Submitted to: Journal of the American Society for Horticultural Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/5/2008
Publication Date: 5/1/2008
Citation: Volk, G.M., Richards, C.M., Reilley, A., Henk, A.D., Reeves, P.A., Forsline, P.L., Aldwinckle, H. 2008. Genetic diversity and disease resistance of wild Malus orientalis from Turkey and southern Russia. Journal of the American Society for Horticultural Science 133:383-389. Interpretive Summary: Apple trees that grow wild in Turkey and southern Russia have disease resistance characteristics that could be valuable to apple breeding programs. The genetic diversity of wild Malus orientalis seedlings grown from seeds collected from four Turkish and two Russian locations was determined. The Russian collection locations were heavily forested and consisted of populations that were fairly homogeneous. In contrast, the M. orientalis trees in Turkey were sparsely distributed in barren landscapes. Three of the four collection locations contained sets of individuals that were genetically distinct. Some of the half-sib families of the M. orientalis seedlings exhibited high levels of disease resistance to apple scab, cedar apple rust, and fire blight. These data suggest wild populations of M. orientalis from regions around the Black Sea are genetically distinguishable and show high levels of diversity.
Technical Abstract: Genetic diversity and disease resistance are described for 496 seedlings from wild populations of Malus orientalis collected in southern Russia and Turkey in 1998 and 1999. Eighty five half-sib families were genotyped using seven microsatellite markers and disease resistance was determined for apple scab (Venturia inaequalis Cooke), cedar apple rust (Gymnosporangium juniperi-virginianae Schwein) and fire blight (Erwinia amylovora Burrill). Individuals from the two Russian Caucasus collection locations were homogeneous compared to populations from the four Turkish collection locations. Within three of the Turkish collection locations, some half-sib families were highly diverse and several of these families had unusually high levels of disease resistance. Bayesian analyses of the population structure revealed six distinct clusters. Most of the individuals segregated into two clusters, one containing individuals primarily from southern Russia and the other containing individuals from both Russia and northern Turkey. Individuals in the four small clusters were specific to Turkish collection locations. These data suggest wild populations of M. orientalis from regions around the Black Sea are genetically distinguishable and show high levels of diversity.