TL;DR: Feeding norvaline greatly enhances the accumulation of 2-hydroxy-2-(1-Hydroxyethyl)pentanoic acid glucoside in wild type but not the UGT76F1 knockout mutant plants, providing evidence for an orthologous C7-necic acid biosynthetic pathway in Arabidopsis despite the apparent lack of pyrrolizidine alkaloids. (via Semantic Scholar)