The Epsin-like clathrin adaptor protein 4 SlECA4 improves tomato heat tolerance via clathrin-mediated endocytosis.

Abstract

Clathrin-mediated endocytosis (CME) is one of the main pathways for plant cells to internalize the membrane proteins in response to changing environmental conditions. The Epsin-like Clathrin adaptor proteins (ECAs) play important roles in the assembly of clathrin coat; however, their involvement in plant response to heat stress remains unclear. Here we report that SlECA4 responded to heat stress, and the silencing and knockout of SlECA4 increased tomato sensitivity to heat stress, while the overexpression of SlECA4 enhanced tomato tolerance to heat stress. Meanwhile, the treatment with a CME inhibitor, ES9-17, reduced tomato heat tolerance. SlECA4 localized to the plasma membrane (PM), the trans-Golgi network/early endosomes (TGN/EE), and the prevacuolar compartment (PVC)/late endosomes. In SlECA4-KO line, both CME and recycling from the TGN/EE to the PM were inhibited. These data suggest that SlECA4 involved in CME. After heat treatment, more punctate structures of SlECA4:GFP accumualted in tobacco leaf epidermal cells by transient expression. Furthermore, compared to WT, the rate of CME was inhibited under heat stress in SlECA4-KO line. Taken together, the Epsin-like Clathrin adaptor protein SlECA4 plays a positive role in tomato tolerance to heat stress via the CME pathway.