A nanosized Ag-silica hybrid complex prepared by γ-irradiation activates the defense response in Arabidopsis

Abstract

Silver nanoparticles have antimicrobial activity against many pathogenic microbes. Here, the preparation of a nanosized Ag-silica hybrid complex (NSS) prepared by γ-irradiation is described. The effects of both NSS and reduced Ag nanoparticles (Ag0) on the growth of the model plant Arabidopsis thaliana were tested. The application of 1-10ppm NSS complex improved Arabidopsis growth in soil, whereas 100ppm NSS resulted in weakly curled leaves. In addition, supplementation of Murashige and Skoog (MS) growth medium with 1ppm NSS promoted the root growth of Arabidopsis seedlings, but root growth was inhibited by supplementation with 10ppm NSS. To investigate whether the NSS complex could induce plant defense responses, the expression of pathogenesis-related (PR) genes that are implicated in systemic acquired resistance (SAR) in Arabidopsis plants was examined. PR1, PR2 and PR5 were significantly up-regulated by each application of 10ppm NSS complex or Ag0 to the rosette leaves. Furthermore, pretreatment with the NSS complex induced more pathogen resistance to the virulent pathogen Pseudomonas syringae pv. tomato DC3000 (Pst) compared to water treatment in Arabidopsis plants.