Characterization and Phylogenetic Analysis of the Complete Chloroplast Genome of Koeleria Macrantha

Koeleria is a genus of great ecological and economic importance in the tribe Poeae. The taxonomy of Koeleria has long been recognized as problematic due to its remarkable morphological plasticity, simplicity of the morphological structures, and overall taxonomic similarity. To address this issue, the complete chloroplast (cp) genome of Koeleria macrantha was sequenced, assembled, and compared to previously sequenced Koeleria species (Koeleria nitidula and Koeleria glauca) and closely related other Poeae species. The K. macrantha whole cp genome was 136,065 bp in length and had a typical quadripartite structure comprising a large single copy (LSC; 80,203 bp), a small single copy (SSC; 12,592 bp), and a pair of inverted repeats (IRs; 21,635 bp). The genome consisted of 129 genes, including 83 protein-coding genes, 38 transfer RNA genes, and 8 ribosomal RNA genes. A total of 44 simple sequence repeats (SSRs) were detected. The highest nucleotide variability among Koeleria was observed in the trnP-psaJ region with the Pi value > 0.025. Moreover, the coding regions were found to be more conserved than non-coding regions. Phylogenetic analysis revealed that Koeleria is monophyletic and that K. macrantha is sister Koeleria nitidula and Koeleria glauca. Overall, the complete cp genome sequence of K. macrantha will provide a solid foundation for future phylogenetic studies, as well as for the analysis of the evolution of Koeleria species.