Skip to main content
. 2019 Apr 4;10:399. doi: 10.3389/fpls.2019.00399

Figure 1.

Figure 1

ER stress responses to RNA viruses, heat and osmotic stress, and stress-related hormones in plants. Under biotic/abiotic conditions, BiP dissociates from IRE1 to bind unfolded proteins that accumulate in the ER. Activated IRE1 splices bZIP60 mRNA (bZIP60), resulting in a frame shift that generates a bZIP60 variant (bZIP60-S) targeted to the nucleus. When BiP is sequestered away, bZIP17/28 transcription factors are released from the ER to the Golgi apparatus, where they are cleaved. The cytosol-facing regions of bZIP17/28 are transported from the Golgi apparatus to the nucleus. After translocation, bZIP transcription factors upregulate the expression of stress response genes. Expression of bZIP60 is increased by viral infection. SA induces IRE1-mediated splicing of bZIP60 mRNA and proteolytic processing of bZIP28. SA regulates the expression of stress response genes via an NPR1-depenedent pathway. ABA promotes proteolytic processing of bZIP17. Dashed arrows indicate yet-uncharacterized molecular pathways.