Quantitative Analysis of the Major Aliphatic Glucosinolates in Doubled Haploid Lines of Radish Plants (Raphanus sativus L.) Obtained By Microspore Culture

Glucosinolates (GSLs) are secondary metabolites commonly occurring in Brassica crops and more than 130 different GSLs have been reported in diverse plants. Recent studies have indicated that isothiocyanate (ITC) derived from GSL by hydrolysis had a potential for anticancer activity against several tumor cells on human. In addition, it was found that glucoraphenin (GRE) and glucoraphasatin (GRH) were abundant and differently regulated in radish plants, depending upon organs and developmental stages. Microspores isolated from radish flowers were cultured in vitro to obtain doubled haploid (DH) (but homozygous) lines in a short time period. Total 41 DH lines were selected based on flow cytometry analysis. The seeds, obtained by bud pollination from the DH lines, were planted and 3-week-old young seedlings were used for the major aliphatic GSLs analysis. Amounts of GRH were highly variable from the DH lines ranging from 2.3 to 31.5 mg/g dry weight (DW). The donor plant (DP) contained 18.4 mg/g DW. It was noticed that there were 6-fold differences in the amounts of GRE between the highest and lowest DH lines. Among 41 lines tested, 14 DH lines of radish plants were significantly reduced in the amount of sum of GRH and GRE compared those of the donor plant (P < 0.05), whereas only three lines increased. The results obtained in the present study will lend to select genotypes with low and high GSLs contents of radish plant. In addition, those DH lines will aid to elucidate a biosynthetic pathway of the aliphatic GSLs in radish plants, which remain for the most part unsolved.