Up-Frameshift Factors from Phytopathogenic Fungi Play a Crucial Role in Nonsense-Mediated mRNA Decay

The nonsense-mediated mRNA decay (NMD) is extensively involved in physiological, pathological, and stress response processes in humans and plants. However, the NMD in phytopathogenic fungi has not yet been thoroughly investigated. In this study, we identified and performed domain analysis on the core components of the NMD in ten globally widespread phytopathogenic fungi that cause significant economic losses. The core components of NMD in these fungi exhibit high similarity to their homologous genes in humans, while also possessing certain specificities. The core factors of the NMD, including the Up-frameshift factors (UPFs) and the exon junction complex (EJC), are generally conserved among phytopathogenic fungi. Notably, suppressors with morphological effects on genitalia (SMG) genes are absent in these fungi, which bears some similarity to the EJC-independent NMD degradation mechanism observed in Saccharomyces cerevisiae. Interestingly, plant pathogenic fungi contain highly homologous genes of the EJC complex, suggesting the presence of an EJC-dependent NMD degradation mechanism. In summary, our findings demonstrate that NMD are prevalent in plant pathogenic fungi, providing a research foundation for subsequent studies on NMD in their growth, development, and involvement in pathogenic processes.