Le développement du bourgeon axillaire du <i>Manihot esculenta</i>

Médard, R.; Sell, Yves; Barnola, P.

doi:10.1139/b92-254

Cited by 3 publications

(6 citation statements)

References 29 publications

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“…Cassava plants grown from cuttings simultaneously develop one or several principal stems from buds, while plants grown from seed have a single stem. The vegetative apparatus of cassava is characterized by two types of orthotropic ramification (Medard et al, 1992). The proleptic ramifications, or secondary branches, result from the development of lateral buds after the breaking of apical dominance.…”

Section: Morphologymentioning

confidence: 99%

Genetic Diversity of Cultivated Tropical Plants

Hamon¹,

Séguin²,

Perrier³

et al. 2003

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These relationships probably vary as a function of the population structure. They are generally strong if there is a serious gametic disequilibrium. To proceed from this reflection, however, we must tackle specific questions: Are the different types of molecular markers equivalent? Are strong structures at the molecular scale, which control the gametic disequilibrium generalized on the genome as a whole, systematically associated with strong structures for agronomic characters? Do the structures at these two levels therefore coincide?Several methods have been proposed to construct the core collections. As a general rule, they are based on a stratification of the base collection and then on a random sample within each group thus defined, according to various modalities. When data are available for morphoagronomic evaluation, it is useful to consider the structure of the genetic diversity established with the help of genetic markers in order to maximize the agronomic diversity and minimize the loss of alleles that are rare overall but occasionally significant.The constitution of a core collection must therefore be founded on an excellent description of the populations and on a sound understanding of their structure. Statistical tools are indispensable here. For each type of marker, it is important to use a measure of difference between the relevant taxonomic units (individuals or populations) from the perspective of their mathematical properties and their interpretation in genetic terms. In the same way, the choice of algorithms of representation of dissimilarities must be based on an equilibrium between maximum efficiency and minimum complexity, irl order to deal with large tables covering more than 100 individuals. By comparing the structures observed with the help of various types of descriptors, we can envisage overall the organization of a plant's genetic diversity. This question can be tackled in various ways, among others, by looking for structures common to two or several trees. In these conditions, how can we construct consensus trees or common minimum trees? What is their reliability and their biological significance?This work provides the elements of an answer to these questions, beginning with the study of eleven types of plants, chosen .so as to cover a wide range of biological characteristics (perennial, annual, autogamous, allogamous, etc.): asian rice, banana, cacao, cassava, citrus, coconut, coffee, pearl millet, rubber tree, sorghum, and sugarcane. Three methodological chapters complement these studies. The first is devoted to the use of biological and molecular markers to analyse the diversity of collections, the second addresses data analysis, and the third describes a method for constituting core collections based on maximization of variability.

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Section: Morphologymentioning

confidence: 99%

Genetic Diversity of Cultivated Tropical Plants

Hamon¹,

Séguin²,

Perrier³

et al. 2003

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“…Sur la tige adulte, et sauf exceptions resultant de contraintes physiques (MCdard et al 1992a), les feuilles sont rangees verticalement de haut en bas suivant leur ordre de surrection. La longueur des entrenoeuds qui les sCparent est naturellement lCgerement variable.…”

Section: Phyllotaxieunclassified

“…Elle aurait lieu en profondeur (MCdard et al 1992a), sur le contact entre 1'Cbauche foliaire et le d6me apical. La dktermination doit s'effectuer A ce stade.…”

Section: Injluences S 'Exercant Sur Le Positionnement De L'kbauche Founclassified

“…L'extrapolation des courbes de croissance de 1'Cbauche foliaire du manioc (MCdard et Miesch 1990;MCdard et al 1992a) pendant 2-3 plastochrones avant la surrection perrnet, au cas ou la croissance serait d'ernblCe exponentielle, dlCvaluer la taille d'origine du territoire feuille. Selon cette Ctude, la taille du territoire feuille sernble augmenter au cours du temps.…”

