Functional characterization of conserved putative effector proteins in the Sebacinales

• Applicant: Professorin Dr. Alga Zuccaro
• Subject Area: Organismic Interactions, Chemical Ecology and Microbiomes of Plant Systems ; Plant Cell and Developmental Biology
• Term: from 2014 to 2018
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 251852814

Piriformospora indica and the closely related basidiomycete Sebacina vermifera (MAFF 305830) belong to the ecologically widely distributed Sebacinales, an order that branched off the Agaricomycotina early in the evolution and harbors a broad spectrum of mycorrhizal types. P. indica and S. vermifera are both root endophytes that display wide-host spectrum beneficial effects, such as growth promotion and increased resistance to pathogens. P. indica was isolated from the rhizosphere of the woody shrubs Prosopis juliflora and Zizyphus nummularia at the Indian Thar desert but environmental molecular analyses have unravelled a ubiquitous distribution of closely related sequences within various plants worldwide including orchids and Arabidopsis. S. vermifera was isolated from a terrestrial Australian orchid (Cyrtostylis reniformis) and is considered an orchid mycorrhizal fungus (ORM) because of its capability to stimulate seed germination and seedling development in these hosts. In cooperation with the JGI the 35 Mb genome of S. vermifera was sequenced with 200 fold coverage. The genetic transformation of this mycobiont has been established and bioinformatics tools for comparative genomics and transcriptomics (microarrays and RNA-seq) were used to identify the in planta-responsive genes. The comparison has revealed that a core of putative effector-proteins is conserved in the related sebacinoid isolates but seems to be absent in more distantly related symbionts and saprotrophic fungi. With respect to insights into how sebacinoid fungi establishes themselves in metabolically active root cells of different hosts and how the plants are reprogrammed for enhanced performance, we propose to use integrated approaches that rely on the combination of reverse genetics, transcriptomics, cell biology, biochemistry, and comparative genomics to find answers to the following questions:A) Are there functionally conserved effectors between P. indica and S. vermifera?B) How do the sebacinoid effector proteins mediate host accommodation and mutualism? C) Do ecologically different root endophytes share common colonization mechanisms and signalling?

• DFG Programme: Research Grants