Seed priming with ZNPs reduced expression of salinity tolerance genes in Glycine max L. and improved yield traits

Abstract

Little has been done to evaluate the molecular role of ZnO nanoparticles (ZNPs) in regulating biochemical processes and plant yield in response to salt-induced stress. In this study, the molecular response of salt-stressed soybean (‘Giza111’) was assessed under different concentrations of ZNPs (25, 50, 100, and 200 mg l-1) by measuring some osmolytes, yield parameters, and Na+ and K+ content. The impact of salinity on the mRNA expression levels of three key salt-tolerance related genes (GmCHX1, GmPAP3, and GmSALT3) using qRT-PCR was also determined. The high level of salinity (250 mM NaCl) led to a significant increase in Na+ content, total soluble proteins, and total soluble carbohydrates and significantly upregulated gene expression of GmCHX1, GmPAP3, and GmSALT3, while reducing K+ content, K+/Na+ ratio and all yield parameters compared to control plants. Soaking soybean seeds in various ZNP concentrations, on the other hand, increased K+ content and K+/Na+ ratio while decreasing Na+ content, total soluble proteins, and total soluble carbohydrates in stressed plants, particularly at 50 mg l-1 ZNPs. Furthermore, GmCHX1, GmPAP3, and GmSALT3 expressions were all downregulated at 50 mg l-1 ZNPs, which ultimately improved soybean yield parameters. Accordingly, these results recommend the application of 50 mg l-1 ZNPs for improving the productivity of soybean cultivated in saline soils.