ATG8i Autophagy activation is mediated by cytosolic Ca²⁺ under osmotic stress in Arabidopsis thaliana

Autophagy is a highly conserved catabolic process in eukaryotic cells that enables the degradation and recycling of damaged or unnecessary cytoplasmic components. It plays essential roles in both development and responses to environmental stress.

In this study, we investigated the regulation of autophagy in response to osmotic stress, focusing on the dynamics of the RFP-tagged ATG8i protein and the potential involvement of cytosolic calcium ion (Ca²⁺) in this process. Our findings indicate that both osmotic stress and Ca²⁺ signaling modulate the accumulation of RFP-ATG8i-labeled autophagosomes in a plant organ-specific manner. Furthermore, the observed colocalization of RFP-ATG8i with the endoplasmic reticulum (ER) marker HDEL suggests a significant role for ATG8i in ER-phagy, highlighting its potential contribution to ER turnover under stress conditions.