Functional Characterization Of The PUK2Genes In Fusarium Graminearum

Head blight, caused by Fusarium graminearum, is a significant disease among cerealcrops, including wheat and barley. The danger posed by this fungus is multifaceted. It causesyield and quality losses due to sterility of the florets and formation of discoloured, blasted andgrain weight-less. These characteristics cause difficulties for marketing, exporting and treatinginfected commissariat. Additionally, infected grains may contain significant levels oftrichothecenes and the oestrogenic mycotoxin, zearelanone, which are dangerous to humansand animals, thus making the grain unfit for food or feed.To date，through plant cultivarshighly to resistant the disease or tolerant the oxin currently are not available. Moreover, it islimited by cost that use of fungicides for controlling the disease, difficulty in efficientapplication to wheat heads. Therefore, to analysis the genes functional characterization inFusarium graminearum is important for control FHB.Plant infection is initiated by ascospores as the primary inoculum in wheat florets fromanthesis through the soft stage of kernel development. In this study, we identified a novelprotein kinase gene, FGSG₀1058, that is necessary for normal sexual production inFusarium graminearum. This gene was well conserved in filamentous fungus but lacks adistinct ortholog in Saccharomyces cerevisiae. It was named PUK2for protein kinase geneunique to filamentous fungi2. It belongs to the AGC/NDR protein kinase family. About thefunactional of PUK2have not to be reported.We got puk2mutant by technique of gene knockout. Research on its biologicalcharacteristics, we found that deletion of the PUK2gene had no effect on growth, conidiation,or colony morphology. The PUK2mutant also was normal in stress responses. However, itwas defective in sexual reproduction. Ascospores produced by the puk2mutant oftenfragmented two-celled and fragmented in the middle. The number of ascospores per ascuswas reduced in the mutant and ascospores were rarely discharged from perithecia. But thegermination of ascospores was normal. In wheat head infection assays, the puk2mutant wasreduced in virulence. When the stalk rot areas were measured, the virulence of the puk2deletion mutants were reduced. However, corn silks assays resulted was normal. We suggestthat puk2mutant may play a host tissue-specific role in plant infection. To determine theexpression and localization of PUK2, we generated an PUK2-GFP fusion construct andtransformed it into the PUK2mutant. GFP signals were not detectable in conidia. However, GFP signals were present in nuclei in12h mycelium. In ascogenous tissues, GFP signals were present incytoplasm. Ascogenous tissues had stronger fluorescence signals than12h mycelium.Through qRT-PCRto measuted the expression of puk2gene, the resulted was consistent with fluorescence microscopy.Because of the important of ascospores in the infection cycle of F. graminearum, PUK2is a suitablefungicide target to control FHB.