From the RIKEN Natural Products Depository (NPDepo) chemical library, we identified small molecules that alter trichothecene 15-acetyldeoxynivalenol (15-ADON) production by Fusarium graminearum. Among trichothecene production activators, a furanocoumarin NPD12671 showed the strongest stimulatory activity on 15-ADON production by the fungus cultured in a 24-well plate. NPD12671 significantly increased the transcription of Tri6, a transcription factor gene necessary for trichothecene biosynthesis, in both trichothecene-inducing and noninducing culture conditions. Dihydroartemisinin (DHA) was identified as the most effective inhibitor of trichothecene production in 24-well plate culture; DHA inhibited trichothecene production (>50% inhibition at 1 μM) without affecting fungal mass by suppressing Tri6 expression. To determine the effect of DHA on trichothecene pathway Tri gene expression, we generated a constitutively Tri6-overexpressing strain that produced 15-ADON in YG_60 medium in Erlenmeyer flasks, conditions under which no trichothecenes are produced by the wild-type. While 5 μM DHA failed to inhibit trichothecene biosynthesis by the overexpressor in trichothecene-inducing YS_60 culture, trichothecene production was suppressed in the YG_60 culture. Regardless of a high Tri6 transcript level in the constitutive overexpressor, the YG_60 culture showed reduced accumulation of Tri5 and Tri4 mRNA upon treatment with 5 μM DHA. Deletion mutants of FgOs2 were also generated and examined; both NPD12671 and DHA modulated trichothecene production as they did in the wild-type strain. These results are discussed in light of the mode of actions of these chemicals on trichothecene biosynthesis.

中文翻译：

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鉴定和鉴定禾谷镰刀菌（Fusarium graminearum）生产单端孢菌素的小分子化合物

从RIKEN天然产物保藏所（NPDepo）化学库中，我们鉴定出了可改变禾谷镰孢（Fusarium graminearum）生产的单端孢菌素15-乙酰基脱氧雪茄烯醇（15-ADON）的小分子。在单端孢菌素生产激活剂中，呋喃香豆素NPD12671在24孔板中培养的真菌对15-ADON的生产表现出最强的刺激活性。NPD12671显著上升的转录Tri6在天花粉诱导和非天花培养条件下，天花粉生物合成所必需的转录因子基因。双氢青蒿素（DHA）被认为是24孔平板培养中最有效的单端孢菌素生产抑制剂；DHA通过抑制Tri6表达来抑制单端孢菌素的产生（在1μM时抑制> 50％），而不会影响真菌的质量。为了确定DHA对单端孢菌素途径Tri基因表达的影响，我们产生了组成型Tri6在锥形瓶的YG_60培养基中产生15-ADON的超表达菌株，在这种条件下野生型不产生任何三态肽。尽管5μMDHA在诱导天花粉诱导的YS_60培养物中不能通过过表达抑制天花粉的生物合成，但在YG_60培养物中却抑制了天花粉的产生。不管组成型过表达子中高的Tri6转录水平如何，YG_60培养物在用5μMDHA处理后均显示Tri5和Tri4 mRNA的积累减少。FgOs2的缺失突变体还生成并检查了；NPD12671和DHA都像在野生型菌株中一样调节天花粉的产生。根据这些化学物质对单端孢菌素生物合成的作用方式，讨论了这些结果。