Plant & Animal Genomes XIII Conference Plant & Animal Genomes XIII ConferenceJanuary 15-19, 2005
Town & Country Convention Center
San Diego, CA
Susanne Brunner , Payorm Srichumpa , Nabila Yahiaoui , Beat Keller
In wheat, race-specific resistance to the fungal pathogen powdery mildew (Blumeria graminis f. sp. tritici) is controlled by Pm genes. There are 10 alleles conferring resistance at the Pm3 locus (Pm3a to j) on chromosome 1AS of hexaploid bread wheat (Triticum aestivum L.). The Pm3b gene was cloned from the large genome of hexaploid wheat by map-based cloning (Yahiaoui et al., Plant J., 37:528-538, 2004). The Pm3b gene, a member of the CC-NBS-LRR type of disease resistance genes conferred race-specific resistance to wheat powdery mildew in a transient single cell transformation assay. Haplotype studies in lines carrying known Pm3 specificities (Pm3a to j) indicated a good conservation of the haplotype in the Pm3 region. This led to the rapid isolation of additional candidate alleles from these wheat lines using a PCR based strategy. The Pm3 candidate alleles were functionally tested in a transient transformation assay. First results indicate that the Pm3 genes form a true allelic series encoded by a single member of a large gene family on wheat chromosome 1A. Sequence comparisons of Pm3 genes from T. aestivum lines and from wild wheat species uncover the mechanisms of evolution of the Pm3 alleles. The successful cloning of the Pm3 genes provided molecular tools to study disease resistance gene specificity determination in cultivated and wild wheat species.