Glucosinolate variation in leaves of Brassica rapa crops.

Total and individual glucosinolate (GSL) content of leaves of vegetable turnip rape (Brassica rapa L. var. rapa) was determined in a set of 45 varieties consisting in early, medium and late types grown at two locations in northwestern Spain. The objectives were to determine the diversity among varieties in GSL content and to relate that variation with earliness and plant habit. Eight GSL were identified, being two aliphatic GSL, gluconapin (84.4 % of the total GSL) and glucobrassicanapin (7.2 % of the total GSL) the most abundant. Indolic and aromatic GSL content were low but also showed significant differences among varieties. Differences in total and individual GSL content were found among varieties, plant habit groups, and earliness groups. Total GSL content ranged from 19 to 37.3 μmol g(-1) dw in early and extra-late groups, respectively, and from 19.5 to 36.3 μmol g(-1) dw for turnips and turnip greens groups, respectively. These differences were consistent to values found for gluconapin content where the turnip group had the highest values (31.8 μmol g(-1) dw) and the turnip top group had the lowest (15.7 μmol g(-1) dw). Two varieties, MBG-BRS0429 and MBG-BRS0550 (from turnip greens and extra-late groups) and MBG-BRS0438 (from turnips and late groups), stood out as they had the highest total GSL content and could be used as a good source of these beneficial bioactive compounds. Elucidation of genetic diversity among crops can provide useful information to assist plant breeders to design improved breeding strategies in order to obtain varieties rich on GSL.