Résumé
To what extent overdominance might contribute to the maintenance of genetic diversity within genomes is still an ongoing research question. Pseudo-overdominance – a particular case of overdominance – created by the complementation of deleterious alleles in heterozygotes has recently become a subject of particular interest. Simulations and theory suggest that pseudo-overdominance may occur in lowrecombining regions. We conducted a comprehensive investigation of low-recombining regions in cultivated populations of pearl millet, an outcrossing diploid African cereal. We studied seven large genomic regions ranging from 5 to 88 Mb. Six of these regions were pericentromeric. These regions exhibit an excess of heterozygotes, a distinctive hallmark of overdominance. They displayed a tendency towards a higher diversity and ratio of non-synonymous and deleterious variants. We conducted a comprehensive study of the largest 88 Mb region identified on chromosome 3. Interestingly, haplotypes of this region have been introgressed from wild relatives. We resequenced multiple genomes and confirmed their strong divergence and the presence of inversions across one of them. One of the haplotypes seemed highly deleterious in the homozygous state. A total of 17% of the cultivated pearl millet genome exhibits a local population structure suggestive of overdominance or possibly pseudo-overdominance. Our empirical results contribute to the accumulation of knowledge that will enhance our understanding of the potential role of overdominance or pseudo-overdominance in maintaining geneticdiversity, particularly in low recombining regions.