盐胁迫下白榆种子萌发期代谢组学分析

Metabonomic Analysis of Seed Germination Period of Ulmus pumila under Salt Stress

白榆(Ulmus pumila)耐盐性强,是盐碱地上的重要生态经济树种,但盐胁迫抑制种子萌发已成为盐碱地白榆天然更新的首要障碍因子。小分子代谢物在非生物胁迫下种子萌发期发挥重要作用,但盐胁迫下白榆种子萌发期代谢组学研究尚未见报道。本研究基于高效液相色谱串联质谱(LC-MS/MS)技术的代谢组学方法,对盐胁迫下白榆种子萌发期代谢组学进行了分析。主成分分析(PCA)及偏最小二乘法判别分析(PLS-DA)结果表明盐胁迫下白榆种子萌发期与对照相比,代谢物呈明显分离状态。利用超几何检验方法,筛选出45个差异代谢物富集KEGG Pathway,包含44个差异代谢物,在KEGG Pathway一级分类环境信息处理中盐胁迫促进了信号转导,抑制了膜转运;在一级分类新陈代谢中盐胁迫促进了脂质代谢,抑制了氨基酸、碳水化合物、能量代谢和其他次生代谢产物的生物合成。综上所述,盐胁迫下白榆种子萌发期可能通过促进信号转导加速生长,以及提升脂质代谢水平增强抗逆性,从而适应外界盐胁迫,其中油菜素内酯和精胺可能是白榆种子萌发期适应盐胁迫的关键调控因子。

Ulmus pumila is an important ecological and economic tree species in saline-alkali land with high salt tolerance. However, the inhibition of seed germination under salt stress has become the primary obstacle to natural regeneration of U. pumila. Small metabolites played a crucial regulatory role in seed germination under abiotic stress. However, research on metabonomics of seed germination period of U. pumila under salt stress has not been found. In this study, non-target analysis based on high performance liquid chromatography tandem mass spectrometry was used to analyze the metabolic profile of the seed germination period of U. pumila under salt stress. Principal component analysis and partial least squares discrimination analysis were carried out for pattern recognition.The results showed that a clear separation was achieved between the control and treated with NaCl of the seed germination period of U. pumila. Using hypergeometric test, 45 KEGG Pathways with significantly different metabolites enrichment were screened, which included 44 differential metabolites. In the environmental information processing, salt stress promoted signal transduction and inhibited membrane transport;in the metabolism, salt stress promoted lipid metabolism, inhibited amino acid metabolism, carbohydrate metabolism, energy meta-bolism and biosynthesis of other secondary metabolites. In conclusion, under salt stress, U. pumila may accelerate growth by promoting signal transduction, and enhance stress resistance by enhancing lipid metabolism, then the seed germination stage adapted to the external salt stress. Brassinolide and spermine may be the key regulatory factors for U.pumila to adapt to salt stress during seed germination period.