Transferability of 116 common wheat expressed sequence tag-simple sequence repeats (EST-SSR) markers was investigated on 168 accessions representing 18 grass species to identify new alleles useful for wheat improvement. Transferability among the Triticeae ranged from 73.7% for Aegilops longissima to 100% for wheat subspecies (Triticum compactum) but was also good for less related species such as rye (72.8%) or maize (40.4%). On average, the number of alleles/locus detected by EST-SSR markers was 3.1 for hexaploid wheat. The polymorphism information content (PIC) values simultaneously estimated for Triticum aestivum and Triticum durum were similar for the two species (0.40 and 0.39, respectively). The allelic diversity within allogamous species was higher (0.352-0.423) compared with that of T. aestivum and T. durum (0.108 and 0.093, respectively). T. aestivum and T. durum shared the largest number of alleles (74.6%) while among the three ancestral diploid species of bread wheat, Aegilops tauschii had the highest percentage of alleles with T. aestivum (57.4%). These results indicate that grass orphan species can be studied using wheat EST-SSRs and can serve as a source of new alleles for wheat genetic improvement.
