Etude de la diversité génétique du maïs en Europe : analyse d'ADN ancien à partir d'échantillons d'herbier et confrontation avec l'analyse moléculaire à grande échelle de collections de populations

European maize was introduced from Central America in the South of Europe at the end of the 15th century, and from Northern America in the North of Europe following the expeditions of the early 16th century. In order to better understand its later history in Europe, we compared the genetic diversity of European maize in the 19th century and the first half of the 20th century, represented by plants collected in an ancient herbarium, with the diversity of American and European maize populations collected around 50 years ago and maintained as living samples in collections. Samples were obtained from the herbarium of Paris (MNHN). Fractions of leaves or spikelets (from 2 to 37 mg) were collected from 17 plates. Samples are 138 years old in average (from the second half of the 18th century to 1949). They originated from all over France, with half in the Paris basin. DNA was successfully extracted from leave or spikelet fragments, using the Kit Qiagen® method. Precautions were taken to avoid contamination with foreign DNA. A total of 80 μl of DNA was obtained per sample. DNA samples were analysed with 14 nuclear mocrosatellite markers, ten of them displaying a tetra nucleotidic motive. From 4 to 14 markers could be analysed per sample.