2017 ASHS Annual Conference

Pak choi is a popularly consumed vegetable in China and is showing an increase in consumption in Europe and North Amercia, primarily due to its comparatively mild flavor. As a Brassica vegetable, pak choi provides a number of phytonutrients; in particular, glucosinolates. Although its popularity is increasing, the nutritional quality of pak choi has not been thoroughly investigated, and only a few studies have reported glucosinolate profiles from pak choi. Glucosinolates, their hydrolysis products, and primary metabolites were analyzed in five pak choi cultivars to determine the effect of 500 µM methyl jasmonate (MeJA) on metabolite flux from primary metabolites to glucosinolates. Among detected glucosinolates, indole glucosinolate concentrations (153-229%) and their hydrolysis products increased with MeJA treatment. Total isothiocyanates concentration changes by MeJA were associated with epithiospecifier protein activity. Total nitrile formation (%) out of total hydrolysis products was significantly increased by MeJA treatment. Goitrin concentration was significantly decreased by MeJA treatment in all cultivar. However, changes in glucosinolates and hydrolysis products differed among cultivars. Primary metabolites including amino acids, organic acids, and sugars also changed with MeJA treatment in a cultivar-specific manner. Decreased sugar level suggests that they might be a carbon source for secondary metabolite biosynthesis in MeJA-treated pak choi. The present study suggests that MeJA can be an effective agent to elevate indole glucosinolates and reduce goitrogenic effect in pak choi.