The phylogeny of the tribe Hyoscyameae based on complete plastomes and the evolution of the cox1 intron

CAROLINA L. GANDINI; VERÓNICA N. IBÁÑEZ; MIKHAJILO K. ZUBKO; M. VIRGINIA SANCHEZ-PUERTA

Congreso; SOL International Online Meeting; 2020

The Hyoscyameae (Solanaceae) tribe comprises eight genera restricted to either the Mediterranean-Turanian region (Atropa and Archihyoscyamus) or the Tibetan Plateau area (Przewalskia, Anisodus, and Atropanthe). The genus Scopolia contains four species distributed disjunctly between eastern Asia and the Mediterranean basin. Several studies intended to resolve the phylogenetic affiliations however, many of them remain unresolved. In this study we assembled the complete chloroplast genome of Scopolia carniolica, the second species of the genus to be described. Using publicly available complete chloroplast genomes we performed genomic comparisons and examined the phylogenetic relationships for seven of the eight Hyoscyameae genera. In general, gene content was identical across the tribe with small differences in genome length. Our attempts to determine variable plastid regions that could be used as potential molecular markers conclude that only full-length chloroplast genomes may be useful for phylogenetic inference at the species level. The major advancement was the detection of a strongly-supported phylogenetic affiliation of Atropanthe, Anisodus, and Hyoscyamus that previous studies were not able to resolve. We also studied the Hyoscyameae phylogeny using a nuclear marker, the internal transcribed spacer 2 (ITS2). Interestingly, even though the resolution of the ITS2 tree was poorly resolved in general; it recovered all genera as monophyletic, excepting Scopolia which resulted to be paraphyletic in respect to Physochlaina. Finally, we assembled the cox1 mitochondrial gene and re-interpreted the intron evolution. Two independent horizontal acquisitions were inferred, one in the ancestor of Przewalskia, Physochlaina and S. japonica, and another in Hyoscyamus, with no intron losses.