Transcriptomics and metabolomics reveal the mechanisms of enhanced constitutive resistance in rice (Oryza Sativa L.) by silica nanomaterials

Abstract

Nano-enabled technology has been showing great potential in green and sustainable agriculture. Here, mechanisms of silica nanomaterials (SiO₂ NMs) enhancing rice constitutive resistance were investigated. Results indicated that the number of physical barriers (trichomes, dumbbell-shaped silica cells, and lignin content) was significantly increased in rice leaves, and the levels of chemical barriers (total phenolics and proline) were improved by 11–126% after soil amendment of 50 mg kg⁻¹ SiO₂ NMs. Importantly, fluorescence labeling experiments demonstrated that the direct deposition of SiO₂ NMs on the leaves is one of the reasons for the strength of silica cells and trichomes. RNA-Seq combined liquid chromatography-tandem mass spectrometry (LC-MS/MS) technology further revealed that the enhanced resistance was due to the increased synthesis of jasmonic acid (JA) and salicylic acid (SA) and activation of their signal transduction pathways. SiO₂ NMs upregulated the expressions of JA biosynthesis genes OsPLD, OsLOX, and OsOPR, and signal pathway gene OsJAZ, as well as SA-dependent defense pathway related genes (OsICS, OsPAL, and OsWRKY45). Accordingly, the content of JA in the stems and SA in the leaves was improved by 142.5% and 37.6%, respectively. Rice biomass remained increased strikingly by 12–30% with SiO₂ NM-insect/pathogen exposure over the insect/pathogen control, the oriental armyworm weight was significantly reduced by 26.8%, and less damage/lesions in rice were observed for the SiO₂ NM-insect/pathogen exposure than for the insect/pathogen control. Moreover, the hundred-grain weight and glutelin content in rice grains were improved by SiO₂ NMs under the insect/pathogen conditions. This study implies the potential of NM utilization to enhance crop resistance against insects and pathogens.