ERAD machinery controls the conditional turnover of PIN-LIKES in plants

Auxin is a crucial phytohormone that regulates plant development and facilitates dynamic responses to environmental changes through subcellular control mechanisms. PIN-LIKES (PILS) are auxin transport facilitators at the endoplasmic reticulum (ER) that mediate nuclear auxin abundance and signaling. Although the posttranslational regulation of PILS is important for acclimating growth responses, the molecular mechanisms involved remain largely unknown. This study demonstrates that components of the ER-associated degradation (ERAD) machinery regulate the proteasome-dependent degradation of functional PILS proteins under nonstressed conditions. We further reveal that both internal and external signals use the ERAD complex to differentially modulate the turnover rates of PILS proteins. Our findings uncover an additional physiological role of the ERAD complex in regulating PILS protein turnover. This finding uncovers the interplay between protein homeostasis at the ER and growth regulation, opening unexplored molecular avenues into how plants acclimate to internal and external cues.