Jongkee Kim

Increase in Aliphatic Glucosinolates Synthesis during Early Seedling Growth and Insect Herbivory in Radish (Raphanus sativus L.) Plant

In an effort to establish a model system to examine the biosynthesis of aliphatic glucosinolates in radish tissues, changes in the glucosinolates content and associated gene expression patterns during seed germination and feeding of beet army worms (Salix exingua) to the radish leaf tissues were investigated. Radish cultivars, ‘Taebaek’, ‘Baekja’, and ‘Gwandong-yeorum’, were chosen to represent the genotypes of high, intermediate, and low in their glucosinolate contents, respectively. The major glucosinolates found in radish were glucoraphenin in seeds and glucoraphasatin in young seedlings. A rapid loss in glucoraphenin content was observed immediately after seed germination along with a sharp increase in glucoraphasatin content. Partial sequences of the genes involved in the biosynthesis of glucosinolates in radish were determined using random primers manufactured based on the sequence of Brassica rapa. The RT-PCR study revealed that the expression of CYP79F1 and CYP83A1 were maintained at a high level for 14 days after germination, followed by a significant decrease, substantiating the decrease in the amount of glucosinolates. Feeding army worm on radish seedlings has resulted in an increase of the glucoraphasatin content by 1.4 folds in all three cultivars tested. Expression of CYP79F1 and CYP83A1 in the leaves were up-regulated, substantiating the increase in glucosinolates content, as compared to the control. This result suggested that there was a positive correlation between the glucosinolates contents and the expressions of CYP79F1 and CYP83A1 genes.

The mechanism of deterioration of the glucosinolate-myrosynase system in radish roots during cold storage after harvest

The hydrolysis of glucosinolates (GSLs) by myrosinase yields varieties of degradation products including isothiocyanates (ITCs). This process is controlled by the glucosinolate-myrosinase (G-M) system. The major ITCs in radish roots are raphasatin and sulforaphene (SFE), and the levels of these compounds decrease during storage after harvest. We investigated the G-M system to understand the mechanism behind the decrease in the ITCs in radish roots. Six varieties of radish roots were stored for 8weeks at 0-1.5°C. The concentrations of GSLs (glucoraphasatin and glucoraphenin) were maintained at harvest levels without significant changes during the storage period. However, SFE concentration and myrosinase activity remarkably decreased for 8weeks. Pearson correlation analysis between ITCs, GSLs, and myrosinase activity showed that a decrease of SFE during storage had a positive correlation with a decrease in myrosinase activity, which resulted from a decrease of ascorbic acid but also a decrease of myrosinase activity-related gene expressions.

Sulforaphene Isolated from Radish (Raphanus Sativus L.) Seeds Inhibits Growth of Six Cancer Cell Lines and Induces Apoptosis of A549 Cells

Sulforaphene (SFE), a major isothiocyanate in radish seeds, is a close chemical relative of sulforaphane (SFA) isolated from broccoli seeds and florets. The anti-proliferative mechanisms of SFA against cancer cells have been well investigated, but little is known about the potential antiproliferative effects of SFE. In this study, we showed that SFE purified from radish seeds inhibited the growth of six cancer cell lines (A549, CHO, HeLa, Hepa1c1c7, HT-29, and LnCaP), with relative Preprints (www.preprints.org) | NOT PEER-REVIEWED | Posted: 3 July 2018 doi:10.20944/preprints201807.0060.v1

The major aliphatic glucosinolate content in Korean radish during vegetative and reproductive growth

Glucosinolates (GSLs) are secondary metabolites abundant in Brassica vegetables and the interest on this compound has been grown due to their health benefits. The amounts of major aliphatic GSLs, glucoraphasatin (GRH), and glucoraphenin (GRE) were measured in five radish cultivars during their vegetative and reproductive growth. The GRE content was higher in seed (ranging from 16.5 to 19.4 mg·g−1 dry weight) than that of leaves or roots in all five genotypes. The GRE content sharply declined during germination and remained stable at the basal level for the subsequent vegetative growth period. In contrast, the amount of GRH, an immediate precursor of the GRE, steadily increased during the early growth period up to 8 weeks and remained at a similar level thereafter. As growth of seedlings progressed, the inner leaves contained higher amounts of GRH than the outer leaves. In roots, smaller amounts of GRE were found, as compared to other tissues. However, the GRH was abundant in roots and mature inner leaves. The GRE tended to accumulate in reproductive organs, while GRH was found primarily in the roots and the inner leaves at the mature stage.