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GSA ‐1/ ARG 1 protects root gravitropism in Arabidopsis under ammonium stress
Author(s) -
Zou Na,
Li Baohai,
Chen Hao,
Su Yanhua,
Kronzucker Herbert J.,
Xiong Liming,
Baluška František,
Shi Weiming
Publication year - 2013
Publication title -
new phytologist
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.742
H-Index - 244
eISSN - 1469-8137
pISSN - 0028-646X
DOI - 10.1111/nph.12365
Subject(s) - gravitropism , arabidopsis thaliana , arabidopsis , biology , rhizosphere , auxin , botany , mutant , biochemistry , gene , genetics , bacteria
Summary Gravitropism plays a critical role in plant growth and development, plant stability and acclimation to changes in water and nutrient availability. Ammonium (NH 4 + ) is well known to have profound effects on root growth, but its impacts on gravitropism are poorly understood. To determine which genes are essential for the maintenance of root gravitropism under NH 4 + stress, we isolated and identified an NH 4 + ‐sensitive mutant, gsa‐1 ( g ravitropism s ensitive to a mmonium‐ 1 ), in Arabidopsis thaliana , using an agar plate root reorientation assay. We found that, under NH 4 + stress, gsa‐1 displayed increased loss of root gravitropism. Gene cloning and sequencing revealed that gsa‐1 contains a G to C transversion mutation at the highly conserved 5′‐ GT splice position of intron 10 of ARG 1 ( A LTERED R ESPONSE TO G RAVITY 1 ), known to participate in the transduction of the root gravity signal. Genetic complement tests established the locus of GSA ‐1 / ARG 1 and its role in resistance to NH 4 + inhibition on root gravitropism. GSA ‐1/ ARG 1 is required for normal AUX 1 expression and basipetal auxin transport in root apices. In addition, PIN‐FORMED2 ( PIN 2) is proposed as a target in the reduction of root gravitropism under NH 4 + stress, a response which can be antagonized by the GSA ‐1/ ARG 1‐dependent pathway. These results suggest that GSA ‐1/ ARG 1 protects root gravitropism in Arabidopsis thaliana under ammonium stress.