Differential Thigmotropic Capacities Among Fusarial Isolates: Fusarium solani Species Complex (FSSC) Isolates Most Potent.

Members of Fusarium oxysporum species complex (FOSC) and Fusarium solani species complex (FSSC) are common etiologic agents of opportunistic mycoses. Their hyphae grow via apical extension followed by invasion of host epithelial surfaces, particularly corneal and epithelial tissues. Thigmotropism is the contact-sensing response of these growing hyphae to change the direction of their apical growth in response to changes in the topography of their contacted surfaces, such as clefts between adjacent host cells. Investigations of fungal thigmotropism among etiologic agents of opportunistic mycoses are sparse. In this study, we assessed thigmotropic capacities of 10 fusarial strains. Thigmotropic activity was quantified using a chemotaxicell system followed by scanning electron microscopy (SEM). Isolates belonging to the FSSC had significantly greater rates of thigmotropism than FOSC strains (p < 0.0001). In summary, this work offers a creative method to assess thigmotropism, a crucial aspect of fungal pathogenesis, and, secondly, demonstrates potent thigmotropic capacities of fusarial isolates belonging to the FSSC.