XVI International Botanical Congess

The insect-borne fungal plant disease Microbotryum violaceum, the well known causative agent of anther smut in Silene latifolia, parasitzes many other species of the family Caryophyllaceae. The distribution of microsatellite marker variation reveals that fungal strains collected from different host plant species are strongly differentiated, sharing almost no alleles. Collections from a number of sites where several host plant species were infected similarly showed strong differentiation by host plant species but not by geographic proximity, indicating strong barriers to gene flow among different strains from different species, even when they grow in potential contact. Here we compare the phylogenies of hosts and parasites. Host phylogenies are based on noncoding chloroplast and nuclear ITS sequences and parasites on tubulin-intron and ITS sequences. We discuss the results with respect to host-parasite coevolution, the importance of host-shifts for parasite speciation, and also investigate whether parasite phylogenies reflect adaptations to particular host life-history characteristics such as life span and growth habit or to pollination syndrome such as pollination by night-flying or day-flying insects.