RESUMEN
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.
RESUMEN
Vesicle transport plays important roles in plant tolerance against abiotic stresses. However, the contribution of a vesicle formation related protein CaSec16 (COPII coat assembly protein Sec16-like) in pepper tolerance to salt stress remains unclear. In this study, we report that the expression of CaSec16 was upregulated by salt stress. Compared to the control, the salt tolerance of pepper with CaSec16-silenced was compromised, which was shown by the corresponding phenotypes and physiological indexes, such as the death of growing point, the aggravated leaf wilting, the higher increment of relative electric leakage (REL), the lower content of total chlorophyll, the higher accumulation of dead cells, H2O2, malonaldehyde (MDA), and proline (Pro), and the inhibited induction of marker genes for salt-tolerance and vesicle transport. In contrast, the salt tolerance of pepper was enhanced by the transient overexpression of CaSec16. In addition, heterogeneously induced CaSec16 protein did not enhance the salt tolerance of Escherichia coli, an organism lacking the vesicle transport system. By yeast two-hybrid method, an ankyrin protein, CaANK2B, was identified as the interacting protein of CaSec16. The expression of CaANK2B showed a downward trend during the process of salt stress. Compared with the control, pepper plants with transient-overexpression of CaANK2B displayed increased salt tolerance, whereas those with CaANK2B-silenced exhibited reduced salt tolerance. Taken together, both the vesicle formation related protein CaSec16 and its interaction partner CaANK2B can improve the pepper tolerance to salt stress.