 126.9° ± 9.3° (mean ± SD) and 135. 8° ± 8.0°. Divergence angles for all apices fluctuate within a range of 115.89° to 157.33°. The mean plastochrone ratios between apices varies from 1.35 ± 0.18 to 1.58 ± 0.12. The plastochrone ratio at each plastochrone for all apices ranges from 1.09 to 2.00. There is no correlation between the angle of divergence and the plastochrone ratio. There is a fluctuation in the value of the divergence angle that falls within the range predicted by the fundamental theorem of phyllotaxis. The high value of the ratio of the diameter of leaf primordia over the diameter of the apex, and the long plastochrone might explain the lack of correlation between certain phyllotactic parameters.

A fate map of the Arabidopsis embryonic shoot apical meristem

Development ◽  
1992 ◽  
Vol 115 (3) ◽  
pp. 745-753 ◽  
Author(s):  
V. F. Irish ◽  
I. M. Sussex
Keyword(s):  
Shoot Apical Meristem ◽  
Apical Meristem ◽  
Histological Analysis ◽  
Cell Number ◽  
Leaf Primordia ◽  
Axillary Buds ◽  
Fate Map ◽  
Seed Embryo ◽  
Sector Analysis ◽  
Pale Green

We have mapped the fate of cells in the Arabidopsis embryonic shoot apical meristem by irradiating seed and scoring the resulting clonally derived sectors. 176 white, yellow, pale green or variegated sectors were identified and scored for their position and extent in the resulting plants. Most sectors were confined to a fraction of a leaf, and only occasionally extended into the inflorescence. Sectors that extended into the inflorescence were larger, and usually encompassed about a third to a half of the inflorescence circumference. We also find that axillary buds in Arabidopsis are clonally related to the subtending leaf. Sections through the dry seed embryo indicate that the embryonic shoot apical meristem contains approximately 110 cells in the three meristematic layers prior to the formation of the first two leaf primordia. The histological analysis of cell number in the shoot apical meristem, in combination with the sector analysis have been used to construct a map of the probable fate of cells in the embryonic shoot apical meristem.

How repeated epiphylly correlates with gene expression of resident knox1 in the leaves of tobacco epiphyllous shoots

2006 ◽  
Vol 1 (2) ◽  
pp. 263-274 ◽  
Author(s):  
Kai Müller ◽  
Jinxing Lin ◽  
Rainer Fischer ◽  
Dirk Prüfer
Keyword(s):  
Gene Expression ◽  
Transgenic Plant ◽  
Shoot Apical Meristem ◽  
Plant Material ◽  
Apical Meristem ◽  
Leaf Primordia ◽  
Wild Type ◽  
Expression Domain ◽  
Enhanced Expression ◽  
Founder Cells

AbstractThe tobacco knox1 genes tokn1 and tokn2 were isolated and their neomorphic capacities were tested while expressed in tobacco and potato. In addition, their neomorphic capacities were compared to barley bkn3 transgenic plant material. While tokn2 and bkn3 induced epiphylly in tobacco and supercompound leaves in potato, tokn1 failed to produce such prominent knox1 specific phenotypes. In wild type tobacco, alleles of the tokn genes were found to be expressed within distinct zones of the shoot apical meristem (SAM), leaving out regions that correlated with leaf founder cells [1]. In contrast, the expression of the tokn genes was detected throughout the meristem and in leaf primordia of epiphyllous shoots that developed in tobacco over-expressing the barley hooded gene bkn3. It was determined that such extended expression domains of resident tobacco knox1 genes were mediated through an enhanced expression domain of bkn3 within the tissue confined to the epiphylls, and this contributed to “repeated epiphylly”, i.e. an iterated development of epiphyllous shoots on leaves of progenitor epiphylls.

DEVELOPMENTAL POTENTIALITIES OF LEAF PRIMORDIA OF OSMUNDA CINNAMOMEA: THE INFLUENCE OF DETERMINED LEAF PRIMORDIA ON UNDETERMINED LEAF PRIMORDIA

1967 ◽  
Vol 45 (11) ◽  
pp. 2109-2113 ◽  
Author(s):  
Charles Carroll Kuehnert
Keyword(s):  
Active Site ◽  
Shoot Apical Meristem ◽  
Apical Meristem ◽  
Alternative Hypothesis ◽  
Leaf Primordia ◽  
Sterile Culture ◽  
Indirect Control

In the fern Osmunda cinnamomea, leaf primorida may be excised and grown in sterile culture before or subsequent to their irreversible determination as leaves. It has been demonstrated that P3 primordia (third-oldest primordia) are not irreversibly determined as leaves at the time of excision for they exhibit a tendency to develop as shoots rather than leaves when cultured aseptically. When grown singly they become shoots 75.0% of the time; when grown in physiological contact as paired units they exhibit a tendency to become shoots at approximately the same level. The hypothesis that the active site of leaf determination is through the direct or indirect control of the shoot apical meristem is questioned and an alternative hypothesis is proposed which suggests that a morphogenetic factor is formed in older primordia which will diffuse to younger primordia to influence younger primordia to develop as leaves rather than shoots. The latter hypothesis is supported by experiments in which P3 primordia grown in physiological contact (as pairs) with P10 or P12 primordia produce more than twice as many leaves as unpaired or paired P3 primordia.

In situ localization of storage protein mRNAs in developing meristems of Brassica napus embryos

Development ◽  
1991 ◽  
Vol 111 (2) ◽  
pp. 299-313 ◽  
Author(s):  
D.E. Fernandez ◽  
F.R. Turner ◽  
M.L. Crouch
Keyword(s):  
Brassica Napus ◽  
Storage Protein ◽  
Shoot Apical Meristem ◽  
Apical Meristem ◽  
Vascular Tissue ◽  
Leaf Primordia ◽  
Root Apical Meristem ◽  
Cdna Clones ◽  
Final Maturation

Probes derived from cDNA clones of napin and cruciferin, the major storage proteins of Brassica napus, and in situ hybridization techniques were used to examine changes in the spatial and temporal distribution of storage protein messages during the course of embryogeny, with a special emphasis on the developing apical meristems. Napin mRNAs begin to accumulate in the cortex of the axis during late heart stage, in the outer faces of the cotyledons during torpedo stage and in the inner faces of the cotyledons during cotyledon stage. Cruciferin mRNAs accumulate in a similar pattern but approximately 5 days later. Cells in the apical regions where root and shoot meristems develop do not accumulate storage protein messages during early stages of embryogeny. In the upper axis, the boundary between these apical cells and immediately adjacent cells that accumulate napin and cruciferin mRNAs is particularly distinct. Our analysis indicates that this boundary is not related to differences in tissue or cell type, but appears instead to be coincident with the site of a particular set of early cell divisions. A major change in the mRNA accumulation patterns occurs halfway through embryogeny, as the embryos enter maturation stage and start drying down. Final maturation of the shoot apical meristem is associated with the development of leaf primordia and the accumulation of napin mRNAs in the meristem, associated leaf primordia and vascular tissue. Cruciferin mRNAs accumulate only in certain zones of the shoot apical meristem and on the flanks of leaf primordia. Neither type of mRNA accumulates in the root apical meristem at any stage.

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