Data_Sheet_2_LaeA Controls Virulence and Secondary Metabolism in Apple Canker Pathogen Valsa mali.docx

Apple Valsa canker is a destructive disease caused by the ascomycete Valsa mali and poses a serious threat to apple production. Toxins synthesized by secondary metabolite biosynthetic gene clusters (SMBGCs) have been proven to be crucial for pathogen virulence. A previous study showed that V. mali genome contains remarkably expanded SMBGCs and some of their genes were significantly upregulated during infection. In this study, we focus on LaeA, a known regulator of secondary metabolism, for its role in SMBGC regulation, toxin production, and virulence of V. mali. Deletion of VmLaeA led to greatly reduced virulence with lesion length reduced by 48% on apple twigs. Toxicity tests proved that toxicity of secondary metabolites (SMs) produced by VmLaeA deletion mutant (ΔVmlaeA) was markedly decreased in comparison with wild-type (WT). Transcriptomic and proteomic analyses of WT and ΔVmlaeA indicated that a portion of transporters and about half (31/60) SMBGCs are regulated by VmLaeA. Function analysis of eight gene clusters including PKS7, PKS11, NRPS14, PKS16, PKS23, PKS31, NRPS/PKS33, and PKS39 that were differentially expressed at both transcriptional and translational levels showed that four of them (i.e., PKS11, PKS16, PKS23, and PKS31) were involved in pigment production and NRPS14 contributed to virulence. Our findings will provide new insights and gene resources for understanding the role of pathogenicity-related toxins in V. mali.

苹果瓦alsa腐烂病，由子囊菌属瓦尔斯梨（Valsa mali）引起，对苹果产量构成严重威胁。研究表明，次生代谢产物生物合成基因簇（SMBGCs）合成的毒素对于病原体致病力至关重要。前期研究表明，V. mali的基因组中SMBGCs显著扩张，其中某些基因在感染期间显著上调。本研究聚焦于LaeA，一种已知的次生代谢调节因子，探讨其在SMBGC调控、毒素产生以及V. mali致病力中的作用。VmLaeA的缺失导致致病力显著降低，苹果枝条上的病斑长度减少了48%。毒性测试证实，与野生型（WT）相比，VmLaeA缺失突变体（ΔVmlaeA）产生的次生代谢产物（SMs）的毒性显著降低。对野生型和ΔVmlaeA的转录组和蛋白质组分析表明，部分转运蛋白和约一半（31/60）的SMBGCs受到VmLaeA的调控。对包括PKS7、PKS11、NRPS14、PKS16、PKS23、PKS31、NRPS/PKS33和PKS39在内的八个基因簇的功能分析显示，其中四个（即PKS11、PKS16、PKS23和PKS31）参与色素生产，而NRPS14则有助于致病力。本研究将为理解V. mali中病原性相关毒素的作用提供新的见解和基因资源。