AUTHOR=Zhu Ruojia , Dong Xiaoxia , Hao Weiwei , Gao Wei , Zhang Wenzhu , Xia Shuyan , Liu Ting , Shang Zhonglin 

TITLE=Heterotrimeric G Protein-Regulated Ca2+ Influx and PIN2 Asymmetric Distribution Are Involved in Arabidopsis thaliana Roots' Avoidance Response to Extracellular ATP

JOURNAL=Frontiers in Plant Science

VOLUME=8

YEAR=2017

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2017.01522

DOI=10.3389/fpls.2017.01522

ISSN=1664-462X

ABSTRACT=<p>Extracellular ATP (eATP) has been reported to be involved in plant growth as a primary messenger in the apoplast. Here, roots of <italic>Arabidopsis thaliana</italic> seedlings growing in jointed medium bent upon contact with ATP-containing medium to keep away from eATP, showing a marked avoidance response. Roots responded similarly to ADP and bz-ATP but did not respond to AMP and GTP. The eATP avoidance response was reduced in loss-of-function mutants of heterotrimeric G protein α subunit (Gα) (<italic>gpa1-1</italic> and <italic>gpa1-2</italic>) and enhanced in Gα-over-expression (OE) lines (<italic>wG</italic>α and <italic>cG</italic>α). Ethylenebis(oxyethylenenitrilo) tetraacetic acid (EGTA) and Gd<sup>3+</sup> remarkably suppressed eATP-induced root bending. ATP-stimulated Ca<sup>2+</sup> influx was impaired in Gα null mutants and increased in its OE lines. DR5-GFP and PIN2 were asymmetrically distributed in ATP-stimulated root tips, this effect was strongly suppressed by EGTA and diminished in Gα null mutants. In addition, some eATP-induced genes' expression was also impaired in Gα null mutants. Based on these results, we propose that heterotrimeric Gα-regulated Ca<sup>2+</sup> influx and PIN2 distribution may be key signaling events in eATP sensing and avoidance response in <italic>Arabidopsis thaliana</italic> roots.</p>