Functional Analysis Of Fgwc1,fgwc2 And Fgvvd Genes In Fusarium Graminearum

Wheat head blight is an important fungal disease that occurs on wheat and widespread in the warm and humid areas of the world.It affects the yield of wheat and the toxins are harmful to the life and health of humans and animals.The perithecium formed in sexual reproduction is the main form of this fungus for overwintering.At the same time there the sexual spores(ascospores)are the initial infection source during epidemics.Sexual reproduction also maintains the genetic diversity and stability of the pathogenicity-related genes,thereby enhancing the ability to adapt host plants.Therefore,the understanding of sexual reproduction is a prerequisite for comprehensive control of wheat head blight.As one of the most important environmental factors affecting the biological growth and development,light plays an important role in the growth and development,metabolic activities and physiological cycle of plant pathogenic fungi.At the same time,Gibberella zeae(Schw.Petch),which is the main pathogenic fungus of wheat head blight,needs to induce the formation of ascospores in blue light,so we think that blue light plays an important role in sexual reproduction in Gibberella zeae.Therefore,in this paper,Fusarium graminearum(Fg),the main pathogenic fungus of wheat head blight,was used to study the function of Fgwc1,Fgwc2 and Fgvvd genes of Fusarium graminearum by means of reverse genetics,so as to better understand the role of light signal played in sexual reproduction and pathogenic process.The main findings are as follows:(1)Firstly the gene sequences of blue light receptor genes Fgwc1,Fgwc2 and Fgvvd were predicted from the F.graminearum database.Bioinformatics analysis showed that the WC genes Fgwc1 and Fgwc2 were highly conserved with other fungus and had the LOV domain as light receptor.(2)In this study,Fgwc1,Fgwc2 and Fgvvd gene of F.graminearum were knocked out and complemented by Split Marker and PEG-mediated protoplast transformation,then the knockout and complementary transformants were obtained.(3)Functional study of Fgwc1 and Fgwc2: Growth and phenotypic analysis showed that the defect of Fgwc1 and Fgwc2 had no effect on colony morphology,mycelial growth rate,conidia sporulation and morphology of F.graminearum.The study of stress screening showed that the absence of Fgwc1 and Fgwc2 did not affect the function of oxygen partial pressure sensitivity,cell wall and cell membrane,buthad a significant effect on osmotic pressure.Compared with wild type strains and complementary mutant strains,Fgwc1 and Fgwc2 knockout mutant strains enhanced the ability of osmotic pressure.Fgwc1 and Fgwc2 did not affect the ability of F.graminearum to produce perithecium,and the morphology of the ascospores were not different from that of the wild type strains.However,the knockout mutation of Fgwc1 and Fgwc2 could advance the eruption time of ascospores.The pathogenicity study found that the deletion of Fgwc1 and Fgwc2 reduced the pathogenicity of F.graminearum..(4)Function study of Fgvvd: The deletion △Fgvvd did not affect the colonymorphology,mycelial growth rate,conidia sporulation and morphology,osmotic pressure,oxygen partial pressure sensitivity,the function of cell wall and cell membrane of F.graminearum.However,the defect of Fgvvd affected the sexual reproduction of F.graminearum.Compared with the wild type strains,which can produce dense and uniform size perithecium,the perithecium produced by the △Fgvvdmutant strain are sparse and small in size and the medium is filled dense and messy white hyphae.Subsequently extruding out of the ascus flowers to observe,△Fgvvd knockout mutant strains like the wild type strains,could produce normalascus,and the morphology of ascospores were also normal.