Effect Of Amino Acids On The Composition And Content Of Glucosinolates Of Cabbage

Glucosinolates (GSs), a group of plant secondary metabolites, are mainly found in the family of Brassica. Over 120 different GSs have been identified in some of oil plants, vegetables, spices, medicament and other economically important varieties. Their enzymatical degradation products are responsible for the characteristic flavor, pathogen defense system and insect attractants of Brassica, and have been shown to possess anti-carcinogenic, cholesterol-reducing and other pharmacological effects. There is abundance of GSs in Crueiferous plants. Exogenous substances and cultivating methods of applying amino acid. Thus it provides the theory for improving the content of GS by a scientific approach.The result showed that nine kinds of GSs were detected in cabbage, but the contents of individual GS varied with cabbage cultivars. Among the 42 cabbage cultivars, S₁BC₂-2, xiangqiang, S₁BC₂-1,06-128 and 06-115 had the higher content of total GS. 927, 06-111, 975, 929, 974 and chungan 3 mainly contained aliphatic GS while NiuXin No. 1, S₁BC₁, S₁BC₂-2, S1BC2-1 and 06-130 mainly contained indolyl GS. Glucoraphanin content was the highest(49.51μmol·100g^-1FW) with 06-115. SP₁, 120, 4239, ZhongGan No. 21 and 06-115 had the higher ratio of RAA to the tatal GS, ranging from 20.9% to 33.5%.Each cabbage cultivar contained 9 glucosinolates in different amino acid treatments. Amino acids had an effect on glucosinolates contents in cabbage cultivar. For cultivar 06-115, the total glucosinolate, aliphatic glucosinolate and Glucoraphanin contents were increased by Cysteine and Methionine significantly. Compared to CK, Cysteine raised total glucosinolate, aliphatic glucosinolate and Glucoraphanin content by 63.0%, 69.6% and 69.1% respectively. Glucobrassicin content increased to 72.56μmol·100g^-1FW in the foliar application treatments of Cysteine. For cultivar ZhongGan No. 21, the total glucosinolate content, aliphatic glucosinolate content, indolyl glucosinolate content and Glucoraphanin content increased by 27.2%, 39.6% ,15.3% and 26.2% respectively in the foliar application treatments of Cysteine compared to CK. Glucobrassicin content was the highest(29.27μmol·100g^-1FW)in the foliar application treatments of Cysteine, followed by Glutamine treatment and Glycine treatment.The contents of various GSs changed in different harvest stage after Cysteine foliar spray. The highest content of total GS, aliphatic glucosinolate and indolyl glucosinolate appeared in the sixth day harvest after the foliar spray with Cysteine. The highest RAA content appeared in the sixth hour harvest after the foliar spray with Cysteine while the highest SIN,PRO,GBC and NAP content occurred in the sixth day.The sixth day harvest after the foliar spray with Cysteine had not significant effect on the component of glucosinolate, but increased the content of total GS, aliphatic glucosinolate, indolyl glucosinolate and RAA. In addition, the amino acids regulation treatment significant reduced the content of nitrate, but the content of water, Vc, soluble sugar, protein and fiber of cabbage was not significant.