DISSERTATION RESEARCH: Origins and Evolution of Oxalis Tuberosa, a Polyploid Domesticate

9623227道尔块茎作物紫花苜蓿，或“OCA”，在印加时代之前很久就在南美洲的安第斯地区被驯化了。它具有广泛种植的潜力，但与另一种安第斯土豆不同的是，Oca在世界其他地方仍然鲜为人知。OCA是土豆、玉米和小麦等多种多倍体作物中的一员，在这种情况下，它们有八组染色体(大多数动植物有两组染色体)。Oca的起源可以通过鉴定其在野生物种中的近亲以及通过确定其八组染色体的来源来更准确地评估。额外的染色体组可能是在驯化过程中产生的，要么是单个祖先物种中存在的染色体的重复，要么是两个或更多祖先物种之间的杂交。在这项研究中，伊芙·埃姆什威勒在杰弗里·道尔的指导下，将利用DNA序列、染色体数量以及植物的形态和解剖学证据来确定OCA及其野生近亲之间的系统发育关系。特别是，研究人员将确定最近在玻利维亚发现的野生含块茎紫花苜蓿物种是否代表OCA的祖先(S)。对种植的OCA及其近缘物种遗传多样性分布的了解将有助于了解驯化的地理起源和历史。这项研究的结果将为保护该作物及其野生近亲的生物多样性提供至关重要的信息，并将为一项相关的民族植物学研究提供信息，该研究正在调查人类对该作物遗传变异性的影响。

9623227 DOYLE The tuber crop Oxalis tuberosa, or "oca", was domesticated in the Andes region of South America long before Inca times. It has the potential for widespread cultivation, but unlike the potato, another Andean native, oca is still little known in the rest of the world. Oca is among the many crops, such as potatoes, maize and wheat, that are polyploid, in this case with eight sets of chromosomes (most plants and animals have two sets). The origins of oca can be more accurately evaluated by identifying its closest relatives among wild species of Oxalis, and by determining the origin of its eight sets of chromosomes. The extra chromosome sets may have arisen during domestication, either by duplication of those present in a single progenitor species or by hybridization among two or more progenitors. In this study, Eve Emshwiller, under the direction of Jeffrey Doyle, will use evidence from DNA sequences, chromosome number, and the form and anatomy of the plants to determine the phylogenetic relationships among oca and its wild relatives. In particular, the researchers will determine if wild tuber-bearing Oxalis species, recently discovered in Bolivia, represent the progenitor(s) of oca. Knowledge of the distribution of genetic diversity in cultivated oca and its relatives will shed light on the geographic origins and history of domestication. The results of the study will provide information crucial for efforts to conserve the biodiversity of the crop and its wild relatives, and will inform a related ethnobotanical study that is investigating human influences on the genetic variability of the crop.