Plant material
Seeds of Arabidopsis thaliana flavonoid transparent testa(tt ) mutants were obtained from Nottingham Arabidopsis Stock center. Artemisia annua (Artemisia F1 seeds, Hyb8001r) was provided by the Center for Novel Agriculture Products, Department of Biology, University of York, England. Seeds of Brassica olearaceavar. italica, cultivar Coronado were provided by Bejo seeds, Warmenhuizen, the Netherlands.