Analysis by PCR-based markers using designed primers to study relationships between species of Hordeum (Poaceae)

An investigation was made into the relationships between six species or subspecies of the genus Hordeum that grow in the Iberian Peninsula and Balearic Islands. Plant material included samples of 19 populations of the annual species H. marinum subsp. marinum, H. marinum subsp. gussoneanum, H. murinum subsp. murinum, and H. murinum subsp. leporinum, and the perennial species H. bulbosum and H. secalinum. Relationships were analysed using PCR-based molecular markers. Thirteen sets of primers were designed and synthesized based on sequences of mapped RFLPs from genomic libraries and conserved regions of structural genes of known function in cultivated species. Primers were used to amplify genomic DNA from all populations. The number of amplified products ranged from 1 to 18 per primer and a total of 168 markers were scored. The markers revealed different degrees of relationships. Hordeum bulbosum was clearly separated from the rest. The populations of both subspecies of H. murinum were closely related. H. marinum subsp. gussoneanum appeared to be closely related to H. secalinum, yet relatively separated from its conspecific subspecies marinum. The use of a large number of DNA markers in this kind of analysis is discussed.