Joint Identification and Application of Microsatellite Markers in Genetic Diversity Study of Closely Related Species Teucrium montanum, T. capitatum and Their Natural Hybrid

Teucrium montanum L. and T. capitatum L. are two plant species with overlapping distribution in the Balkan Peninsula, especially in Croatia, where several occurrences of their putative hybrid species T. × rohlenae have been recorded. Next-generation sequencing of both species and de novo assembly was carried out resulting in 120 contigs for T. montanum and 1685 contigs for T. capitatum assembled. The Dig-up primers pipeline was used for SSR mining of both assemblies, applying different criteria that resulted in 112 SSR candidates for testing. A subset of 41 SSRs was selected and after two rounds of testing, twelve SSRs were developed and characterized. A total of 232 alleles were detected with 5 to 29 alleles per locus, based on the test sample. The genetic diversity analysis of three Teucrium taxa from a single location revealed a higher level of diversity in T. montanum than in T. capitatum with intermediate values for the hybrid species. The NeighborNet diagram and genetic structure analysis grouped the taxa into two separate clusters, the first of which consisted exclusively of T. montanum, while the other was composed of intermixed T. capitatum and T. × rohlenae individuals. The availability of SSR markers for two Teucrium taxa will allow in-depth analysis of genetic diversity and structure, as well as molecular identification of their putative hybrids in the future.