Priming with humic acid nanoparticles reduces copper cytogenotoxicity in hydroponic culture of wheat seedlings

Growing anthropogenic pollution of soil ecosystems with heavy metals necessitates the engineering of metal-resistant phenotypes of various plant species, including crops. Currently, priming is widely used for this purpose. The priming procedure is based on the induction of pre-adaptations, which increase plant tolerance to subsequent exposure to various stress factors. Thus, the influence of priming agent-induced pre-adaptations in the root extracellular trap (RET) system on the copper cytogenotoxicity in hydroponic culture of wheat seedlings was investigated in this research. Humic acid nanoparticles (nHA) with different mean diameters (68 nm and 6.5 nm, 100 mg/L) were used as priming agents. nHA were shown to increase border cell (BC) population size, as well as protein and extracellular DNA (exDNA) content in the RET matrix. Moreover, nHA priming reduced cytogenotoxicity of copper (31 × 10-5 M): BC number and viability were higher, while the copper content in the root apex and the number of cells with mitotic abnormalities in the root apex meristem were lower than in the cultivation variant without nanopriming. The obtained findings reveal that pre-adaptations in the RET system play a crucial role in the development of the root system tolerance to various soil pollutants.