Transferability of wheat microsatellites to diploid Triticeae species carrying the A, B and D genomes

Hexaploid wheat (Triticum aestivum L em Thell) is derived from a complex hy bridization procedure involving three diploid species carrying the A, B and D genomes. In this study, we evaluated the ability of microsatellite seque nces from T. aestivum to be revealed on different ancestral diploid species more or less closely related, i.e. to test for their transferability. Fift y five primer pairs, evenly distributed all over the genome, were investiga ted. Forty three of them mapped to single loci on the hexaploid wheat genet ic map although only 20 (46%) gave single PCR products; the 23 others (54%) gave more than one band with either only one being polymorphic, the others remaining monomorphic, or with several co-segregating polymorphic bands. T he other 12 detected two (9) or three (3) different loci. From the 20 prime r pairs which gave one amplification product on hexaploid wheat, nine (45%) also amplified products on only one of the diploid species, and seven (35% ) on more than one. Four microsatellites (20%) which mapped to chromosomes from the B genome of wheat, did not give any amplification signal on any of the diploid species. This suggests that some regions of the B genome have evolved more rapidly compared to the A or D genomes since the emergence of polyploidy, or else that the donor(s) of this B genome has(have) not yet be en identified. Our results confirm that Triticum monococcum ssp. urartu and Triticum tauschii were the main donors of the A and D genomes respectively , and that Aegilops speltoides is related to the ancestor(s) of the wheat p olyploid B genome.