Section: Injluences S 'Exercant Sur Le Positionnement De L'kbauche Founclassified

“…Dans un ensemble de travaux concernant les dCveloppements de la feuille (MCdard 1988(MCdard , 1989, de l'entre-noeud (MCdard et al 1992a) et du bourgeon axillaire (MCdard et al 1992b), analysCs en amont des organogenbses, nous avons constamment recherchC les dkterminations, c'est-8-dire l'enclenchement du dCveloppement, 8 l'origine des organes Cmis par le mCristbme apical. Dans la m&me optique, nous avons cherchC, dans,llCtude prCsentCe ici, 8 cerner le dCbut de l'initiation foliaire.…”

Section: Introductionunclassified

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Détermination de l'ébauche foliaire, du bourgeon axillaire et de l'entre-noeud chez le Manihot esculenta : étude microchirurgicale

Médard¹

1994

Can. J. Bot.

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MEDARD, R. 1994. Determination de 1'Cbauche foliaire, du bourgeon axillaire et de I'entre-noeud chez le Manihot esculenta : Ctude microchirurgicale. Can. J. Bot. 72 : 1329-1342. L'Ctude microchirurgicale permet de dCterminer, chez le Manihot esculenta, la date de la dktermination de la feuille, plus de deux plastochrones avant sa surrection, ainsi que celle de son bourgeon axillaire, contemporaine du dCbut de la surrection. Des lesions effectuCes sur le trajet du futur cordon procambial de l'initium foliaire le plus bgC provoquent un retard de la surrection de cet initium, laquelle s'effectuera aprbs celle de l'initium suivant. Ce retard provoque une inversion de 1'Ctagement vertical sur la tige adulte des deux feuilles qui rCsultent du dCveloppement de ces deux initiums. I1 y a donc formation, lors de chaque surrection foliaire, d'un intervalle de mCristbme ou prC-entre-noeud mis en place au-dessus du premier primordium. Cet intervalle sera ulterieurement t i l'origine de l'entre-noeud. L'espacement vertical des feuilles ne rCsulte donc pas necessairement de dkterminations CchelonnCes verticalement sur l'apex. Par ailleurs, le positionnement de l'initium foliaire en voie de dktermination est influencC par des informations qui circulent dans l'apex, notamment partir du premier primordium en surrection. La nature de ces informations est discutCe. L'ensemble des risultats obtenus est analysC la lumibre des problbmes de phyllotaxie.Mots c l b : manioc, feuille, initiation foliaire, mCristbme apical, phyllotaxie, entre-noeud.MEDARD, R. 1994. DCtermination de 1'Cbauche foliaire, du bourgeon axillaire et de I'entre-noeud chez le Manihot esculenta : Ctude microchirurgicale. Can. J. Bot. 72: 1329-1342. A microsurgical study on Manihot esculenta shows that foliar initiation occurs more than two plastochrons before bulging out. Initiation of the axillary bud of the leaf occurs at the beginning of bulging out. Injuries produced along the path of the future procambial bundle of the older foliar initial create a delay in the bulging out of this initial, which will occur only after the bulging out of the following initial. This delay generates a reversal of the final vertical stem spacing of the two leaves that emerge from those two initials. Therefore, with each leaf bulging out, a preinternode appears above the first primordium. The vertical spacing of leaves does not necessarily result from the vertical spacing of initials. Moreover, the position of the foliar initial is affected by information moving in the apex, especially from the bulging out of the first primordium. The nature of this information is discussed and the results obtained are analysed in the light of the literature on phyllotaxy.

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Diversité génétique des plantes tropicales cultivées

1999

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Le développement du bourgeon axillaire du Manihot esculenta

Cited by 3 publications

References 29 publications

Genetic Diversity of Cultivated Tropical Plants

Genetic Diversity of Cultivated Tropical Plants

Détermination de l'ébauche foliaire, du bourgeon axillaire et de l'entre-noeud chez le Manihot esculenta : étude microchirurgicale

Diversité génétique des plantes tropicales cultivées

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