Sixteen New Complete Plastid Genomes in the Tribe Loteae (Leguminosae): Structure and Phylogenetic Analysis

The tribe Loteae (Papilioniodeae-Leguminosae), according to plastid data, belongs to the Robinioid clade, which also includes the tribes Robinieae and Sesbanieae. The tribe Loteae contains 16 genera and about two hundred seventy-five species, of which the plastid genomes of five species have been studied to date. The main objectives of our study were to obtain new information on the plastid genome structure of the Loteae representatives in order to assess plastid genome variability and reconstruct phylogenetic relationships within the tribe Loteae. We performed sequencing, assembly, structural and phylogenetic analyses of the Loteae plastid genomes. All assembled Loteae plastomes showed a quadripartite structure with an overall length ranging from 150,069 to 152,206 bp and showed relative stability of inverted repeat borders. The Loteae plastomes demonstrated full collinearity; the most variable sites of the studied plastomes were found in <i>pet</i>N-<i>trn</i>C and <i>rps</i>16-<i>acc</i>D spacers from the LSC region and in the <i>ycf</i>1 gene within the SSC. All inferred relationships attained maximal support with the <i>Hippocrepis</i> lineage separated first, followed by <i>Coronilla</i> and <i>Anthyllis</i>; <i>Lotus</i> is a sister group to the clade <i>Acmispon</i> + <i>Ornithopus</i>. In this study, completely resolved relationships representing a backbone of plastid phylogeny were produced. The obtained results demonstrated that plastid genomes in the tribe Loteae are structurally conservative in contrast to the closely related tribes Robinieae and Sesbanieae.