Comparative analyses and phylogenetic relationships of 15 Trapa (Trapaceae) species based on Complete Chloroplast Genomes

Abstract

Trapa L. is floating-leaved aquatic plants with important economic and ecological values. However, species identification and phylogenetic relationship are still unresolved for Trapa. In this study, complete chloroplast genomes of 13 Trapa species/taxa were sequenced and annotated. Combined with released sequences of the other two species, comparative analysis of cp genomes was first performed on the 15 Trapa species/taxa. The 15 cp genomes exhibited quadripartite structures with medium size of 155, 453-155, 559 bp. IR/SC junctions were conservative with no obvious change found. Long repetitive repeats and SSRs were mostly detected in the intergenic and LSC regions, providing useful plastid markers for species and relationship identification. Three phylogenetic analyses (MP, ML and BI) consistently showed two clusters within Trapa, including large- and small-seed species/taxa, respectively. This study provided the baseline information for phylogeography of Trapa, which would facilitate the management and utilization of genetic resources of the genus.