Endogenous Cytokinin Overproduction Modulates ROS Homeostasis and Decreases Salt Stress Resistance in Arabidopsis Thaliana.

Yanping Wang,Zhulong Chan,Yan Wu,Wenzhong Shen

doi:10.3389/fpls.2015.01004

Abstract

Cytokinins in plants are crucial for numerous biological processes, including seed germination, cell division and differentiation, floral initiation and adaptation to abiotic stresses. The salt stress can promote reactive oxygen species (ROS) production in plants which are highly toxic and ultimately results in oxidative stress. However, the correlation between endogenous cytokinin production and ROS homeostasis in responding to salt stress is poorly understood. In this study, we analyzed the correlation of overexpressing the cytokinin biosynthetic gene AtIPT8 (adenosine phosphate-isopentenyl transferase 8) and the response of salt stress in Arabidopsis. Overproduction of cytokinins, which was resulted by the inducible overexpression of AtIPT8, significantly inhibited the primary root growth and true leaf emergence, especially under the conditions of exogenous salt, glucose and mannitol treatments. Upon cytokinin overproduction, the salt stress resistance was declined, and resulted in less survival rates and chlorophyll content. Interestingly, ROS production was obviously increased with the salt treatment, accompanied by endogenously overproduced cytokinins. The activities of catalase (CAT) and superoxide dismutase (SOD), which are responsible for scavenging ROS, were also affected. Transcription profiling revealed that the differential expressions of ROS-producing and scavenging related genes, the photosynthesis-related genes and stress responsive genes were existed in transgenic plants of overproducing cytokinins. Our results suggested that broken in the homeostasis of cytokinins in plant cells could modulate the salt stress responses through a ROS-mediated regulation in Arabidopsis.

Highlights

Cytokinins play important and complex roles in plant growth and abiotic stress responses (Wang et al, 2011; Ha et al, 2012; Hwang et al, 2012; Zwack and Rashotte, 2015)
Through analyzing inducible-AtIPT8 overexpression transgenic plants we investigated the effects of modulating endogenous cytokinin production in salt treatments
Results in this study demonstrated that inducible AtIPT8 overexpression could significantly promote endogenous cytokinin overproduction, and affect the responses of Arabidopsis plants to salt stresses

Summary

Introduction

Cytokinins play important and complex roles in plant growth and abiotic stress responses (Wang et al, 2011; Ha et al, 2012; Hwang et al, 2012; Zwack and Rashotte, 2015). Cytokinins Overproduction and Salt Responses in plants (Kudoyarova et al, 2007; Ghanem et al, 2008; Merewitz et al, 2011; Nishiyama et al, 2011). Both short-term and sustained increase in cytokinin levels may occur in plants while encountering severe stress conditions (Pospisilova et al, 2005; Alvarez et al, 2008; Dobra et al, 2010). Many studies have examined the effects of exogenous cytokinin applications in abiotic stress responses. Decrease in cytokinin levels produce a positive consequence in drought tolerance (Rivero et al, 2007; Werner et al, 2010; Qin et al, 2011; Macková et al, 2013)

Methods

Results

Conclusion