Phylogenetic analysis of nine Impatiens species from Subgenus Clavicarpa and Subgenus Impatiens (Sect. Impatiens and Sect. Racemosae) based on chloroplast genomes

Mengqing Yang Wenxiang Lan Jianhui Zhong Hui Ma Xi Huang Meijuan Huang ^* Haiquan Huang ^*

• Southwest Forestry University, Kunming, China

The genus Impatiens L. ( Balsaminaceae) is one of the three most important bedding plant genera globally, valued for its medicinal, ornamental, and economic properties. However, the morphological overlap among species and the lack of genomic data have limited our understanding of their molecular phylogenetic relationships. This study involved the sequencing of the chloroplast genomes of 9 Impatiens species, including Impatiens lateristachys, Impatiens siculifer var. porphyrea, Impatiens apalophylla, Impatiens pritzelii, Impatiens menghuochengensis, Impatiens membranifolia, Impatiens qingchengshanica, Impatiens aquatilis, and Impatiens racemosa. The study compared genomic features and repeat sequences, evaluated sequence divergence, and established phylogenetic relationships. The results indicated that the chloroplast genome sizes ranged from 151, 784 bp (I. racemosa) to 152, 628 bp (I. apalophylla), encoding between 108-115genes[77 to 81 protein-coding genes, 27 to 30 tRNA genes, and 4 rRNA genes]. Additionally, A detailed analysis was performed on the characteristics of repeat sequences, codon preferences, and IR region. Coding sections were more conserved than non-coding regions, and the IR regions were more conserved than the LSC and SSC regions, according to sequence variation and mutation hotspot analyses. The phylogenetic tree constructed using the maximum likelihood method, revealed the evolutionary relationships among the species, classifying them into subgenera Clavicarpa, section Impatiens, and Racemosae. This study provides new molecular evidence for the classification of the Impatiens genus.