Glucosinolate abundance and composition in Brassicaceae influence sequestration in a specialist flea beetle

Autor: Johannes Körnig, Franziska Beran, Zhi-Ling Yang, Theresa Sporer, Grit Kunert
Rok vydání: 2020
Předmět:
Zdroj: Journal of Chemical Ecology
Popis: The horseradish flea beetlePhyllotreta armoraciaeexclusively feeds on Brassicaceae, which contain glucosinolates as characteristic defense compounds. Although glucosinolates are usually degraded by plant enzymes (myrosinases) to toxic isothiocyanates after ingestion,P. armoraciaebeetles sequester glucosinolates. Between and within brassicaceous plants, the glucosinolate content and composition can differ drastically. But how do these factors influence sequestration inP. armoraciae? To address this question, we performed a five-day feeding experiment with threeArabidopsis thalianalines that differ four-fold in glucosinolate content and the composition of aliphatic and indolic glucosinolates. We quantified the amounts of ingested, sequestered, and excreted glucosinolates, and analyzed the changes in glucosinolate levels and composition in beetles before and after feeding onArabidopsis.P. armoraciaeaccumulated almost all ingested glucosinolate types. However, some glucosinolates were accumulated more efficiently than others, and selected glucosinolates were modified by the beetles. The uptake of new glucosinolates correlated with a decrease in the level of stored glucosinolates so that the total glucosinolate content remained stable at around 35 nmol/mg beetle fresh weight. Beetles excreted previously stored as well as ingested glucosinolates fromArabidopsis, which suggests thatP. armoraciaeregulate their endogenous glucosinolate level by excretion. The metabolic fate of ingested glucosinolates, i.e. the proportions of sequestered and excreted glucosinolates, depended on glucosinolate type, content, and composition in the food plant. Overall,P. armoraciaesequestered and excreted up to 41% and 31% of the total ingested aliphatic and indolic glucosinolates fromArabidopsis, respectively. In summary, we show that glucosinolate variability in Brassicaceae influences the composition but not the level of sequestered glucosinolates inP. armoraciaebeetles.
Databáze: OpenAIRE