Silencing of OsGRXS17 in rice improves drought stress tolerance by modulating ROS accumulation and stomatal closure

Ying Hu,Eduard Akhunov,Jungeun Park,Sunghun Park,Stuart A Sprague,Frank F White,Paul A Nakata,Ninghui Cheng,Zhao Peng,Wei Wang,Qingyu Wu,Krishna S V Jagadish,Kendal D Hirschi

doi:10.1038/s41598-017-16230-7

Abstract

Glutaredoxins (GRXs) modulate redox-dependent signaling pathways and have emerged as key mediators in plant responses to environmental stimuli. Here we report that RNAi-mediated suppression of Oryza sativa GRXS17 (OsGRXS17) improved drought tolerance in rice. Gene expression studies showed that OsGRXS17 was present throughout the plant and that transcript abundance increased in response to drought stress and abscisic acid (ABA) treatment. Localization studies, utilizing GFP-OsGRXS17 fusion proteins, indicated that OsGRXS17 resides in both the cytoplasm and the nuclear envelope. Under drought stress conditions, rice plants with reduced OsGRXS17 expression showed lower rates of water loss and stomatal conductance, higher relative water content, and enhanced survival compared to wild-type controls. Further characterization of the OsGRXS17 down-regulated plants revealed an elevation in H2O2 production within the guard cells, increased sensitivity to ABA, and a reduction in stomatal apertures. The findings demonstrate a critical link between OsGRXS17, the modulation of guard cell H2O2 concentrations, and stomatal closure, expanding our understanding of the mechanisms governing plant responses to drought.

Highlights

To mitigate cellular damage, plants have evolved a versatile ROS scavenging system that functions in conjunction with the mechanisms regulating ROS production to control cellular ROS concentrations[14,15,16]
We examined the spatial expression of OsGRXS17 in rice plants under normal and drought stress conditions and used OsGRXS17 silenced rice plants to investigate a role for OsGRXS17 in drought stress responses
Evidence was found in rice for an alternatively spliced short isoform (Os10g35720.2), which encodes a protein of 384 amino acids and consists of the TRX-like homology domain (HD) and only two monothiol GRX-HDs (Fig. 1a,b)

Summary

Introduction

Plants have evolved a versatile ROS scavenging system that functions in conjunction with the mechanisms regulating ROS production to control cellular ROS concentrations[14,15,16]. Glutaredoxins (GRXs) are ubiquitous oxidoreductases in the thioredoxin (TRX) family and are involved in maintaining cellular redox homeostasis and regulating the redox-dependent signal pathway. Based on the predicted active sites, plant GRXs can be subdivided into four groups[26,27]. Class III GRXs are specific to higher plants and have a peculiar CCxx active site. GRXs of class IV harbor a CxDC/S active site. Many studies have demonstrated Class II GRXs involvement in stress adaptation of plants[28,29,30,31,32]. A function for GRXS17 in drought stress response has not been investigated. We examined the spatial expression of OsGRXS17 in rice plants under normal and drought stress conditions and used OsGRXS17 silenced rice plants to investigate a role for OsGRXS17 in drought stress responses

Methods

Results

Conclusion