为研究发光二极管（Light-emitting diodes，LED）处理对上海青采后硫代葡萄糖苷（简称硫苷）代谢的作用机理，本文首先采用不同颜色和光密度的光照处理上海青，得出6.5 μmol/(m2·s)的红色LED光照处理可显著抑制上海青中叶绿素降解，延缓其黄化。在此基础上，研究了6.5 μmol/(m2·s)红色LED光照处理对贮藏期间上海青中硫苷代谢相关物质及基因表达水平的影响。结果表明，上海青叶柄中总硫苷和异硫氰酸酯含量分别为叶片的2.72倍和1.32倍；红色LED光照处理可显著上调上海青叶柄中脂肪族合成关键基因MYB28，CYP83A1，GSTF11等的表达水平，从而促进叶柄中主要硫苷物质3-丁烯基硫苷等的合成；由此，上海青叶柄中总硫苷含量在贮藏4~8 d期间为对照组的1.62~1.99倍；同时，该处理提升了上海青叶柄的黑芥子酶活性，从而促进了总异硫氰酸酯的积累，且在贮藏4~8 d期间，对照组上海青叶柄的总异硫氰酸酯含量为红光处理组的77.43%~91.98%。综上，红色LED光照处理通过调控硫苷合成关键基因和黑芥子酶活性来延缓上海青中硫苷物质和异硫氰酸酯的流失。
To investigate the effect of red light-emitting diodes (LED) irradiation on the metabolism of glucosinolates of postharvest pakchoi (Brassica rapa L subsp. chinensis). Firstly, the materials were treated with different conditions of LED irradiation with different color and density. The results showed that the degradation of chlorophyll and the yellowing of pakchoi were inhibited by red LED irradiation with a density of 6.5 μmol/(m2·s). Then, the red LED irradiation with 6.5 μmol/(m2·s) was selected for treating the pakchoi. Then, the changes of glucosinolate content and relative expression level of genes involved in the glucosinolate metabolism of pakchoi after red LED irradiation were analyzed to explored the possible regulatory mechanism of this treatment. The results indicated that the contents of total glucosinolate and isothiocyanate in petiole of pakchoi were 2.72 times and 1.32 times higher than those in leaves, respectively. Additionally, the relative expression of genes including MYB28, CYP83A1, and GSTF11 were up-regulated by the red LED irradiation, thus promoting the synthesis of glucosinolate such as gluconapin. As a result, the content of total glucosinolate in the treated petiole of pakchoi was 1.62~1.99 times higher than that in the control during 4~8 day of storage. The myrosinase activity in the petiole of pakchoi was also promoted by the red LED irradiation, and consequently, the accumulation of total isothiocyanate in the petiole of pakchoi was increased. Notably, the total isothiocyanate contents in the control group were lower by 77.43%~91.98% than those in the red LED irradiation treated group during 4~8 day. In conclusion, the red LED light treatment could delay the losses of glucosinolates and isothiocyanates in pakchoi, which could be explained by the upregulated relative expression level of genes involved in the synthesis of aliphatic glucosinolate and the increased myrosinase activity in the sample.