Zinc (Zn) is an essential micronutrient that plays major roles in several physiological and biochemical processes of plants. Zinc deficiency results in impairment of cellular processes and thus reduces the growth and development of plants. Deficiency of this nutrient is common in soils under wheat cultivation, particularly in calcareous soils of Iran. Development and use of Zn-deficiency tolerant cultivars is one of the most effective and sustainable ways to solve Zn deficiency in wheat grain and human. Different factors affecting absorption of zinc by roots and translocation of this element to shoots may contribute to crop tolerance to Zn-deficiency conditions. Large differences among Zn-deficiency tolerant and sensitive wheat genotypes have been reported in exudation of organic acids i.e., amino acids from the roots. Amino acids are suggested to form stable complexes with metals and affect uptake and translocation of metals from roots to shoots. This study aimed to investigate the effects of histidine on apoplastic and symplastic uptake of Zn, H + -ATPase activity and pH of rhizosphere of five wheat genotypes differing in Zn-deficiency tolerance. The research was set up in two studies. In the first study, wheat cultivars were grown in nutrient solution for four weeks and then were transferred to treatment solutions consisted of two concentrations of histidine (0 and 50 µM) and two concentrations of Zn (0 and 10 M). Solutions with no histidine and no Zn were also included as control. Differences among cultivars were observed in apoplastic and symplastic Zn uptake and rhizosphere pH in the presence of histidine, but these differences were not related to Zn-deficiency tolerance of cultivars. Based on the results, the effect of histidine on symplastic and apoplastic root Zn was depended on the wheat cultivar. In the second study, Falat and Kavir wheat cultivars were selected to investigate the role of H + -ATPase activity in the plants Zn deficiency in the presence and absence of histidine. The wheat cultivars after planting were transferred to an uptake solution. The root cells plasma membrane (PM) was then isolated and the hydrolytic activity of PM H + -ATPase was determined based on the protein content of the isolated microsomes. Activity of PM H + -ATPase and H + pumping in Flat cultivar was higher than Kavir cultivar. According to the results obtained from the present study, differences in activity of ATPase proton pump can partly explain differential Zn-efficiency of wheat cultivars. Keywords : Zn efficiency, Amino acid, Histidine, wheat, H + -ATPase