Characterization of the complete chloroplast genome sequence of Elaeagnus henryi Warb. ex Diels (Elaeagnaceae)

Decoding the mitogenome of rosemary (Salvia rosmarinus): insights into genome evolution, structural dynamics and prospects for mitochondrial engineering

BACKGROUND

Rosemary (Salvia rosmarinus), an aromatic evergreen shrub of the Salvia (Lamiaceae), is native to the Mediterranean region, thriving in rocky or arid soils. Widely used in food, pharmaceuticals, and cosmetics, its clonal reproduction poses significant challenges for breeding and germplasm innovation. While mitogenome engineering holds promise for introducing heritable mutations, incomplete mitogenome information for rosemary has hindered such efforts. This study addresses this gap by assembling and analyzing the complete mitogenome of S. rosmarinus, focusing on its structure, repetitive sequences, RNA editing events, intracellular gene transfer (IGT), and phylogenetic relationships.

RESULTS

The S. rosmarinus mitogenome spans 384,113 bp with a GC content of 44.8%, containing 34 unique protein-coding genes and 114 simple sequence repeats. Comparative analysis revealed 28 homologous segments shared between the mitogenome and plastome, totaling 18,675 bp in length. Furthermore, homologous fragments between nuclear and organellar genomes were identified, including 1,069,255 bp of organelle-derived sequences in the nuclear genome, with 194,689 bp from nuclear plastid DNA transfers (NUPTs) and 15,192 bp from nuclear mitochondrial DNA transfers (NUMTs). NUPTs were more abundant and contributed more significantly to the total length. Synteny analysis of eight Lamiales species revealed extensive mitogenomic recombination and structural rearrangements. These findings highlight the dynamic nature of mitogenomes, offering insights into genome evolution and supporting future breeding programs to enhance the genetic diversity and adaptability of S. rosmarinus.

CONCLUSIONS

This study provides the first complete mitogenome of S. rosmarinus, revealing dispersed repeats, RNA editing, and horizontal gene transfer between the nuclear and organelle genomes. The mitogenome exhibits a typical circular structure with evidence of frequent recombination, providing valuable insights into Salvia mitochondrial genetics, genome evolution, and molecular biology.

Comprehensive Chloroplast Genomic Insights into Amaranthus: Resolving the Phylogenetic and Taxonomic Status of A. powellii and A. bouchonii

Amaranthus, a genus in Amaranthaceae, is divided into three subgenera-Amaranthus, Acnida, and Albersia-and contains approximately 70 to 80 species. Understanding its phylogenetic relationships is essential for species classification, genetic diversity assessment, and evolutionary studies. This knowledge is vital for improving Amaranthus utilization in crop improvement and managing the ecological impacts of invasive weeds. In this study, we analyzed the chloroplast genomes of 27 Amaranthus species across all three subgenera to characterize their genomic features and construct a comprehensive phylogenetic tree. Our aim was to elucidate the phylogenetic relationships within the genus and evaluate interspecific affinities among the subgenera. We also addressed the taxonomic ambiguity surrounding A. bouchonii and A. powellii to determine their distinct species within the genus. Chloroplast genome sizes ranged from 149,949 to 150,818 bp, with GC content varying between 36.52% and 36.63%. Comparative structural analyses confirmed highly conserved quadripartite structures, gene content, and organization, comprising 87 protein-coding genes, 37 tRNAs, and 8 rRNAs. Repeat and codon usage analyses revealed conserved repeat patterns and a preference for codons ending in A or U. Selection pressure analysis indicated a predominantly purifying selection, with matK showing signs of positive selection, particularly in A. spinosus. Phylogenetic analysis of 80 protein-coding genes confirmed the monophyly of subgenus Amaranthus but found Alberisa and Acnida to be paraphyletic. Despite their morphological similarity, A. bouchonii and A. powellii were placed in separate clades within subgenus Amaranthus, with A. bouchonii clustering with A. retroflexus, and A. powellii aligning with the A. hybridus complex. Additionally, we identified 16 variable regions as potential molecular markers for species identification. Our study provides the most comprehensive Amaranthus chloroplast genome dataset to date, offering new insights into its evolutionary relationships and valuable genomic resources for taxonomy, germplasm management, and invasive risk assessment.

The complete chloroplast genome and phylogenetic analysis of Elaeagnus oldhamii (Elaeagnaceae) from Fujian, southeastern China

Elaeagnus oldhamii Maximowicz 1870 is an important medicinal plant mainly distributing in the southeastern coastal region of China. However, the complete chloroplast genome of E. oldhamii has never been studied at present. We obtained the complete chloroplast genome of E. oldhamii, which was 152,283 bp in length, with a typical quadripartite structure that includes a large single-copy region of 82,229 bp, a small single-copy region of 18,256 bp, and 2 inverted repeat (IR) regions of 25,899 bp. The genome contained 128 unique genes with a GC content of 37%, including 83 protein-coding genes, 37 tRNAs, and 8 rRNAs. Phylogenetic analysis suggested that E. oldhamii was closely related to E. glabra and E. macrophylla.

Deciphering the Plastomic Code of Chinese Hog-Peanut (Amphicarpaea edgeworthii Benth., Leguminosae): Comparative Genomics and Evolutionary Insights within the Phaseoleae Tribe

The classification and phylogenetic relationships within the Phaseoleae tribe (Leguminosae) have consistently posed challenges to botanists. This study addresses these taxonomic intricacies, with a specific focus on the Glycininae subtribe, by conducting a comprehensive analysis of the highly conserved plastome in Amphicarpaea edgeworthii Benth., a critical species within this subtribe. Through meticulous genomic sequencing, we identified a plastome size of 148,650 bp, composed of 128 genes, including 84 protein-coding genes, 36 tRNA genes, and 8 rRNA genes. Comparative genomic analysis across seven Glycininae species illuminated a universally conserved circular and quadripartite structure, with nine genes exhibiting notable nucleotide diversity, signifying a remarkable genomic variability. Phylogenetic reconstruction of 35 Phaseoleae species underscores the affinity of Amphicarpaea with Glycine, placing Apios as a sister lineage to all other Phaseoleae species, excluding Clitorinae and Diocleinae subtribes. Intriguingly, Apios, Butea, Erythrina, and Spatholobus, traditionally clumped together in the Erythrininae subtribe, display paraphyletic divergence, thereby contesting their taxonomic coherence. The pronounced structural differences in the quadripartite boundary genes among taxa with unresolved subtribal affiliations demand a reevaluation of Erythrininae's taxonomic classification, potentially refining the phylogenetic contours of the tribe.