Structure and genetic diversity of two Andean tuber crops, oca (Oxalis tuberosa Mol.) and mashua (Tropaeolum tuberosum R.&P.) : influence of the mode of conservation and of the agronomic and biological characteristics
(2008)
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- Authors
- Supervisors
- Bertin, Pierre
- Abstract
- Oca (Oxalis tuberosa) and mashua (Tropaeolum tuberosum) are vegetatively propagated tuber crops cultivated in the Andean highlands since pre-Inca times. Despite their numerous qualities and uses in the staple diet of many peasants, they are currently marginal crops. Although some studies have been realized, their genetic diversity and structure have never been clearly investigated. Thus, this research aims to study the genetic diversity and structure of oca and mashua using the ISSR technique. The oca was studied at the species, morphotype, and varietal levels and a comparison of the germplasm maintained ex situ vs. in situ was carried out. For the mashua, as few accessions were available, the analysis was performed at the species level only. The analysis of the oca at the species level showed a relatively low level of genetic diversity and a genetic structure influenced by the collection site. The analysis of the morphotypes revealed that the morphotype constitutes an almost homogenous unit from a genetic point of view. All the oca varieties analysed showed a genetic and morphological variability, thus attesting that they are not pure clones. Finally, the comparison between both strategies of conservation indicated that the in situ germplasm has not evolved during the last decades. The analysis of the mashua revealed a moderate level of genetic diversity and a genetic structure influenced by the collection site. Its higher genetic variability compared to the oca was discussed in relation to their breeding system, cropping practices and specific uses. This research has provided valuable information on the genetic diversity and structure of oca and mashua. However, further investigations are necessary to guarantee the conservation of their genetic resources and to better comprehend the evolution of these species, which could be considered as genetic models of vegetatively propagated species since they have been influenced only by both natural and human selections.
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Citations
Pissard, A. (2008). Structure and genetic diversity of two Andean tuber crops, oca (Oxalis tuberosa Mol.) and mashua (Tropaeolum tuberosum R.&P.) : influence of the mode of conservation and of the agronomic and biological characteristics. https://hdl.handle.net/2078.5/98553