Effect of jasmonic acid on glucosinolate metabolism in different organs of broccoli sprouts
Edible sprouts, especially Brassica sprouts, contain high levels of health-promoting compounds. Exogenous elicitors have been used as strategies to improve the nutraceutical quality of Brassica sprouts. In this study, effects of jasmonic acid (JA) treatment on growth, the levels of glucosinolates and isothiocyanates, as well as myrosinase activity in different organs of broccoli sprouts were investigated. JA treatment markedly increased the contents of glucosinolates (GSLs), especially glucoraphanin, glucobrassicin and neoglucobrassicin in broccoli sprouts. However, gluconapin was not affected even decreased by JA treatment. Cotyledon, hypocotyl and root obtained the different results in induction of GSLs. Among these, neoglucobrassicin obtained the highest enhancement in three organs. Myrosinase activity in cotyledon of broccoli increased after JA treatment, while decreased in hypocotyl. Three concentrations of JA all significantly increased sulforaphane and isothiocyanates formation in cotyledon, hypocotyl and root of broccoli sprouts. Application of 100 μM JA led to the highest myrosinase activity, the least gluconapin and the most sulforaphane and isothiocyanates in cotyledon, as well as the most isothiocyanates in root. These results indicated that JA treatment could be an effective way to improve the cancer-prevention benefits of broccoli sprouts via enhancing sulforaphane and total isothiocyanates.