Concurrent Session
Alex Wegner (he/him/his)
Department of Molecular Plant Physiology, RWTH Aachen University
Aachen
Carl L. McCombe
Research School of Biology, The Australian National University
Canberra, Australian Capital Territory, Australia
Louisa Wirtz
Department of Molecular Plant Physiology, RWTH Aachen University
Aachen, Nordrhein-Westfalen, Germany
Ely Oliveira-Garcia
Department of Plant Pathology and Crop Physiology, Louisiana State University Agricultural Center
Baton Rouge, Louisiana, United States
Simon J. Williams, PhD (he/him/his)
The Australian National University
Canberra, Australian Capital Territory, Australia
Ulrich Schaffrath
Department of Molecular Plant Physiology, RWTH Aachen University
Aachen, Nordrhein-Westfalen, Germany
To infect plants, phytopathogenic fungi have evolved a sophisticated mechanism, utilizing secretion of small effector proteins into host cells, to suppress plant immunity. In our study*, we reported on a conserved family of effectors, known as Nudix-proteins, that play a crucial role in host colonization by forcing the plant to activate the phosphate starvation response (PSR). Using gene deletion mutants of Magnaporthe oryzae, Colletotrichum higginsianum and Colletotrichum graminicola, we demonstrated that these Nudix-effectors are essential for full virulence, suggesting a conserved mechanism among different hemi-biotrophic fungal pathogens. Cross-species complementation experiments and expression of inactive Nudix-variants in M. oryzae confirmed the importance of enzymatic activity for virulence. We solved the crystal structure of MoNUDIX and identified inositol pyrophosphate (InsP7) as its substrate. As InsP7 is sensed by plants to regulate phosphate homeostasis, its depletion caused by Nudix effectors disrupts the SPX/PHR complex, leading to translocation of the PHR transcription factor into the nucleus, followed by activation of PSR and suppression of resistance. RNA-Seq analysis confirmed the expression of PSR-related genes in relation to presence or absence of the Nudix effector. These findings provide new insights into fungal pathogenesis and may pave the way for engineering more resilient crops.
* Science, Vol 387, Issue 6737, pp. 955-962