Different vegetative growth stages of Kimchi cabbage (Brassica rapa L.) exhibit specific glucosinolate composition and content

This study aimed to simultaneously investigate the changes in growth characteristics and glucosinolate (GL) content during different growth stages in Kimchi cabbage. Two Kimchi cabbage cultivars 'Chuweol' and 'HwiparamGold' were grown in the field and plant characteristics such as leaf length, number and fresh weight, and GL contents were measured weekly from 2 to 9 weeks after transplanting (WAT). The only significant difference between the two cultivars for either plant growth or GL content was observed for GL contents during 3 and 7 WAT. Leaf length increased until 4 WAT and then remained unchanged, exhibiting logarithmic growth. The fresh weight and number of leaves increased linearly until 9 WAT. Five GLs (two aliphatic GLs: progoitrin and gluconapin, two indole GSLs: glucobrassicin and neoglucobrassicin, and one aromatic GL: gluconasturtiin) of the nine GLs investigated in this study (glucoiberin, progoitrin, glucoraphanin, sinigrin, gluconapin, glucobrassicin, gluconasturtiin, 4-methoxy glucobrassicin and neoglucobrassin) were detected in the two cultivars. The contents of these five GLs were similar in the two cultivars during 2 WAT, but gluconapin and gluconasturtiin increased more dramatically than the others. The increasing pattern of total GL more closely resembled the leaf growth pattern than the fresh weight. Our results suggest that the change in total GL content positively correlates to leaf length, and the increase in total GL content is attributed to the increase in the amount of gluconasturtiin and gluconapin during the autumn growing season.