Mapping highly informative SSR markers in the genome of Magnaporthe oryzae from wheat

Wheat blast, caused by Magnaporthe oryzae (Triticum haplotype - MoT), is an important disease of wheat in Brazil. In this study, we designed 38 new SSR markers based on the genome sequence of different MoT isolates, compared the informativeness of those markers with other 52 from the literature and mapped the polymorphic ones. Among the 90 SSR markers, 53 were polymorphic resulting in, on average, 3.02 alleles per locus and polymorphism information content (PIC) of 0.41. Most (81.1 %) of the polymorphic markers presented 11 or more motif repeats. Seventeen highly informative markers were detected and mapped in all chromosomes except for chromosome 5. On average, polymorphic markers on chromosome 6 showed the highest PIC followed by chromosomes 2 and 7. Clustering analysis showed a clear separation of one isolate from rice from the rest of the isolates from wheat. In each of the three clusters detected, the MoT isolates were similar among them regardless of the year and location sampled, suggesting that the pathogen is widely dispersed across wheat growing regions in Brazil. The highly informative markers detailed here should be useful for population biology studies of the wheat blast pathogen.