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Poster

Session: Session 2 Presenting Authors at Posters (Evens)

P-092 - Light induces Phytochrome B SUMOylation to recruit the immune regulator NPR1 in nuclear condensates to activate systemic acquired resistance

Thursday, July 17, 2025
13:30 - 15:15  
Location: Confex Hall 3
Discrimination of friend from foe
Abstract Text:
The role of light in plant growth and photosynthesis, as well as its contribution to the activation of plant defense mechanisms against pathogens, remains an enigma that has yet to be fully elucidated. During infection, plants produce salicylic acid (SA), which triggers the activation of the transcriptional machinery responsible for cellular defense in distant uninfected plant regions, commonly referred to as systemic acquired resistance. In our study, we demonstrate the influence of light on the recruitment of PhyB to the chromatin of defense genes, mediated by hyperSUMOylation. Through the night this increased SA substitutes for light to maintain PhyB SUMOylation by stimulating the degradation of PhyB targeting deSUMOylase, OTS1. SUMOylated PhyB interacts with NPR1 and TGA together which binds to the promoter of PR1 defense gene. SUMOylation of PhyB in systemic tissues promotes its transition into liquid-liquid phase separation and subsequent interaction with NPR1 in the nucleus. We unravel a mechanism where light establishes and maintains immunity by regulating NPR1 function in a day/night cycle through SUMOylation of photoreceptors.