Population Structure of in Australian Pyrethrum Reveals High Evolutionary Potential.

, the causal agent of anthracnose, is an emerging pathogen of commercially grown pyrethrum () in Australia. A microsatellite marker library was developed to understand the spatio-genetic structure over three sampled years and across two regions where pyrethrum is cultivated in Australia. Results indicated that was highly diverse with a mixed reproductive mode; comprising both sexual and clonal reproduction. Sexual reproduction of was more prevalent in Tasmania than in Victoria. Little differentiation was observed among field populations likely due to isolation by colonization but most of the genetic variation was occurring within populations. was likely to have had a long-distance gene and genotype flow among distant populations within a state and between states. Anthropogenic transmission of propagules and wind dispersal of ascospores are the most probable mechanisms of long-distance dispersal of . Evaluation of putative population histories suggested that most likely originated in Tasmania and expanded from an unidentified host onto pyrethrum. Victoria was later invaded by the Tasmanian population. With the mixed mode of reproduction and possible long-distance gene flow, is likely to have a high evolutionary potential and thereby has ability to adapt to management practices in the future.