Background Impatiens L. is a genus of complex taxonomy that belongs to the family Balsaminaceae (Ericales) and contains approximately 1000 species. The genus is well known for its economic, medicinal, ornamental, and horticultural value. However, knowledge about its germplasm identification, molecular phylogeny, and chloroplast genomics is limited, and taxonomic uncertainties still exist due to overlapping morphological features and insufficient genomic resources. Results We sequenced the chloroplast genomes of six different species (Impatiens chlorosepala, Impatiens fanjingshanica, Impatiens guizhouensis, Impatiens linearisepala, Impatiens loulanensis, and Impatiens stenosepala) in the karst area of China and compared them with those of six previously published Balsaminaceae species. We contrasted genomic features and repeat sequences, assessed sequence divergence and constructed phylogenetic relationships. Except for those of I. alpicola, I. pritzelii and I. glandulifera, the complete chloroplast genomes ranging in size from 151,366 bp (I. alpicola) to 154,189 bp (Hydrocera triflora) encoded 115 distinct genes [81 protein-coding, 30 transfer RNA (tRNA), and 4 ribosomal RNA (rRNA) genes]. Moreover, the characteristics of the long repeat sequences and simple sequence repeats (SSRs) were determined. psbK-psbI, trnT-GGU-psbD, rpl36-rps8, rpoB-trnC-GCA, trnK-UUU-rps16, trnQ-UUG, trnP-UGG-psaJ, trnT-UGU-trnL-UAA, and ycf4-cemA were identified as divergence hotspot regions and thus might be suitable for species identification and phylogenetic studies. Additionally, the phylogenetic relationships based on Maximum likelihood (ML) and Bayesian inference (BI) of the whole chloroplast genomes showed that the chloroplast genome structure of I. guizhouensis represents the ancestral state of the Balsaminaceae family. Conclusion Our study provided detailed information about nucleotide diversity hotspots and the types of repeats, which can be used to develop molecular markers applicable to Balsaminaceae species. We also reconstructed and analyzed the relationships of some Impatiens species and assessed their taxonomic statuses based on the complete chloroplast genomes. Together, the findings of the current study might provide valuable genomic resources for systematic evolution of the Balsaminaceae species.

The complete chloroplast genome sequence of Impatiens uliginosa Franch., an endemic species in Southwest China, we research genetic and phylogenetic relationship with other species in an effort to provide genomic resources useful for promoting its conservation and utilization. The total chloroplast genome size of I. uliginosa is 152,609 bp, with a typical quadripartite structure including a pair of inverted repeat (IRs, 25,871 bp) regions separated by a small single copy (SSC, 17,502 bp) region and a large single copy (LSC, 83,365 bp) region. The overall GC content of I. uliginosa plastid genome was 36.8%. The whole chloroplast genome contains 136 genes, including 89 protein-coding genes (PCGs), 38 transfer RNA genes (tRNAs), and 8 ribosomal RNA genes (rRNAs). Among these genes, 15 genes have one intron and 2 genes contain two introns. To investigate the evolution status, the phylogenetic tree based on APG III from 12 complete chloroplast plastomes of Ericales supports close relationships. According to the phylogenetic topologies, I. uliginosa was closely related to I. piufanensis.

Background: Impatiens, a controversial and complex genus, which belongs to the family Balsaminaceae with approximately 1000 species. The genus is well known for economical, medicinal, ornamental, and horticultural values. However, Due to the morphological features and insufficient genomic resources, their analyses of germplasm identification and molecular phylogeny are very limited. Results: We have sequenced the chloroplast genomes of six different species (I. chlorosepala, I. fanjingshanica, I. guizhouensis, I. linearisepala, I. loulanensis, and I. stenosepala) in the karst area of China and compared them with previously published species and the monospecific sister Hydrocera triflora belonging to Balsaminaceae family. We comtrasted the genome features, repeat sequences, sequence divergence, and constructed the phylogenetic relationships. The 12 complete chloroplast genomes of the Balsaminaceae species ranged in size from 151,538 bp (I. fanjingshanica) to 154,189bp (H. triflora ) encoded 114 total distinct genes except for I. glandulifera and H. triflora, including 81 protein-coding, 29 transfer RNA genes(tRNA), and 4 ribosomal RNA genes (rRNA). Moreover, the characteristics of the long repeats sequences and simple sequence repeats (SSRs) were found. Divergent hotspots regions psbK-psbI,trnT-GGU-psbD, rpl36-rps8, rpoB-trnC-GCA, trnK-UUU-rps16, trnQ-UUG, trnP-UGG-psaJ, trnT-UGU-trnL-UAA, and ycf4-cemA were identified in the 12 Balsaminaceae chloroplast genomes, which could be suitable for species identification and phylogenetic studies. Additionally, phylogenetic relationships based on Maximum likelihood (ML) and Bayesian inference (BI) among whole chloroplast genomes showed that H. triflora was the basal group in Balsaminaceae and I. guizhouensis was the basal group in impatiens species. Besides this, cultivated species(I. balsamina, I. hawkeri, and I. walleriana) were clustered together. Conclusion: Our study provides detailed information about nucleotide diversity hotspots and characterized types of repeats, which can be used for developing molecular markers applicable in Balsaminaceae species. And also we reconstructed and analyzed the relationships of some impatiens species and discovered their status based on the complete chloroplast genomes. The current study might provide valuable significant genomic information for the systematics and evolution in the Balsaminaceae.

The complete chloroplast genome sequence of Impatiens hawker, a widely cultivated horticultural species in the world is 151,692 bp, with a typical quadripartite structure including a pair of inverted repeat (IRs, 25,584 bp) regions separated by a small single copy (SSC, 17,494 bp) region and a large single copy (LSC, 83,029 bp) region. The overall GC content of I. hawker plastid genome was 36.8%. The whole chloroplast genome contains 135 genes, including 89 protein-coding genes (PCGs), 38 transfer RNA genes(tRNAs), and 8 ribosomal RNA genes (rRNAs). Among these genes, 15 genes have one intron and 2 genes contain two introns. To investigate its evolution status, the phylogenetic tree based on APGIII reveal that there are close relationships to the same genus species I. uliginosa and I. piufanensis.