Molecular investigation in few spices of Dacocephalum in Iran: Species relationship, reticulation and divergence time

Abstract

It is believed that Lamiaceae or the Mint family has numerous paraphyletic genera and the relationship between the species has not been fully determined in several cases. The genus Dracocephalum is one of the genera, which has not been investigated thoroughly. In the family Lamiaceae, Dracocephalum is the second largest genus consisting of about 186 species. Eight Dracocephalum species were reported of Iran belonging to the Irano-Turanian phytogeographical region. The present study has attempted to investigate Dracocephalum in terms of the molecular phylogeny for the first time and gather data on their species relationship, divergence time, and show how they are distributed geographically. To report the results, Chloroplast DNA (ribosomal protein L16 (rpL16)) sequences and Inter Simple Sequence Repeat (ISSR) molecular markers have been used. According to the results, the genus Dracocephalum is paraphyletic and has close affinity with Lallemantia. The results of horizontal gene transfer (HGT) analysis confirmed the inter-specific hybridization in the genus. Chronogram obtained by Bayesian Evolutionary Analysis Sampling Trees (BEAST) date revealed Dracocephalum species divergence time back to 2–10 million years ago(MYA). These findings extend the knowledge on the evolution of Lamiaceae.