GSA‐1/ARG1 protects root gravitropism in Arabidopsis under ammonium stress. Issue 1 (20th June 2013)

• Record Type: Journal Article
• Authors: Zou, Na; Li, Baohai; Chen, Hao; Su, Yanhua; Kronzucker, Herbert J.; Xiong, Liming; Baluška, František; Shi, Weiming
• Is Part Of: New phytologist. Volume 200:Issue 1(2013)
• Page Start: 97
• Page End: 111
• Publication Date: 2013-06-20
• Subjects: Botany -- Periodicals; 580
• DOI: 10.1111/nph.12365
• Languages: English
• ISSNs: 0028-646X

Abstract

<abstract abstract-type="main" id="nph12365-abs-0001"> <title>Summary</title> <p> <list id="nph12365-list-0001" list-type="bullet"> <list-item> <p>Gravitropism plays a critical role in plant growth and development, plant stability and acclimation to changes in water and nutrient availability. Ammonium (NH<sub>4</sub><sup>+</sup>) is well known to have profound effects on root growth, but its impacts on gravitropism are poorly understood.</p> </list-item> <list-item> <p>To determine which genes are essential for the maintenance of root gravitropism under NH<sub>4</sub><sup>+</sup> stress, we isolated and identified an NH<sub>4</sub><sup>+</sup>‐sensitive mutant, <italic>gsa‐1</italic> (<italic>g</italic>ravitropism <italic>s</italic>ensitive to <italic>a</italic>mmonium‐<italic>1</italic>), in <italic>Arabidopsis thaliana</italic>, using an agar plate root reorientation assay.</p> </list-item> <list-item> <p>We found that, under NH<sub>4</sub><sup>+</sup> stress, <italic>gsa‐1</italic> displayed increased loss of root gravitropism. Gene cloning and sequencing revealed that <italic>gsa‐1</italic> contains a G to C transversion mutation at the highly conserved 5′‐GT splice position of intron 10 of <italic>ARG1</italic> (<italic>A</italic>LTERED <italic>R</italic>ESPONSE TO <italic>G</italic>RAVITY<italic>1</italic>), known to participate in the transduction of the root gravity signal. Genetic complement tests established the locus of <italic>GSA‐1</italic>/<italic>ARG1</italic> and its role in resistance to NH<sub>4</sub><sup>+</sup> inhibition on root gravitropism. GSA‐1/ARG1 is required for normal AUX1 expression and basipetal auxin transport in root apices. In addition, PIN‐FORMED2 (PIN2) is proposed as a target in the reduction of root gravitropism under NH<sub>4</sub><sup>+</sup> stress, a response which can be antagonized by the GSA‐1/ARG1‐dependent pathway.</p> </list-item> <list-item> <p>These results suggest that GSA‐1/ARG1 protects root gravitropism in <italic>Arabidopsis thaliana</italic> under ammonium stress.</p> </list-item> </list> </p> </abstract>