Comparative Analyses of Plastomes of Four (Araceae) Taxa, Tropical Aquatic Plants Endemic to Africa.

Schott (Araceae) have high ornamental properties as aquarium plants. However, the genus has difficulties in species identification, and the mechanism of its adaptation to the aquatic environment is unknown. To better identify species and understand the evolutionary history of , the plastomes of Schott, var. (Engl.) Crusio, and Engl., were sequenced. The sizes of the plastomes of ranged from 169,841 bp to 170,037 bp. These plastomes were composed of conserved quadripartite circular structures and comprised 112 unique genes, including 78 protein-coding genes, 30 transfer RNA genes, and 4 ribosomal RNA genes. The comparative analysis of genome structure, repeat sequences, codon usage and RNA editing sites revealed high similarities among the plastomes, indicating the conservation of plastomes of . Three spacer regions with relatively high nucleotide diversity, , , and , were found within the plastomes of . Phylogenetic analysis, based on 75 protein-coding genes, showed that was sister to (L.) Schott (BS = 99). In addition, four genes (, , , and ) that contain sites undergoing positive selection were identified within the plastomes. These genes may play an important role in the adaptation of to the aquatic environment. The present study provides a valuable resource for further studies on species identification and the evolutionary history of .