Members of the NDR (nuclear Dbf2-related) protein-kinase family are essential for cell differentiation and polarized morphogenesis. However, their functions in plant pathogenic fungi are not well understood. Here, we characterized the NDR kinase FgCot1 and its activator FgMob2 in Fusarium graminearum, a major pathogen causing Fusarium head blight (FHB) in wheat. FgCot1 and FgMob2 formed a NDR kinase–MOB protein complex. Localization assays using FgCot1-GFP or FgMob2-RFP constructs showed diverse subcellular localizations, including cytoplasm, septum, nucleus and hyphal tip. ΔFgcot1 and ΔFgmob2 exhibited serious defects in hyphal growth, polarity, fungal development and cell wall integrity as well as reduced virulence in planta. In contrast, lipid droplet accumulation was significantly increased in these two mutants. Phosphorylation of FgCot1 at two highly conserved residues (S462 and T630) as well as five new sites synergistically contributed its role in various cellular processes. In addition, non-synonymous mutations in two MAPK (mitogen-activated protein kinase) proteins, FgSte11 and FgGpmk1, partially rescued the growth defect of ΔFgmob2, indicating a functional link between the FgCot1–Mob2 complex and the FgGpmk1 signalling pathway in regulating filamentous fungal growth. These results indicated that the FgCot1–Mob2 complex is critical for polarity, fungal development, cell wall organization, lipid metabolism and virulence in F. graminearum.

中文翻译：

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NDR激酶-MOB复合物FgCot1-Mob2调节禾谷镰刀菌的极性和脂质代谢

NDR（核 Dbf2 相关）蛋白激酶家族的成员对于细胞分化和极化形态发生至关重要。然而，它们在植物病原真菌中的功能尚不清楚。在这里，我们表征了禾谷镰刀菌中的 NDR 激酶 FgCot1 及其激活剂 FgMob2，禾谷镰刀菌是小麦中引起镰刀菌枯萎病 (FHB) 的主要病原体。FgCot1 和 FgMob2 形成了 NDR 激酶-MOB 蛋白复合物。使用 FgCot1-GFP 或 FgMob2-RFP 构建体的定位分析显示出不同的亚细胞定位，包括细胞质、隔膜、细胞核和菌丝尖端。Δ Fgcot 1 和 Δ Fgmob 2 在菌丝生长、极性、真菌发育和细胞壁完整性方面表现出严重缺陷，以及在植物中的毒力降低. 相比之下，这两个突变体的脂滴积累显着增加。FgCot1 在两个高度保守的残基（S462 和 T630）以及五个新位点处的磷酸化协同作用于其在各种细胞过程中的作用。此外，两种 MAPK（丝裂原活化蛋白激酶）蛋白 FgSte11 和 FgGpmk1 的非同义突变部分挽救了 Δ Fgmob2的生长缺陷，表明 FgCot1-Mob2 复合物与 FgGpmk1 信号通路在调节丝状真菌生长。这些结果表明，FgCot1-MOB2复杂的是极性，真菌发展，细胞壁组织，脂质代谢和毒力关键禾谷镰刀菌。