# The sugar transporter ZmSWEET11 participates in plant autophagy to respond to salt stress

## TL;DR

The ZmSWEET11 protein helps plants tolerate salt stress by enhancing autophagy, a process that helps cells survive under stress.

## Contribution

This study is the first to show a direct interaction between ZmSWEET11 and autophagy-related proteins in response to salt stress.

## Key findings

- ZmSWEET11 is localized to the plasma membrane and is induced by salt stress in maize seedlings.
- Overexpression of ZmSWEET11 in Arabidopsis increases salt tolerance and autophagosome abundance.
- ZmSWEET11 interacts with autophagy-related proteins ZmATG2a, ZmATG2b, ZmATG8e, and ZmATG18f.

## Abstract

The sugar will eventually be exported transporters (SWEET) proteins play an important role in plant growth, development and stress responses. However, current research on the function of SWEET proteins in maize in response to salt stress is limited. In this study, we characterized the function of ZmSWEET11, a gene involved in salt stress response and autophagy induced by salt stress in plants. ZmSWEET11 is primarily expressed in the stems and is significantly induced by salt stress at maize seedlings stage. Subcellular localization analysis showed that ZmSWEET11 is localized to the plasma membrane. Gene silencing of ZmSWEET11 via the technology of virus-induced gene silencing (VIGS) impaired maize salt tolerance and autophagic activity. Furthermore, we also determined that ZmSWEET11 interacts with autophagy-related (ATG) proteins (ZmATG2a, ZmATG2b, ZmATG8e and ZmATG18f). Overexpression of ZmSWEET11 in Arabidopsis led to enhanced salt tolerance and increased autophagosome abundance, whereas the atsweet11 mutant exhibited salt sensitivity. Taken together, our study demonstrated that ZmSWEET11 improves salt tolerance and autophagic activity both in maize and Arabidopsis seedlings, thereby mediating tolerance to abiotic stresses in plants. This is the first confirmation of a direct interaction between ZmSWEET11 and autophagic proteins, and shows that autophagy is closely with sugar transport in response to salt stress, thereby filling a gap in understanding the molecular mechanism of autophagy.

Our study demonstrated that ZmSWEET11 (sugar will eventually be exported transporters) improves salt tolerance by regulating autophagic activity both in maize and Arabidopsis seedlings, thereby mediating tolerance to their abiotic tolerance under salt stress.