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.