Abstract: Ubiquitination, a critical post-translational modification, plays a pivotal role in fine tuning the immune responses of plants. The tomato (Solanum lycopersicum) suffers significant yield and quality losses caused by the devastating pathogen Botrytis cinerea. We have discovered the role of SlRAE1, a gene encoding an E3 ubiquitin ligase, as a pivotal negative regulator of resistance to B. cinerea. SlRAE1 interacts with SlSKP1, a component of the SKP1–Cullin1–F-box (SCF) complex, to modulate the protein stability of the transcription factor SlWRKY1 through the 26S proteasome pathway. SlWRKY1 targets and inhibits the transcription of SlJAZ7, a suppressor of jasmonic acid (JA) signaling, thereby activating the JA-induced defense system and affecting tomato susceptibility to B. cinerea. The resistance enhancement observed with knock-out SlRAE1 was reduced when SlWRKY1 was also knocked out, highlighting SlWRKY1's role in SlRAE1's regulation of tomato defense against B. cinerea. Our findings elucidate the defense mechanism in tomato and suggest that targeting SlRAE1, by modulating SlWRKY1 stability, could help to develop resistant tomato varieties. These insights have broader implications for using gene-editing technologies to enhance crop defense against fungi.

Key words: B. cinerea, E3 ubiquitin ligase, JA signaling, SCF complex, tomato, WRKY