CRISPR-Cas9 helps solve a piece of the puzzle of the biosynthesis of salicinoids and suggests a role in the growth-defense trade-off in poplar

Abstract

Willow tree bark has been in use as a reliever of pain and fever for around 3,500 years (Desborough and Keeling, 2017). Unknown to our ancient ancestors, willow bark contains salicin, a salicinoid compound that is the original source of aspirin. Salicinoids are phenolic glycosides found only in willows and poplars. They are plant defense compounds and help willow and poplar trees to deter herbivores. Despite their medicinal value and importance in plant defense, salicinoid biosynthesis remains puzzling. Recent studies have provided a clue that a UDP-glycosyltransferase (UGT71L1) is essential for salicinoid biosynthesis in poplar (Fellenberg et al., 2020; Kulasekaran et al., 2021). In this issue, Harley Gordon and coauthors (Gordon et al., 2022) generated CRISPR-Cas9-mediated UGT71L1 knock-out mutants of poplar and revealed a central role of UGT71L1 in salicinoid biosynthesis and herbivore defense (see Figure).