A constitutively active form of a durum wheat Na+/H+ antiporter SOS1 confers high salt tolerance to transgenic Arabidopsis
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Expression of a truncated form of wheat TdSOS1 in Arabidopsis exhibited an improved salt tolerance. This finding provides new hints about this protein that can be considered as a salt tolerance determinant.
The SOS signaling pathway has emerged as a key mechanism in preserving the homeostasis of Na+ and K+ under saline conditions. We have recently identified and functionally characterized, by complementation studies in yeast, the gene encoding the durum wheat plasma membrane Na+/H+ antiporter (TdSOS1). To extend these functional studies to the whole plant level, we complemented Arabidopsis sos1-1 mutant with wild-type TdSOS1 or with the hyperactive form TdSOS1∆972 and compared them to the Arabidopsis AtSOS1 protein. The Arabidopsis sos1-1 mutant is hypersensitive to both Na+ and Li+ ions. Compared with sos1-1 mutant transformed with the empty binary vector, seeds from TdSOS1 or TdSOS1∆972 transgenic plants had better germination under salt stress and more robust seedling growth in agar plates as well as in nutritive solution containing Na+ or Li+ salts. The root elongation of TdSOS1∆972 transgenic lines was higher than that of Arabidopsis sos1-1 mutant transformed with TdSOS1 or with the endogenous AtSOS1 gene. Under salt stress, TdSOS1∆972 transgenic lines showed greater water retention capacity and retained low Na+ and high K+ in their shoots and roots. Our data showed that the hyperactive form TdSOS1∆972 conferred a significant ionic stress tolerance to Arabidopsis plants and suggest that selection of hyperactive alleles of the SOS1 transport protein may pave the way for obtaining salt-tolerant crops.
KeywordsDurum wheat Arabidopsis Na+/H+ antiporter SOS1 Hyperactive form Ionic stress tolerance
This study was supported by a grant from the Ministry of Higher Education and Scientific Research of Tunisia and the grants A/8077/07 from the Spanish Agency for International Development Cooperation (AECID), BIO2009-08641 from the Ministry of Science and Innovation (MICINN) and BIO2012-36533 from the Ministry of Economy and Competitiveness (MINECO), with the co-finance of the European Regional Development Fund.
Conflict of interest
The authors declare that they have no conflict of interest.
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