Molecular diversity in Puccinia triticina isolates from Ethiopia and Germany

A total of 43 isolates of the wheat leaf rust fungus, Puccinia triticina Eriks, collected from Ethiopia and Germany were analysed for their genetic diversity using the amplified fragment length polymorphism (AFLP) technique. Out of 18 EcoRI/MseI primer combinations screened, 15 produced 219 highly polymorphic fragments. The average AFLP difference between pairs of the leaf rust isolates (26 from Ethiopia, 17 from Germany) was calculated using Dice's genetic similarity (GS) coefficient. The overall GS for the 43 isolates was 0.67 +/- 0.13. The Ethiopian leaf rust isolates had lower average GS (0.63 +/- 0.13) than the German ones (0.76 +/- 0.10). A cluster analysis and a two-dimensional principal coordinate analysis (PCoA) grouped the 43 isolates into two significantly different (P <= 0.01) clusters. Isolates in cluster I (35 isolates) had an average GS of 0.76 +/- 0.06 while the isolates in cluster II (8 isolates) had an average GS of 0.55 +/- 0.12. Isolates were also grouped into three regions of collection, central Ethiopia, south and south-east Ethiopia, and Germany. The regions were significantly different at P <= 0.01 indicating regional variation in terms of molecular diversity of the leaf rust isolates studied. Each isolate, however, had a unique AFLP fingerprint. The results indicated that the leaf rust population in central Ethiopia is genetically distinct and this might be related to the predominant cultivation of durum wheat cultivars in this area.