Relationships of Worldwide Onobrychis species: from seed & pod morphology and molecular perspective

The present study aimed to investigate the phylogeny of 31 Onobrychis species with the help of seed and fruit macro & micro-morphological traits and ISSR molecular markers. The species were found to be highly variable in their seed and fruit morphological traits. Also, a new type of fruit (O. crista galli type), in addition to the three predefined types of fruit, was introduced. From molecular perspective, a set of 22 ISSR primers were shown to have a good efficiency for genetic discrimination among the species. Bayesian model based STRUCTURE analysis grouped the genotypes into 4 genetic clusters, and the high value of Fst calculated for these clusters indicated a high level of genetic differentiation among them. On the other hand, based on the Maximum Likelihood phylogenetic tree, our results are in agreement with the subgenus classification (Onobrychis and Sisyrosema), while contrary to Sisyrosema, the Onobrychis subgenus (the Lophobrychis and Onobrychis sections) appears not to be monophyletic. Furthermore, in contrast to the traditional taxonomic classification, species belonging to the Lophobrychis section do not form a coherent group, indicating that this section could be considered as a heterogeneous unit and perhaps could be merge into the Onobrychis section. HighlightThis paper discusses a worldwide phylogenic analysis and population structures of Onobrychis genus. The results of this paper provide a comprehensive answer to complexity of subgenus and section discrimination.