Ubiquitination, an important process in post-translational modification, regulates various mechanisms in eukaryotes including protein degradation and interaction, cell cycle, stress response, and pathogenicity. The Skp1/Cullin/F-box and the endoplasmic reticulum-associated degradation (ERAD) complexes, RING E3 ligase complexes, are involved in ubiquitin-mediated proteolysis and protein quality control. The F-box protein has FBXO (F-box only or others), FBXW (with WD40), and FBXL (with LRR) classes depending on which interaction domain is present on the C-terminus. The ubiquitin system component cue (CUE) protein is a key factor of ERAD. However, the biological roles of FBXO and CUE proteins are largely unknown in plant pathogenic fungi including Magnaporthe oryzae. To elucidate the roles of FBXO and CUE proteins in fungal development and pathogenicity, MoFBX15 and MoCUE1 were functionally characterized in M. oryzae. Two ubiquitination-associated genes were crucial for conidiation, alkaline stress tolerance, and pathogenicity in M. oryzae. In particular, MoCUE1 was important for ER stress response and localization and translocation of cytoplasmic effectors. Moreover, ubiquitination and SUMOylation levels were decreased and transcript levels of deSUMOylation-associated genes were increased in ΔMofbx15 and ΔMocue1. This study will provide not only comprehensive understanding of the role of ubiquitination but also new insights on crosstalk between ubiquitination and SUMOylation in rice blast fungus and other fungal pathogens.

泛素化是翻译后修饰的一个重要过程，可调节真核生物的各种机制，包括蛋白质降解和相互作用、细胞周期、应激反应和致病性。Skp1/Cullin/F-box 和内质网相关降解 (ERAD) 复合物 RING E3 连接酶复合物参与泛素介导的蛋白水解和蛋白质质量控​​制。F-box 蛋白具有 FBXO（仅 F-box 或其他）、FBXW（带有 WD40）和 FBXL（带有 LRR）类别，具体取决于 C 端存在哪个相互作用域。泛素系统成分提示 (CUE) 蛋白是 ERAD 的关键因素。然而，FBXO 和 CUE 蛋白在包括Magnaporthe oryzae在内的植物病原真菌中的生物学作用在很大程度上是未知的。. 为了阐明FBXO和 CUE 蛋白在真菌发育和致病性中的作用，MoFBX15和MoCUE1在M. oryzae 中进行了功能表征。两个泛素化相关基因对于米曲霉的分生孢子、碱性胁迫耐受性和致病性至关重要。特别是，MoCUE1 对内质网应激反应和细胞质效应器的定位和易位很重要。此外，泛素化和 SUMOylation 水平降低，而 deSUMOylation 相关基因的转录水平在 Δ Mofbx15和 Δ Mocue1中增加. 这项研究不仅将提供对泛素化作用的全面理解，还将提供对稻瘟病真菌和其他真菌病原体中泛素化和 SUMO 化之间串扰的新见解。