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Abstract：
Fusarium oxysporum f. sp. niveum (Fon), a soilborne phytopathogenic fungus, causes watermelon Fusarium wilt, resulting in serious yield losses worldwide. However, the underlying molecular mechanism of Fon virulence is largely unknown. The present study investigated the biological functions of six FonPUFs, encoding RNA binding Pumilio proteins, and especially explored the molecular mechanism of FonPUF1 in Fon virulence. A series of phenotypic analyses indicated that FonPUFs have distinct but diverse functions in vegetative growth, asexual reproduction, macroconidia morphology, spore germination, cell wall, or abiotic stress response of Fon. Notably, the deletion of FonPUF1 attenuates Fon virulence by impairing the invasive growth and colonization ability inside the watermelon plants. FonPUF1 possesses RNA binding activity, and its biochemical activity and virulence function depend on the RNA recognition motif or Pumilio domains. FonPUF1 associates with the actin-related protein 2/3 (ARP2/3) complex by interacting with FonARC18, which is also required for Fon virulence and plays an important role in regulating mitochondrial functions, such as ATP generation and reactive oxygen species production. Transcriptomic profiling of ΔFonPUF1 identified a set of putative FonPUF1-dependent virulence-related genes in Fon, possessing a novel A-rich binding motif in the 3\' untranslated region (UTR), indicating that FonPUF1 participates in additional mechanisms critical for Fon virulence. These findings highlight the functions and molecular mechanism of FonPUFs in Fon virulence. IMPORTANCE Fusarium oxysporum is a devastating plant-pathogenic fungus that causes vascular wilt disease in many economically important crops, including watermelon, worldwide. F. oxysporum f. sp. nievum (Fon) causes serious yield loss in watermelon production. However, the molecular mechanism of Fusarium wilt development by Fon remains largely unknown. Here, we demonstrate that six putative Pumilio proteins-encoding genes (FonPUFs) differentially operate diverse basic biological processes, including stress response, and that FonPUF1 is required for Fon virulence. Notably, FonPUF1 possesses RNA binding activity and associates with the actin-related protein 2/3 complex to control mitochondrial functions. Furthermore, FonPUF1 coordinates the expression of a set of putative virulence-related genes in Fon by binding to a novel A-rich motif present in the 3\' UTR of a diverse set of target mRNAs. Our study disentangles the previously unexplored molecular mechanism involved in regulating Fon virulence, providing a possibility for the development of novel strategies for disease management.
摘要：
尖孢镰刀菌f.sp.niveum(Fon),一种土壤传播的植物病原真菌，导致西瓜枯萎病，导致全球严重的产量损失。然而,Fon毒力的潜在分子机制在很大程度上是未知的。本研究调查了六种FonPUFs的生物学功能，编码RNA结合Pumilio蛋白，并特别探讨了FonPUF1在Fon毒力中的分子机制。一系列表型分析表明，FonPUFs在营养生长中具有不同但不同的功能，无性繁殖,大分生孢子形态，孢子萌发,细胞壁,或Fon的非生物应激反应。值得注意的是,FonPUF1的缺失通过损害西瓜植株的入侵生长和定殖能力来减弱Fon毒力。FonPUF1具有RNA结合活性，其生化活性和毒力功能取决于RNA识别基序或Pumilio结构域。FonPUF1通过与FonARC18相互作用与肌动蛋白相关蛋白2/3（ARP2/3）复合物结合，FonARC18也是Fon毒力所必需的，在调节线粒体功能中起重要作用，如ATP的产生和活性氧的产生。ΔFonPUF1的转录组学分析鉴定了Fon中一组推定的FonPUF1依赖性毒力相关基因，在3'非翻译区（UTR）中具有新的富含A的结合基序，表明FonPUF1参与了对Fon毒力至关重要的其他机制。这些发现强调了FonPUFs在Fon毒力中的功能和分子机制。重要性尖孢镰刀菌是一种毁灭性的植物病原真菌，在许多经济上重要的作物中引起血管枯萎病，包括西瓜,全世界。F.尖孢菌f.sp.nievum（Fon）在西瓜生产中导致严重的产量损失。然而,Fon发展枯萎病的分子机制仍然未知。这里,我们证明了六个推定的Pumilio蛋白编码基因（FonPUFs）差异操作不同的基本生物过程，包括应激反应，FonPUF1是Fon毒力所必需的。值得注意的是,FonPUF1具有RNA结合活性，并与肌动蛋白相关蛋白2/3复合物结合以控制线粒体功能。此外，FonPUF1通过与一组不同靶mRNA的3'UTR中存在的新型富含A的基序结合来协调Fon中一组推定的毒力相关基因的表达。我们的研究解开了以前从未探索过的调节Fon毒力的分子机制，为疾病管理的新策略的发展提供了可能。
