Arabidopsis C‐terminal binding protein ANGUSTIFOLIA modulates transcriptional co‐regulation of MYB46 and WRKY33

Abstract

The apparent antagonism between Salicylic Acid (SA) and Jasmonic acid (JA)/Ethylene (ET) signaling resulting in tradeoffs between defense against (hemi)biotrophic and necrotrophic pathogens has been widely described across multiple plant species. However, the underlying mechanism remains to be fully established. The molecular and cellular function of ANGUSTIFOLIA (AN) were characterized, and its roles in regulating pathogenic response were studied in Arabidopsis. We demonstrated that AN, a plant homolog of mammalian C‐TERMINAL BINDING PROTEIN (CtBP), antagonistically regulates plant resistance to the hemibiotrophic pathogen Pseudomonas syringae and the necrotrophic pathogen Botrytis cinerea . Consistent with the phenotypic observations, transcription of genes involved in SA and JA/ET pathways was antagonistically regulated by AN. By interacting with another nuclear protein TYROSYL‐DNA PHOSPHODIESTERASE1 (TDP1), AN imposes transcriptional repression on MYB46 , encoding a transcriptional activator of PHENYLALANINE AMMONIA‐LYASE (PAL ) genes which are required for SA biosynthesis, while releasing the TDP1‐imposed transcriptional repression on WRKY33 , a master regulator of the JA/ET signaling pathway. These findings demonstrate that the transcriptional co‐regulation of MYB46 and WRKY33 by AN mediates the coordination of SA and JA/ET pathways to optimize defenses against (hemi)biotrophic and necrotrophic pathogens.