Penicillium expansum is a destructive phytopathogen causing postharvest decay on many stored fruits. To develop effective and safe management strategies, it is important to investigate its pathogenicity-related mechanisms. In this study, a bioinformatic pipeline was constructed and 50 core effector genes were identified in P. expansum using multiple RNA-seq data sets and their putative functions were implicated by comparatively homologous analyses using pathogen–host interaction database. To functionally characterize P. expansum LysM domain proteins during infection, null mutants for the 15 uncharacterized putative LysM effectors were constructed and the fungal growth rate on either PDA or Cazpek medium or lesion expansion rate on the infected apple fruits was evaluated. The results showed the growth rate of knockout mutants from PeLysM5, PeLysM12 and PeLysM15 was retarded on PDA medium. No significant difference in growth rate was observed between wild type and all mutants on solid Cazpek medium. Nevertheless, the hypha of wild type displayed deeper yellow on the back of Cazpek medium than those of knockout mutants. On the infecting apples fruits, the knockout mutants from PeLysM5, PeLysM7, PeLysM8, PeLysM9, PeLysM10, PeLysM11, PeLysM14, PeLysM15, PeLysM16, PeLysM18 and PeLysM19 showed enhanced fungal virulence, with faster decaying on infected fruits than those from wild type. By contrast, the knockout mutation at PeLysM12 locus led to reduced lesion expansion rate on the infected apple fruits. In addition, P. expansum-apple interaction RNA-seq experiment was performed using apple fruit tissues infected by the wild type and knockout mutant ΔPeLysM15, respectively. Transcriptome analyses indicated that deletion of PeLysM15 could activate expression of several core effector genes, such as PEX2_055830, PEX2_036960 and PEX2_108150, and a chitin-binding protein, PEX2_064520. These results suggest PeLysM15 may play pivotal roles in fungal growth and development and involve pathogen–host interaction by modulating other effector genes’ expression. Our results could provide solid data reference and good candidates for further pathogen-related studies in P. expansum.

扩张青霉是一种破坏性的植物病原体，可导致许多贮藏水果的采后腐烂。为了制定有效和安全的管理策略，研究其致病性相关机制非常重要。在这项研究中，构建了一条生物信息学管道，并使用多个RNA-seq数据集在膨胀假单胞菌中鉴定了50个核心效应基因，并使用病原体-宿主相互作用数据库进行了相对同源的分析，推测了它们的推定功能。在功能上表征膨胀假单胞菌感染过程中的LysM结构域蛋白，构建了15个未表征的假定LysM效应子的无效突变体，并评估了PDA或Cazpek培养基上的真菌生长速率或感染的苹果果实上的病变扩展率。结果表明，在PDA培养基上，PeLysM5，PeLysM12和PeLysM15的敲除突变体的生长速率受到抑制。在野生型和固体Cazpek培养基上的所有突变体之间，均未观察到生长速率的显着差异。然而，野生型的菌丝在Cazpek培养基的背面显示出比敲除突变体更深的黄色。在感染的苹果果实上，PeLysM5，PeLysM7，PeLysM8，PeLysM9，PeLysM10，PeLysM11，PeLysM14，PeLysM15，PeLysM16，PeLysM18和PeLysM19表现出增强的真菌毒力，受感染果实的腐烂速度快于野生型。相比之下，PeLysM12位点的敲除突变导致受感染苹果果实上的病灶扩展率降低。另外，P。对扩展-苹果相互作用RNA-SEQ实验使用由野生型感染苹果果实组织进行和敲除突变体ΔPeLysM15，分别。转录组分析表明，删除PeLysM15可以激活几个核心效应基因的表达，例如PEX2_055830，PEX2_036960和PEX2_108150以及几丁质结合蛋白PEX2_064520。这些结果表明，PeLysM15可能在真菌的生长和发育中起关键作用，并通过调节其他效应基因的表达而参与病原体与宿主的相互作用。我们的结果可以为扩展的体育病原体相关研究提供可靠的数据参考和良好的候选人。