Fusarium circinatum is an important pathogen of pine trees. However, little is known regarding the molecular processes underlying its pathogenesis. We explored the potential role of the phytotoxin fusaric acid (FA) in the pathogenicity of the fungus. FA is produced by products of the FUB biosynthesis gene cluster, containing FUB1-12. Of these, FUB1 encodes the core polyketide synthase, which we disrupted. We used the resulting mutant strain to investigate whether FUB1 and FA production play a role in the virulence of F. circinatum on pine. Our results showed that FA production was abolished both in vitro and in planta. However, bikaverin production was increased in the knockout mutant. FUB1 disruption also corresponded with downregulation of a F. circinatum homologue of LaeA, a master transcriptional regulator of secondary metabolism. Lesion lengths produced by the FUB1 knockout mutant on inoculated Pinus patula seedlings were significantly smaller than those produced by the wild type strain. Collectively, these results show that FUB1 plays a role in FA production in F. circinatum, and that this gene contributes to the aggressiveness of F. circinatum on P. patula. This study will contribute to the limited knowledge we have about the molecular basis of pathogenicity in this fungus.

Fusarium circinatum 是一种重要的松树病原菌。然而，关于其发病机制的分子过程知之甚少。我们探讨了植物毒素镰刀酸 (FA) 在真菌致病性中的潜在作用。FA由 含有FUB1-12的FUB 生物合成基因簇的产物产生。 其中，  FUB1 编码我们破坏的核心聚酮化合物合酶。我们使用产生的突变菌株来研究 FUB1和 FA 的产生是否在F. circinatum 对松树 的毒力中起作用 。我们的结果表明，FA 的产生 在体外 和植物体内都被消除了. 然而，敲除突变体中比卡维林的产量增加。 FUB1 破坏也对应于 F. circinatum 同源物 LaeA 的下调，LaeA 是次级代谢的主要转录调节因子。FUB1 敲除突变体在接种 的Pinus patula幼苗上产生的病斑长度  明显小于野生型菌株产生的病斑长度。总的来说，这些结果表明 FUB1在F. circinatum的 FA 产生中起作用 ，并且该基因有助于 F. 的 侵袭性。 P 上的 circinatum。 帕图拉. 这项研究将有助于我们对这种真菌致病性的分子基础了解有限。