Down-Regulation of OsSPX1 Causes High Sensitivity to Cold and Oxidative Stresses in Rice Seedlings

Chunchao Wang,Chao Di,Hong Yan,Kang Zhang,Yuanjun Tan,Ling Wang,Fengxia Liu,Wenying Xu,Jingjuan Yu,Zhen Su,Linna Zhao,Qiang Wei,Chuanqing Sun,Wenqiong J Chen,Tai Wang

doi:10.1371/journal.pone.0081849

Chunchao Wang, Chao Di + Show 13 more

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https://doi.org/10.1371/journal.pone.0081849

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Abstract

Rice SPX domain gene, OsSPX1, plays an important role in the phosphate (Pi) signaling network. Our previous work showed that constitutive overexpression of OsSPX1 in tobacco and Arabidopsis plants improved cold tolerance while also decreasing total leaf Pi. In the present study, we generated rice antisense and sense transgenic lines of OsSPX1 and found that down-regulation of OsSPX1 caused high sensitivity to cold and oxidative stresses in rice seedlings. Compared to wild-type and OsSPX1-sense transgenic lines, more hydrogen peroxide accumulated in seedling leaves of OsSPX1-antisense transgenic lines for controls, cold and methyl viologen (MV) treatments. Glutathione as a ROS scavenger could protect the antisense transgenic lines from cold and MV stress. Rice whole genome GeneChip analysis showed that some oxidative-stress marker genes (e.g. glutathione S-transferase and P450s) and Pi-signaling pathway related genes (e.g. OsPHO2) were significantly down-regulated by the antisense of OsSPX1. The microarray results were validated by real-time RT-PCR. Our study indicated that OsSPX1 may be involved in cross-talks between oxidative stress, cold stress and phosphate homeostasis in rice seedling leaves.

Highlights

The SPX domain, a domain of 180 residues in length at the N-termini of the proteins, was defined after the SYG1/Pho81/ XPR1 proteins
Many proteins possessing the SPX domain have been suggested to be involved in phosphate (Pi) signaling, for example, the N-terminus of yeast SYG1 binds to the G-protein beta subunit and inhibits mating pheromone signal transduction [1]
Several independent hygromycin-resistant transgenic lines were generated for Ubi::OsSPX1-antisense and -sense

Summary

Introduction

The SPX domain, a domain of 180 residues in length at the N-termini of the proteins, was defined after the SYG1/Pho81/ XPR1 proteins. Many proteins possessing the SPX domain have been suggested to be involved in phosphate (Pi) signaling, for example, the N-terminus of yeast SYG1 binds to the G-protein beta subunit and inhibits mating pheromone signal transduction [1]. The putative Pi-level sensors, Pho and NUC-2, have a SPX domain in their N-termini and may be involved in regulation of Pi transport [2,3,4]. The human XPR1 functions as a Pi sensor and may be involved in G-protein associated signal transduction [5,6]. Many SPX domain proteins were identified as involved in the Pi-related signal transduction pathway and regulation pathways. Phosphorus (P) is well-known as a major macronutrient for plant growth and development

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