Variation of glucosinolates on position orders of flower buds in turnip rape (Brassica rapa)

To glucosinolate (GSL) contents on flower buds depending on their position orders in turnip rape (Brassica rapa), three Japanese 'Nabana' cultivars such as cv. No. 21 (Brassica rapa, early type), cv. Husanohana (B. rapa, late type) and cv. Norin No. 20 (B. napus) were investigated using HPLC analysis. Ten GSLs including glucoraphanin, sinigrin, glucoalyssin, napoleiferin, gluconapin, 4-hydroxyglucobrassicin, glucobrassicanapin, glucobrassicin, and gluconasturtiin were detected. Differences in individual and total GSL contents were found between two plant varieties, which are also depending on various developmental stages. Among the GSLs, gluconapin (mean 23.11 lmole/g dry weight (DW) and glucobrassicanapin (mean 13.41 lmole/g DW) documented the most abundant compounds and contributed average 39 and 27% of the total GSLs, but indolyl and aromatic GSLs together accounted > 10% of the total GSLs. The presence of significant quantities of gluconapin in the cultivars should be studied more extensively, since the GSL is mainly responsible for the bitter taste. (C) 2017 Production and hosting by Elsevier B.V. on behalf of King Saud University.