Metal nanoparticles serves as plant growth regulators

Engineered nanomaterials (EMs) negatively or positively affect plant growth and development attributed to their physiochemical properties, application, and concentrations. Previous studies have shown that ferroferric oxide (Fe₃O₄) nanoparticles affect tobacco (Nicotiana tabacum) seed germination in size- and dosage-dependent manners. However, little attention has been paid to EMs mediated tobacco response to heavy metals.

In a study published in Journal of Nanobiotechnology, researchers from the Xishuangbanna Tropical Botanical Garden (XTBG) of the Chinese Academy of Sciences and Shanxi Agricultural University investigated the mechanisms of nanoparticle-mediated cadmium (Cd) tolerance in plants.

Using the tobacco cultivar Yunyan 87 (N. tabacum), the researchers investigated the effects of Fe₃O₄ or zinc oxide nanoparticles (ZnO NPs) on plant growth and Cd responses in tobacco seedlings.

They first determined the effects of Cd on tobacco seedling growth and found that Cd treatment markedly induced growth inhibition in plant height, shoot fresh weight, root length and fresh weight.

To confirm whether Fe₃O₄ and ZnO NPs played roles in mediating Cd response, they further applied foliar exposure to Fe₃O₄, ZnO NPs, and ion solutions to tobacco seedlings. Foliar exposure to Fe₃O₄ or ZnO NPs showed great potential in alleviating plant growth under Cd stress.

Compared with Cd-treated seedlings alone, Fe₃O₄, ZnO NPs, and ions significantly promoted root growth and fresh weight. Fe₃O₄ or ZnO NPs reprogrammed critical metabolic pathways, including alkaloids, amino acids, flavonoids, and the differentially accumulated metabolites involved in these pathways were significantly correlated with plant growth.

"Our results collectively indicate that metal nanoparticles can serve as plant growth regulators and provide insights into using them for improving crops in heavy metal-contaminated areas," said Wan Jinpeng of XTBG.