Endophytes are microbes capable of colonizing the inner part of plants without causing disease. In some cases, they improve host plant resilience to biotic and abiotic stresses and promote plant growth. The plant-endophyte interaction involves complex mechanisms ranging from the recruitment of the microorganisms to the colonization of internal plant tissue, with the need to escape the plant immune system. These processes are regulated by different plant and endophyte signalling molecules. Phytohormones are among these signalling compounds, but little is known about the specific ways by which they influence recruitment and colonization. The current project aims to obtain a deeper knowledge of the role of signalling compounds in plant-endophyte interactions.
To understand how phytohormones influence the composition of endophytic communities, a microbiome analysis (isolation and amplicon sequencing) of endophytic fungi was conducted on roots of tomato mutants impaired in synthesis of ethylene and jasmonic acid. The amplicon sequencing analysis showed a significant effect of the phytohormones, but only the relative abundance of a few taxa was affected (e.g. Fusarium and Pseudogymnoascus). In contrast, there was a stronger effect of plant genotype (comparison of the two wild-types) where the abundance of e.g. Thielaviopsis, Apiotrichum, Fusarium, Saitozyma and Pyrenochaeta differed significantly. The community analysis also revealed high abundance of potential pathogens (e.g. Thielaviopsis basicola and Pyrenochaeta lycopersici) and isolated strains of these species were pathogenic when tested in planta. To understand why healthy plants can harbour such a high amount of pathogenic fungi, experiments with synthetic communities holding both endophytic and pathogenic isolates are currently conducted in order to elucidate possible “natural biocontrol effects” by the endophytic fungi present in the microbiome.
“This project has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No. 676480”.