Effect and mechanism of nano iron oxide on muskmelon under cadmium stress

Cadmium (Cd) pollution is the most dangerous and widespread heavy metal pollution in our country, which seriously affects food safety and human health. It is urgent to study the method and mechanism of alleviating Cd toxicity. In the experiment, we examined the effects of normal growth, Cd stress (400 mg/kg) and a-Fe2O3 nanoparticles (NPs) (50 mg/kg) + Cd stress (400 mg/kg) on muskmelon seedlings through pot experiments. The distribution of Cd in the system and the physiological indicators such as antioxidant enzymes in muskmelon leaves were measured. The transcriptome of muskmelon seedling leaves was sequenced by Illumina sequencing technology. The results showed that a-Fe2O3 NPs could reduce the content of Cd in muskmelon fruits by 52.25% compared with the Cd treatment. In addition, a-Fe2O3 NPs could reduce the activity of superoxide dismutase (SOD) and catalase (CAT) by 24.98% and 29.54%, respectively. The results of transcriptome analysis showed that muskmelon seedlings mainly responded to cadmium stress by up-regulating the expression of 312 differentially expressed genes (DEGs), while the application of a-Fe2O3 NPs mainly responded to Cd stress by down-regulating the expression of DEGs (369 down-regulated genes). After a-Fe2O3 NPs application, the expression of Psb and Psa genes encoding structural proteins of photosystem II and photosystem I increased significantly, protecting the photosynthetic system. a-Fe2O3 NPs protects plants by activating auxin responsive genes, inhibiting the overexpression of abscisic acid (ABA) signal transduction factors, and relieving the inhibition effect of Jasmonate ZIM-domain (JAZ) on jasmonic acid-mediated hormone signal transduction pathways. The enrichment analysis of mitogen-activated protein kinase (MAPK) signal transduction pathway suggested that a-Fe2O3 NPs could improve plant tolerance to Cd by regulating the balance of reactive oxygen species in plants. In conclusion, a-Fe2O3 NPs can alleviate muskmelon Cd toxicity and protect the human body from Cd damage. In this study, the molecular mechanism of a-Fe2O3 NPs alleviating Cd stress in muskmelon was thoroughly investigated, which provides a basis for further application in genetic engineering and phytoremediation. (c) 2023 SAAB. Published by Elsevier B.V. All rights reserved.