Le développement du bourgeon axillaire du Manihot esculenta

1992 ◽  
Vol 70 (10) ◽  
pp. 2041-2052
Author(s):  
R. Médard ◽  
Y. Sell ◽  
P. Barnola
Keyword(s):  
Latent Period ◽  
Manihot Esculenta ◽  
Apical Meristem ◽  
Leaf Primordium ◽  
Axillary Meristem ◽  
Latent Stage ◽  
Stem Development ◽  
Morphological Differences ◽  
Advanced Development ◽  
Axillary Leaf

The vegetative aerial apparatus of cassava consists of two kinds of axes: sylleptic and proleptic. After its determination, an axillary meristem may have either an advanced development, which characterizes a sylleptic axis, or a later development, which characterizes a proleptic axis. The morphological differences between the two categories of axes are easily explained as the result of differences in development. Proleptic development undergoes four stages: (i) determination, (ii) first latent period in the apical meristem, (iii) organogenesis, and (iv) second latency. The second and fourth stages do not occur in the advanced form of development. The first latent stage is due to a double precedency of both the upper part of the apical meristem and the axillary leaf primordium. The hypothesis of a control of the determination and the first latency of the axils from the whole apical meristem is discussed. The regulation of the two types of interruptions of development do not take place on the same scale and are probably not of the same type. Key words: axillary bud, stem, development, cassava, proleptic, sylleptic.

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.

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 Ontogenetic Changes in Auxin Biosynthesis and Distribution Determine the Organogenic Activity of the Shoot Apical Meristem in pin1 Mutants

2019 ◽  
Vol 20 (1) ◽  
pp. 180 ◽  
Author(s):  
Alicja Banasiak ◽  
Magdalena Biedroń ◽  
Alicja Dolzblasz ◽  
Mateusz Adam Berezowski
Keyword(s):  
Shoot Apical Meristem ◽  
Apical Meristem ◽  
Auxin Transport ◽  
Vascular System ◽  
Auxin Biosynthesis ◽  
Wild Type ◽  
Ontogenetic Changes ◽  
Auxin Distribution ◽  
Stem Development ◽  
Knockout Mutation

In the shoot apical meristem (SAM) of Arabidopsis, PIN1-dependent polar auxin transport (PAT) regulates two crucial developmental processes: organogenesis and vascular system formation. However, the knockout mutation in the PIN1 gene does not fully inhibit these two processes. Therefore, we investigated a potential source of auxin for organogenesis and vascularization during inflorescence stem development. We analyzed auxin distribution in wild-type (WT) and pin1 mutant plants using a refined protocol of auxin immunolocalization; auxin activity, with the response reporter pDR5:GFP; and expression of auxin biosynthesis genes YUC1 and YUC4. Our results revealed that regardless of the functionality of PIN1-mediated PAT, auxin is present in the SAM and vascular strands. In WT plants, auxin always accumulates in all cells of the SAM, whereas in pin1 mutants, its localization within the SAM changes ontogenetically and is related to changes in the structure of the vascular system, organogenic activity of SAM, and expression levels of YUC1 and YUC4 genes. Our findings indicate that the presence of auxin in the meristem of pin1 mutants is an outcome of at least two PIN1-independent mechanisms: acropetal auxin transport from differentiated tissues with the use of vascular strands and auxin biosynthesis within the SAM.

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

scholarly journals Grass Meristems I: Shoot Apical Meristem Maintenance, Axillary Meristem Determinacy and the Floral Transition

2013 ◽  
Vol 54 (3) ◽  
pp. 302-312 ◽  
Author(s):  
Michael Pautler ◽  
Wakana Tanaka ◽  
Hiro-Yuki Hirano ◽  
David Jackson
Keyword(s):  
Shoot Apical Meristem ◽  
Apical Meristem ◽  
Floral Transition ◽  
Axillary Meristem ◽  
Meristem Maintenance

