Development and characterization of small translocations between the Pm13 introgression from Aegilops longissima and wheat homoeologous A, B and D chromosomes

BackgroundWild relatives have substantial impacts on the resistance of wheat to biotic and abiotic stresses. The genetic diversity of these wild varieties can be employed to widen the wheat gene pool by introducing wild allele introgression and genome structure variations. The powdery mildew resistance gene Pm13 was derived from the wheat wild relative species Aegilops longissima (S1S1, 2n = 2x = 14) and was transferred into wheat chromosome 3BS over 30 years. Until recently, it has not been widely used in wheat breeding, possibly because of the linkage drag associated with Pm13 introgression or poor alien segment compensation to 3BS.ResultsIn this study, translocations between the Pm13 introgression and wheat homoeologous A, B and D chromosomes were developed by using a wheat ph1b mutant. The 3Sl (3B) substitution line was hybridized with the CS nullisomic-tetrasomic line N3AT3B, and then F1 was hybridized with the CSph1b mutant. Individuals homozygous for the ph1b mutant carrying the alien chromosome 3Sl were identified from the segregating populations via molecular markers and cytological analysis. Whole-arm recombinant translocations T3SlS.3AL and T3SlS.3BL and small recombinant translocations T3SlS-3AS.3AL, T3SlS-3BS.3BL and T3DS-3SlS-3DS.3DL carrying Pm13 introgression were subsequently identified via molecular cytological analysis. Furthermore, 4 disomic T3SlS-3BS.3BL recombinants carrying the homozygous Pm13 introgression were identified. All the translocations were nearly immune to powdery mildew.ConclusionsOur results provide novel alien homoeologous Pm13 translocations for improving powdery mildew resistance in wheat and insights into the interactions between different wheat genomes and alien chromosome segments.