Crops of the Brassicaceae contain glucosinolates(GSs), which when hydrolyzed by the enzyme myrosinase, generate products involved in cancer chemoprotection, plant defense, and plant-insect interactions. A rapid-cycling base population of B. oleracea L. was grown in a hydroponic system in a controlled environment to determine the roles of temperature, photosynthetic photon flux (PPF), and photoperiod in GS concentration and myrosinase activity. The concentration of total GSs in leaves was 44% and 114% higher at 12 and 32 °C respectively than at 22 °C under constant light of 300 μmol·m-2·s-1. The concentration of glucoraphanin, the precursor to sulforaphane, a compound with chemoprotective properties, was 5-fold higher at 32 than at 22 °C. Total GSs were ≈50% lower in roots at 12 °C and 32 than at 22 °C. Total GSs in leaves decreased 20% when PPF was increased from 200 to 400 μmol·m-2·s-1. Myrosinase activity on a fresh weight basis (activity-FW) was ≈30% higher in leaves and stems at 12 and 32 °C than at 22 °C, and ≈30% higher in leaves grown at 200 and 400 μmol·m-2·s-1 than at 300 μmol·m-2·s-1. Consideration of climatic factors that influence the glucosinolate-myrosinase system may be necessary to optimize the planting and cultivation of Brassica crops for maximum health benefits.
Craig S. Charron and Carl E. Sams
Vincent A. Fritz, Veronica L. Justen, Ann M. Bode, Todd Schuster and Min Wang
compounds with aliphatic, aromatic, or indolic groups depending on which modified amino acid they contain. Upon hydrolysis with myrosinase, a β-thioglucosidase, GSLs yield bioactive compounds, including volatile isothiocyanates. GSLs and their subsequent
Carl E. Sams, Dilip R. Panthee, Craig S. Charron, Dean A. Kopsell and Joshua S. Yuan
number of agriculturally important plant species ( Holst and Williamson, 2004 ). More than 100 types of GSs have been identified with 23 different GSs reported in Arabidopsis thaliana . Glucosinolates are hydrolyzed by myrosinase [β-thioglucosidase (E