Repeatome Diversity in Argentine Native Maize Landraces

Northern Argentina represents one of the southernmost regions where native maize landraces are cultivated. These landraces constitute an important reservoir of genetic diversity and have long been recognized for their agronomic, taxonomic, and cytogenetic value. In Argentine maize, genome size ranges from 4.4 to 6.9 pg, with this variation being largely explained by differences in the abundance of repetitive DNA, including heterochromatic knobs, ribosomal DNA, centromeric repeats, and transposable elements. In this study, nine accessions representing native maize landraces from northern Argentina and the reference inbred line B73 were analyzed by integrating fluorescence in situ hybridization (FISH) and repeatome analyses based on low-coverage whole-genome sequencing. FISH was performed using probes specific for the 180-bp knob repeat, TR-1 knob repeat, CentC centromeric repeat, and 5S and 45S ribosomal DNA sequences. The genomic abundance of these repetitive DNA families was estimated by BLAST searches against consensus reference sequences, followed by normalization of repeat counts to allow comparisons among accessions. FISH analyses revealed differential chromosomal distribution patterns of satellite DNA among landraces, whereas repeatome analysis identified substantial variation in the composition and abundance of repetitive DNA families. Integrating cytogenetic and genomic data enabled the characterization of cytogenomic diversity among the studied landraces and provided new insights into the genetic diversity of native maize from northern Argentina.