Effect of jasmonic acid on glucosinolate metabolism in different organs of broccoli sprouts

Yinglian Zhu, Fengwu Wang, Liping Guo

doi:10.9755/ejfa.2019.v31.i2.1908

Abstract

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.

Highlights

Brassica vegetables are recognized as wellness and health-promoting foods because of their high levels of bioactive compounds, such as vitamin C, carotenoids, tocopherols, polyphenolics and glucosinolates (GSLS) (Björkman et al, 2011)
The results of this study indicated that the cotyledon of broccoli sprouts contained the highest glucosinolate content except neoglucobrassicin
Except gluconapin, the content of other GSLs in broccoli sprouts increased after Jasmonic acid (JA) treatment

Summary

Introduction

Brassica vegetables are recognized as wellness and health-promoting foods because of their high levels of bioactive compounds, such as vitamin C, carotenoids, tocopherols, polyphenolics and glucosinolates (GSLS) (Björkman et al, 2011). When the plant tissue is disrupted, glucosinolates could be hydrolyzed into isothiocyanates (ITCs), thiocyanates, nitriles, epithionitriles and oxazolidines by the action of myrosinase (Bones and Rossiter, 2006; Gu et al, 2012). Among these compounds, ITCs, especially sulforaphane, displays diverse and important physiological activities including carcinogen detoxification, reducing the risk of cardiovascular diseases, anti-inflammatory and inhibition of pathogenic fungal growth as well as reducing blood glucose, etc. Addition of exogenous JA enhanced indole GSLS content, 1-methoxyindolyl-3-methyl glucosinolate in hairy root cultures of Sinapis alba and Brassica rapa (Kastell et al, 2013).

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