Phylogenetic relationships and genetic diversity of Tunisian maize landraces

Abstract

Based on history, maize was first introduced into Tunisia and northern Africa, at large, from the south of Spain. Several subsequent introductions were made from diverse origins, generating new landraces by recombination and selection for adaptation to arid environments. This study aimed to investigate the phylogenetic relationships among Tunisian maize landraces with possible sources of introduction from neighboring countries. Ten Tunisian landraces were genotyped with 23656SNPs along with a panel of diversity of 171 landraces originating from Algeria, Europe, and America. The Tunisian maize landraces were very diverse and distinct from those from neighboring countries, and they were classified into three main clusters that could be the basis for investigating heterotic groups. The phylogenetic relationships among Tunisian and other landraces from neighboring countries supported the hypothesis of a first introduction from the south of Spain and subsequent introductions from other countries. These germplasm groups could be the basis for studying heterotic patterns and sample maize germplasm from Tunisia and North Africa in general. The Tunisian maize germplasm could be a basis for identifying sources of favorable alleles to improve tolerance to abiotic stresses.

Fig 1. Principal Coordinate Analysis (PCoA) of the genetic diversity among of 191 populations from Europe, America and North Africa based on their modified Roger’s distance (MRD).

Fig 2. Dendrogram of 191 maize populations from nine origins, namely Northern Flint, Corn Belt Dent, Mexican, Andean, Caribbean, Atlantic European coast (Pyrenean-Galicia), Mediterranean (Italian flint), Algeria and Tunisia, made by neighbor joining using the modified Roger’s distance (MRD).

Fig 3. Dendrogram of 15 landraces from Algerian and 10 from Tunisian, made by neighbor joining based on their modified Roger’s distance.

Fig 4. Spatial genetic structuration of North Africa Mediterranean maize and ten Tunisian maize landraces compared to European maize landrace from Mediterranean countries.