Marker-free transgenic durum wheat cv. Karim expressing the AlSAP gene exhibits a high level of tolerance to salinity and dehydration stresses
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We have recently isolated the AlSAP (stress-associated protein) gene from the halophyte grass Aeluropus littoralis and demonstrated that AlSAP expression improves tolerance to continuous salt and drought stresses in transgenic tobacco. To extend these findings to an important crop, we generated marker-free transgenic durum wheat plants of the commercial cv. Karim expressing the AlSAP gene. The integration and expression of AlSAP in T3 homozygous plants were ascertained by Southern, Northern and Western blotting respectively. AlSAP wheat lines exhibited improved germination rates and biomass production under severe salinity and osmotic stress conditions. Following a long-term salt or drought stress greenhouse trial, AlSAP lines produced normally filled grains whereas wild-type (WT) plants either died at the vegetative stage under salt stress or showed markedly reduced grain filling under drought stress. Measurements of the RWC (relative water content) and endogenous Na+ and K+ levels in leaves of AlSAP plants, showed a lower water loss rate and a higher Na+ accumulation in senescent-basal leaves, respectively, compared to those of WT plants. Taken together, these results extend to cereals the high potential of the AlSAP gene for engineering effective drought and salt tolerance.
KeywordsAeluropus littoralis AlSAP Abiotic stresses Durum wheat In-embryo transformation Marker-free transgenic plants
Special thanks are extended to Kh. Belhaj (CBS) and S. Abid (a teacher of English) for their critical review of the manuscript. This work was supported by the Ministry of Higher Education Scientific Research of Tunisia (contract programme 2006–2010), by the European project CEDROME (INCO-CT-2005-015468), Agropolis Fondation under the REFUGE platform, Montpellier France and The National Program for Sciences, Technology, & Innovation (NPST, King Saud University Saudi Arabia).
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