Oomycete Soil Diversity Associated with Betula and Alnus in Forests and Urban Settings in the Nordic–Baltic Region

• Published in: Journal of Fungi
• Main Authors: Taavi Riit, Michelle Cleary, Kalev Adamson, Mimmi Blomquist, Daiva Burokienė, Diana Marčiulynienė, Jonàs Oliva, Anna Poimala, Miguel Angel Redondo, Gunn Mari Strømeng, Venche Talgø, Leho Tedersoo, Iben Margrete Thomsen, Anne Uimari, Johanna Witzell, Rein Drenkhan
• Format: Article in Journal/Newspaper
• Language: English
• Published: MDPI AG 2023
• Subjects: oomycete community; metabarcoding; soil community; soil microbe; Phytophthora; plant pathogen; Biology (General); QH301-705.5; Fennoscandian
• Online Access: https://doi.org/10.3390/jof9090926; https://doaj.org/article/38a89d1be596468491c76f9cb5589b13

This study aimed to determine the differences and drivers of oomycete diversity and community composition in alder- and birch-dominated park and natural forest soils of the Fennoscandian and Baltic countries of Estonia, Finland, Lithuania, Norway, and Sweden. For this, we sequenced libraries of PCR products generated from the DNA of 111 soil samples collected across a climate gradient using oomycete-specific primers on a PacBio high-throughput sequencing platform. We found that oomycete communities are most affected by temperature seasonality, annual mean temperature, and mean temperature of the warmest quarter. Differences in composition were partly explained by the higher diversity of Saprolegniales in Sweden and Norway, as both total oomycete and Saprolegniales richness decreased significantly at higher longitudes, potentially indicating the preference of this group of oomycetes for a more temperate maritime climate. None of the evaluated climatic variables significantly affected the richness of Pythiales or Peronosporales. Interestingly, the relative abundance and richness of Pythiales was higher at urban sites compared to forest sites, whereas the opposite was true for Saprolegniales. Additionally, this is the first report of Phytophthora gallica and P . plurivora in Estonia. Our results indicate that the composition of oomycetes in soils is strongly influenced by climatic factors, and, therefore, changes in climate conditions associated with global warming may have the potential to significantly alter the distribution range of these microbes, which comprise many important pathogens of plants.