Comparative metabolomics of the interaction between rice and the brown planthopper

Introduction

The interactions between plants and insect herbivores are complex and multifaceted. Rice and its specialist insect pest the brown planthopper (BPH), Nilaparvata lugens Stål (Hemiptera: Delphacidae) constitute an ideal system for studying plant–insect interactions.

Objectives

Combined metabolomics analyses of rice plant and BPH were conducted to understand the mechanism of host rice plant defense and BPH insect response.

Methods

Metabolite dynamics in rice leaf sheath and BPH honeydew was investigated using the gas chromatography–mass spectrometry (GC–MS) method. The GC–MS data were analyzed by principal component analysis and partial least squares-discriminant analysis.

Results

Twenty-six metabolites were detected in the leaf sheath extracts. Rice leaf sheath metabolomics analysis results show that BPH feeding induces distinct changes in the metabolite profiles of YHY15 and TN1 plants. These results suggest that BPH infestation enhance fatty acid oxidation, the glyoxylate cycle, gluconeogenesis and the GABA shunt in TN1 plants, and glycolysis and the shikimate pathway in YHY15. We propose that the BPH15 gene mediates a resistance reaction that increases the synthesis of secondary metabolites through the shikimate pathway. Thirty-three metabolites were identified in BPH honeydew. Honeydew metabolomics analysis results show that when BPH insects were fed on resistant YHY15 plants, most of the amino acids in honeydew were significantly decreased compared to those of BPH fed on TN1 plants. Based on metabolomics results, we propose that BPH feeding on resistant YHY15 plants would enhance amino acid absorption. At the same time, urea was significantly increased in BPH fed on YHY15.

Conclusion

Metabolomics study is valuable in understanding the complex and multifaceted interaction between plants and insect herbivores and provide essential clue for development of novel control BPH strategies.