Biochemical and molecular responses of two native landraces of bread wheat to salt stress at different time periods

Environmental stresses have an irreversible effect on the production of bread wheat (Triticum aestivum L.), one of the most important crop plants. On the other hand, AP2/ERF members are the most important transcriptional regulators that influence plant growth and response to biotic and abiotic stresses. To evaluate the mechanism of salt stress tolerance in wheat the activities of superoxide dismutase, ascorbate peroxidase and catalase in two tolerant wheat landraces (3623 and 3625) under salinity were investigated by completely randomized factorial experiment at control and 250 mM salinity in three replications. Seedlings were sampled at 0, 1, 3, 6, 12 and 24 h and 10 days after stress. The activity of enzymes was measured in the root and shoot of plants. The AP2-21 nucleotide sequence was extracted from the NCBI database and primers were designed and the gene fragment was isolated from wheat and then cloned and sequenced and confirmed by the presence of AP2 conserved domain. TaAP2-21 expression was evaluated by qPCR using specific primers and β-actin housekeeping genes. The results showed a significant difference in enzyme activity at different times compared to control in both tissues of both landraces and the highest was observed in short and medium-term stresses, however, apparently in long term stress the antioxidant mechanism of the enzymes is more active in 3623 than in 3625. Gene expression decreased significantly under salinity in both tissues. The TaAP2-21 gene is probably one of the inhibitors of the transcription of saline responsive genes and causes salt sensitivity in wheat.