The Cell Cycle Checkpoint Regulator ATR Is Required for Internal Aluminum Toxicity-Mediated Root Growth Inhibition in Arabidopsis.

Yang Zhang,Lihua Wang,Lun Li,Chao-Feng Huang,Jinliang Guo,Mo Chen

doi:10.3389/fpls.2018.00118

Abstract

Aluminum (Al) can target multiple sites of root cells for toxicity, including the cell wall, the plasma membrane and symplastic components. Previous work revealed that the cell cycle checkpoint regulator (ATR) Ataxia Telangiectasia-mutated and Rad3-related is required for Al toxicity-induced root growth inhibition in als3 and that the symplastic component DNA is an important target site of Al for the toxicity. However, whether monitoring DNA integrity through ATR-regulated pathway is required for Al-induced root growth inhibition in other Al-sensitive mutants remains unknown. In this study, we demonstrated that the atr mutation could also rescue the Al hypersensitivity and Al-induced cell cycle arrest in star1, which supports the hypothesis that ALS3 and STAR1 function together to be involved in the detoxification of Al in Arabidopsis. However, mutation of ATR could not rescue the Al-sensitive phenotype of almt1 or stop1, both of which are defective in external detoxification mechanisms of Al. We further showed that the Al hypersensitivity and Al-induced quiescent center (QC) differentiation in als1 could also be rescued by the atr mutation. Therefore, our results suggest that ATR-regulated pathway is involved in the modulation of internal Al toxicity-mediated root growth inhibition in Arabidopsis.

Highlights

Aluminum (Al) comprises about 7% of the earth’s crust and is the most abundant metallic element
To confirm the previous observation that mutation of ATR could rescue the Al-sensitive phenotype of als3 (Rounds and Larsen, 2008), we generated als3atr double mutant through a genetic cross between atr and als3 single mutants
We evaluated the tolerance of WT, atr, als3, and als3atr mutants to Al in both hydroponic and soaked gel conditions

Summary

Introduction

Aluminum (Al) comprises about 7% of the earth’s crust and is the most abundant metallic element. Al toxicity on acid soils becomes one of the most severe global problems since these soils comprise approximately 50% of the world’s potentially arable land (von Uexkull and Mutert, 1995; Kochian et al, 2004). Hard metal ions have strong interactions with organic molecules bearing oxygen groups (Poschenrieder et al, 2008). Considering the components of a plant cell, Al is believed to target multiple sites for toxicity, including the cell wall, the plasma membrane and inside the cells. Al can bind to the plasma membrane and alter the membrane fluidity and surface potential (Kinraide, 2001), block ion channel activity (Pineros and Kochian, 2001), and induce the reactive oxygen species (ROS) as well as lipid peroxidation on the plasma membrane (Yamamoto et al, 2001). Al can interact with DNA (Karlik et al, 1980; Karlik and Eichhorn, 1989), which is expected to have serious effects on gene expression and chromosome structure

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Conclusion