The Phytophthora Research Centre team based at Mendel University in Brno has a long history of uncovering Oomycete diversity on terrestrial forest ecosystems all over the world… and now, within the RestoreSeas project, we are taking this challenge to another environment: hunting Oomycetes in marine forests! Understanding the impact of these pathogens in marine ecosystems is of crucial importance to develop best management, conservation and restoration practices.
As researchers with a firm foot on dryland, we don’t have enough diving experience to chase our targets in their natural habitats: we must rely on other strategies to attain our goals…
The survey of Oomycete species diversity in marine and estuarine ecosystems along the Atlantic coast of Portugal is a task included in the project RestoreSeas and it is being conducted in cooperation with the Centre of Marine Sciences (CCMAR, Faro), a collaboration with Dr. Aschwin Engelen and his colleagues.
In Autumn 2023, the MendelU team made an expedition to the Northwest (Viana do Castelo, Braga, Porto) and South coast (Faro) of Portugal.
Our work comprised fieldtrips to estuarine and marine areas for placing/collecting baiting rafts and to collect floating leaves of freshwater and terrestrial plants, seagrasses, kelp and other macroalgae.
Fortunately for us, the worst stormy days that tormented Portugal during our stay were spent in hotel rooms, plating the plant and algae tissues onto selective media that allow us to inhibit the growth of most bacterial and fungal species, enabling the development of Oomycete isolates. The next few days were a little bit like Christmas: checking the petri dishes felt like unwrapping long awaited gifts… and what gifts we had! The sub-culturing of the Oomycete isolates and purification of bacteria-contaminated cultures is not an easy task: fast growing oomycetes, particularly Pythium and Phytopythium species, have to be recovered, too, but sometimes we must eliminate them to give also the slow growing species a chance to be isolated…
Our hunt was incredibly successful: in total, more than 400 isolates were obtained and transported to the PRC laboratory at MendelU, for morphological characterisation and molecular identification. Already the preliminary morphological characterisation revealed a huge diversity of oomycete species along the Portuguese coast, including the first records of oomycetes from kelp, Fucus, red algae and Zostera noltei and very high isolation frequencies of oomycetes from the seagrass species Cymodocea nodosa in South Portugal. DNA was extracted and the first batch of sequencing results is expected to arrive in the second half of January 2024… stay tuned for upcoming news!
Our results suggest that oomycete pathogens may, indeed, pose a high risk to the success of marine restorations: pathogenicity trials are planned and will be performed soon, as this knowledge is of crucial importance.
Written by Marília Horta Jung, MENDELU