Identifying Key Metabolites Associated with Glucosinolate Biosynthesis in Response to Nitrogen Management Strategies in Two Rapeseed (Brassica napus) Varieties

A high
glucosinolate (GSL) concentration, an undesirable substance,
has severely restricted rapeseed (Brassica species) development. We performed widely targeted metabolomics
analysis based on the ultra-high-performance liquid chromatography–electrospray
ionization–tandem mass spectrometry (UPLC–ESI–MS/MS)
technology to analyze the metabolic profiles and identify the differential
metabolites and GSL components in response to different nitrogen (N)
levels in two rapeseed varieties. A total of 341 metabolites and 38
GSL components were detected in the seeds. A total of 188 differential
metabolites, including 34 GSL components, were identified in response
to different treatments, which were mapped into 2-oxocarboxylic acid
metabolism, tryptophan metabolism, and GSL biosynthesis. Key indicators
of GSL components highly responsible for different N levels under
two contrasting varieties were recognized, i.e., 1-methylpropyl GSL
and 4-methylthiobutyl GSL. This study suggests that the efficient
N management and variety selection are important strategies for developing
rapeseed with low GSLs.

高浓度硫代葡萄糖苷（glucosinolate, GSL）作为一类有害代谢物，严重制约了油菜（芸苔属）的产业发展。本研究基于超高效液相色谱-电喷雾电离-串联质谱（UPLC-ESI-MS/MS）技术开展广泛靶向代谢组学分析，对两个供试油菜品种在不同氮（N）水平处理下的代谢谱进行解析，并鉴定差异代谢物与硫代葡萄糖苷组分。本研究在油菜种子中共检测到341种代谢物与38种硫代葡萄糖苷组分；经不同处理后共鉴定出188种差异代谢物，其中包含34种硫代葡萄糖苷组分，这些差异代谢物富集于2-氧代羧酸代谢、色氨酸代谢及硫代葡萄糖苷生物合成通路。本研究进一步筛选出在两个供试品种中对不同氮水平响应最为关键的硫代葡萄糖苷组分，即1-甲基丙基硫代葡萄糖苷与4-甲硫基丁基硫代葡萄糖苷。本研究表明，优化氮肥管理与选育适宜品种是培育低硫代葡萄糖苷油菜的重要策略。