| Fusarium head blight(FHB)caused by Fusarium graminearum,is a devastating fungal disease that occurs in wheat-growing regions worldwide.The disease not only causes a serious decline in wheat yield and quality,but also secretes and accumulates a large amount of mycotoxins,such as deoxynivalenol(DON)in wheat grains.Accidental ingestion by humans and animals will cause acute poisoning symptoms such as dizziness,fever,and diarrhea,reduce the body’s immunity and fertility,and seriously threaten the health of humans and animals.China is one of the countries with the largest wheat planting area in the world.The high and stable yield of wheat is directly related to the country’s food security.Therefore,the effective prevention and control of wheat scab is an important guarantee for national food security.Whi2 was first discovered in a study to identify a cell cycle arrest gene in yeast,in addition to its involvement in the cell’s stress response.In the plant pathogens anthracnose and rice blast,Whi2 is involved in the regulation of pathogenicity.We previously identified the homologous protein Fg Whi2 of yeast Whi2 in F.graminearum.Protein multiple sequence alignment and phylogenetic tree analysis showed that Whi2 homologous proteins are relatively conserved in fungi,and therefore have relatively conserved biological functions in fungi.Analysis of RNA-seq data showed that Fg WHI2 gene was expressed in F.graminearum during sexual reproduction,asexual reproduction,plant infection,and liquid toxin production,but the expression level was low.In this study,the target gene was knocked out by PEG-mediated homologous recombination method,and the Fg WHI2 knockout mutant and the complementary strain were obtained.The biological function of Fg Whi2 in F.graminearum was revealed by systematically comparing the phenotypic differences between Fgwhi2 mutants and wild-type strains and complementary strains.The main results are as follows:1.Compared with the wild-type strains,the Fgwhi2 mutant had significantly slower colony growth rate and shorter aerial hyphae on PDA plates.It was further found that the sensitivity of Fgwhi2 mutant to oxidative stress and cell wall stress was significantly decreased;2.Shake culture in sodium carboxymethylcellulose(CMC)medium,we found that the sporulation of Fgwhi2 mutant decreased.Further observation found that its conidia became shorter,the septum was reduced,and the germination rate of conidia was also significantly reduced.it was found that Fg Whi2 was mainly located in cell septum,plasma membrane and vacuole in conidia and mycelium cells;3.During the observation of sexual reproduction,it was found that the Fgwhi2 mutant could not form ascus or ascus precursors,indicating that its sexual reproduction ability was lost;4.The pathogenicity of Fgwhi2 mutant to wheat panicle and wheat coleoptile was significantly decreased,and the synthesis of DON toxin was also significantly decreased;5.Through Western blot detection,it was found that the deletion of Fg WHI2 gene would significantly increase the degradation rate of Fg Atg8,indicating that Fg Whi2 negatively regulates the level of autophagy in cells;6.Multiple Fg Whi2 interacting proteins were identified by Pull Down and mass spectrometry data analysis,including FGRRES＿05940,FGRRES＿03319,FGRRES＿05187＿M,FGRRES＿05713＿M,FGRRES＿06576＿M,FGRRES＿09471.In summary,Fg Whi2 is involved in the process of colony growth,asexual reproduction,sexual reproduction,stress response,plant infection,DON toxin synthesis,and autophagy regulation of F.graminearum.However,the specific mechanism of Fg Whi2 remains to be further studied. |
