The Chinese wild grapevine (Vitis pseudoreticulata) E3 ubiquitin ligase Erysiphe necator-induced RING finger protein 1 (EIRP1) activates plant defense responses by inducing proteolysis of the VpWRKY11 transcription factor.

Summary Ubiquitin-mediated regulation responds rapidly to specific stimuli; this rapidity is particularly important for defense responses to pathogen attack. Here, we investigated the role of the E3 ubiquitin ligase Erysiphenecator-induced RING fingerprotein 1 (EIRP1) in the defense response of Chinese wild grapevine Vitis pseudoreticulata. The regulatory function of E3 ubiquitin ligaseEIRP1 was investigated using molecular, genetic and biochemical approaches. EIRP1 encodes a C3HC4-type Really Interesting New Gene ( RING) fingerprotein that harbors E3 ligase activity. This activity requires the conserved RING domain, and VpWRKY11 also interacts with EIRP1 through the RING domain. VpWRKY11 localizes to the nucleus and activates W-box-dependent transcription in planta. EIRP1 targeted VpWRKY11 in vivo, resulting in VpWRKY11 degradation. The expression of EIRP1 and VpWRKY11 responds rapidly to powdery mildewin Vitis pseudoreticulata grapevine; also, overexpression of EIRP1 in Arabidopsis confers enhanced resistance to the pathogens Golovinomyces cichoracearum and Pseudomonas syringaepv tomato DC3000. Our data suggest that the EIRP1 E3 ligase positively regulates plant disease resistanceby mediating proteolysis of the negative regulator VpWRKY11 via degradation by the 26S proteasome.