Heat induces the splicing by IRE1 of a mRNA encoding a transcription factor involved in the unfolded protein response in Arabidopsis

TLDR

Environmental stress induces ER stress in plants. Heat or ER stress triggers Arabidopsis to activate IRE1b, which splices bZIP60 mRNA to produce a transcription factor for the unfolded protein response. bZIP60 activation by IRE1b‑mediated splicing is essential for BIP3 induction during ER stress, highlighting a target for monitoring and manipulating plant stress responses.

Abstract

Adverse environmental conditions produce endoplasmic reticulum (ER) stress in plants. In response to heat or ER stress agents, Arabidopsis seedlings mitigate stress damage by activating ER-associated transcription factors and a RNA splicing factor, IRE1b. IRE1b splices the mRNA-encoding bZIP60, a basic leucine-zipper domain containing transcription factor associated with the unfolded protein response in plants. bZIP60 is required for the up-regulation of BINDING PROTEIN3 ( BIP3 ) in response to ER stress, and loss-of-function mutations in IRE1b or point mutations in the splicing site of bZIP60 mRNA are defective in BIP3 induction. These findings demonstrate that bZIP60 in plants is activated by RNA splicing and afford opportunities for monitoring and modulating stress responses in plants.