Genetic structure and north-south decrease of genetic diversity in the Patagonian maqui berry (Aristotelia chilensis [Molina] Stuntz) determined by SSR marker analysis

Maqui (Aristotelia chilensis [Molina] Stuntz) is a small endemic Patagonian tree that is currently being domesticated actively because of its edible berries, which have extremely high polyphenol content and anti-oxidant capability. Maqui can be easily propagated and is an efficient colonizer of deforested habitats to the point of often becoming an invasive species. However, little is known about its population structure and evolutionary history, limiting the design of conservation and domestication strategies. Genetic diversity of 14 populations (183 samples) from throughout the geographic distribution of the species in Chile was assessed with 13 polymorphic microsatellite markers. Samples were assigned to clusters based on Bayesian genetic and spatial structure analyses and the results were used to reconstruct patterns of phylogeographic and demographic history. We found that maqui populations are well-structured, with a dramatic reduction of genetic diversity from north to south, most notably in areas that were covered by ice during the quaternary glaciation. Three main genetic groups were revealed by Structure analysis. In conclusion, a clear pattern of genetic diversity reduction from its northern limit in central Chile to the Patagonian region was revealed, suggesting that an active recolonization process took place during the last few millennia following the last glacial period. These results will help to define the identification of accessions from different regions and contribute to support conservation and domestication initiatives.