Genetic variation of Heterobasidion abietinum in Southern Europe and the Mediterranean BasinForest Pathology

Heterobasidion abietinum causes root and butt rot on Abies species occurring in central Europe and the Mediterranean Basin in a distribution extending from Spain in the west to Turkey and Caucasia in the east. To investigate the genetic diversity within H. abietinum, 95 isolates from different regions were analysed with 61 polymorphic molecular markers. The markers showed genetic differentiation amongst the H. abietinum populations. The most diversified population is that on A. pinsapo in southern Spain, which is isolated from gene flow with other populations. Lower but still significant differences were found amongst other European populations. Isolates from Turkey showed little diversification compared with the south European isolates from east of the Alps. The genetic structure of the H. abietinum populations in relation to postglacial recolonization of Abies is discussed.