Comparative Analysis of Chromosome Repeat DNA Patterns in Four Amaranthus Species

Amaranthus L. includes valuable and promising crops of multi-purpose use, having high morphological diversity and complicated taxonomy. Their karyotypes and genomic relationships remain insufficiently studied. For the first time, a comparative repeatome analysis of Amaranthus tricolor L., Amaranthus cruentus L., and Amaranthus hypochondriacus L. was performed based on the high-throughput sequencing data obtained via bioinformatic analyses using the RepeatExplorer2/TAREAN/DANTE_LTR pipelines. Interspecific variations in the abundance of Ty1 Copia and Ty3 Gypsy retroelements, DNA transposons, and ribosomal and satellite DNA (satDNA) were detected. Based on fluorescence in situ hybridization (FISH), chromosome mapping of 45S rDNA, 5S rDNA, and satDNAs AmC9 and AmC70, and unique karyograms of A. tricolor, A. cruentus, Amaranthus paniculatus L., and A. hypochondriacus were constructed. The analysis of the interspecies genome diversity/similarity in DNA repeat contents, sequences of the identified satDNAs, and chromosome distribution patterns of the studied molecular markers indicated that these species might also share a common evolutionary ancestor. However, the genomes of A. cruentus, A. paniculatus, and A. hypochondriacus were more similar compared to A. tricolor, which aligns with the previous phylogenetic data. Our results demonstrate that cytogenomic studies might provide important data on Amaranthus species relationships elucidating taxonomy and evolution of these valuable crops.