NBR1-mediated selective chloroplast autophagy is important to plant stress tolerance

ABSTRACT

Macroautophagy/autophagy is a conserved process in eukaryotes responsible for degrading unwanted or damaged macromolecules and organelles through the lysosome or vacuole for recycling and reutilization. Our previous studies revealed the degradation of chloroplast proteins through a pathway dependent on the ubiquitin proteasome system, known as CHLORAD. Recently, we demonstrated a role for selective autophagy in regulating chloroplast protein import and enhancing stress tolerance in plants. Specifically, we found that K63-ubiquitination of TOC components at the chloroplast outer envelope membrane is recognized by the selective autophagy adaptor NBR1, leading to the degradation of TOC proteins under UV-B irradiation and heat stresses in Arabidopsis. This process was shown to control chloroplast protein import and influence photosynthetic activity. Based on our results, we have, for the first time, demonstrated that selective autophagy plays a vital role in chloroplast protein degradation, specifically in response to certain abiotic stresses.

KEYWORDS:

• Arabidopsis thaliana
• chloroplast
• NBR1
• protein import
• selective autophagy

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was funded by grants from the Chinese Academy of Sciences (CAS) Strategic Priority Research Program (Type-B; project XDB27020107) to Q.L.; the National Natural Science Foundation of China (NSFC) (project 32070260) to Q.L.; NSFC (project32100193) to H.Z.