1.State Key Laboratory of North China Crop Improvement and Regulation/Key Laboratory for Vegetable Germplasm Enhancement and Utilization of Hebei/Collaborative Innovation Center of Vegetable Industry in Hebei/ College of Horticulture,Hebei Agricultural University;2.China;3.Beijing Vegetable Research Center,Beijing Academy of Agriculture and Forestry Sciences,Key Laboratory of Biology and Genetic Improvement of Horticultural Crops North China,Ministry of Agriculture;4.Institute of Vegetables and Flowers,Chinese Academy of Agricultural Sciences
The National Natural Science Foundation of China (General Program, Key Program, Major Research Plan)
Glucosinolates and their degradation products are important secondary metabolite of cruciferous vegetables with the function of anti-cancer. MAMs (Methylthioalkylmalate synthases) are involved in glucosinolate side-chain elongation. MAM1 catalyzes the aliphatic glucosinolate synthesis with short-chain, while MAM3 catalyzes that with long-chain. In this study, the glucosinolate content and the relative expression of MAM genes was analyzed in Chinese cabbage and cabbage inbred lines during seedling and rosette stages to analyze the relationship between MAM gene expression and the accumulation of beneficial glucosinolates. The results showed that the glucosinolate content in cabbage was higher than that in Chinese cabbage from seedling to rosette stage. The content of 5C and 4C aliphatic glucosinolates (GBN and NAP) were dominant in Chinese cabbage, whereas the main glucosinolates in cabbage were 3C and 4C aliphatic glucosinolates (IBE, SIN and GRA). The anti-cancer component SIN and GRA was significantly higher in cabbage than that in Chinese cabbage. The genome of Chinese cabbage and cabbage contains seven MAM paralogues each. By analyzing the expression levels of MAMs, we found that there was a significant difference in the relative expression level of MAM1 and MAM3 between Chinese cabbage and cabbage. The expression level of BraMAM1.1 and BraMAM1.2 in Chinese cabbage was significantly lower than that of BoMAM1.1 and BoMAM1.2 in cabbage, while the expression level of BraMAM3.2 and BraMAM3.3 was significantly higher than that of BoMAM3.1. Moreover, the content of 3C aliphatic glucosinolates in cabbage was positively correlated with the expression of BoMAM1.1, and the content of 5C aliphatic glucosinolates in Chinese cabbage was positively correlated with the expression of BraMAM3.2. We speculated that the low expression of BraMAM1.1 and the high expression of BraMAM3.2 may lead to the low accumulation of 3C aliphatic glucosinolates (SIN) and the high accumulation of 5C aliphatic glucosinolates (GBN) in Chinese cabbage.