Genetic diversity of subtropical double-haploid maize lines selected for high oil content

The inclusion of high-oil maize germplasm into breeding programs may be an excellent alternative for increasing grain nutritional quality. Knowing the germplasm genetic diversity is crucial for assisting breeding programs. Here, the genetic diversity and population structure of four high-oil-content maize (Zea mays L.) populations (Bajio yellow population [BYP], northwestern yellow population [NYP], Bajio white population [BWP], and northwestern white population [NWP]) were analyzed by Diversity Arrays Technology sequencing. Three-hundred ten double-haploid (DH) lines were genotyped, and 19,078 single-nucleotide polymorphism (SNP) markers were uniformly detected among populations after filtering by missing data >20% and minor allele frequency ≥0.05. Genetic diversity indexes showed polymorphic information content (PIC) values of 0.346, 0.352, 0.353, and 0.353; observed heterozygosity values of 0.221, 0.194, 0.284, and 0.177; and expected heterozygosity values of 0.188, 0.165, 0.219, and 0.152, for BYP, NYP, BWP, and NWP, respectively. Genetic structure results showed variations in pairwise genetic distance comparisons among the 310 DH lines, ranging from 0.119 to 0.385. Multidimensional scaling analysis and discriminant analysis of principal components grouped the DH lines into three different and five clusters, respectively, based on their origin region and grain color. On the other hand, STRUCTURE analysis revealed the presence of two different groups unrelated to grain color or origin region. The wide genetic variability among the analyzed DH lines highlights their potential to contribute new beneficial alleles into subtropical maize breeding programs and will facilitate the selection of parental lines and the identification of heterotic groups to generate high-oil maize hybrids.