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bioRxiv · 10.1101/2022.05.17.492292

A conserved enzyme of smut fungi facilitates cell-to-cell movement in the plant bundle sheath

Oekmen, B.·Jaeger, E.·Schilling, L.·Finke, N.·Lee, Y. J.·Wemhoener, R.·Pauly, M.·Neumann, U.·Doehlemann, G.
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Abstract

The smut fungi are one of the largest groups of fungal plant pathogens, causing disease in all cereal crops. They directly penetrate their hosts and establish a biotrophic interaction. During colonization of the plant, smut fungi secrete a wide range of effector proteins, which suppress plant immunity and modulate cellular functions as well as development of the host, thereby determining the pathogens life-style and virulence potential. The conserved effector Erc1 (enzyme required for cell-to-cell movement) contributes to virulence of the corn smut Ustilago maydis in maize leaves, but not on the tassel. Erc1 binds to host cell wall components and has a 1,3-{beta}-glucanase activity, which is required to attenuate {beta}-glucan-induced defense responses in host leaves. Confocal microscopy revealed that Erc1 has a cell type-specific virulence function, being necessary for fungal cell-to-cell movement in the plant bundle sheath. This cell type-specific virulence function of Erc1 is fully conserved in the barley pathogen Ustilago hordei, which has a functionally conserved Erc1 orthologue. Thus, Erc1 is an enzymatically active core virulence factor with a cell type-specific virulence function in different hosts, which is important for cell-to-cell movement during host colonization of pathogenic smut fungi.

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Oekmen, B., Jaeger, E., Schilling, L., Finke, N., Lee, Y. J., Wemhoener, R., Pauly, M., Neumann, U., Doehlemann, G.. 2022-05-18. A conserved enzyme of smut fungi facilitates cell-to-cell movement in the plant bundle sheath. https://doi.org/10.1101/2022.05.17.492292

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