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

## TL;DR

This study explores how calcium oxide nanoparticles can reduce cadmium toxicity in emmer wheat varieties, helping protect plants from harmful effects.

## Contribution

The study introduces CaO nanoparticles as a novel strategy to mitigate Cd stress in emmer wheat through gene and physiological responses.

## Key findings

- CaO NPs upregulated gene expression related to Cd stress in emmer wheat.
- Co-treatment with CaO NPs and CdCl2 reduced cellular damage and improved physiological parameters.
- SEM analysis showed recovery of membranous structures with CaO NP application.

## Abstract

Cadmium (Cd) toxicity, a significant global issue, directly impacts agricultural ecosystems, leading to yield losses in cereal crops like wheat. Cd also disrupts the uptake and utilization of the essential nutrient calcium (Ca) from the soil. Minimizing Cd absorption in cereals is therefore critical, but current strategies are limited. One promising approach involves using calcium oxide nanoparticles (CaO NPs), an innovative tool that could aid in reducing Cd uptake. In this context, ancestral emmer wheat, a species-rich in genetic diversity and cultivated on a limited scale in Türkiye, has gained attention. Genotypes of this species may provide effective solutions for reducing Cd absorption, transport, and their associated negative effects. Additionally, studying variations in local genotypes may help clarify the molecular and physiological mechanisms underlying these processes. This study aimed to investigate the effects of different levels of Cd and CaO NPs on emmer wheat varieties grown in vitro. By examining gene expression and physiological parameters linked to Cd stress, it was determined that CaO NPs serve as a useful strategy for mitigating cellular damage caused by Cd toxicity.

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.