Agropyron cristatum (L.)
Gaertner, a perennial grass in the tribe Triticeae (Poaceae), is a wild
relative of cereal crops that is suitable for genetic improvement. In
this study, we first sequenced the complete chloroplast (cp) genome of Ag. cristatum using Hiseq4000 PE150. The Ag. cristatum chloroplast
genome is 135,554 bp in length, has a typical quadripartite structure
and contains 76 protein-coding genes, 29 tRNA genes and four rRNA genes.
The cp genome of Ag. cristatum was used for comparison with other seven Triticeae species. One large variable region (800 bp), which primarily contained the rpl23 (non-reciprocally translocated from IRs) and accD genes, was detected between rbcL gene and psaI gene within LSC region. The deletion of the accD and translocated rpl23 genes in Ag. cristatum indicated
an independent gene-loss events or an additional divergence in
Triticeae. Analyses of the dn/ds ratio and K2-P's genetic distance for
76 protein-coding genes showed that genes with evolutionary divergence
might suffer from the effect of sequence regional constraints or gene
functional constraints in Triticeae species. Our research will generally
contribute to the knowledge of plastid genome evolution in Triticeae.