Abstract

Banana Fusarium wilt, caused by Fusarium oxysporum f. sp. cubense tropical race 4 (Foc TR4), poses a severe threat to the sustainable development of the global banana industry. Glycosylphosphatidylinositol (GPI)-anchored proteins play essential roles in maintaining fungal cell wall integrity and mediating host interactions; however, their functions in Foc TR4 remain largely unknown. In this study, we identified and characterized a GPI-anchored protein gene, FocGPI1 , in Foc TR4. Bioinformatic analyses showed that FocGPI1 is highly conserved among plant pathogenic fungi and contains a functional signal peptide and a predicted GPI-anchoring site. We further generated knockout (Δ FocGPI1 ), complementation ( FocGPI1 -C), and overexpression ( FocGPI1 -OE) mutant strains via homologous recombination. Pathogenicity assays demonstrated that deletion of FocGPI1 significantly reduced the virulence of Foc TR4 on banana. Δ FocGPI1 also exhibited markedly impaired hyphal growth, conidiation and hyphal penetration. In addition, Δ FocGPI1 showed increased sensitivity to oxidative, and cell wall integrity stresses and altered utilization of cellulose, pectin, and chitin. Transcriptome analysis revealed that, during early infection, Δ FocGPI1 significantly induced host reactive oxygen species bursts and callose deposition, accompanied by upregulation of multiple plant defense-related genes. Subcellular localization analysis indicated that FocGPI1 exhibits a special dual localization at the plasma membrane and nucleus in plant cells. Collectively, FocGPI1 is a critical effector required for virulence in Foc TR4. It facilitates successful infection by modulating fungal growth, stress tolerance, and suppression of host basal immune responses. This study provides new insights into the pathogenic mechanisms of Foc TR4 and suggests that FocGPI1 could serve as a potential molecular target for effective control of banana wilt.