Thiol, volatile and semi-volatile compounds alleviate the stress of zinc oxide nanoparticles of the pomegranate callus.

Pomegranate trees are tropical and subtropical shrubs with nutritional benefits and pharmaceutical and therapeutic uses. Antioxidative systems protect the structure and function of cellular membranes. This study demonstrated the connection between oxidative stress generated by excess nanoparticles ZnO (ZnO-NPs) accumulation in pomegranate calli and the involvement of thiol groups and volatile and semi-volatile compounds in alleviating this stress. The effect of the non-enzymatic antioxidant system was studied using callus treated with three levels of ZnO-NPs or bulk particles (ZnO-BPs). With rising ZnO levels in the media, callus growth was gradually decreased by ZnO in both forms (NPs and BPs). Malondialdehyde (MDA) measurements revealed that different concentrations of both forms promoted lipid peroxidation. The supply of both forms had a considerable stimulatory influence on the cysteine (Cys) content in calli. Raised ZnO-NP concentrations increased glutathione (GSH) and non-protein thiols (NPTs) content in calli, but higher ZnO-BP concentrations lowered their content. Conversely, ZnO-NP levels reduced the protein thiols (PTs) content in calli, but ZnO-BP concentrations increased their content. GC-MS analysis was employed to investigate the volatile and semi-volatile chemical profiles within calli following exposure to 0 and 150 µg mL-1 of ZnO in both forms. GC-MS analysis detected 77, 67, and 83 compounds in ZnO-treated calli, of which 14, 16, and 20 with a similarity value greater than 70%, based on a NIST library, were recognized as metabolites for ZnO untreated and NPs- and BPs-treated calli, respectively. Six substances, including five alkanes and one morphinan, showed similarities in metabolite composition between control and NPs- or BPs-treated calli. ZnO-NPs-treated calli contained two alkane compounds only similar to the control, but ZnO-BPs-treated calli had six metabolites, including four alkanes, one carboxylic acid, and one ester. However, eight alkanes were similar within the callus treated with NPs and BPs.

Alleviating excess boron stress in tomato calli by applying benzoic acid to various biochemical strategies.

Benzoic acid (BA) represents vital roles in plant activity and response to diverse unfavorable conditions. However, its participation in mitigating excess boron (EB) stress in plants is elusive. Herein, we have examined the impacts of BA (1 µM) in controlling boron (B) uptake in tomato (Solanum lycopersicum L.) calli exposed to various EB levels (0, 1, 2, and 3 mM). The free, semi-bound, and bound B forms were stimulated by EB, while these forms were reduced in B-stressed calli by BA supplementation (40.37%, 36.08%, and 66.91%, respectively, less than 3 mM B-stressed calli alone). EB caused a reduction in the uptake of potassium (K+), calcium (Ca2+), magnesium (Mg2+), and nitrite (NO2-) while increasing the concentration of phosphorus (P), nitrate (NO3-), sulfur (S), and sulfate (SO42-) in B-stressed calli. BA application induced the uptake of K+, Ca2+, Mg2+, NO3-, S, and SO42-; however, it reduced P and NO2- concentrations in B-stressed calli. EB reduced nitrate reductase activity (NR), while BA application did not alleviate this reduction. EB treatments significantly, in most cases, increased sulfite oxidase (SO) activity. Supplementation of BA along with EB further enhanced SO activity. Cell wall components (cellulose, hemicellulose, and pectin) were decreased under EB treatments but considerably increased in B-stressed calli by BA application. Fourier Transform Infrared Spectrometer (FT-IR) output showed that EB treatments with/without BA led to alterations in cell wall functional groups of calli. Our findings indicated that BA application enabled tomato callus to counteract the harmful effect of EB, leading to improved callus growth.

Impacts of zinc oxide nano and bulk particles on redox-enzymes of the Punica granatum callus.

The structure and function of cellular membranes were sustained by redox-enzymes. We studied the interaction between the oxidative stress caused by excessive accumulation of ZnO-nanoparticles (ZnO-NPs) in plants and the role of redox-enzymes that can alleviate this stress. The crude callus extract from pomegranate, which was treated with 0, 10, and 150 µg mL-1 ZnO-NPs or bulk particles (ZnO-BPs), was applied to study the activity and kinetics of redox-enzymes. The elevated ZnO-NPs, enhanced the lipoxygenase and polyphenol oxidase activity, while the ZnO-BPs did not modify them. The activities of superoxide dismutase, catalase, and phenylalanine ammonia-lyase were induced under ZnO-NPs or BPs treatments, whilst the opposite trend of peroxidase was observed. Ascorbate peroxidase activity increased under ZnO-NPs treatments but decreased under ZnO-BPs. The kinetics activity of enzymes showed changes under different levels of NPs and BPs. Additionally, NPs or BPs treatments reduced the uptake of copper, iron, magnesium, but increased zinc accumulation in callus tissues. Meanwhile, these treatments enhanced the accumulation of manganese ions but did not affect the accumulation of potassium and phosphorous in ZnO-NPs or BPs-stressed calli. Collectively, these results gave a quantitative evaluation of the competition of zinc and other minerals on the carriers, and in addition, they provided a basis for how to control ZnO-NPs or BPs toxicity via redox-enzymes.