A novel metabolic complementation pattern: The synergistic response between Sogatella furcifera and its symbionts...

Insects and their symbionts respond synergistically to environmental changes, and metabolites are one of the important linkers in their interaction. Little is known about how plant growth regulators (PGR) affect planthoppers and their interacting symbiotic bacteria through sprayed rice.

Here, we observed abnormalities in the planthopper's growth length and developmental duration when rice seedlings treated with near-field concentrations of chitosan oligosaccharide (COS) were fed to first-instar nymphs of the white-backed planthopper (WBPH, Sogatella furcifera) for one week. The differentially expressed genes of WBPH were mostly enriched in downregulated metabolic pathways, suggesting the potential involvement of its symbionts. Amplicon sequencing results validated our hypothesis that the abundance of Acetobacteraceae Unclassified (closely related to Asaia sp.) was significantly increased (from an average of 1.24% to 74.68%) under COS stress, manifested in a significant upregulation of three major metabolic pathways involving carbohydrates, lipids, and amino acids. Analysis of their shared differential metabolites and the resulting three bioindicators' interaction networks revealed a close triangular relationship among them. They exhibited reciprocal changes in main metabolic functions confirming that metabolites are important intermediaries between insects and symbiotic bacteria.

Our research provides a reference for the scientific use of PGR and the exploration of insect-symbiotic interaction mechanisms.