Developmental potentialities of leaf primordia of Osmunda cinnamomea. V. Toward greater understanding of the final morphogenetic expression of isolated set I cinnamon fern leaf primordia

1969 ◽  
Vol 47 (3) ◽  
pp. 481-488 ◽  
Author(s):  
Thomas H. Haight ◽  
Charles Carroll Kuehnert
Keyword(s):  
Shoot Apical Meristem ◽  
Apical Meristem ◽  
Leaf Primordia ◽  
Leaf Primordium ◽  
Bud Formation ◽  
State Bearing ◽  
Leaves And Roots

Arguments supported by the data given favor the interpretation that (1) adaxial buds are produced by Osmunda cinnamomea leaf primordia; (2) they are produced in addition to the leaf which bears them; (3) they are to be considered adventitious rather than axial; (4) they are of a strictly foliar rather than cauline nature; and (5) they are produced only when a primordium has been isolated from the rest of the shoot system.In O. cinnamomea, the bud, which is formed in addition to the leaf primordium, is evident at the end of the fifth to sixth week on singly cultured P3 and P4 leaf primordia. With younger leaf primordia, e.g. P2’s, often the only evidence of bud formation at the termination of an 8-week culturing period is the presence of the new apical meristem (the SAM′). In the case of older primordia, however, such as P4’s, whether cultured singly or isolated from the shoot apical meristem (SAM) on a plug of tissue, the bud is observed to consist of the SAM′, and from one to seven new leaf primordia. At this stage, the meristematic outgrowth can be considered to be in the true bud state. If the culturing period is extended beyond 8 weeks, the SAM′ develops from the bud state into the plantlet state bearing miniature juvenile leaves, and roots.

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.

scholarly journals Extended expression of MaKN1 contributes to the leaf morphology in aquatic forms of Myriophyllum aquaticum

Botany ◽  
2015 ◽  
Vol 93 (9) ◽  
pp. 611-621
Author(s):  
M.D. Shafiullah ◽  
Christian R. Lacroix
Keyword(s):  
Apical Meristem ◽  
Leaf Morphology ◽  
Expression Patterns ◽  
Homeobox Gene ◽  
Leaf Primordia ◽  
Leaf Primordium ◽  
Myriophyllum Aquaticum ◽  
Knox Gene ◽  
Leaf Morphogenesis

Myriophyllum aquaticum (Vell.) Verdc. is heterophyllous in nature with highly dissected simple leaves consisting of several lobes. KNOX (KNOTTED1-LIKE HOMEOBOX) genes are believed to have played an important role in the evolution of leaf diversity. Up-regulation of KNOX during leaf primordium initiation can lead to leaf dissection in plants with simple leaves and, if overexpressed, can produce ectopic meristems on leaves. A previous study on KNOX gene expression in the aerial form of this species showed that this gene is expressed in the shoot apical meristem (SAM), as well as in leaf primordia P0 to P8. Based on these results, it was hypothesized that the prolonged expression of the MaKN1 (Myriophyllum aquaticum Knotted1-like homeobox) gene beyond P8, might play an important role in the generation of more lobes, longer lobes, and hydathode formation in the aquatic leaves of M. aquaticum. The technique of in situ hybridization was carried out using a previously sequenced 300 bp fragment of MaKN1 to determine the expression patterns of this gene in the shoot of aquatic forms of the plant. Expression patterns of MaKN1 revealed that the SAM and leaf primordia of aquatic forms of M. aquaticum at levels P0 (youngest) to P4 were distributed throughout these structures. The level of expression of this MaKN1 gene progressively became more localized to lobes in older leaf primordia (levels P5 to P12). Previous studies of aerial forms of this plant showed MaKN1 expression until P8. Our results with aquatic forms show that the highly dissected leaf morphology in aquatic forms was the result of the prolonged expression of MaKN1 beyond P8. This resulted in the formation of elongated and slightly more numerous lobes, and hydathodes in aquatic forms. These findings support the view that KNOX genes are important developmental regulators of leaf morphogenesis and have played an important role in the evolution of leaf forms in the plant kingdom.

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.

scholarly journals SHOOT ORGANIZATION Genes Regulate Shoot Apical Meristem Organization and the Pattern of Leaf Primordium Initiation in Rice

2000 ◽  
Vol 12 (11) ◽  
pp. 2161-2174 ◽  
Author(s):  
Jun-Ichi Itoh ◽  
Hidemi Kitano ◽  
Makoto Matsuoka ◽  
Yasuo Nagato
Keyword(s):  
Shoot Apical Meristem ◽  
Apical Meristem ◽  
Leaf Primordium

Does growth rate determine leaf form in Pisum sativum?

1989 ◽  
Vol 67 (9) ◽  
pp. 2590-2595 ◽  
Author(s):  
Kevin S. Gould ◽  
Elizabeth G. Cutter ◽  
J. Peter W. Young
Keyword(s):  
Growth Rate ◽  
Relative Growth Rate ◽  
Shoot Apical Meristem ◽  
Apical Meristem ◽  
Vertical Displacement ◽  
Significant Rise ◽  
Leaf Primordium ◽  
Relative Growth ◽  
Leaf Extension ◽  
Mutant Pea

We have examined the long-standing hypothesis that leaves are morphologically more complex following prolonged proximity to the shoot apical meristem. Growth rates of the petiole and rachis of conventional and mutant pea leaves were compared for successive nodes of insertion in seedling plants. Leaves were longer at higher nodes, though the relative growth rate did not vary. Mature afila leaves were longer than those of conventional and tendril-less genotypes. The afila leaf alone exhibited a transient, highly significant rise in relative growth rate during the plastochron interval P4.5–P5.5. This rise occurred after the stage at which leaves of the different genotypes were anatomically distinguishable (stage P2–P3). Rates of vertical displacement of the leaf primordium from the shoot apical meristem did not differ significantly among genotypes. Our data suggest that the rate of leaf extension is one of the consequences, rather than a cause, of leaf morphology.

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.

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