The Deubiquitinating Enzyme AMSH1 Contributes to Plant Immunity Through Regulating the Stability of BDA1.

Plants utilize plasma membrane localized receptors like kinases (RLKs) or receptor-like proteins (RLPs) to recognize pathogens and activate pattern-triggered immunity (PTI) responses. A gain-of-function mutation in the RLP leads to constitutive activation of defense responses in mutant plants. Transcription factors, SYSTEMIC ACQUIRED RESISTANCE DEFICIENT 1 (SARD1) and CALMODULIN-BINDING PROTEIN 60g (CBP60g), define two parallel pathways downstream of SNC2. The autoimmunity of was partially affected by single mutations in or but completely suppressed by the double mutant. From a suppressor screen using , we identified a deubiquitinating enzyme ASSOCIATED MOLECULE WITH THE SH3 DOMAIN OF STAM 1 (AMSH1) as a key component in SNC2-mediated plant immunity. A loss-of-function mutation in can suppress the autoimmune responses of . In eukaryotes, selective protein degradation often occurs through the ubiquitination/deubiquitination system. The deubiquitinating enzymes that remove ubiquitin from target proteins play essential roles in controlling the level of target protein ubiquitination and degradation. As loss of results in decreased BDA1 abundance and BDA1 is a transmembrane protein required for SNC2-mediated immunity, AMSH1 likely contributes to immunity regulation through controlling BDA1 stability.