XVI International Botanical Congess

Using phylogencies inferred from ITS region sequences, evolutionary pathways between pathogenism and endophytism in Rhabdocline (Hemiphaciadiaceae) and Lophodermium (Rhytismataceae) are discussed using outgroup comparison. The single endophytic species in the genus Rhabdocline, R. parkeri, appears to be derived from pathogenic congeners that cause needle casts. Endophytism is more prevalent in Lophodermium and may the ancestral state. Members of these genera have similar infection mechanisms, but endophytic species have an extended latency period and subequent growth phase that has no noticeable influence on host fitness. Endophytes exhibit specific host requirements a observed in pathogen, but there is no evidence of host resistance. Despite a delay in the time until reproduction, numbers of endophytic individuals is inferred to be order of magnitude higher than numbers of patogenci individuals, suggesting that endophytism can be successful alternative life history strategy to pthogenism.