High-Quality Draft Genome Assemblies and Comparative Genomics of Three Bouteloua Species (Poaceae: Chloridoideae)

Abstract

Bouteloua is a PACMAD grass genus that dominates much of the central and southern North American prairies and plains, where species such as sideoats grama (B. curtipendula), blue grama (B. gracilis), and black grama (B. eriopoda) are both ecologically dominant and among the most valuable forage grasses of arid rangelands. Yet, genomic resources for the genus remain limited. We generated PacBio HiFi draft assemblies for B. curtipendula (653 Mb, N50 25.5 Mb), B. gracilis (808 Mb, N50 4.1 Mb), and B. eriopoda (1.67 Gb, N50 1.0 Mb). All assemblies showed >98.5% BUSCO completeness. Helixer predicted 83,877-215,536 gene models per assembly. However, syntenic copy numbers (2 in B. curtipendula, 3 in B. gracilis, and 6 in B. eriopoda) indicate that at least two species are polyploid, and the inflated gene model counts likely reflect homeologous copies and fragmented predictions rather than true gene numbers. panEDTA identified 25-40% transposable-element content, dominated by LTR retrotransposons. These assemblies provide foundational genomic references for Bouteloua and support comparative studies across PACMAD grasses.