Expression Pattern of NAS1, NAS2 and NAS3 Genes under Zn Deficiency Conditions in Bread Wheat (Triticum aestivum L.)

A greenhouse factorial experiment was conducted in completely randomized design (CRD) with three replications to investigate the effect of soil Zn deficiency stress on the expression of three genes involved in the synthesis of metal chelating agents (NAS1, NAS2 and NAS3) in bread wheat. Hamoun and Hirmand (Zn-efficient and inefficient cultivars, respectively) cultivars were planted under Zn deficiency (0 mg Zn / kg soil) and adequacy (5 mg Zn / kg soil) conditions and relative expression of the genes was measured in root and leaf of the cultivars at two growth stages: stem elongation (vegetative stage) and 30% of flowering (reproductive stage) using Real time PCR technique. The results revealed the highest expression of NAS1 (7-fold) and NAS2 (5-fold) in Zn deficiency conditions in the root of Zn-efficient cultivar (Hamoun) at reproductive stage and in the leaf of the same cultivar at vegetative stage, respectively. The highest expression of NAS3 (7-fold) was observed in the root of Hamoun cultivar at reproductive stage. The expression of this gene was also enhanced in the leaf of both cultivars at reproductive stage under Zn deficiency conditions. In conclusion, the results of the present study demonstrated that the expression of NAS1, NAS2 and NAS3 genes in Zn-efficient cultivar under Zn deficiency stress was enhanced more than Zn-inefficient cultivar which probably facilitate Zn uptake and translocation in Zn-efficient cultivars through increasing the synthesis of Zn-chelating agents such as nicotianamine and mugineic acid in the root and leaf of the plants.