Key Laboratory of Plant Resources, Institute of Botany, Chinese Academy of Sciences, Beijing, 100093, China.
Key Laboratory of Post-Harvest Handing of Fruits, Ministry of Agriculture, Beijing, 100093, China.
Environ Microbiol. 2021 Sep;23(9):5555-5568. doi: 10.1111/1462-2920.15704. Epub 2021 Aug 10.
Penicillium expansum, as the causal agent of blue mould and a main producer of mycotoxin patulin, is a global concern for economic and food safety. To date, the nutritional requirements of the pathogen during infection and patulin biosynthesis are poorly understood. Here, we genetically characterized the role of the bZIP transcription factor PeMetR in sulfur metabolism, virulence and patulin biosynthesis of P. expansum. The PeMetR regulator is crucial for normal germination and growth on inorganic S-sources but dispensable for utilization of organic S-sources. Accordingly, it is involved in regulating the expression of genes in sulfur assimilation pathway rather than methionine metabolic processes. Disruption of PeMetR resulted in a complete loss of virulence on various fruits. Additionally, the mutant showed a remarkably reduced ability to produce patulin. Exogenous methionine could partially or completely rescue the impaired phenotypes of the mutant. Inactivation of the sulfur assimilation pathway genes, PesA, PesB, PesC, PesF, generated growth, virulence and patulin production defects similar to those of ΔPeMetR. Overall, our study provides evidence that PeMetR-mediated sulfur assimilation is essential for growth and infection and shows for the first time that regulation of sulfur assimilation affects biosynthesis of an important mycotoxin patulin in P. expansum.
扩展青霉是导致青霉病和主要产生展青霉素毒素的病原体，它对经济和食品安全构成了全球性的威胁。迄今为止，人们对病原体在感染和展青霉素生物合成过程中的营养需求知之甚少。在这里，我们通过遗传学方法研究了 bZIP 转录因子 PeMetR 在扩展青霉硫代谢、毒性和展青霉素生物合成中的作用。PeMetR 调节剂对于病原体在无机 S 源上的正常发芽和生长至关重要，但对于有机 S 源的利用是可有可无的。因此，它参与调节硫同化途径中的基因表达，而不是蛋氨酸代谢过程。PeMetR 的缺失导致其在各种水果上的毒力完全丧失。此外，突变体产生展青霉素的能力显著降低。外源性蛋氨酸可以部分或完全挽救突变体的表型缺陷。硫同化途径基因 PesA、PesB、PesC、PesF 的失活导致生长、毒性和展青霉素产生缺陷，与 ΔPeMetR 相似。总的来说，我们的研究提供了证据表明，PeMetR 介导的硫同化对于生长和感染是必不可少的，并且首次表明硫同化的调控会影响扩展青霉中一种重要真菌毒素展青霉素的生物合成。
