ZnONPs alleviate cadmium toxicity in pepper by reducing oxidative damage

Sidra Tahira; Saraj Bahadur; Xu Lu; Jiancheng Liu; Zhiwei Wang

doi:10.1016/j.jenvman.2024.123796

ZnONPs alleviate cadmium toxicity in pepper by reducing oxidative damage

J Environ Manage. 2024 Dec 24:373:123796. doi: 10.1016/j.jenvman.2024.123796. Online ahead of print.

Authors

Sidra Tahira¹, Saraj Bahadur², Xu Lu¹, Jiancheng Liu¹, Zhiwei Wang³

Affiliations

¹ National Key Laboratory for Tropical Crop Breeding, Sanya Institute of Breeding and Multiplication, Hainan University, Sanya, 572025, China; Key Laboratory for Quality Regulation of Tropical Horticultural Crops of Hainan Province, School of Tropical Agriculture and Forestry, Hainan University, Haikou, 570228, China.
² Key Laboratory for Quality Regulation of Tropical Horticultural Crops of Hainan Province, School of Tropical Agriculture and Forestry, Hainan University, Haikou, 570228, China.
³ National Key Laboratory for Tropical Crop Breeding, Sanya Institute of Breeding and Multiplication, Hainan University, Sanya, 572025, China; Key Laboratory for Quality Regulation of Tropical Horticultural Crops of Hainan Province, School of Tropical Agriculture and Forestry, Hainan University, Haikou, 570228, China. Electronic address: wangzhiwei@hainanu.edu.cn.

PMID: 39721396
DOI: 10.1016/j.jenvman.2024.123796

Abstract

Cadmium (Cd) is a genotoxic heavy metal causing severe toxicity symptoms in plants, which has been a major threat to worldwide crop production. Recently, nanoparticles (NPs) have been employed as a novel strategy to facilitate the Cd stress and act as nano-fertilizers directly. Therefore, this study aims to explore the effects of zinc oxide nanoparticles (ZnONPs; 15 mg/L) on plant growth, photosynthetic activity, antioxidant activity and root morphology in Capsicum chinense Jacq. under Cd (CdCl₂; 50 μM/L) stress. The pepper plants were treated with Cd stress for 14 days, and the treatment was given directly into the hydroponic solution, while ZnONPs were applied as foliar spray two times a day (9 a.m. - 3 p.m.). The results revealed that Cd stress inhibited plant growth and biomass by impairing photosynthesis in photosystem function, gas exchange parameters, root activity, and morphology. In contrast, ZnONPs application notably reinforced the plant growth traits, increased photosynthesis efficiency in terms of chlorophyll content, SPAD index, gas exchange parameters and PSII maximum efficiency (Fv/Fm) and decreased Cd accumulation in leaf and root by 30% and 75%. Furthermore, ZnONPs efficiently restricted the hydrogen peroxide, superoxide ion (H₂O₂, O₂^•-). They restored cellular integrity (less MDA production) by triggering the antioxidant enzyme activities such as superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), ascorbate peroxidase (APX) and glutathione reductase (GR), protein content, sugar level and proline content. Besides, ZnONPs treatment enhanced secondary metabolites (phenols and flavonoids) contents and these metabolites potentially restricted excess H₂O₂ accumulation. In conclusion, our findings deciphered the potential functions of ZnONPs in alleviating Cd-induced phytotoxicity in pepper plants by boosting biomass production, photosynthesis, secondary metabolism and reducing oxidative stress.

Keywords: Antioxidant enzymes; Cadmium; Nanoparticles; Pepper; Photosynthesis; Ultra-structure.