Physiological and Molecular Responses to Salt Stress in Wild Emmer and Cultivated Wheat

Salinity severely influences growth and grain yield of wheat. Modern breeding efforts have contributed to severe loss of genetic diversity and reduced tolerance to salt stress in cultivated plants. Wild emmer wheat (Triticum dicoccoides), the progenitor of cultivated wheat, is well-adapted to a wide range of environments and exhibits tolerance to abiotic stress. However, there is lack of fundamental knowledge of the mechanism of salt stress tolerance in wild emmer wheat and how it differs from that of the cultivated wheat. By screening wild emmer genotypes, we identified a promising salt-tolerant line from Gitit in the eastern Samaria steppes. We investigated the physiological difference of wild emmer and cultivated wheats in response to salt stress. Our results revealed that salt stress resulted in an increase in lipid peroxidation (malondialdehyde) content and electrolyte leakage, to a greater extent in cultivated wheat genotype, Zheng 9023, than in salt-resistant wild emmer wheat genotype 18-35, but the latter had higher relative dry weight. Differential expression analysis showed that higher transcript induction folds of genes encoding transcription factor were detected in the resistant plants (wild emmer) than in sensitive plants (cultivated wheat) after salt treatment. In conclusion, wild emmer wheat demonstrated better tolerance to salt stress than cultivated wheat, and the higher tolerance of wild emmer wheat is because of high expression of stress-responsive genes encoding transcription factor, including NAC2F, NAC8, DREB3A, MYB3R, and MYB2A. Therefore, our results suggest that wild emmer wheat is an important germplasm for salt tolerance breeding in cultivated wheat.