Until recently, Fusarium fujikuroi was widely described as a non‐producer or a producer of little B‐series fumonisin toxins despite having a complement of fumonisin biosynthetic genes similar to those in F. verticillioides and F. proliferatum. Although high and low fumonisin‐producing F. fujikuroi strains have been shown to induce typical disease symptoms, the relationship between fumonisin production and virulence in F. fujikuroi has not been fully established. Following recent reports on the roles of bacterial endosymbionts in influencing the biology of their fungal hosts, including virulence, reproduction and the production of secondary metabolites, this study investigated the association of two strains of bacteria of the genus Enterobacter with a F. fujikuroi strain isolated from wheat in Nebraska. Results demonstrated the intracellular localization of bacteria within the hyphae of the fungus. The association with the bacteria was also correlated with macroconidia production and higher levels of virulence in the fungus. Additionally, fumonisin production was consistently and significantly (α = 0.05) higher in the bacteria‐containing F. fujikuroi strain compared with the bacteria‐free strain. Furthermore, higher levels of fumonisin production by bacteria‐containing F. fujikuroi correlated with higher expression levels of the fumonisin biosynthetic genes fum1, fum8 and fum21 under fumonisin‐inducing and non‐inducing conditions. Expression of fum15, which encodes a P450 monooxygenase, was similarly observed to be significantly (α = 0.05) higher in the bacteria‐containing fungus. Analysis of transcripts also revealed significantly (α = 0.05) higher expression of the sexual and asexual development activator protein, VeA, in the bacteria‐containing F. fujikuroi under fumonisin‐inducing conditions.

中文翻译：

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与藤本镰刀菌W343的毒力，伏马菌素生物合成基因的表达增加以及伏马菌素和大分生孢子有关的内吞菌

直到最近，藤黄镰刀菌被广泛描述为非B系列伏马菌素毒素的非生产者或生产者，尽管其伏马菌素生物合成基因的互补性与褐藻F. proticroides和F. proliferatum类似。尽管已证明高和低产伏马菌素的富士果黑菌菌株均可诱发典型的疾病症状，但伏马菌素的产生与富士果黑素菌的毒力之间的关系尚未完全建立。继有关细菌内共生菌在影响其真菌宿主生物学（包括毒力，繁殖和次级代谢产物）的生物学作用方面的最新报道之后，本研究调查了两种肠杆菌属细菌菌株与分离的F. fujikuroi菌株之间的关系。来自内布拉斯加州的小麦。结果表明细菌在真菌菌丝内的细胞内定位。与细菌的关联还与大型分生孢子的产生和真菌中较高的毒力有关。此外， 含细菌的F.fujikuroi中的伏马菌素产量持续且显着（α = 0.05）高与无细菌菌株相比。此外，在诱导伏马毒素的条件下和非诱导条件下，含细菌的F.kujikuroi产生的伏马菌素水平较高与伏马菌素生物合成基因fum1，fum8和fum21的较高表达水平相关。类似地，在含细菌的真菌中，编码P450单加氧酶的fum15的表达也显着提高（α  = 0.05）。转录本分析还显示 ，在含有伏马菌素的条件下，含有细菌的富士果黑穗病菌中性和无性发育激活蛋白VeA的表达显着（α = 0.05）。