In this study, the mitigating effects of CaO NPs obtained from pomegranate extract via environmentally friendly green synthesis on CdCl2 stress in two varieties (Yolboyu and Kirac) of Turkish Kavilca wheat (Triticum dicoccum Schrank) under in vitro callus culture conditions were investigated. The calluses developed from embryos of both wheat varieties were exposed to either CaO NPs alone (1 and 2 mg/L), CdCl2 alone (1 or 10 mM) or the different combinations of these two compounds in MS medium for 4 weeks. Changes in the expressions of two genes (Traes_5BL_9A790E8CF and Traes_6BL_986D595B9) known to be involved in wheat's response to CdCl2 stress were analyzed by qRT-PCR. Additionally, certain physiological parameters, such as lipid peroxidation (LPO), H2O2, proline and soluble sugar content, and SEM-EDX analysis were used to assess the response of calluses to the applications. The CaO NPs treatments alone generally upregulated the expression of the 5BL and 6BL genes, while the CdCl2 applications decreased their expression in both cultivars. The CaO NPs reduced the proline content in both cultivars compared to the control. Co-treatment with CdCl2 and CaO NPs increased the sugar content and decreased the MDA content, but did not cause a significant change in the H2O2 content. SEM analysis showed that when CdCl2 and CaO NPs were applied to calluses together, the membranous and mucilaginous spherical structures were regained. The application of CaO NPs reduces the amount of cellular damage caused by CdCl2 stress and improves gene expressions.
