Construction of gold-siRNANPR1 nanoparticles for effective and quick silencing of NPR1 in Arabidopsis thaliana

In recent years, gold nanoparticles (AuNPs) have been widely used as gene silencing agents and therapeutics for treatment of cancers due to their high transfection efficiency and lack of cytotoxicity, but their roles in gene silencing in plants have not yet been reported. Here, we report synthesis of AuNPs-branched polyethylenimine and its integration with the small interfering RNAs (siRNA) of NPR1 to form a AuNPs-siRNANPR1 compound. Our results showed that AuNPs-siRNANPR1 was capable of infiltrating into Arabidopsis cells. AuNPs-siRNANPR1 silenced 80% of the NPR1 gene in Arabidopsis. Bacteriostatic and ion leakage experiments suggest that the NPR1 gene in Arabidopsis leaves was silenced by AuNPs-siRNANPR1. In Columbia-0 plants, compared with the control group treated with buffer solution, the AuNPs-siRNANPR1 treatment significantly increased the number of colonies and cell death, and the leaves turned yellow, similar to the phenotype of the npr1 leaves. These results indicated this AuNPs-siRNANPR1 silencing the NPR1 gene method is simple, effective and quick (3 days), and a powerful tool to study gene functions in plants.