Growing evidence indicates that actin cytoskeleton is involved in plant innate immune responses,but the functional mechanism remains largely unknown.Here,we investigated the behavior of a cotton profilin gene(GhPFN2) in response to Verticillium dahliae invasion,and evaluated its contribution to plant defense against this soil-borne fungal pathogen.GhPFN2 expression was up-regulated when cotton root was inoculated with V.dahliae,and the actin architecture was reorganized in the infected root cells,with a clear increase in the density of filamentous actin and the extent of actin bundling.Compared to the wild type,GhPFN2-overexpressing cotton plants showed enhanced protection against V.dahliae infection and the actin cytoskeleton organization in root epidermal cells was clearly altered,which phenocopied that of the wild-type(WT) root cells challenged with V.dahliae.These results provide a solid line of evidence showing that actin cytoskeleton reorganization involving GhPFN2 is important for defense against V.dahliae infection. Growing evidence indicates that actin cytoskeleton is involved in plant innate immune responses, but the functional mechanism remains substantial unknown. Here, we investigated the behavior of a cotton profilin gene (GhPFN2) in response to Verticillium dahliae invasion, and evaluated its contribution to plant defense against this soil-borne fungal pathogen. GhPFN2 expression was up-regulated when cotton root was inoculated with V.dahliae, and the actin architecture was reorganized in the infected root cells, with a clear increase in the actin bundling .Compared to the wild type, GhPFN2-overexpressing cotton plants showed enhanced protection against V.dahliae infection and the actin cytoskeleton organization in root epidermal cells was clearly altered, which phenocopied that of the wild-type (WT) root cells challenged with V.dahliae.These results provide a solid line of evidence that that actin cytoskeleton reorganization involving GhPFN2 is important f or defense against V.dahliae infection.