Indications of programmed cell death in wheat roots upon exposure to silver nanoparticles

Programmed cell death (PCD) can occur at every developmental stage as a plant’s response to various biotic and abiotic environmental factors. Silver nanoparticles (AgNPs) are widely used in consumer products and possess antimicrobial properties, making them important in assessing nanoparticle effects on plants. In the present study, we examined the impact of AgNPs (0, 0.5, 1, 5, 10, and 20 mg L-1) on wheat root PCD by evaluating parameters such as the mitotic index, chromosomal behaviors, nuclear deformation, cytochrome c release, caspase-1-like activity, and the expression of cysteine protease genes (TaVPE4, TaMCA1, and TaMCA4). Our findings revealed a dose-dependent decrease in the mitotic index ratio and increased chromosomal abnormalities induced by AgNPs. Additionally, we observed various hallmarks of PCD, including chromatin condensation, slight DNA smear, reduction in mitochondrial inner membrane potential, and cytochrome c release to the cytoplasm as well as increased caspase-1-like activity and TaVPE4 gene expression. Notably, the gene expressions of TaMCA1 and TaMCA4 were found to be antagonistically regulated by AgNPs, further indicating the induction of PCD by AgNP treatment. Overall, our study provides evidence of AgNP-induced PCD in wheat roots, elucidating the involvement of cysteine protease genes in this process.