The TaSep15–like-B-TaUGGT-B2–TaVSR-B pathway positively regulates nickel stress in wheat

Abstract

The function and mechanism of proteins involved in the endoplasmic reticulum (ER) quality control system in plants in the response to heavy metals remain largely unknown. In this study, 15-kDa selenoprotein (Sep15) homolog gene (Sep15-like) was characterized in wheat. Its transcript, induced by nickel treatment, was abundant in the roots and leaves, and its protein localized to the ER. Constitutive TaSep15-like-B expression enhanced tolerance to nickel stress in wheat and Arabidopsis, likely via the regulation of ER stress homeostasis and ROS balance. Wheat UDP-glucose:glycoprotein glucosyltransferase (UGGT)-B2, a key enzyme in ER quality control with the reglucosylation of the glycoprotein, was identified as a partner of TaSep15-like-B. Further studies revealed that TaUGGT-B2 interacted with a wheat vacuolar sorting receptor B, TaVSR-B, which mediates the sorting of soluble proteins to vacuoles in the secretory pathway. Our findings revealed a mechanistic framework underlying the TaSep15-like-B-TaUGGT-B2-TaVSR-B module-mediated regulation of nickel response.