OsHLP1 is an endoplasmic-reticulum-phagy receptor in rice plants

The endoplasmic reticulum (ER) is the largest intracellular endomembrane system; it shows dynamic changes upon environmental stress. To maintain ER morphology and homeostasis under stress, the excessive ER membrane and the associated unwanted proteins can be removed via ER-phagy. Although a few ER-phagy receptors have been reported in mammals and yeast, their functional counterparts in plants remain largely unexplored. Here, we report that the HVA22 family protein OsHLP1 is an uncharacterized ER-phagy receptor in rice (Oryza sativa L.). OsHLP1 interacts with OsATG8b and recruits ER subdomains and the cargo protein OsNTL6, a negative immune regulator, to autophagosomes upon infection with the fungus Magnaporthe oryzae, which substantially activates disease resistance in rice. AtHVA22J, an Arabidopsis thaliana OsHLP1 ortholog, induced similar ER-phagy in plants. Altogether, we unraveled a conservative protein family that may act as ER-phagy receptors in higher plants, and in particular, we highlighted their roles in rice immune responses. [Display omitted] •OsHLP1 maintains endoplasmic reticulum (ER) homeostasis by ER-phagy in rice plants•OsHLP1 associates with OsATG8b via LIR motifs and IDR domain to activate ER-phagy•The immune regulator OsNTL6 is the cargo protein of OsHLP1-mediated ER-phagy•OsHLP1-OsATG8b-OsNTL6 module contributes to immune activation in rice plants Liang et al. report that the HVA22 family protein OsHLP1 is an endoplasmic reticulum-phagy receptor in rice (Oryza sativa L.) plants. OsHLP1 interacts with OsATG8b and recruits ER-located cargo protein OsNTL6, a negative immune regulator, to autophagosomes for degradation, which subsequently activates disease resistance in rice.