Variation Characteristics of Glucosinolate Contents in Leaf Mustard (Brassica juncea)

Mustard, which belongs to the family Brassicaceae, is an annual or biennial herb and is considered as one of the most important native vegetables in China. Glucosinolates are important secondary metabolites containing sulfur and nitrogen in plants, which form a network with other metabolic pathways that play important roles in plant growth, development, and interaction with the environment. We studied varied phenotypic and glucosinolate contents of 60 mustard resources collected from various areas of China. The results showed both agronomic traits and glucosinolates varied greatly among mustard resources. We detected nine glucosinolates in mustard resources and the contents of total glucosinolates ranged from 1.2023 to 30.7310 μmol/g. Through the correlation analysis, we preliminarily found a significant negative correlation between leaf color and glucosinolate contents but needed further validation. For mustard resource JC 18-56, we analyzed the glucosinolate contents in different organs of different growth stages. The results indicated a significant difference among organs in both glucosinolates concentration and composition. The contents of glucosinolatess in alabastrums at bolting stage were highest, up to 140.1257 μmol/g dry weight (DW). We found that the main glucosinolates in roots were 4-methoxyglucobrassicin, while in other organs the glucosinolates were sinigrin. The contents of glucosinolatess in different organs of mustard were as follows: alabastrums > seeds > flowers > siliques > leaves > flower stems > stems > roots. This study provides important references for the selection and cultivation of high-quality mustard varieties.