Enhancing crop genepool use: capturing wild relative and landrace diversity for crop improvement, 2000
ABSTRACT Unconscious incorporation of sexually-produced new genotypes into the cultivated germpla... more ABSTRACT Unconscious incorporation of sexually-produced new genotypes into the cultivated germplasm of oca (Oxalis tuberosa Mol.), a vegetatively-propagated crop of the Andes, has been demonstrated as highly probable. Farmers would voluntarily seek spontaneous plants in previously cultivated fields and use their tubers as seeds, thinking of these plants as vegetative propagules of the landraces they possess. But an active sexual reproduction is also the source of those spontaneous plants and new genotypes can therefore be incorporated into cultivated landraces. Such incorporations would enhance the dynamics of the conservation of genetic resources of oca. Interviews have been realized with 38 farmers of 4 communities of the Candelaria district (Colomi, Bolivia) in order to assess the extent of such practices and the farmers’ knowledge on the sexual reproduction of oca. Half of the interviewed farmers use tubers from spontaneous plants as seeds. Frequency of use varies between farmers. Utilization as seeds of tubers of spontaneous plants is usually due to seed shortage. The new seeds are assigned to existing landraces based on the color criteria, which is poorly selective. Only 7 of the 38 interviewed farmers are aware of the sexual reproduction of oca, having observed pods, seeds or plantlets. Only one of them is aware of the potential of those seeds for propagation or breeding purposes. During a group restitution phase organized with each community, farmers expressed their interests in obtaining new landraces by means of sexual reproduction, as they already sporadically use this technique to obtain new potato landraces. This could be encouraged by local institutions in order to enhance the creation and conservation of genetic diversity for this species.
Many crops are polyploids, and it can be challenging to untangle the often complicated history of... more Many crops are polyploids, and it can be challenging to untangle the often complicated history of their origins of domestication and origins of polyploidy. To complement other studies of the origins of polyploidy of the octoploid tuber crop oca (Oxalis tuberosa) that used DNA sequence data and phylogenetic methods, we here compared AFLP data for oca with four wild, tuber-bearing Oxalis taxa found in different regions of the central Andes. Results confirmed the divergence of two use-categories of cultivated oca that indigenous farmers use for different purposes, suggesting the possibility that they might have had separate origins of domestication. Despite previous results with nuclear-encoded, chloroplast-expressed glutamine synthetase suggesting that O. picchensis might be a progenitor of oca, AFLP data of this species, as well as different populations of wild, tuber-bearing Oxalis found in Lima Department, Peru, were relatively divergent from O. tuberosa. Results from all analytical methods suggested that the unnamed wild, tuber-bearing Oxalis found in Bolivia and O. chicligastensis in NW Argentina are the best candidates as the genome donors for polyploid O. tuberosa, but the results were somewhat equivocal about which of these two taxa is the more strongly supported as oca’s progenitor.
Enhancing crop genepool use: capturing wild relative and landrace diversity for crop improvement, 2000
ABSTRACT Unconscious incorporation of sexually-produced new genotypes into the cultivated germpla... more ABSTRACT Unconscious incorporation of sexually-produced new genotypes into the cultivated germplasm of oca (Oxalis tuberosa Mol.), a vegetatively-propagated crop of the Andes, has been demonstrated as highly probable. Farmers would voluntarily seek spontaneous plants in previously cultivated fields and use their tubers as seeds, thinking of these plants as vegetative propagules of the landraces they possess. But an active sexual reproduction is also the source of those spontaneous plants and new genotypes can therefore be incorporated into cultivated landraces. Such incorporations would enhance the dynamics of the conservation of genetic resources of oca. Interviews have been realized with 38 farmers of 4 communities of the Candelaria district (Colomi, Bolivia) in order to assess the extent of such practices and the farmers’ knowledge on the sexual reproduction of oca. Half of the interviewed farmers use tubers from spontaneous plants as seeds. Frequency of use varies between farmers. Utilization as seeds of tubers of spontaneous plants is usually due to seed shortage. The new seeds are assigned to existing landraces based on the color criteria, which is poorly selective. Only 7 of the 38 interviewed farmers are aware of the sexual reproduction of oca, having observed pods, seeds or plantlets. Only one of them is aware of the potential of those seeds for propagation or breeding purposes. During a group restitution phase organized with each community, farmers expressed their interests in obtaining new landraces by means of sexual reproduction, as they already sporadically use this technique to obtain new potato landraces. This could be encouraged by local institutions in order to enhance the creation and conservation of genetic diversity for this species.
Many crops are polyploids, and it can be challenging to untangle the often complicated history of... more Many crops are polyploids, and it can be challenging to untangle the often complicated history of their origins of domestication and origins of polyploidy. To complement other studies of the origins of polyploidy of the octoploid tuber crop oca (Oxalis tuberosa) that used DNA sequence data and phylogenetic methods, we here compared AFLP data for oca with four wild, tuber-bearing Oxalis taxa found in different regions of the central Andes. Results confirmed the divergence of two use-categories of cultivated oca that indigenous farmers use for different purposes, suggesting the possibility that they might have had separate origins of domestication. Despite previous results with nuclear-encoded, chloroplast-expressed glutamine synthetase suggesting that O. picchensis might be a progenitor of oca, AFLP data of this species, as well as different populations of wild, tuber-bearing Oxalis found in Lima Department, Peru, were relatively divergent from O. tuberosa. Results from all analytical methods suggested that the unnamed wild, tuber-bearing Oxalis found in Bolivia and O. chicligastensis in NW Argentina are the best candidates as the genome donors for polyploid O. tuberosa, but the results were somewhat equivocal about which of these two taxa is the more strongly supported as oca’s progenitor.
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