Synergistic action of silicon nanoparticles and indole acetic acid in alleviation of chromium (CrVI) toxicity in Oryza sativa seedlings

The present study investigates ameliorative effect of silicon nanoparticles (SiNPs) and indole acetic acid (IAA) alone and in combination against hexavalent chromium (Cr-VI) toxicity in rice seedlings. The results of the study revealed protective effects of SiNPs and IAA against Cr-VI toxicity. The 100 mu M of Cr-VI imposed toxic effects in rice seedlings at morphological, physiological and biochemical levels which coincided with increased level of intracellular Cr-VI and declined level of endogenous nitric oxide (NO). The Cr-VI enhanced levels of superoxide radicals (SOR) (59.51% and 50.1% in shoot and root, respectively) and H2O2 (19.5% and 23.69% in shoot and root, respectively). However, when SiNPs and IAA were applied to plants under Cr-VI stress, they enhanced tolerance and defence mechanisms as manifested in terms of increased biomass, endogenous NO, photosynthetic pigments, and antioxidants level. It was also noticed that Cr-VI arrested cell cycle at G2/M phase whereas growth was restored as compared to control when SiNPs and IAA were supplemented. Thus, the hypothesis that combined application of SiNPs and IAA will be effective in alleviating Cr-VI toxicity is validated from the results of this study. Moreover, in SiNPs and IAA-mediated mitigation of Cr-VI toxicity, endogenous NO has a positive role. The importance of the study will be that the combination of SiNPs and IAA can be utilized against heavy metal stress and even when supplied alone, they will enhance the crop productivity parameters with and without stress conditions.

Automated summary

This study investigates the ameliorative effects of silicon nanoparticles (SiNPs) and indole acetic acid (IAA) alone and in combination against hexavalent chromium (Cr-VI) toxicity in rice seedlings. The results show that SiNPs and IAA have protective effects against Cr-VI toxicity, enhancing tolerance and defense mechanisms in the plants.