Abstract: To investigate the metabolic response of Caucasian clover (Trifolium ambiguum Bieb.) to low-temperature stress of different cooling modes, gradual cooling (GC) and sudden cooling (SC) were used in this study. The metabolites in leaves were detected by widely-targeted metabolomics, and the differences of metabolites between the two treatment groups and the control group (CK) were compared. The results showed a total of 894 metabolites were identified in Caucasian clover leaves. Compared with CK, 124 and 139 different metabolites (DMs) were screened in GC and SC, respectively. DMs in the two treatment groups were mainly enriched in amino acid metabolism and biosynthesis of secondary metabolites. The content of butein was increased significantly only in GC group (P < 0.05), and the content of tyrosine and neohesperidin increased significantly only in the SC group (P < 0.05). The content of gamma-aminobutyric acid (GABA), leucine, histidine, lysine, citrate, cyanidin and luteolin were significantly increased in the two treatment groups (P < 0.05). The increase of these metabolites might be the main mechanism of Caucasian clover adaption to low-temperature stress.

Key words: Caucasian clover, Low-temperature stress, Metabolome, Different metabolites

摘要： 为探究高加索三叶草（Trifolium ambiguum Bieb.）对不同降温模式低温胁迫的代谢响应机制，本试验对其分别进行缓慢降温（Gradual cooling，GC）和骤然降温（Sudden cooling，SC）处理，利用广泛靶向代谢组学技术检测叶片代谢物，并比较2个处理组与常温对照组（CK）间的代谢物差异。结果表明：在高加索三叶草叶片中共检测出894种代谢物；与CK相比，在GC和SC处理组中分别筛选出124个和139个差异代谢物（Differential metabolites，DMs）；2处理组的DMs均主要富集在氨基酸代谢和次生代谢产物的生物合成；紫铆因含量仅在GC组中显著增加（P < 0.05），酪氨酸和新橙皮苷含量仅在SC组中显著增加（P < 0.05）；γ-氨基丁酸、亮氨酸、组氨酸、赖氨酸、柠檬酸、矢车菊素和木犀草素含量在2处理组均显著增加（P < 0.05）。这些代谢物含量的增加可能是高加索三叶草适应低温胁迫的主要机制。

关键词: 高加索三叶草, 低温胁迫, 代谢组, 差异代谢物