The secreted FoAPY1 peptidase promotes Fusarium oxysporum invasion

Abstract

The secretion of peptidases from several pathogens has been reported, but the biological function of these proteins in plant-pathogen interactions is poorly understood. Fusarium oxysporum, a soil-borne plant pathogenic fungus that causes Fusarium wilt in its host, can secrete proteins into host plant cells during the infection process to interfere with the host plant defense response and promote disease occurrence. In this study, we identified a peptidase, FoAPY1, that could be secreted from F. oxysporum depending on the N-terminal signal peptide of the protein. FoAPY1 belongs to the peptidase M28 family and exerts peptidase activity in vitro. Furthermore, the FoAYP1 gene knockout strain (∆FoAYP1) presented reduced virulence to tomato plants, but its mycelial growth and conidiation were unchanged. Moreover, FoAYP1 overexpression tomato seedlings exhibited enhanced susceptibility to F. oxysporum and Botrytis cinerea strains. These data demonstrated that FoAYP1 contributes to the virulence of F. oxysporum may through peptidase activity against host plant proteins.

The secreted FolAsp aspartic protease facilitates the virulence of Fusarium oxysporum f. sp. lycopersici

“…When pathogens infect and secrete effectors to host cells, the basal defense responses of plants, such as ROS bursts, resistance gene expression, and cell death, are activated to inhibit the pathogen growth and development ( Lyu et al, 2016 ; Kettles et al, 2018 ; Yang et al, 2018 ). In our study, transient expression of FolAsp protein in N. benthamiana did not induce cell death, similar to the recent findings of a peptidase effector FoAPY1 from Fol , which does not have the ability to induce cell death ( Qian et al, 2022b ). This family of aspartate proteases is also annotated by the MEROPS database as the peptidase family A1 (pepsin A, clan AA) ( Santos et al, 2013 ).…”

“…We previously performed a secretome-wide analysis in Fol to provide new sight of infection-related proteins and found that most of them with an N-terminal SP were annotated as enzymes ( Li J. et al, 2020 ). To date, three secreted proteins are shown to contribute virulence, and two of them encode the ribonuclease and peptidase, respectively ( Li et al, 2022 ; Qian et al, 2022a , b ). In this study, we characterized one aspartic protease FolAsp from the Fol secretome.…”

“…10. 3389/fmicb.2023.1103418 Proteins secreted from pathogens can be divided into two classes according to their functions: enzymatic functional proteins and non-enzymatic functional proteins (Qian et al, 2022b). Cell walldegrading enzymes (CWDEs), cutinases, proteases, peptidases, and ribonucleases can be secreted from pathogens to proceed with enzymatic function.…”

“…FoRnt2, a secreted ribonuclease T2 protein, contributes to the full virulence of F. oxysporum in tomato plants depending on its RNase activity ( Qian et al, 2022a ). The FoAYP1 contributes to the virulence of Fol through peptidase activity on host protein ( Qian et al, 2022b ). However, the function of some other secreted proteins in fungal virulence remains largely unknown.…”