Chloroplast genome characteristics and phylogenetic analysis of Elytrigia elongata and Elymus trachycaulus

Although Elytrigia elongata and Elymus trachycaulus are plants of considerable ecological and forage significance, the highly similar morphological characteristics of these two species often present challenges with respect to species identification and phylogenetic analysis. In this study, to address the current deficiencies and disputes in this regard, we utilized the Illumina NovaSeq platform, a second-generation sequencing technology, to characterize the chloroplast genome sequences of these species. The genomes were assembled, annotated, and analyzed, and a phylogenetic tree was constructed using these sequences along with those of 17 other grass species. The findings revealed that the chloroplast genomes of E. elongata and E. trachycaulus are 135,040 and 135,052 bp in length, respectively, and have a typical circular tetrad structure. A total of 133 genes were annotated, among which there are 85 protein-coding, 39 tRNA, and eight rRNA genes, and one pseudogene, with a negligible difference in GC contents of 0.01%. In E. elongata, we identified 54 scattered repetitive sequences and 164 simple sequence repeat (SSR) loci, whereas in E. trachycaulus there are 53 scattered repetitive sequences and 162 SSR loci. In addition, the genomic regions of E. elongata and E. trachycaulus were found to be relatively conserved, showing no significant contractions or expansions, and the gene composition at each boundary is identical. Furthermore, the results of the phylogenetic analysis revealed close genetic relationships between E. trachycaulus and Elymus. sibiricus and Elymus pendulinus, and between Elytrigia elongata and Elytrigia bessarabica.