title: GSA-1/ARG1 protects root gravitropism in Arabidopsis under ammonium stress.
abstract: Gravitropism plays a critical role in plant growth and development, plant stability and acclimation to changes in water and nutrient availability. Ammonium (NH4(+)) 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 NH4(+) stress, we isolated and identified an NH4 (+)-sensitive mutant, gsa-1 (gravitropism sensitive to ammonium-1), in Arabidopsis thaliana, using an agar plate root reorientation assay. We found that, under NH4(+) 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 ARG1 (ALTERED RESPONSE TO GRAVITY1), known to participate in the transduction of the root gravity signal. Genetic complement tests established the locus of GSA-1/ARG1 and its role in resistance to NH4 (+) 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 NH4(+) stress, a response which can be antagonized by the GSA-1/ARG1-dependent pathway. These results suggest that GSA-1/ARG1 protects root gravitropism in Arabidopsis thaliana under ammonium stress.
authors.affiliation: College of Landscape and Art, Jiangxi Agricultural University, Nanchang, 330045, China.|State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, No. 71 East Beijing Road, Nanjing, 210008, China.
authors.forename: Na
authors.initials: N
authors.lastname: Zou
authors.affiliation: State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, No. 71 East Beijing Road, Nanjing, 210008, China.
authors.forename: Baohai
authors.initials: B
authors.lastname: Li
authors.affiliation: Donald Danforth Plant Science Center, St Louis, MO, 63132, USA.
authors.forename: Hao
authors.initials: H
authors.lastname: Chen
authors.affiliation: State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, No. 71 East Beijing Road, Nanjing, 210008, China.
authors.forename: Yanhua
authors.initials: Y
authors.lastname: Su
authors.affiliation: Department of Biological Sciences, University of Toronto, 1265 Military Trail, Toronto, ON, M1C 1A4, Canada.
authors.forename: Herbert J
authors.initials: HJ
authors.lastname: Kronzucker
authors.affiliation: Donald Danforth Plant Science Center, St Louis, MO, 63132, USA.
authors.forename: Liming
authors.initials: L
authors.lastname: Xiong
authors.affiliation: Institute of Cellular and Molecular Botany, University of Bonn, Kirschallee 1, D-53115, Bonn, Germany.
authors.forename: František
authors.initials: F
authors.lastname: Baluška
authors.affiliation: State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, No. 71 East Beijing Road, Nanjing, 210008, China.
authors.forename: Weiming
authors.initials: W
authors.lastname: Shi
mesh_terms: D000222:Adaptation, Physiological / Q000235:genetics*; D064751:Ammonium Compounds / Q000378:metabolism*; D017360:Arabidopsis / Q000235:genetics* / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism; D017343:Genes, Plant; D006112:Gravitation; D018522:Gravitropism / Q000235:genetics*; D009154:Mutation; D018517:Plant Roots / Q000378:metabolism / Q000502:physiology; D013312:Stress, Physiological
chemical_list: D064751:Ammonium Compounds; D029681:Arabidopsis Proteins; C479927:ARG1 protein, Arabidopsis; C100794:AUX1 protein, Arabidopsis; C587815:GSA-1 protein, Arabidopsis; C117013:AT5G57090 protein, Arabidopsis
keywords: AUX1; GSA-1/ARG1; PIN2; ammonium; auxin transport; root gravitropism