Salinity is a devastating abiotic stress accounting for major crop losses yearly. Plant roots can strikingly grow away from high-salt patches. This response is termed halotropism and occurs through auxin redistribution in roots in response to a salt gradient. Here, a natural variation screen for the early and NaCl-specific halotropic response of 333 Arabidopsis accessions revealed quantitative differences in the first 24 h. These data were successfully used to identify genetic components associated with the response through Genome-Wide Association Study (GWAS). Follow-up characterization of knockout mutants in Col-0 background confirmed the role of transcription factor WRKY25, cation-proton exchanger CHX13, and a gene of unknown function DOB1 (Double Bending 1) in halotropism. In chx13 and dob1 mutants, ion accumulation and shoot biomass under salt stress were also affected. Thus, our GWAS has identified genetic components contributing to main root halotropism that provide insight into the genetic architecture underlying plant salt responses.
Bibliographical noteKAUST Repository Item: Exported on 2020-10-01
Acknowledgements: The authors are grateful to David E Salt and Paulina Flis of the Future Food Beacon of Excellence and the School of Biosciences, University of Nottingham for the ICP-MS ion measurements of CHX13 and DOB1 shoot samples. This work was funded by European Research Council (ERC), European Union Consolidator grant 724321 “Sense2SurviveSalt” to C.T. The project was conceived and experiments were designed by A.O.D.-A. and C.T. GWAS analysis with scan_GLS was performed by A.O.D.-A. and fine mapping was performed by M.M.J. Gene expression analysis was performed by A.J.M. Halotropism assays and other experiments and analysis were performed by A.O.D.-A. A.O.D.-A. wrote the draft of the manuscript, and M.M.J. M.A.H. and C.T. provided feedback. All the authors read and approved the final manuscript. The authors declare no competing interests.