Effector Protein OhEF 2 Positively Regulates The Susceptibility Of Arabidopsis To Oidium Heveae

Powdery mildew is an obligate living parasitic fungus of the phylum Ascomycota.Through the formation of haustorium in plant cells,powdery mildew produces a large number of effector proteins to complete its infection in host cells,which causes significant crop production losses worldwide.According to previous studies,133 potential effector proteins have been predicted by the genome and transcriptome sequencing of Oidium heveae.However,the functions of these proteins in plant cell are still unclear.In this study,one of the effector protein genes,OhEF 2(Gene＿id: OH＿02339),was cloned.This gene encodes 543 amino acids.Signal peptide analysis revealed that 1-21 amino acids are signal peptide sequence.In order to study the mechanism of this effector protein in plants,the signal peptide sequence was removed and primers were designed to PCR the coding sequence which was ligated into the estrogen-induced transgenic vector p ER8.Three independent OhEF 2 transgenic plants,OhEF 2-1,OhEF 2-2 and OhEF 2-3 were screened out by estrogen induction and Western blot analysis in Arabidopsis Col-0 background.Through inoculation assay,overexpression of OhEF 2 can significantly promote the susceptibility of Arabidopsis to powdery mildew of rubber tree,but cannot improve the virulence function of Pseudomonas DC 3000,indicating that OhEF 2 may only play a role in the process of powdery mildew infection.Furthermore,effector protein OhEF 2significantly reduced the callose deposition and PR1(Pathogen-Related Gene1)gene expression induced by powdery mildew on Arabidopsis thaliana.Overall these results lay the fundation for the future study of OhEF 2 virulence mechanisms in host plants.