禾谷镰刀菌缺氧诱导脱氢酶参与发育和致病性

 缺氧诱导脱氢酶(hypoxia-induced dehydrogenase, HorA)参与辅酶Q(coenzyme Q, CoQ)的生物合成。在禾谷镰刀菌(Fusarium graminearum)基因组中确定了一个缺氧诱导脱氢酶基因,命名为FgHorA。通过同源重组的方法获得FgHorA敲除突变体。研究发现,FgHorA敲除突变体出现生长和产孢的缺陷,并且延迟了分生孢子萌发,FgHorA突变体不能产生子囊壳。FgHorA突变体在小麦胚芽鞘上的致病力和产生的脱氧雪腐镰刀菌烯醇(deoxynivalenol, DON)毒素含量明显下降。FgHorA突变体表现出对盐胁迫的抗性提高,而对氧胁迫抗性降低。此外,FgHorA突变体产生的内源性活性氧明显减少。研究结果表明,禾谷镰刀菌FgHorA参与菌丝生长、无性和有性生殖、胁迫反应和致病性。

Hypoxia-induced dehydrogenase regulates development and pathogenicity in Fusarium graminearum

Hypoxia-induced dehydrogenase (HorA) participates in the biosynthesis of coenzyme Q, which is a redox carrier in the respiratory chain and responsible for ATP. A hypoxia-induced dehydrogenase gene was identified in the Fusarium graminearum genome and named FgHorA. Results showed that deletion of FgHorA is defective in mycelial growth and conidiation and delayed the germination of conidia in F. graminearum. Meanwhile, the FgHorA mutant was defective in perithecium production. The pathogenicity of the FgHorA mutant was reduced, correspondingly, the content of deoxynivalenol toxin in the FgHorA mutant was significantly decreased. Using fluorescence quantitative analysis, the expression of two genes related to toxin production, TRI5 and TRI6, was also decreased significantly compared with the wild type strain PH-1. The FgHorA mutant showed increased resistance to salt stress but decreased resistance to oxygen stress. In addition, the endogenous reactive oxygen species produced by the FgHorA mutant were reduced compared with PH-1. In summary, these results suggested that FgHorA regulates mycelial growth, asexual and sexual reproduction, stress response and pathogenicity in F. graminearum.