Complete mitochondrial genome assembly and analysis of Astragalus (Papilionoideae: Fabaceae) species revealed its RNA...

Astragalus (Fabaceae), the largest genus of flowering plants with its phytogeographic center in Southwest Asia, is ecologically and medicinally vital, as high-quality forage and a source of traditional medicine. However, its ambiguous morphological traits hinder taxonomic clarity, prompting increased reliance on molecular phylogenetic approaches to resolve relationships.

In the research, we assembled and annotated mitochondrial genomes of three Astragalus species, integrating them with two published mitochondrial genomes for comparative analysis. Newly sequenced genomes (269,019-364,431 bp) encoded 55-59 genes (31-34 protein-coding, 22-25 tRNAs, 3 rRNAs). Comparative analysis identified four genes (cox2, rps4, atp8, rps12) with high nucleotide variability, establishing them as reliable molecular markers for Astragalus phylogenetics, critical for future taxonomic and evolutionary studies. Mitochondrial plastid sequences were widespread across all five species, with petG and trnW-CCA conserved as chloroplast-derived fragments. Phylogenetic trees based on concatenated mitochondrial genes revealed Astragalus species shared close affinities with A. cicer and A.laxmanii, refining subgeneric classification frameworks.

Our study confirms mitochondrial genomes as powerful tools for resolving relationships in morphologically cryptic genera. The novel genomic resources, including repeats and RNA editing sites, and validated markers, lay a foundation for future research into Astragalus biogeography, adaptive evolution, and medicinal resource development-thereby, enhancing the genus' ecological and economic value.