灰葡萄孢是一种典型的坏死性植物病原真菌,可以故意酸化宿主组织并触发其中的氧化爆发以促进其毒力。白领情结(WCC),由BcWCL1和BcWCL2组成,被认为是灰霉病中的主要光受体。然而,WCC组件的具体机制,特别是BcWCL2作为GATA转录因子,控制毒力尚未完全了解。该研究表明BcWCL2的缺失导致光敏表型特征的丧失。此外,Δbcwcl2菌株表现出柠檬酸盐分泌减少,延迟感染垫发育,菌丝穿透力较弱,并降低毒力。发现外源性柠檬酸的应用可以恢复感染垫的形成,菌丝渗透,和Δbcwcl2菌株的毒力。接种后48小时的转录组分析显示,两种柠檬酸合酶,推定的柠檬酸盐转运蛋白,水解酶,和活性氧清除相关基因在Δbcwcl2中下调,而外源柠檬酸的应用恢复了上述参与Δbcwcl2早期感染过程的基因的表达。此外,已知的柠檬酸盐分泌调节剂Bcvel1的表达,组织酸化,和次生代谢,在Δbcwcl2中下调,但在Δbcwcl1中不下调。ChIP-qPCR和电泳迁移率变化分析显示,BcWCL2可以与Bcvel1的启动子序列结合。发现在Δbcwcl2中过表达Bcvel1可以挽救突变缺陷。总的来说,我们的发现表明,BcWCL2调节整体调节因子Bcvel1的表达以影响柠檬酸盐的分泌,组织酸化,氧化还原稳态,和B.cinerea的毒力。重要意义本研究说明了真菌蓝光受体成分BcWCL2蛋白在调节灰葡萄孢中柠檬酸盐分泌中的意义。与BcWCL1不同,BcWCL2可能有助于在感染垫形成过程中维持氧化还原稳态,最终证明对完全毒力至关重要。还证明了BcWCL2可以调节Bcvel1的表达以影响宿主组织酸化,柠檬酸盐分泌,感染垫发育,和毒力。虽然植物病原真菌分泌的有机酸在真菌-宿主相互作用中的作用已被认识到,本文揭示了重要性,监管机制,和控制有机酸分泌的关键转录因子。这些对植物病原体致病机制的理解可以为制定有效的真菌疾病预防和治疗策略提供有价值的见解。
Botrytis cinerea is a typical necrotrophic plant pathogenic fungus which can deliberately acidify host tissues and trigger oxidative bursts therein to facilitate its virulence. The white collar complex (WCC), consisting of BcWCL1 and BcWCL2, is recognized as the primary light receptor in B. cinerea. Nevertheless, the specific mechanisms through which the WCC components, particularly BcWCL2 as a GATA transcription factor, control virulence are not yet fully understood. This study demonstrates that deletion of BcWCL2 results in the loss of light-sensitive phenotypic characteristics. Additionally, the Δbcwcl2 strain exhibits reduced secretion of citrate, delayed infection cushion development, weaker hyphal penetration, and decreased virulence. The application of exogenous citric acid was found to restore infection cushion formation, hyphal penetration, and virulence of the Δbcwcl2 strain. Transcriptome analysis at 48 h post-inoculation revealed that two citrate synthases, putative citrate transporters, hydrolytic enzymes, and reactive oxygen species scavenging-related genes were down-regulated in Δbcwcl2, whereas exogenous citric acid application restored the expression of the above genes involved in the early infection process of Δbcwcl2. Moreover, the expression of Bcvel1, a known regulator of citrate secretion, tissue acidification, and secondary metabolism, was down-regulated in Δbcwcl2 but not in Δbcwcl1. ChIP-qPCR and electrophoretic mobility shift assays revealed that BcWCL2 can bind to the promoter sequences of Bcvel1. Overexpressing Bcvel1 in Δbcwcl2 was found to rescue the mutant defects. Collectively, our findings indicate that BcWCL2 regulates the expression of the global regulator Bcvel1 to influence citrate secretion, tissue acidification, redox homeostasis, and virulence of B. cinerea.IMPORTANCEThis study illustrated the significance of the fungal blue light receptor component BcWCL2 protein in regulating citrate secretion in Botrytis cinerea. Unlike BcWCL1, BcWCL2 may contribute to redox homeostasis maintenance during infection cushion formation, ultimately proving to be essential for full virulence. It is also demonstrated that BcWCL2 can regulate the expression of Bcvel1 to influence host tissue acidification, citrate secretion, infection cushion development, and virulence. While the role of organic acids secreted by plant pathogenic fungi in fungus-host interactions has been recognized, this paper revealed the importance, regulatory mechanisms, and key transcription factors that control organic acid secretion. These understanding of the pathogenetic mechanism of plant pathogens can provide valuable insights for developing effective prevention and treatment strategies against fungal diseases.