Morphological and genome-wide evidence for natural hybridisation within the genus Stipa (Poaceae)

Hybridisation in the wild between closely related species is a common mechanism of speciation in the plant kingdom and, in particular, in the grass family. Here we explore the potential for natural hybridisation in Stipa (one of the largest genera in Poaceae) between genetically distant species at their distribution edges in Mountains of Central Asia using integrative taxonomy. Our research highlights the applicability of classical morphological and genome reduction approaches in studies on wild plant species. The obtained results revealed a new nothospecies, Stipa × lazkovii, which exhibits intermediate characters to S. krylovii and S. bungeana. A high-density DArTseq assay disclosed that S. × lazkovii is an F1 hybrid, and established that the plastid and mitochondrial DNA was inherited from S. bungeana. In addition, molecular markers detected a hybridisation event between morphologically and genetically distant species S. bungeana and probably S. glareosa. Moreover, our findings demonstrated an uncertainty on the taxonomic status of S. bungeana that currently belongs to the section Leiostipa, but it is genetically closer to S. breviflora from the section Barbatae. Finally, we noticed a discrepancy between the current molecular data with the previous findings on S. capillata and S. sareptana.