Premise of the study: The amaranth genus contains many important grain and weedy species. We further our understanding of the genus through the development of a complete reference chloroplast genome.
Methods and results: A high-quality Amaranthus hypochondriacus (Amaranthaceae) chloroplast genome assembly was developed using long-read technology. This reference genome was used to reconstruct the chloroplast genomes for two closely related grain species (A. cruentus and A. caudatus) and their putative progenitor (A. hybridus). The reference genome was 150,518 bp and possesses a circular structure of two inverted repeats (24,352 bp) separated by small (17,941 bp) and large (83,873 bp) single-copy regions; it encodes 111 genes, 72 for proteins. Relative to the reference chloroplast genome, an average of 210 single-nucleotide polymorphisms (SNPs) and 122 insertion/deletion polymorphisms (indels) were identified across the analyzed genomes.
Conclusions: This reference chloroplast genome, along with the reported simple sequence repeats, SNPs, and indels, is an invaluable genetic resource for studying the phylogeny and genetic diversity within the amaranth genus.
Keywords: Amaranthaceae; Amaranthus hypochondriacus; chloroplast genome; grain amaranths; next-generation sequencing; pigweed.