First results on diversity patterns and selective sweeps in a Southeast European panel of maize inbred lines as combined with two West European panels

Abstract

More than one third of European grain maize is produced in South Eastearn Europe (SEE) and utilization of historical maize material developed in SEE for its favorable alleles and diversity has long been speculated. However, molecular diversity of the SEE maize genetic material is scarce. The objectives of this study were i) to analyze diversity patterns in a large panel of densely genotyped historical accessions from SEE, ii) to compare the data with those obtained from other two European panels, and iii) to identify genomic regions that have undergone selection (selective sweeps) in response to adaptation to SEE conditions. 572 accessions of the historical inbred lines from Maize Research Institute Zemun Polje representing the SEE material were genotyped using the 600k maize genotyping Axiom array. The genotyping results were merged with two European panels DROPS and TUM. Genetic structure and diversity were analyzed using neighbor-joining cladogram, PcoA, Admixture, Structure and sNMF. To detect the selective sweep signals, Tajimas D statistic and RAiSD were employed. The best number of ancestral populations was K=7, whereby one of them is a subpopulation containing inbreds belong exclusively to the SEE panel. The prevalence of inbreds linked to historical US inbred lines Wf9, Oh43, Pa91 and A374 was detected in SEE. Possible soft selective sweep was detected in chromosome 2 in region harboring a gene linked to promotion of flowering FPF1. Additional scan for selective sweeps using the RAiSD methodology yielded four signals in chromosomes 5 and 6, all in gene-rich regions. Several candidates of selection were identified, influencing the plant morphology and adaptation. Our study provides the first step towards the utilization of the SEE genetic materials for use in maize breeding. Phenotypic analysis is needed for assessment of SEE accessions for favorable alleles, and identification of breeding targets.