Blast of foxtail millet,caused by Pyricularia setariae in the genus Pyricularia,is an epidemic fungal disease of foxtail millet.In recent years, due to climate change and the deterioration of disease resistance of millet cultivars,blast of foxtail millet has become a major threat to foxtail millet production,seriously threatening both yield and quality of foxtail millet.Therefore,it is of great significance to clarify the interaction process between P. setariae and foxtail millet for the prevention and control of millet blast.In this study,the pathogenic strain HEB07 of P. setariae was used to construct the recombinant strain HEB07 expressing green fluorescent protein(GFP).Using a fluorescence microscope,the infection process of the HEB07 recombinant strain was dynamically observed under 488 nm excitation.The experimental results revealed that the infection process of the strain exhibited distinct temporal characteristics:In the initial stage(0~12 h),conidial germination on the host surface and the formation of functional appressoria were observed. During the middle stage(12~24 h),the appressoria differentiated to produce infection pegs,followed by tissue colonization via polar growth of the hyphal tips.In the later stage(post 24 h),a hyphal network was gradually established,ultimately leading to the formation of typical lesions.The results from this study can provide strong support for the exploration of molecular mechanisms of disease resistance in foxtail millet and facilitate the breeding of disease resistant varieties.