Succinate dehydrogenase (SDH) is an integral component of the tricarboxylic acid cycle (TCA) and respiratory electron transport chain (ETC), targeted by succinate dehydrogenase inhibitors (SDHIs). Fusarium asiaticum is a prominent phytopathogen causing Fusarium head blight (FHB) on wheat. Here, we characterized the functions of the FaSdhA, FaSdhB, FaSdhC₁, FaSdhC₂, and FaSdhD subunits. Deletion of FaSdhA, FaSdhB, or FaSdhD resulted in significant growth defects in F. asiaticum. The FaSdhC₁ or FaSdhC₂ deletion mutants exhibited substantial reductions in fungal growth, conidiation, virulence, and reactive oxygen species (ROS). The FaSdhC₁ expression was significantly induced by pydiflumetofen (PYD). The ΔFaSdhC₁ mutant displayed hypersensitivity to SDHIs, whereas the ΔFaSdhC₂ mutant exhibited resistance against most SDHIs. The transmembrane domains of FaSdhC₁ are essential for regulating mycelial growth, virulence, and sensitivity to SDHIs. These findings provided valuable insights into how the two SdhC paralogues regulated the functional integrity of SDH, ROS homeostasis, and the sensitivity to SDHIs in phytopathogenic fungi.

中文翻译：

---

琥珀酸脱氢酶亚基 SdhC 的功能分化控制亚洲镰刀菌对 SDHI 杀菌剂的敏感性、ROS 稳态和致病性

琥珀酸脱氢酶 (SDH) 是三羧酸循环 (TCA) 和呼吸电子传递链 (ETC) 的重要组成部分，是琥珀酸脱氢酶抑制剂 (SDHI) 的靶标。亚洲镰刀菌 (Fusarium asiaticum)是一种重要的植物病原体，可引起小麦赤霉病 (FHB)。在这里，我们表征了 FaSdhA、FaSdhB、FaSdhC ₁、FaSdhC ₂和 FaSdhD 亚基的功能。 FaSdhA、FaSdhB或FaSdhD的缺失会导致亚洲镰刀菌显着的生长缺陷。 FaSdhC ₁或FaSdhC ₂缺失突变体表现出真菌生长、分生孢子形成、毒力和活性氧 (ROS) 的大幅减少。pydiflumetofen (PYD) 显着诱导FaSdhC ₁表达。 Δ FaSdhC ₁突变体对 SDHI 表现出超敏性，而 Δ FaSdhC ₂突变体则对大多数 SDHI 表现出抗性。 FaSdhC ₁的跨膜结构域对于调节菌丝生长、毒力和对 SDHI 的敏感性至关重要。这些发现为了解两个 SdhC 旁系同源物如何调节植物病原真菌中 SDH 的功能完整性、ROS 稳态以及对 SDHI 的敏感性提供了宝贵的见解。