The ARLA1A-NAC089 module coordinates ER-phagy with the unfolded protein response (UPR) to maintain cellular homeostasis in plant

The endoplasmic reticulum (ER) is a critical quality-control organelle for protein homeostasis within the cell. The accumulation of misfolded or unfolded proteins triggers ER stress, which can be alleviated through the unfolded protein response (UPR) and ER-phagy. These processes work in concert to preserve ER homeostasis, yet the molecular interactions between them remain poorly understood in plant. In this study, we identify the ER-anchored transcription factor NAC089 as an ER-phagy receptor acting downstream of the ADP-ribosylation factor (ARF)-like (ARL) GTPase ARLA1A under carbon starvation. Furthermore, we demonstrate that active ARLA1A inhibits ER-phagy by negatively regulating NAC089. Notably, the ARLA1A-NAC089 axis coordinates ER-phagy with the UPR to balance cell survival and death. Our findings unveil a multi-layered regulatory network that is essential for maintaining cellular homeostasis and enhancing plant adaptation to environmental stresses.