The Small Cysteine-Rich Protein VdSCP23 Manipulates Host Immunity

Verticillium wilt caused by is a notorious soil-borne fungal disease and seriously threatens the yield of economic crops worldwide. During host infection, secretes many effectors that manipulate host immunity, among which small cysteine-rich proteins (SCPs) play an important role. However, the exact roles of many SCPs from are unknown and varied. In this study, we show that the small cysteine-rich protein VdSCP23 inhibits cell necrosis in leaves, as well as the reactive oxygen species (ROS) burst, electrolyte leakage and the expression of defense-related genes. VdSCP23 is mainly localized in the plant cell plasma membrane and nucleus, but its inhibition of immune responses was independent of its nuclear localization. Site-directed mutagenesis and peptide truncation showed that the inhibition function of VdSCP23 was independent of cysteine residues but was dependent on the -glycosylation sites and the integrity of VdSCP23 protein structure. Deletion of did not affect the growth and development of mycelia or conidial production in . Unexpectedly, deletion strains still maintained their virulence for , and seedlings. This study demonstrates an important role for VdSCP23 in the inhibition of plant immune responses; however, it is not required for normal growth or virulence in .