Subproject 02: Protist plant pathogens as drivers of eco-evolutionary dynamics and BEF relationships in plant communities

This project investigates the roles of protist plant pathogens as microbial drivers for negative soil legacy effects in plant communities. The protist groups Oomycetes (eg Pythium) and Cercozoa (eg Plasmodiophora) contain some of the most destructive ubiquituous plant pathogens. Their resting stages accumulate and can be still viable for up to twenty years in soil, causing negative plant-soil feedbacks. Apart from crop plants, they colonize a wide range of hosts and potentially have an important but yet unknown impact on the diversity of natural plant communities. Targeted molecular environmental sequencing approaches now allow to investigate in unprecedented detail the diversity and distribution of these microbial pathogens in soil. We plan to assess the diversity and natural reservoirs of Oomycetes and Cercozoa in soils of the Jena Experiment using high-throughput Illumina sequencing. These two groups of protists are functionally diverse, spanning a range of facultative and obligatory parasites. Our central hypothesis is that microbial pathogens play a significant role in biodiversity-ecosystem function (BEF) relationships. In particular, improved productivity in plant mixtures can result from decreased plant performance at low diversity due to accumulation of microbial pathogens.