Genetic properties of 240 maize inbred lines and identity-by-descent segments revealed by high-density SNP markers

Characterization of the genetic properties of maize inbred lines is beneficial not only for increasing knowledge of genetic diversity, but also for maize breeding. In the present study, a panel of 240 maize inbred lines commonly used in China, including three foundation parents Dan340, Mo17, and Huangzao4, and their derivatives, was genotyped using the MaizeSNP50 BeadChip, which contains 56,110 single-nucleotide polymorphism (SNP) markers. As a result, 40,757 SNPs with unique physical positions were successfully recalled in this panel with an average coverage of 50 kb per SNP. Five subgroups including Lan, LRC, PB, Reid, and SPT were inferred using 4000 SNPs with minor allele frequency ≥0.200, a result that was largely consistent with the pedigree information for these 240 inbred lines. With a cutoff value of r 2 < 0.100, linkage disequilibrium (LD) decay distances along the ten chromosomes of maize ranged from 397 to 819 kb, with an average of 643 kb. A subtotal of 26, 35, and 23 identity-by-descent segments, which were longer than both the average LD decay distance on the corresponding chromosomes and the local LD decay distance of r 2 < 0.100, were identified in the Dan340, Huangzao4, and Mo17 derivatives, respectively. Three lower peaks for Tajima’s D overlapped with three major quantitative trait loci (qkrn7, scmv1, and qHS2.09) in these derivatives. Elucidating the genetic properties of this panel provides information for investigating the genetic architecture of agronomic traits and heterotic grouping during maize breeding.