Assembly and comparative analysis of the complete mitochondrial genome of Isopyrum anemonoides (Ranunculaceae).

Ranunculaceae is a large family of angiosperms comprising 2500 known species-a few with medicinal and ornamental values. Despite this, only two mitochondrial genomes (mitogenomes) of the family have been released in GenBank. Isopyrum anemonoides is a medicinal plant belonging to the family Ranunculaceae, and its chloroplast genome has recently been reported; however, its mitogenome remains unexplored. In this study, we assembled and analyzed the complete mitochondrial genome of I. anemonoides and performed a comparative analysis against different Ranunculaceae species, reconstructing the phylogenetic framework of Isopyrum. The circular mitogenome of I. anemonoides has a length of 206,722 bp, with a nucleotide composition of A (26.4%), T (26.4%), C (23.6%), and G (23.6%), and contains 62 genes, comprising 37 protein-coding genes (PCGs), 22 transfer RNA (tRNA) genes, and three ribosomal RNA (rRNA) genes. Abundantly interspersed repetitive and simple sequence repeat (SSR) loci were detected in the I. anemonoides mitogenome, with tetranucleotide repeats accounting for the highest proportion of SSRs. By detecting gene migration, we observed gene exchange between the chloroplast and mitogenome in I. anemonoides, including six intact tRNA genes, six PCG fragments, and fragments from two rRNA genes. Comparative mitogenome analysis of three Ranunculaceae species indicated that the PCG contents were conserved and the GC contents were similar. Selective pressure analysis revealed that only two genes (nad1 and rpl5) were under positive selection during their evolution in Ranunculales, and two specific RNA editing sites (atp6 and mttB) were detected in the I. anemonoides mitogenome. Moreover, a phylogenetic analysis based on the mitogenomes of I. anemonoides and the other 15 taxa accurately reflected the evolutionary and taxonomic status of I. anemonoides. Overall, this study provides new insights into the genetics, systematics, and evolution of mitochondrial evolution in Ranunculaceae, particularly I. anemonoides.

[Characteristics of the chloroplast genome of Isopyrum anemonoides].

In order to characterize the chloroplast genome and phylogenetic relationships of Isopyrum anemonoides, we performed Illumina Hiseq high-throughput sequencing to sequence the complete chloroplast genome of this plant and constructed a whole-genome map based on contig assembly and annotation. The chloroplast genome of I. anemonoides is 161 034 bp in length and has a typical tetrad structure, comprising 85 protein-coding genes, 37 tRNA genes, and 8 rRNA genes. The genome also contains a total of 44 dispersed repeat sequences and 47 simple sequence repeats. Among the genome's 53 678 codons, the largest proportion are leucine-encoding codons (5 251), whereas the smallest proportion encode tryptophan (712). Colinear analysis revealed an absence of inversions and rearrangements between I. anemonoides and related species at the chloroplast genome level. Whereas phylogenetic analysis indicated that I. anemonoides did not cluster in a clade with I. manshuricum, it did show a very close phylogenetic relationship with Paraquilegia microphylla. The findings of this study provide basic data that will contribute to further species identification and phylogenetic study of the genus Isopyrum.