Genetic characterization of the Golovinomyces cichoracearum complex in Australia

To characterize the evolutionary lineages of the Golovinomyces cichoracearum complex on introduced plants in Australia, the rDNA ITS regions from 47 herbarium specimens were compared by RFLPs and sequencing. Six RFLP groups were found, each corresponding to a previously reported evolutionary lineage in the complex. The largest of these groups (Group 1) contained 15 specimens infecting a range of tribes in the Asteraceae, despite a previous report that this lineage is largely restricted to the Tribe Heliantheae (Asteraceae). This group contained the only specimens with ascomata. Curved foot cells were formed by two lineages; one (Groups 5 & 6) containing specimens from a range of host families including the Asteraceae (Tribe Lactucae only), the other (Groups 2 & 3) containing members of the Asteraceae (Tribe Anthemidae only). Group 5 may represent G. orontii sensu stricto, while Group 6 is currently unnamed. Golovinomyces cichoracearum sensu stricto (specimens from Scorzonera) formed a distinct group that did not contain any specimens from Australia. Suggestions are made for future species delimitation in the complex.