MORPHOLOGICALLY DISTINCT STAGES IN THE GROWTH AND DEVELOPMENT OF RHIZOMES OF POA PRATENSIS L. AND THEIR CORRELATION WITH SPECIFIC GEOTROPIC RESPONSES

1965 ◽  
Vol 43 (10) ◽  
pp. 1163-1175 ◽  
Author(s):  
John E. Fisher
Keyword(s):  
Cross Section ◽  
Growth And Development ◽  
Apical Meristem ◽  
Poa Pratensis ◽  
Soil Surface ◽  
Leaf Primordium ◽  
Primary Stage ◽  
Secondary Stage ◽  
Small Pore ◽  
Tertiary Stage

Three distinct stages in the growth and development of the rhizomes of Poa pratensis L. can be distinguished. The names, primary, secondary, and tertiary are proposed to identify the stages. Primary stage rhizomes produce cataphylls elliptical in cross section, and poreless, or with a very small pore. Cataphyll primordia, initiated by the apical meristem, develop disproportionately, producing a hood-like cowling enclosing the apical meristem. The opening partially or completely closes by ontogenetic fusion. The geotropic response is plagiotropic Secondary stage rhizomes produce cataphylls with a marked longitudinal invagination. They are seldom poreless, and then only early in this stage. The apices are similar to primary stage apices. The geotropic response is diageotropic. Tertiary stage rhizomes progressively exhibit characteristics of true aerial shoots. Cataphylls develop a rudimentary leaf blade, ligule, and buliform-cell leaf-closure apparatus. However, a collar between blade and sheath does not form until the rhizome reaches the soil surface. The apex progressively develops the broad shield-shaped leaf primordium characteristic of aerial shoots. The geotropic response becomes strongly negatively orthogeotropic. Both the secondary and the tertiary stages are initiated by a change in the morphology of the apex and the cataphyll that precedes changes in the geotropic response of the rhizomes.

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.

scholarly journals Neonatal Exposure to the Phytoestrogen Genistein Alters Mammary Gland Growth and Developmental Programming of Hormone Receptor Levels

Endocrinology ◽  
2006 ◽  
Vol 147 (10) ◽  
pp. 4871-4882 ◽  
Author(s):  
Elizabeth Padilla-Banks ◽  
Wendy N. Jefferson ◽  
Retha R. Newbold
Keyword(s):  
Mammary Gland ◽  
Hormone Receptor ◽  
Morphological Changes ◽  
Receptor Protein ◽  
Developmental Effects ◽  
Alveolar Development ◽  
Terminal End Buds ◽  
Morphological Differences ◽  
Higher Doses ◽  
Advanced Development

Developmental effects of genistein (Gen) on the mammary gland were investigated using outbred female CD-1 mice treated neonatally on d 1–5 by sc injections at doses of 0.5, 5, or 50 mg/kg·d. Examination of mammary gland whole mounts (no. 4) before puberty (4 wk) revealed no morphological differences in development after Gen treatment. However, mice treated with Gen-50 had stunted development characterized by less branching at 5 wk and decreased numbers of terminal end buds at 5 and 6 wk. Conversely, at 6 wk, Gen-0.5-treated mice exhibited advanced development with increased ductal elongation compared with controls. Measurements of hormone receptor levels showed increased levels of progesterone receptor protein and estrogen receptor-β mRNA in Gen-0.5-treated mice compared with controls; ERα expression was decreased after all doses of Gen treatment. Lactation ability, measured by pup weight gain and survival, was not affected after neonatal Gen-0.5 and Gen-5. Mice treated with Gen-50 did not deliver live pups; therefore, lactation ability could not be determined. Evaluation of mammary glands in aged mice (9 months) showed no differences between Gen-0.5-treated mice and controls but mice treated with Gen-5 and Gen-50 exhibited altered morphology including reduced lobular alveolar development, dilated ducts, and focal areas of “beaded” ducts lined with hyperplastic ductal epithelium. In summary, neonatal Gen exposure altered mammary gland growth and development as well as hormone receptor levels at all doses examined; higher doses of Gen led to permanent long-lasting morphological changes.

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