Diversity of maize landraces from south-west of France: origin and morphological differentiation analyzes

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Diaw, Yacine | Tollon-Cordet, Christine | Zanetto, Anne | Charcosset, Alain | David, Jacques | Ronfort, Joelle | Gouesnard, Brigitte

Edité par CCSD -

International audience. In south-west of France, maize landraces had evolved under environmental condition and human management since 17th century and until the arrival of the hybrids in1960s. In the sixties, these landraces have been conserved ex situ at the maize biological resource center (INRA, Mauguio, France). Previous genetic studies of a sample of this collection allowed identifying a distinct genetic group named Pyrenees-Galicia. This group has been hypothesized to come from an hybridization between the Northern Flint group and the Caribbean group In this study, we analysed a broader sample of the INRA collection in order to determine their genetic structure and to describe their morphological diversity. Firstly, we analysed genetic diversity of 194 maize landraces from south-west of France with the 50K SNPs array and using a bulk DNA sample of 15 plants. A non-supervised admixture analysis was performed by adding 148 American and European landraces. This analysis shown that there were 8 genetic groups. In fact, two separate genetic groups were identified in South-west of France, one in the Western part and one in the Eastern part. Secondly, we assessed morphological differentiation between the two genetic groups found in south-west of France, using a principal component analysis and an analysis of variance on 15 traits. Landraces located in West part of south-western France are earlier with bigger kernels and ears with a lower number of rows than landraces located in East part. Finally, we performed a principal coordinate analysis (PCoA) on 194 maize landraces from south-west of France. We showed that landraces were distributed continuously along the first component of PCoA analysis. This component was correlated with geographical coordinates of the landrace collection sites, highlighting a longitudinal gradient and a latitudinal gradient.

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