Complete mitochondrial genome assembly and structural feature analysis of Thinopyrum elongatum (Poaceae)

To our knowledge, this study analyzed, for the first time, the mitogenome characteristics of Thinopyrum elongatum, including the identification of repetitive sequences in the mitogenome, RNA site editing, KaKs, and Pi and phylogenetic analysis. Thinopyrum elongatum is a perennial forage and ecological grass widely used in improving food crops and remediating saline-alkali soils in China owing to its characteristics, such as drought and waterlogging tolerance, salt-alkali resistance, and high yield with superior quality. Herein, we sequenced, annotated, and assembled the complete mitogenome of T. elongatum to understand its genetic diversity and phylogenetic relationships. The mitogenome length and GC content of T. elongatum are 390,404 bp and 44.38%, respectively. The mitogenome was annotated to contain 33 protein-coding genes (PCGs), 8 ribosomal RNA genes, 21 transfer RNA genes, and 2 pseudogenes. Codon use bias analysis revealed that T. elongatum preferentially used leucine (Leu), followed by serine (Ser) and arginine (Arg), respectively. Tryptophan (Trp) and methionine (Met) were the least frequently used. Among the 30 mitogenomic PCGs analyzed, 304 RNA editing sites were identified; among them, nad2 and ccmFn have been edited more frequently with 29 and 24 edits, respectively, confirming C-to-T RNA editing. Phylogenetic analysis indicated that T. elongatum and T. obtusiflorum were the most closely related species within the Thinopyrum genus, a conclusion supported by a phylogenetic tree constructed from 35 plant species. Moreover, genomic information from organelles can provide insights into plant phylogenies. The results of this study provide valuable data support for the subsequent in-depth analysis of the genome of T. elongatum. At the same time, it provides an important reference for exploring the mechanism of genetic variation, evolutionary history, and molecular breeding strategy of the genus Thinopyrum.