Diversity and host specificity of the oomycete-parasitic oomycete genus Olpidiopsis

• Applicant: Professor Dr. Marco Thines
• Subject Area: Evolution and Systematics of Plants and Fungi
• Term: from 2020 to 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 456555282

The genus Olpidiopsis belongs to the early-diverging lineages of the oomycetes and contains more than a dozen species parasitic to oomycetes. Among the hosts of Olpidiopsis are several economically relevant oomycete genera, such as Aphanomyces, Pythium, and Saprolegnia. However, species of the genus Olpidiopsis cannot live without their living host, which makes it necessary to first grow a suitable host, which then can be used to propagate and bait Olpidiopsis species. However, this complicated procedure has not been carried out for a long time, until we have recently brought a few species of Olpidiopsis into dual culture with their respective hosts.Even though in these preliminary tests only few of the described species could be isolated, there was already an unexpected diversity found, leading to the description of one new species, and in an unpublished study two additional species of the genus could be isolated. This suggests that the methodology we have developed is highly efficient in isolating species of the genus. On the basis of these advances, we are now aiming in the proposed research to isolate a wide spectrum of Olpidiopsis species, to test three main hypotheses – 1) Olpidiopsis species are much more diverse than currently known, 2) Olpidiopsis species composition and richness is strongly influenced by the habitat, 3) Olpidiopsis species are highly host specific. These hypotheses will be tested using baiting, establishment of dual cultures, cross-infection experiments, environmental sequencing and phylogenetics.The findings of the proposed research will lead to fundamental progress with respect to understand the evolution and ecology of the oomycete-parasitic genus Olpidiopsis, which is a potential regulator of oomycete-caused diseases in plants and animals. With the establishment of dual cultures, several downstream research lines will become feasible, such as dissecting the molecular interaction of oomycete parasites and their oomycete hosts, as well as the testing of Olpidiopsis strains as biocontrol agent against important oomycete-caused diseases, such as Pythium-induced damping off of seedlings, crayfish plague and saprolegniosis in fish.

• DFG Programme: Research Grants