Topless proteins, a key to gall formation for Ustilago maydis?

• Applicant: Professor Dr. Armin Djamei
• Subject Area: Organismic Interactions, Chemical Ecology and Microbiomes of Plant Systems ; Plant Breeding and Plant Pathology
• Term: since 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 536218570

Many plant-interacting biotrophs cause galls in their hosts by an induction of excessive cell division and cell enlargement. Despite their biological relevance and after many decades of intense research, till today neither the physiological networks nor the exact mechanisms of gall induction and development have been fully elucidated. Ustilago maydis, a pathogenic fungus, forms galls on all aerial parts of the maize plant which are considered a delicacy since the Aztecs time in Mexico. The U. maydis genome was first published in 2006 since then, the hunt to identify the first fungal gall-inducing effector started, but so far without success. In our preliminary work we found the involvement of a Topless-interacting effector in the induction of uncontrolled cell-division leading to callus formation if expressed in planta without the pathogen. Topless proteins are central and highly conserved co-repressors in all land plants. The callus-inducing effector provides now the opportunity to unravel the role of Topless und the underlying repressed signaling pathways employed by U. maydis to trigger uncontrolled cell-divisions. The plant signaling pathway targeted by the callus-inducing Topless-interacting effector will be revealed by biochemical, cell-biological and genetic approaches as outlined in the application. Beside the fundamental understanding which plant developmental pathway(s) the leaf-gall inducer U. maydis employs for its purpose, this research project provides with the Topless-interacting and cell-division stimulating fungal effector(s) new genetic tools to plant developmental researchers and bio-engineers.

• DFG Programme: Research Grants