Functional Analysis Of Genes Associated With Small RNA Pathways In Fusarium Graminearum

Fusarium head blight is a fungal disease worldwide, Fusarium graminearum is the main pathogenic species of wheat scab. Scab is an economically devastating plant disease,which can cause significant reduction in seed yields and quality and produce trichothecene and estrogenic mycotoxins that possess a serious threat to animal health and food safety.Small RNAs play important roles in regulatoion of gene expression. Several key genes are significant for small RNA biogenesis and functions. Dicer splics dsRNA or stem-loop structure of the RNA to small RNAs molecules, and the Argonaute protein is a core component of the RNA-induced silencing complex (RISC). The function of the small RNA pathway related genes have been reported in many species, including some fungi, while it is not clear in F. graminearum.RT-PCR results showed that FGDCL2and FGAGL2were expressed in all detected time point in F. graminearum PH-1. We used the method of split PCR to construct the knockout vector for DCL2and AGL2. Both of them obtained two knockout transformants after PCR confirmation.We carried out a series experiments to study the biological character of knock-outstrains KOD21and KOA21. The results showed that there were no significant difference in mycelial and colony morphology, growth rate, conidia sporulation and morphology, perithecia production, ascospore morphology and pathogenicity between these knock-out strais and the original strain PH-1. But the spore germination rate, germed tube length and expression of toxin DON in KOD21and the mycelium growth during spore germination in KOA21were significant differences compared with the original strain. These results indicated that DCL2and AGO2genes are associated with spore germination and toxin production in F. graminearum. The role of these genes in regulation of small RNA processing and function in F. graminearum is need to further study. The molecular mechanism of these genes in development and pathogenicity of F. graminearum is then studied, which will serve theoretical basis for pathogenic mechanism on the other hand.