Submitted to: National Fusarium Head Blight Forum Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 11/12/2015
Publication Date: 12/31/2015
Citation: Baldwin, T.T., Bregitzer, P.P. 2015. Analysis of the small interfering RNA profiles of randomly inserted pTRM-TRI6 Fusarium graminearum mutants and their DON related phenotypes. National Fusarium Head Blight Forum 2015, St. Louis MO, December 6-8, 2015, p.43. Interpretive Summary:
Technical Abstract: Deoxynivalenol (DON) production by Fusarium graminearum requires activation of the trichothecene pathway in which TRI5 catalyzes the first step of trichothecene synthesis and TRI6 is a transcription factor activates the pathway. RNA interference (RNAi) has emerged as a useful fungal genetics tool for reducing the expression of specific genes such as TRI6. Reduced DON production and virulence on wheat has been demonstrated as a result of RNAi-induced reduction of TRI6 expression via transformation of F. graminearum with the plasmid pTRM-TRI6. This plasmid contains the GDPA promoter driving TRI6 linked to an inverted repeat of TRI6 to generate a hairpin loop mRNA. Hairpin loop structures are known to be processed by the endoribonuclease dicer to produce a population of a specific type of non-coding small RNA approximately 20¬-–30 bp long, called small interfering RNA (siRNA), that silence genes with homology to siRNAs. To verify and expand on the previous study, six additional fungal transformants containing pTRM-TRI6 were produced and evaluated by next generation sequencing for siRNA with homology to TRI6 and for the genomic location of the pTRM-TRI6 insertions. The results support previous conclusions that expression of pTRM-TRI6 reduced DON production and virulence on wheat. Furthermore, experiments measuring the mycotoxin production capacity independent of host-pathogen interactions showed reduction in mycotoxin accumulation on rice cultures and lower expression of TRI5 on toxin-inducing media (TBI) in association with the production of siRNAs with homology to TRI6. Understanding the resulting siRNA profiles from RNAi constructs is critical to optimizing RNAi applications. The results are being used to guide the development of vectors for barley transformation with the goal of elevating resistance to Fusarium head blight via host induced gene silencing, which is a promising application of RNAi.