Systematic Characterization of the Nine Components Involved in the MAPK Cascades in the Peach Shoot Blight Fungus <i>Diaporthe amygdali</i>

As a causative agent of peach shoot blight, <i>Diaporthe amygdali</i> poses a substantial threat to the peach industry. However, no molecular studies on this pathogen have been reported to date. The three mitogen-activated protein kinase (MAPK) cascades are highly conserved among fungal species and exert a considerable influence on the developmental and pathogenic processes of these organisms. Here, the genome of <i>D. amygdali</i> strain ZN32 was sequenced and compared with that of four other <i>Diaporthe</i> isolates. Nine proteins involved in the three MAPK cascades were identified: Mst11-Mst7-Pmk1 (Pmk1-MAPK cascade), Mck1-Mkk1-Mps1 (Mps1-MAPK cascade), and Ssk2-Pbs2-Osm1 (Osm1-MAPK cascade). Deletion of the genes encoding the Pmk1- and Mps1-MAPK cascade proteins and an adaptor protein, DaMst50, significantly attenuated the vegetative growth, abolished the asexual reproduction, compromised the stress response, impacted the surface hydrophobicity, and markedly reduced the pathogenicity of <i>D. amygdali</i>. However, deletion of the genes encoding the Osm1-MAPK cascade proteins only affected stress response regulation. Additionally, DaMst11 interacted with both DaMst7 and DaMst50, and no interactions were observed between other proteins in Pmk1- and Mps1-MAPK cascades using a yeast two-hybrid system. Finally, heterologous expression of Pmk1-encoding genes from <i>Magnaporthe oryzae</i> and <i>Valsa mali</i> completely rescued the asexual reproduction and virulence defects in the Δ<i>Dapmk1</i> mutants but only partially restored the vegetative growth. Overall, our findings expand the existing knowledge about the role of the MAPK cascades in plant-pathogenic fungi. The genomic information and genetic transformation system provided by this study will greatly contribute to elucidating the pathogenic mechanism of <i>D. amygdali</i> and effectively managing orchard diseases. [Formula: see text] Copyright © 2025 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.