Mitogenome Assembly Reveals Gene Migration and RNA Editing Events in Plateau Hongliu (Myricaria elegans Royle.)

The Plateau Hongliu (Myricaria elegans Royle.) is a woody shrub halophyte that thrives in arid areas of western Tibet, in the Himalayan Mountains. It is acclaimed as superior in saline stress acclimation and as a critical pharmaceutical resource of the Tibetan traditional herb. Nevertheless, the mitogenome in the genus Myricaria remains unknown. Here, using the Illumina and PacBio sequencing assays, the first complete mitogenome of the M. elegans revealed a multi-branched skeleton with a total length of 416,354 bp and GC content of 44.33%, comprising two circular molecules (M1 and 2). The complete mitogenome annotates 31 unique protein-encoding genes (PEGs), fifteen tRNAs, and three rRNA genes. The UAA exhibits the most prominent codon usage preference as a termination, followed by UUA codons for leucine. The mitogenome contains 99 simple sequence repeats and 353 pairs of dispersed repeats, displaying the most frequent in palindromic repeats. Gene transfer analyses identified 8438 bp of 18 homologous fragments from the plastome, accounting for 2.03% of the total length. Using the PREP suite, 350 C-U RNA editing sites were predicted, of which nad4 and ccmB were on the top frequency. Syntenic and phylogenetic analyses suggested weakly conserved patterns of M. elegans in Caryophyllales owing to the genome rearrangement. In summary, the deciphered unique features and complexities of the mitogenome in M. elegans provide novel insights into understanding the evolution and biological conservation underlying climate resilience in halophytes.