Glucosinolates induce transcriptomic and metabolic reprogramming in Helicoverpa armigera

Glucosinolates protect plants from herbivorous insects. Lepidopteran insects have developed resistance to glucosinolates and its mechanism is studied in various insects. However, their molecular effects on insects are still unknown. To elucidate the molecular response of insects to the glucosinolates we performed transcriptomics and metabolomics of sinigrin-fed Helicoverpa armigera. Transcriptomics indicates that the expressions of several enzymes (hydrolase, oxidoreductase, and transferase) are majorly affected. The negative impact is significant and localized in the endomembrane system and mitochondria. Furthermore, H. armigera putative myrosinase-like enzymes may catalyze the breakdown of sinigrin to allyl isothiocyanate (AITC). Sinigrin target the electron transport chain causing oxidative stress, which upregulates oxidative phosphorylation. This activates glutathione synthesis for sinigrin detoxification. Differential gene expression indicates that the genes related to glutathione metabolism are upregulated. Information from transcriptomics is enriched by metabolomics that shows changes in serine, methionine, ornithine, and other metabolite levels. It corroborates well with the transcript alterations supporting the increased glutathione production. Thus, our data suggest that sinigrin generates oxidative stress in H. armigera and insects alter their metabolic wiring to overcome sinigrin-mediated deleterious effects.