Arabidopsis ubiquitin ligase MIEL1 mediatesdegradation of the transcription factorMYB30 weakening plant defence

摘要

One of the most efficient plant resistance reactions to pathogen attack is the hypersensitiveresponse, a form of programmed cell death at infection sites. The Arabidopsis transcriptionfactor MYB30 is a positive regulator of hypersensitive cell death responses. Here we showthat MIEL1 (MYB30-Interacting E3 Ligase1), an Arabidopsis RING-type E3 ubiquitin ligasethat interacts with and ubiquitinates MYB30, leads to MYB30 proteasomal degradation anddownregulation of its transcriptional activity. In non-infected plants, MIEL1 attenuates celldeath and defence through degradation of MYB30. Following bacterial inoculation, repressionof MIEL1 expression removes this negative regulation allowing sufficient MYB30 accumulationin the inoculated zone to trigger the hypersensitive response and restrict pathogengrowth. Our work underlines the important role played by ubiquitination to control thehypersensitive response and highlights the sophisticated fine-tuning of plant responses topathogen attack. Overall, this work emphasizes the importance of protein modification byubiquitination during the regulation of transcriptional responses to stress in eukaryotic cells.