Phospholipase D1 Of Fusarium Graminearum Influences Lipid Droplet Accumulation And Autophagy And The Functional Verification Of PX Domain

Fusarium head blight（FHB）caused mainly by Fusarium graminearum is one of the main diseases in cereal crops.Phospholipase D（PLD）is an important phospholipase hydrolase,which is ubiquitous in animals,plants and microorganisms and participates in biological physiological functions and biochemical processes.Previous studies showed that FgPLD1knockout mutants of Fusarium graminearum seriously affected mycelial growth,asexual reproduction and sexual reproduction.Based on the research of FgPLD1 gene previously studied,the physiological and biochemical functions of lipid droplet accumulation regulated by FgPLD1 gene were studied.Nile red staining of FgPLD1 gene knockout mutants showed that the fluorescence signals in spores and mycelia were stronger than those in wild type.In?pld1,fluorescence quantitative PCR of genes related to lipid synthesis and degradation in Fusarium graminearum showed that the expression of FgAre2 genes related to lipid synthesis did not increase significantly,while the expression of FgDga1 and FgLor1 genes increased significantly.However,the expression of degradation-related gene FgTgl1 decreased significantly and the expression of FgYeh1 did not increase significantly,suggesting that?pld1 increased lipid accumulation in conidia and mycelia.In order to verify the function of PX domain of FgPLD1,FgPLD1 fragment of PX domain was removed and inserted into pFL2 plasmid by in vitro cloning and heat shock transformation of Escherichia coli.The above pFL2 plasmid was introduced into mutant?pld1 and FgPLD1^?PX strain was obtained by PEG mediated protoplast transformation.Phenotypic analysis of wild type,?pld1 and FgPLD1^?PX showed that the phenotype of FgPLD1^?PX was similar to that of mutant?pld1,including colony morphology,slow mycelial growth,conidial malformation and serious decline in yield and pathogenicity.These results showed that PX domain played a key role in the normal functioning of FgPLD1 gene.In conclusion,FgPLD1 plays an important role in increasing lipid droplet accumulation in conidia and mycelia,aggravating mycelial autophagy and decreasing mycelial endocytosis.By obtaining FgPLD1^?PX strains,phenotypic analysis of wild type and?pld1 showed that PX region was the key area for FgPLD1 to function normally.