Abstract
Impatiens L., the largest genus in the family Balsaminaceae with approximately 1000 species, is a controversial and complex genus that includes many economically important species well known for medicinal and ornamental values. However, there is limited knowledge of molecular phylogeny and chloroplast genomics, and uncertainties still exist at a taxonomic level. In this study, we have assembled four chloroplast genomics specimens of Impatiens cyanantha and Impatiens monticola, which are found at the different altitudes of Guizhou and Yunnan in China, and compared them with previously published three wild Balsaminaceae species (Impatiens piufanensis, Impatiens glandlifera, and Hydrocera triflora). The complete chloroplast genome sequences ranged from 152,236 bp (I. piufanensis) to 154,189 bp (H. triflora) and encoded 115 total distinct genes, of which 81 were protein-coding, 30 were distinct transfer RNA genes(tRNA), and 4 were ribosomal RNA genes (rRNA). A comparative analysis of I. cyanantha (Guizhou) vs. I. cyanantha (Yunnan) and I. monticola (Guizhou) vs. I. monticola (Yunnan) revealed minor changes in lengths; however, similar gene contents, gene orders, and GC contents existed among them. Interestingly, highly coding and non-coding genes, and regions matK, psbK, atpH-atpI, trnC-trnT, petN, psbM, atpE, rbcL, accD, psaL, rps3-rps19, ndhG-ndhA,rpl16, rpoB, ndhB, ndhF, ycf1, and ndhH were found, which could be suitable for identification of species and phylogenetic studies. During the comparison between I. cyanantha (Guizhou) and I. cyanantha (Yunnan), we observed that the rps4, ycf2, ndhF, ycf1, and rpoC2 genes underwent positive selection. Meanwhile, in the comparative study of I. monticola (Guizhou) vs. I. monticola (Yunnan), The accD and ycf1 genes were positively selected. Additionally, phylogenetic relationships based on maximum likelihood (ML) and Bayesian inference (BI) among whole chloroplast genomes showed that a sister relationship with I. monticola (Guizhou) and I. monticola (Yunnan) formed a clade with I.piufanensis proving their close connection. Besides, I.cyanantha (Guizhou) and I. cyanantha (Yunnan) formed a clade with I. glandlifera. Along with the findings and the results, the current study might provide valuable significant genomic resources for systematics and evolution of the genus impatiens in different altitudes of regions.
Highlights
Impatiens L., which belong to the family Balsaminaceae, have been well known and used as medicinal, horticultural, and ornamental plants in North America, Europe, and China [1]
PacBio chloroplast sequencing data have been submitted to the NCBI with SRA numbers SUB8890373 and SUB8894092 for I. monticola, and with SRA numbers SUB8894240 and SUB8894445 for I. cyanantha
All of these raw data are in the bioprojects PRJNA691973, PRJNA692235, PRJNA692243, PRJNA692246, in the order given
Summary
Impatiens L., which belong to the family Balsaminaceae, have been well known and used as medicinal, horticultural, and ornamental plants in North America, Europe, and China [1]. The family of Balsaminaceae consists of only two genera of Impatiens and the monospecific sister species Hydrocera triflora, with strong similarity in morphology and genomics DNA datasets [2]. About 1000 species are involved in Impatiens, distributing from tropics to subtropics, and extending from sea level to an altitude of 4,000 meters [3]. Tropical Africa, Madagascar, Sri Lanka, Himalayas, and Southeast Asia are the biodiversity hotspots for the endemic Balsaminaceae [5]. Southwest China is the original biodiversity and distribution center of the Balsaminaceae species [6, 7]
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