Metabonomics Analysis On Germination Of Davidia Involucrate Baill Seeds

Davidia involucrata Baill is one of the most endangered protected plants in China.It has high economic value ? ornamental value and academic value.The metabolism of Davidia involucrata Baill seeds is of great significance to its germination.At present?there is no systematic study on its metabolism level.In order to further explore the dynamic changes of main target metabolites ? metabolic spectrum differences and metabolic pathways during seed germination of Davidia involucrata Baill ? this study used Davidia involucrata Baill seeds as the research object ? UHPLC-QE-MS as the research technology ? plant metabonomics as the platform ? and multivariate statistical methods to screen different metabolites of Davidia involucrata Baill seeds(hypocotyl?cotyledon)at different germination stages.Metabolic pathways were analyzed by principal component analysis ? orthogonal partial least squares method-discrimination ? thermogram ? KEGG annotation ?metabolic pathway and other non-targeted metabonomics methods?which provided theoretical basis and data value for exploring the metabolic rules of seed germination?establishing the metabolic regulation mechanism of seed germination?and exploring the conservation strategies of endangered plant germplasm resources.The main results are as follows:1.According to the metabolic characteristics of Davidia involucrata Baill seeds at germination stage ? the germination stage can be divided into three stages:germination sedimentation stage(0M-6M): accumulation of energy for seed germination?gradual initiation of internal metabolic activities of seeds;germination preparation stage(6M-18M): vigorous metabolic activities within seeds ? adequate energy preparation and germination stage(18M-30M): gradual suboutgrowth of germinating seed hypocotyl.The seed coat is broken and the seed germinates.2.The coverage rate of metabolites in positive ion mode was better than that in negative ion mode;the total and differential metabolites in the hypocotyls of Davidia involucrata Baill seeds were more than those in cotyledons at the same stratification time?and the main metabolic activities of seed germination were carried out in the hypocotyls;the metabolites in the germination process of Davidia involucrata Baill seeds increased first and then decreased at different stratification time ? and the metabolites between 6M and 12 M were the most in the germination process.During this period?the metabolic difference was the most obvious and the metabolic activity was the most vigorous?which may mean that the seed of Davidia involucrata Baill began to germinate from dormancy.During germination?the up-regulated differential metabolites between 0M-6M and 12M-18 M were less than down-regulateddifferential metabolites?indicating that during this period?most metabolites decreased with the increase of stratification time?while the up-regulated metabolites between6M-12M?18M-24 M and 24M-30 M were more than those during germination.The contents of most metabolites increased with the prolongation of stratification time.The metabolic activity of Davidia involucrata Baill seeds increased with the prolongation of stratification time?which tended to be vigorous at the germination point and then gradually weakened.3.Significant differences in multiple of positive and negative ion modes in the hypocotyls of Davidia involucrata Baill during seed germination were as follows:Methyllycaconitine,Fetidine;Adenosine 5'-phosphate disodium,Gallagic acid;dTDP-3,4-dioxo-2,6-dideoxy-D-glucos,Phosphoribosyl-ATP;3-O-Sulfogalactosy lceramide,Hydroxytriphenylstannane;beta-Citryl-L-glutamate,Dichlorophen;The order of positive and negative ion modes in cotyledons is:Methyllycaconitine,Fetidine;Cliomide,Flusulfamide;TG,1-(2-Carboxyphenylamino)-1-deoxy-D-ribulose 5-phosphate;3-Oxybutylamine,dTDP-5-dimethyl-L-lyxose;EET Ethanolamide,Hydroxytriphenylstannane.These distinct metabolites explain the distinct differences during germination to the greatest extent,and are the key substances that can reflect the metabolic changes in Davidia involucrata Baill different stages.4.There are 11 metabolic markers involved in all stages of seeds germination of Davidia involucrata Baill: 2'-Deoxyguanosine,L-Glutamine,N-Acetylneuraminic acid,N-Heptanoyl-DL-homoserine lactone,beta-Nicotinamide adenine dinucleotide,4-Aminobutanoic acid,DL-pipecolic acid,Dl-Glutamic acid,(R)-(+)-Lactamide,Glucoheptonic acid,L-Glutamine is the same metabolic marker in the whole germination process of Davidia involucrata Baill seeds.These substances promote energy synthesis and material metabolism in seeds,and play an important role in regulating seed dormancy and germination..5.Twenty-six metabolic markers,including L-tyrosine?L-serine?L-tryptophan?Alpha-linolenic acid?Acetyl coenzyme A?Pyruvic acid?Pentose phosphoric acid pathway?Isoquinoline alkaloid biosynthesis?Arginine and proline metabolismand so on,were enriched in many metabolic pathways during the whole germination ofDavidia involucrata Baill seeds.The biological functions of Davidia involucrata Baill seeds provide important information for studying the changes of metabolites and pathways during seed germination.6.Vitamin B6 metabolism,Purine metabolism,Pyrimidine metabolism,Triglyceride metabolism,Fatty acid metabolism,Starch and sucrose metabolism are the most differentiated key metabolic pathways in the whole germination process of Davidia involucrata Baill seeds,while Purine Metabolism and Pyrimidine Metabolism are the most common key metabolic pathways in the hypocotyl and cotyledon.These metabolic pathways are the key factors to promote the seed germination of Davidia involucrata Baill from dormancy.The regulation of dormancy and germination mechanism of Davidia involucrata Baill seeds can be achieved by regulating the key metabolic pathways,which is of far-reaching significance for the further study of the conservation of seed germplasm resources of Davidia involucrata Baill.