Deciphering the complete mitochondrial genome of Halogeton glomeratus structural features and RNA editing events

Halogeton glomeratus, a halophytic species in the Amaranthaceae family, is well adapted to extreme saline-alkaline environments. To better understand its adaptive mechanisms at the genomic level, we assembled and analyzed the complete mitochondrial genome (mitogenome) of H. glomeratus. The genomic DNA was extracted and libraries were constructed for Illumina short-read and Oxford Nanopore long-read sequencing. The mitogenome was assembled using a hybrid strategy combining GetOrganelle, PMAT, and Unicycler, with gene annotation performed via CPGAVAS2, CPGView, and the PMGA web server. The final assembly revealed a multipartite mitogenome comprising three chromosomes: two circular chromosomes (168,414 bp and 144,793 bp) and one additional chromosome (19,991 bp) treated as linear in this analysis, although alternative configurations may exist. Twelve mitochondrial plastid DNA (MTPT) sequences were identified, accounting for 0.75 % of the mitogenome, with considerable variation in sequence length and composition compared to related species. Phylogenetic analysis based on 35 mitogenomes confirmed the evolutionary position of H. glomeratus within Amaranthaceae. Furthermore, 354 RNA editing sites were identified in 28 protein-coding genes (PCGs), and 136 editing sites were detected in 35 distinct open reading frames (ORFs), including events that generated novel start and stop codons. The H. glomeratus mitogenome exhibits complex structural organization and inter-organellar sequence migration. These findings offer valuable insights into mitochondrial genome evolution and may contribute to understanding the molecular mechanisms underlying halophyte adaptation.