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Weigela Thunb. is a genus in the family Caprifoliaceae. All species in this genus have high ornamental and medicinal value. However, the genetic divergence between species and the phylogeny within Weigela is still unclear. Therefore, we sequenced and analyzed four plastomes from four different Weigela species to reveal the genetic divergence among species of this genus, and the phylogeny within Weigela. The four plastomes from Weigela ranged from 156,909 bp to 157,739 bp in size, and presented a typical circular quadripartite structure. Each complete plastome contained a pair of inverted repeat regions (23,592~24,957 bp), a larger single-copy (LSC) region (89,922~90,229 bp), and a small single-copy (SSC) region (17,668~20,429 bp). We identified three types of repeats, corresponding to 268 forward repeats, 128 palindromic repeats, and 867 tandem repeats, for a total of 1,263 long repeats. A total of 352 SSRs were identified from the four plastomes, and most of them were concentrated in the LSC region and the noncoding regions. Mononucleotide repeat units were the most frequently detected types of repeats, of which A/T repeat units were the most abundant. Three mutational hotspots (trnH-psbA , trnR-ndhF , and trnN-ndhF) were identified as candidate barcodes for Weigela species. Weigela belongs to Diervilloideae located at an early diverging position in the Caprifoliaceae. Within Weigela , W. japonica and W. floribunda were sister with W. subsessilis and W. florida. This study revealed the plastome structure and variation of four well-known Weigela species, and found three candidate barcodes for further study of four well-known Weigela species. In addition, the phylogenetic location of Weigela within the Caprifoliaceae was identified. [ABSTRACT FROM AUTHOR]

Caragana sensu lato (s.l.) includes approximately 100 species that are mainly distributed in arid and semi-arid regions. Caragana species are ecologically valuable for their roles in windbreaking and sand fixation. However, the taxonomy and phylogenetic relationships of the genus Caragana are still unclear. In this study, we sequenced and assembled the chloroplast genomes of representative species of Caragana and reconstructed robust phylogenetic relationships at the section level. The Caragana chloroplast genome has lost the inverted repeat region and wascategorized in the inverted repeat loss clade (IRLC). The chloroplast genomes of the eight species ranged from 128,458 bp to 135,401 bp and contained 110 unique genes. All the Caragana chloroplast genomes have a highly conserved structure and gene order. The number of long repeats and simple sequence repeats (SSRs) showed significant variation among the eight species, indicating heterogeneous evolution in Caragana. Selective pressure analysis of the genes revealed that most of the protein-coding genes evolved under purifying selection. The phylogenetic analyses indicated that each section forms a clade, except the section Spinosae, which was divided into two clades. This study elucidated the evolution of the chloroplast genome within the widely distributed genus Caragana. The detailed information obtained from this study can serve as a valuable resource for understanding the molecular dynamics and phylogenetic relationships within Caragana. [ABSTRACT FROM AUTHOR]