Deubiquitinase Ubp3 regulates ribophagy and deubiquitinates Smo1 for appressorium‐mediated infection by Magnaporthe oryzae

• Published in: Molecular plant pathology Vol. 23; no. 6; pp. 832 - 844
• Main Authors: Cai, Xuan, Xiang, Shikun, He, Wenhui, Tang, Mengxi, Zhang, Shimei, Chen, Deng, Zhang, Xinrong, Liu, Caiyun, Li, Guotian, Xing, Junjie, Li, Yunfeng, Chen, Xiao‐Lin, Nie, Yanfang
• Format: Journal Article
• Language: English
• Published: England John Wiley & Sons, Inc 01.06.2022; John Wiley and Sons Inc
• Subjects: appressorium formation; Ascomycota; Autophagy; Deletion mutant; deubiquitinating enzyme; Deubiquitinating Enzymes - metabolism; Fungal Proteins - genetics; Fungal Proteins - metabolism; Glycerol; Glycogen; Glycogens; GTPase-Activating Proteins - metabolism; Hydrophobic surfaces; Infections; Lipid metabolism; Lipids; Magnaporthe - metabolism; Magnaporthe oryzae; Morphology; Mutants; Nitrogen; Nitrogen - metabolism; Original; Oryza - microbiology; Plant Diseases - microbiology; Polyethylene glycol; Proteins; Rapamycin; Ras signalling; Regulation; Regulatory mechanisms (biology); ribophagy; Sirolimus - metabolism; Spores, Fungal - metabolism; Statistical analysis; Turgor; Ubiquitination; ribophagy; deubiquitinating enzyme; ubiquitination; Ras signalling; appressorium formation
• ISSN: 1464-6722; 1364-3703
• DOI: 10.1111/mpp.13196

The Ubp family of deubiquitinating enzymes has been found to play important roles in plant‐pathogenic fungi, but their regulatory mechanisms are still largely unknown. In this study, we revealed the regulatory mechanism of the deubiquitinating enzyme Ubp3 during the infection process of Magnaporthe oryzae. AUBP3 deletion mutant was severely defective in appressorium turgor accumulation, leading to the impairment of appressorial penetration. During appressorium formation, the mutant was also defective in glycogen and lipid metabolism. Interestingly, we found that nitrogen starvation and rapamycin treatment induced the ribophagy process in M. oryzae, which is closely dependent on Ubp3. In the ∆ubp3 mutant, the ribosome proteins and rRNAs were not well degraded on nitrogen starvation and rapamycin treatment. We also found that Ubp3 interacted with the GTPase‐activating protein Smo1 and regulated its de‐ubiquitination. Ubp3‐dependent de‐ubiquitination of Smo1 may be required for Smo1 to coordinate Ras signalling. Taken together, our results showed at least two roles of Ubp3 in M. oryzae: it regulates the ribophagy process and it regulates de‐ubiquitination of GTPase‐activating protein Smo1 for appressorium‐mediated infection. The deubiquitinating enzyme Ubp3 of Magnaporthe oryzae regulates the ribophagy process and de‐ubiquitinates GTPase‐activating protein Smo1 for appressorium‐mediated infection.