Gestions locales et dynamiques régionales de la diversité variétale du manioc en Amazonie

McKey, Doyle; Emperalre, Laure; Élias, Marianne; Pinton, Florence; Robert, Thierry; Desmoulière, Sylvain J M; Rival, Laura

doi:10.1186/bf03500895

Cited by 33 publications

(21 citation statements)

References 17 publications

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Section: Resultsmentioning

confidence: 85%

“…There is an urgent need for defining strategies of dynamic conservation of genetic resources (FAO 1996); our findings argue in favour of in situ conservation of genetic resources of crop plants as an important component of such a dynamic strategy (see also McKey et al 2001). Ecological and social determinants that allow a dynamic management of genetic resources of crop plants in traditional farming systems may be relatively fragile, especially when faced with forces such as modernization of farming practices and economic pressures.…”

Section: Resultsmentioning

confidence: 99%

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Unmanaged sexual reproduction and the dynamics of genetic diversity of a vegetatively propagated crop plant, cassava (Manihot esculenta Crantz), in a traditional farming system

et al. 2001

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Occurrence of intervarietal or interspecific natural crosses has been reported for many crop plants in traditional farming systems, underlining the potential importance of this source of genetic exchange for the dynamics of genetic diversity of crop plants. In this study, we use microsatellite loci to investigate the role of volunteer seedlings (plants originating from unmanaged sexual reproduction) in the dynamics of genetic diversity of cassava (Manihot esculenta Crantz), a vegetatively propagated crop, in a traditional farming system in Guyana. A previous field study showed that farmers incorporate such plants into the germplasm for vegetative propagation, and that many of them are likely to be assigned by farmers to recognized varieties. Under strict vegetative propagation clonality of varieties is expected. The high proportion of polyclonal varieties observed suggests that incorporation of seedlings into the germplasm for propagation is a frequent event. The molecular variability assessed with microsatellite markers shows that there is high differentiation among heterozygous varieties, whereas populations of seedlings do not depart from the proportions expected under Hardy-Weinberg assumptions. Assignment of seedlings to a recognized variety on the basis of morphological similarity greatly increases genetic diversity within the variety. We argue that recombination and gene flow play a major role in the dynamics of genetic diversity of cassava in traditional farming systems. Documenting unmanaged sexual reproduction and its genetic consequences is a prerequisite for defining strategies of in situ conservation of crop plant genetic resources.

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Section: Resultsmentioning

confidence: 85%

Section: Resultsmentioning

confidence: 99%

Unmanaged sexual reproduction and the dynamics of genetic diversity of a vegetatively propagated crop plant, cassava (Manihot esculenta Crantz), in a traditional farming system

et al. 2001

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“…Molecular markers are preferred for such studies since they cannot be influenced by environmental factors. A comparison of the phenotypic features of varieties grown by Makushi Amerindians in the experimental garden by Elias et al (2001) showed that the different accessions of a local group show inheritable genetic variation in morphological features and the plasticity of expression of these traits as a function of the environment.…”

Section: Discussionmentioning

confidence: 99%

“…Several techniques, including molecular, biological and morphological techniques, make it possible to establish the authenticity of the crop material. However, the analysis of morphological descriptors seems the cheapest and reveals the diversity as perceived and adopted by local farmers; the main actors of the varietal diversity (Mckey et al, 2001;Empaire et al, 2003).…”

Section: Introductionmentioning

confidence: 99%

Establishment of simple criteria for the identification of cassava clones produced in Côte d'Ivoire

Troare¹,

Sylla²,

Bamba³

et al. 2020

Int. J. Bio. Chem. Sci

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In Côte d'Ivoire, cassava is widely grown all over the country, and a large variety of varieties is encountered. This diversity is due, on the one hand, to the fact that genotypes respond differently to various soil, climate and biotic factors and, on the other hand, to the continuous exchange of seeds among producers. The objective of this study was to find a limited number of reliable and stable morphological criteria that would allow clones to be identified throughout the cassava chain. The study first consisted of a visit in the experimental station with the aim of identifying all the clones found on the different plots. Twenty clones were randomly selected. Then, cassava descriptors developed by the International Institute of Tropical Agriculture (IITA) were used to identify differences between these clones. The PCA analysis method highlighted seven main criteria: "color of the last branch", "color of the leaf", "color of the petiole", "color of the rib", "number of branches", "profile of the petioles" and " shape of the branches". These criteria made it possible to differentiate eleven clones.

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“…Amerindian farmers allow volunteer seedlings to grow, and some are used by farmers to prepare stem cuttings, adding new clones to landraces. These products of sexual reproduction are important in the evolutionary dynamics of this clonally propagated crop [28], [32]–[39]. Notably, it is their incorporation that leads to the recombination/selection cycles necessary for the accumulation of numerous adaptations during domestication.…”

Section: Introductionmentioning

confidence: 99%

The Evolutionary Fate of Phenotypic Plasticity and Functional Traits under Domestication in Manioc: Changes in Stem Biomechanics and the Appearance of Stem Brittleness

et al. 2013

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Domestication can influence many functional traits in plants, from overall life-history and growth form to wood density and cell wall ultrastructure. Such changes can increase fitness of the domesticate in agricultural environments but may negatively affect survival in the wild. We studied effects of domestication on stem biomechanics in manioc by comparing domesticated and ancestral wild taxa from two different regions of greater Amazonia. We compared mechanical properties, tissue organisation and wood characteristics including microfibril angles in both wild and domesticated plants, each growing in two different habitats (forest or savannah) and varying in growth form (shrub or liana). Wild taxa grew as shrubs in open savannah but as lianas in overgrown and forested habitats. Growth form plasticity was retained in domesticated manioc. However, stems of the domesticate showed brittle failure. Wild plants differed in mechanical architecture between shrub and liana phenotypes, a difference that diminished between shrubs and lianas of the domesticate. Stems of wild plants were generally stiffer, failed at higher bending stresses and were less prone to brittle fracture compared with shrub and liana phenotypes of the domesticate. Biomechanical differences between stems of wild and domesticated plants were mainly due to changes in wood density and cellulose microfibril angle rather than changes in secondary growth or tissue geometry. Domestication did not significantly modify “large-scale” trait development or growth form plasticity, since both wild and domesticated manioc can develop as shrubs or lianas. However, “finer-scale” developmental traits crucial to mechanical stability and thus ecological success of the plant were significantly modified. This profoundly influenced the likelihood of brittle failure, particularly in long climbing stems, thereby also influencing the survival of the domesticate in natural situations vulnerable to mechanical perturbation. We discuss the different selective pressures that could explain evolutionary modifications of stem biomechanical properties under domestication in manioc.

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Gestions locales et dynamiques régionales de la diversité variétale du manioc en Amazonie

Cited by 33 publications

References 17 publications

Unmanaged sexual reproduction and the dynamics of genetic diversity of a vegetatively propagated crop plant, cassava (Manihot esculenta Crantz), in a traditional farming system

Unmanaged sexual reproduction and the dynamics of genetic diversity of a vegetatively propagated crop plant, cassava (Manihot esculenta Crantz), in a traditional farming system

Establishment of simple criteria for the identification of cassava clones produced in Côte d'Ivoire

The Evolutionary Fate of Phenotypic Plasticity and Functional Traits under Domestication in Manioc: Changes in Stem Biomechanics and the Appearance of Stem Brittleness

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