Dicer-like genes are essential for efficient plant infection in the rubber tree powdery mildew fungus Erysiphe quercicola

Abstract The obligate parasitic fungus Erysiphe quercicola is the causal agent of powdery mildew of rubber tree (Hevea brasiliensis), posing a significant threat to the rubber tree growth and latex production. Pathogens secrete sRNAs that are crucial virulence factors capable of suppressing plant immunity. Dicer-like proteins (DCLs), as endoribonucleases, play a pivotal role in sRNA biosynthesis. However, the function of DCL in E. quercicola remains unclear. In this study, we identified and characterized two DCLs from E. quercicola, EqDCL1 and EqDCL2. Protein domain analysis and phylogenetic analysis confirmed that EqDCL1 and EqDCL2 are typical DCL proteins. Gene expression analysis revealed that EqDCL1 and EqDCL2 were induced at 10 hpi during the peak of appressorium formation. HIGS targeting EqDCL1, EqDCL2, or both EqDCL1 and EqDCL2 resulted in reduced pathogenicity of E. quercicola and increased immune responses in plants after infection. Overall, our findings demonstrate the essential role of EqDCLs during the infection process of E. quercicola, providing a foundation for further studies on RNAi mechanisms and pathogenic sRNAs in E. quercicola.