Cd Stress Response in Emmer Wheat (Triticum dicoccum Schrank) Varieties Under In Vitro Conditions and Remedial Effect of CaO Nanoparticles

In this study, the mitigating effects of CaO NPs obtained from pomegranate extract via environmentally friendly green synthesis on CdCl₂ stress in two varieties (<i>Yolboyu</i> and <i>Kirac</i>) of Turkish Kavilca wheat (<i>Triticum dicoccum</i> 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 (<i>Traes_5BL_9A790E8CF</i> and <i>Traes_6BL_986D595B9</i>) 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 <i>5BL</i> and <i>6BL</i> 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.