Genetic diversity and population structure of Hemileia vastatrix from Ethiopian Arabica coffee

Coffee leaf rust caused by Hemileia vastatrix is the most devastating diseases of Coffea arabica. This study was undertaken to characterise the genetic diversity and structure of the fungal populations collected from major coffee-growing areas of Ethiopia using 17 Simple Sequence Repeat (SSR) polymorphic markers. Observed alleles per locus ranged from 2 to 13, with an average of 5.22. Diversity indices as, total Shannon diversity index and total Shannon pairwise diversity index were 0.89 and 0.92, respectively. The variation observed within population, was 92%. Most of the paired populations showed very low (<0.07) genetic differentiation values, corresponding to high levels of gene flow between populations. Populations of H. vastatrix in Ethiopia result highly variable, in contrast to studies from other coffee growing regions of the world, and the vast majority of genetic variation was distributed within all coffee growing districts of the country.