Metal(loid) toxicity seriously inhibits plant growth and development, thus influencing yield and quality. It is crucial to seek favourable measures to improve plant survival under toxic metal(loid)s conditions.
Previous studies have identified the complex mechanisms of Panax  notoginseng, a traditional medicinal plant, responses to biotic and abiotic stress. However, the effects of nanoparticles (NPs), especially iron oxide (Fe₃O₄  ) NPs involved in the P. notoginseng response to cadmium (Cd) and arsenic (As) stress stresses, remain to be further explained.
In a study published in Environmental Pollution, researchers from Xishuangbanna Tropical Botanical Garden (XTBG) of the Chinese Academy of Sciences (CAS) examined the effects of Fe₃O₄NPs on Panax  notoginseng under Cd and As stress. By combining physiological and metabolomic analyses, the researchers intended to examine the the mechanisms of the P. notoginseng seedling response to Cd/As stress with or without foliar exposure to Fe₃O₄NPs.
The researchers found that Cd/As treatment severely inhibited seedling growth,  as indicated by decreasing shoot fresh weight, rootlet length and root fresh weight. Through regulating ion balance, antioxidant contents and metabolic profiling, Fe₃O₄NPs ameliorated Cd/As-induced growth inhibition.
Fe3O4 NPs altered essential metabolites significantly enriched in amino sugar and nucleotide sugar metabolism, flavonoid biosynthesis and phenylalanine metabolism, thus modulating the trade-off between plant growth and defense against metal toxicity.
More significantly, Fe₃O₄NPs recovered many Cd/As-induced DAMs to normal levels, further supporting that Fe₃O₄NPs were beneficial for seedling growth under stress. In addition, terpenoids were notably induced when subjected to Cd/As stress, and Fe₃O₄NPs altered these key metabolites, thus affecting potential medicinal value.
"Our study suggests that metal nanoparticles can serve as nanoregulators to combat metal(loid) stresses in the genuine production area of medicinal plants. They can be used to improve potential active ingredients of medicinal plants in metal(loid)-contaminated areas," said WAN Jinpeng of XTBG.
The study was partly supported by the China National Natural Sciences Foundation, the Youth Innovation Promotion Association of CAS, and the CAS “Light of West China” Program. 

Contact
WAN Jinpeng Ph.D
Key Laboratory of Tropical Plant Resources and Sustainable Use, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Menglun 666303, Yunnan, China
E-mail:  wanjinpeng@xtbg.org.cn
Published: 17 September 2023
 

Fe₃O₄ nanoparticles ameliorate cadmium and arsenic toxicity in Panax notoginseng. (Image by LU Tianquan ）