Functional Analysis Of FgATG9 In Fusarium Graminearum

Fusarium graminearum is a hemibiotrophic pathogen which causes Fusarium head blight?FHB?of small grain cereals including wheat and barley.FHB,as a global problem,can severely reduce grain yield and quality.Autophagy is a highly conserved lysosomal/vacuolar degradation pathway that is essential for cellular homeostasis and closely related to plant pathogenic fungi in some physiological functions,such as cell differentiation,pathogenicity and apoptosis.Genetic analyses performed in the yeast have identified more than 30 autophagy-related?ATG?proteins.Atg9 is one component of autophagy and plays an important role in autophagosome formation,which is a multispanning membrane protein and can provide membranes for the formation of the PAS.We identified FgATG9?FGSG₁3660?gene in Fusarium genome database using the sequence of MoAtg9?MGG₀9559?in Magnaporthe oryzae as a bait.We obtained AFgatg9 mutants and confirmed them by PCR and Southern blotting assay.Phenotypic analyses showed that disruption of FgATG9 caused reduction of growth rate and aerial hyphae,and defects in plant infection.The capacity to accumulate lipid droplets in carbon rich conditions shows no significantly difference between ?Fgatg9 mutant and wild type.However,the capacity to consume lipid droplets after a shift from carbon rich conditions to carbon starvation is severely inhibited in the ?Fgatg9 mutant strain which suggests that FgATG9 is involved in lipid metabolism.GFP-FgAtg9 is expressed during hyphal growth and spore germination stage that is similar to MoAtg9 expression pattern.And introducing MoATG9 into ?Fgatg9 mutant could restore the defects in?Fgatg9 mutant.The localization and proteolysis of GFP-FgAtg8 had changed in ?Fgatg9 mutant.Taken together,our results suggest that FgAtg9 is an important component of autophagy,and plays an important role in the vegetative growth and pathogenicity of F.graminearum.