Genotypic Variation of the Glucosinolate Profile in Pak Choi (Brassica rapa ssp. chinensis)

Abstract

Thirteen different pak choi (Brassica rapa ssp. chinensis) cultivars were characterized regarding their glucosinolate profile analyzed by HPLC-DAD-MS. The identified glucosinolates were subjected to principal component analysis, and three distinct groups of pak choi sprouts were identified. Group differences were marked mainly by variations in the aliphatic glucosinolate profile such as differing levels of 3-butenyl glucosinolate and 2-hydroxy-3-butenyl glucosinolate as well as by their varying proportional ratios. In addition, the three groups of pak choi sprouts varied by the presence or absence of 2-hydroxy-4-pentenyl glucosinolate and in level and composition of butyl glucosinolates. This classification is reflected by relative mRNA expression level of 2-oxoacid-dependent dioxygenase. As in sprouts, the major glucosinolates in mature leaves were found to be the aliphatic glucosinolates. However, unlike in sprouts, an additional aliphatic glucosinolate, 5-methylsulfinylpentyl glucosinolate, was detected as characteristic ontogenetic variation in mature leaves in 12 of the 13 pak choi cultivars analyzed.

Glucosinolate metabolism, functionality and breeding for the improvement of Brassicaceae vegetables

“…Major aliphatic glucosinolates found in each crop are shown in * symbol.Data sources:aWiesner et al (2013),bKirkegaard and Sarwar (1998),cIshida et al (2012a),dKim and Ishii (2007).…”

Functional identification of genes responsible for the biosynthesis of 1-methoxy-indol-3-ylmethyl-glucosinolate in Brassica rapa ssp. chinensis

“…chinensis ) contain a certain amount of indole GS in their green leaf tissue [30]. The different cultivars can be classified in distinct groups depending on their GS profiles, which are partly linked to the expression of specific genes involved in the aliphatic GS biosynthetic pathway.…”

Glucosinolates in Food

“…Leaves, preferably if young, can be eaten raw in salads or cooked by brief steaming or stir-frying. While an average total GLS content of 100 mg/100 g FW results from recent data reported in the literature (Table 1), a remarkable variability can be observed in the total GLS content found in the different studies, ranging from 8 [94,100] to 207 mg/ 100 g FW [99] (Table 2). This marked variation may be due not only to different genetic backgrounds but also to differences in the developmental stages considered in these studies: prolonging plant growing time, in environmentally controlled conditions, from 10 to 25 days, has been shown to markedly increase the total GLS content of the leaves at harvest [100].…”

“…Pak choi is an Asian leafy vegetable, also known as Chinese celery cabbage, bok choy, and horse's ear, which has traditionally been highly used in China, but whose consumption is also increasing in Europe in salads or Asian-style cooking [99]. Sometimes the species Brassica rapa ssp.…”

“…The aliphatic GLSs are the predominant group in pak choi leaves, with gluconapin, glucobrassicanapin, progoitrin, and glucoalyssin giving the main contribution, whereas indolic GLSs (neoglucobrassicin and glucobrassicin) and aromatic GLSs (gluconasturtiin) are also present at a lower level [99] (Fig. 2).…”