Fig 1.
Genetic diversity analysis of SWF landraces.
Histogram of (a) allelic richness and (b) expected heterozygosity values estimated for each of the 194 landraces.
Fig 2.
Geographical representation of the 158 maize landraces from the South-West of France (36 landraces having no geographical coordinates were not plotted).
The districts of collection sites are represented with administrative numbers. Landraces for which pie-diagrams had both blue and cyan colors exhibited mixed genetic origins between E-SWF and W-SWF groups. The map was created using R software (libraries maps, plotrix, mapproj, devEMF).
Fig 3.
Spatial genetic structuration analysis of SWF landraces.
(a) Principal coordinate analysis on SNP data using Rogers ‘genetic distance matrix estimated among the 194 landraces. (b) Longitudinal and (c) latitudinal gradient analyses on SNP data of 158 landraces from South-West France using coordinates values on the first axis of PCoA analysis. SWF landraces were colored according to their assignation to E-SWF and W-SWF groups identified with admixture analysis at K = 2. (d) Isolation by distance (IBD) analysis of 158 landraces from South-West France using FST / (1- FST) matrix for genetic differentiation estimated following Rousset [32] and geographical distance matrix estimated for each pair of landraces. R = coefficient of correlation. *** = p-value<0.001.
Table 1.
Allelic richness (Ar) and gene diversity (expected heterozygosity, He) for the two SWF groups identified with admixture at K = 2 and the 7 genetic groups previously identified in Camus-Kulandaivelu et al. [10].
Table 2.
Negative values of f3-stat and Z-score on TreeMix 3-population test with E-SWF group as focus groups.
Fig 4.
PCA analysis on SNP data of 72 American maize landraces with 260 maize landraces from Europe and those of CBD as supplementary data.
Labels indicate landrace country of origins (see S2 Table). South-West France landraces were colored according to their admixture result at K = 2 allowing to distinguish East (in blue) and West South-West France (in cyan) genetic groups. The remaining American and European landraces were colored according to their genetic groups previously identified by Camus-Kulandaivelu et al. [10]: Corn Belt Dent in red, Caribbean in green, Northern Flint in yellow, Mexican in brown, Italian Flint in orange, Andean in magenta, Pyrenees_Galicia_2 in grey. The 9 landraces from South America and 2 landraces from Portugal studied by Mir et al (2017) were colored in black.
Fig 5.
Neighbor joining tree for the 342 populations obtained from Rogers distance matrix.
South-West France landraces were colored according to their admixture result at K = 2, allowing to distinguish East (in blue) and West South-West France (in cyan) genetic groups. The remaining American and European landraces were colored according to their genetic groups previously identified by Camus-Kulandaivelu et al. [10]: Corn Belt Dent in red, Caribbean in green, Northern Flint in yellow, Mexican in brown, Italian Flint in orange, Andean in magenta, Pyrenees_Galicia_2 in grey. The 9 landraces from South America and 2 landraces from Portugal studied by Mir et al (2017) were colored in black. SWF landraces assigned to the 3 other groups identified with our ADMIXTURE analysis on SNP data of 194 SWF landraces at K = 5 were represented with star symbols in blue and cyan. The European Northern Flint landraces (NFE) were represented by an @ symbol in yellow.