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About Lisa Mahdi and her project

Lisa obtained her Master degree in Biology at the University of Cologne and the Max Planck Institute for Plant Breeding Research Cologne in 2018. Her interest is in molecular plant-microbe interactions and cell death. The main objective of her PhD is to characterize molecular mechanisms underlying root-microbe multispecies interactions and cell death regulation during the accommodation of beneficial and pathogenic microbes in the root.

Tripartite system of barley and two fungi of contrasting lifestyles

The beneficial root endophyte Serendipita vermifera belongs to the ecologically relevant order Sebacinales and features a wide geographical distribution and host range. Despite a host cell death associated phase, colonization with S. vermifera results in beneficial effects on host plants, including enhanced plant biomass and increased resistance against biotic and abiotic stresses.

We recently showed that S. vermifera is able to antagonize the cereal pathogen Bipolaris sorokiniana (teleomorph Cochiobolus sativus). In the tripartite interaction with barley, S. vermifera significantly reduces the biomass of B. sorokiniana as well as disease symptoms on barley. However, this reduction does not result from lucid changes in host transcription. The genes putatively involved in fungal antagonism in soil are not induced during the tripartite interaction in planta suggesting that S. vermifera successfully antagonizes B. sorokiniana outside the plant host (Sarkar et al. 2019).

Aim of Lisa’s study is to understand how plants discriminate between beneficial and pathogenic microbes, and to identify how S. vermifera and B. sorokiniana colonize barley roots. Thereby, she wants to determine the role of host cell death in endophytic and pathogenic colonization. Secondly, she aims to determine how S. vermifera counteracts B. sorokiniana. Finally, she will focus on how the tripartite system is influenced by biotic triggers such as a bacterial synthetic community (SynCom). This project is part of the DFG funded SPP2125 DECRyPT.

Time course PAM fluorometry images of Arabidopsis seedlings from 1 to 7 days post transfer in tripartite conditions. From left to right: water (mock), S. vermifera, B. sorokiniana, S. vermifera + B. sorokiniana.