| Liquid chromatography-mass spectrometry(LC-MS)is an analysis and detection technology that combined liquid chromatography as a separation system with mass spectrometry as a detection system.This technology has a wide range of applications in the separation and analysis of natural products.It is efficient,fast and sensitive compared with the traditional analysis and detection technology.The samples only need simple pretreatment or derivatization and it is especially suitable for the analysis of components with small content which is difficult to be separated or easy to inactivate in the separation process.This thesis includes three aspects of research content: Firstly,the structure of strigolactone compounds in root exudates of safflower was analyzed by LC-MS;Secondly,the allelopathic effects of root exudates of safflower on seed germination and seedling growth of Portulaca oleracea L.and Setaria viridis(L.)Beauv.were measured by the petri dish filter paper method;Thirdly,the metabolomics of Dendrobium officinale from different habitats was studied by liquid chromatography-mass spectrometry.The details are as follows:1.The root exudates of safflower seedlings were collected in hydroponic solution and analyzed by ultra-performance liquid chromatography-quadrupole time-of-flight tandem mass spectrometry(UPLC-Q-TOF-MS).Firstly,construct the UNIFY database of known strigolactone compounds.Secondly,by comparing the data of liquid chromatography-mass spectrometry with the UNIFY database,analysing the mass spectrometric cleavage data and referencing the mass spectrometry data of known compounds to analyse the strigolactone compounds in root exudates of safflower.Finally,five strigolactone compounds were identified from root exudates of safflower which were Orobanchol,7-Oxoorobanchyl acetate,Orobanchyl acetate,5-Deoxystrigol,Fabacyl acetate.2.The collected root exudates of safflower were diluted into five concentration gradients of 0.1mg/m L,0.5 mg/m L,1.0 mg/m L,2.5 mg/m L,5.0 mg/m L,and the effects of different concentrations of safflower root exudates on seed germination and seedling growth of P.oleracea L.and S.viridis(L.)Beauv.were studied by petri dish filter paper method.The study showed that the root exudates of safflower at a concentration of 0.1～1.0 mg/m L significantly promoted seed germination and seedling growth of P.oleracea L.and S.viridis(L.)Beauv.,while the concentration of 2.5～5.0 mg/m L of safflower root exudates inhibited the seed germination and seedling growth of P.oleracea L.and S.viridis(L.)Beauv..The results showed that low concentration of safflower root exudates obviously promoted the growth of P.oleracea L.and S.viridis(L.)Beauv.,while high concentration of safflower root exudates inhibited the growth of P.oleracea L.and S.viridis(L.)Beauv..Therefore,we can evaluate the weed control ability of safflower root exudates from agroecosystems,which provides a theoretical basis for the application of safflower root exudates in weed control and the development and application of new herbicides in the future.3.The samples of D.officinale from Guiping,Guangxi,Wenshan,Yunnan,Yueqing,zhejiang were collected.The chemical compositions of D.officinale were analyzed by UPLC-Q-TOF-MS,the differences in metabolites of D.officinale from three different habitats were studyed by combining with software SIMCA-Pt 13.0 and using multivariate statistical analysis methods such as principal component analysis(PCA)and partial least squares discriminant analysis(OPLS-DA),and the differential metabolites were identified by Chem Spider and HMDB database based on relative molecular weight and secondary fragments.The results showed that 27 compounds were isolated and identified from D.officinale and PCA analysis showed that the D.officinale samples from the same origin were clustered together,while the samples from different sources were completely separated,indicating that the intraspecific difference between the samples from the same origin was small,but the intraspecific difference between the samples from different origin was large.The OPLS-DA analysis showed that there were four different metabolites in D.officinale from Guiping of Guangxi and Yueqing of Zhejiang and four different metabolites in D.officinale from Wenshan of Yunnan and Yueqing of Zhejiang,which mainly were flavonoids and terpenoids.This research method can better distinguish D.officinale from different regions,thus contributing to the origin tracing of D.officinale. |
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