Comparison of MAPK and thioredoxin gene expression in wheat seedlings exposed to silver nitrate and silver nanoparticle

Abstract

The extensive use of heavy metals and nanoparticles (NPs) has led to their release into the environment that might have negative impacts on both organisms and the environment. In this study, the molecular responses of wheat seedlings to silver nitrate and silver nanoparticles (AgNPs) were assessed by transcript accumulation analysis of genes coding for products potentially involved in heavy metal tolerance. A quantitative Real-time PCR experiment was performed with MAPK (Mitogen-activated protein kinase) and thioredoxin genes using RNA isolated from wheat shoots treated for 0, 2, 6, 12 and 24 h with AgNO₃ and AgNPs at 100 mg^-1L concentration. Results indicated that stressful conditions led to the antioxidant responses of wheat seedlings that could be reflected as changes in MAPK and thioredoxin gene transcripts. The genes expression patterns were slightly different. The expression of these genes in response to both treatments was high at the beginning of the stress and was decreased with time. Our results showed the effects of AgNO₃ treatment were faster than AgNPs. We found that wheat seedlings might develop different strategies to cope with AgNO₃ and AgNPs toxicity with change in the expression of MAPK and thioredoxin heavy metal-related genes.