Endoplasmic Reticulum Plays a Critical Role in Integrating Signals Generated by Both Biotic and Abiotic Stress in Plants.

Chang-Jin Park,Jeong Mee Park

doi:10.3389/fpls.2019.00399

Abstract

Most studies of environmental adaptations in plants have focused on either biotic or abiotic stress factors in an attempt to understand the defense mechanisms of plants against individual stresses. However, in the natural ecosystem, plants are simultaneously exposed to multiple stresses. Stress-tolerant crops developed in translational studies based on a single stress often fail to exhibit the expected traits in the field. To adapt to abiotic stress, recent studies have identified the need for interactions of plants with various microorganisms. These findings highlight the need to understand the multifaceted interactions of plants with biotic and abiotic stress factors. The endoplasmic reticulum (ER) is an organelle that links various stress responses. To gain insight into the molecular integration of biotic and abiotic stress responses in the ER, we focused on the interactions of plants with RNA viruses. This interaction points toward the relevance of ER in viral pathogenicity as well as plant responses. In this mini review, we explore the molecular crosstalk between biotic and abiotic stress signaling through the ER by elaborating ER-mediated signaling in response to RNA viruses and abiotic stresses. Additionally, we summarize the results of a recent study on phytohormones that induce ER-mediated stress response. These studies will facilitate the development of multi-stress-tolerant transgenic crops in the future.

Highlights

Being sessile organisms, plants rely on their interactions with various organisms to adapt to environmental changes
The mechanism of activation of bZIP17, which triggers abscisic acid (ABA) signaling in response to endoplasmic reticulum (ER) stress, has been elucidated in a study on seed germination in Arabidopsis; the authors showed that the Golgi apparatus-resident site-2 protease (S2P) cleaves and activates bZIP17, regulating downstream target genes that encode negative regulators of ABA signaling (Zhou et al, 2015)
Of the three known ER stress sensors, inositol-requiring enzyme 1 (IRE1) and bZIP28 are both involved in ER stress responses to viral infection and abiotic stress, whereas bZIP17 appears to be only an abiotic stress-specific sensor

Summary

Introduction

Plants rely on their interactions with various organisms to adapt to environmental changes. Two main types of ER stress sensors, which regulate different UPR signaling pathways, have been identified: ER membrane-associated basic leucine zipper (bZIP) transcription factors, bZIP28 (Srivastava et al, 2014) and bZIP17 (Liu et al, 2008), and an ER resident transmembrane protein, inositol-requiring enzyme 1 (IRE1) (Koizumi et al, 2001) (Figure 1).

Results

Conclusion