| Eucommia wulmoides Oliv.belongs to a single family and a single genus.Its stems,leaves and fruits have high medicinal value and economic benefits.Prune is a common measure in forestry cultivation and management.Reasonable prune can maintain plant regeneration ability,achieve high and excellent yield.Axillary buds are the main sources of germination shoots in plants.Their growth and development ability determine the integrity of plant regeneration structure.The Eucommia ulmoides leaves as the research object in our study,using multiple omics(metabolome and transcriptome)methods to detect the sapling physiological and biochemical changes,metabolic pathways and gene expression of key enzymes involved in the germination buds of Eucommia ulmoides.To analyze the regulation mechanism of axillary bud growth and development.It provides a theoretical basis for resource oriented ecological cultivation of Eucommia ulmoides and optimization of forestry industry.The main results were as follows:(1)After pruned treatment,leaves biomass and photosynthetic physiological parameters net photosynthetic rate(Pn),stomatal conductance(Gs)and transpiration rate(Tr)reached the maximum in pruned 20 cm group;The maximum photosynthetic rate(Fv/Fm),non photochemical quenching coefficient(NPQ)and regulatory energy dissipation(YNOQ)were increased,the photochemical quenching coefficient(qP)and non regulatory energy dissipation(YNO)were decreased.The contents of leaves photosynthetic pigment were significantly increased in pruned 10 cm group.Between the total numbers of leaves per plant and numbers of branches,Pn,Fv/Fm were significantly positively correlated,it indicated that photosynthesis was closely related to plant biomass accumulation.(2)A total of 28 different primary metabolites were obtained after pruned treatment,which acids were the most.All treatment groups were adopted the carbohydrate metabolism.The contents of chlorogenic acid,geniposide,genipin,aucubin,caffeic acid and asperuloside significantly decreased after pruned treatment in Eucommia ulmoides leaves.The content of geniposide acid was increased in the 10 cm pruned group,and decreased in the 20 cm pruned group.The contents of harpagoside and pinestinol diglucoside were decreased in the 10 cm group,but increased in the 20 cm group.(3)Based on transcriptome sequencing,the numbers of differentially expressed genes were the highest in germination buds of Eucommia ulmoides,the lowest in basal dormant buds.Through the enrichment analysis with the GO,COG and KEGG metabolic pathways,it was found that the up-regulated genes in germination buds were mainly concentrated in carbohydrate,sucrose and starch metabolism and transport pathways,the dormant buds were concentrated in plant hormones signal transduction and pathogen interaction pathways.The qRT-PCR results of 10 randomly selected genes were consistent with the results of transcriptome sequencing,which verified the reliability of transcriptome data.(4)A total of 26 primary metabolites and 33 phenolic compounds were identified in the six development stages of Eucommia ulmoides germination buds and dormant buds after pruned treatment.Phenolic compounds had the strongest response vat the early stage of axillary bud growth,which mainly branched acids in phenylpropane metabolic pathways,their contents were decreased with the increase of axillary bud development days.Pruned could activate the expression of the enzyme and promote the accumulation of auxin(IAA)in the axillary buds.IAA overexpression inhibited the expression of the syzygium oleosum probable indole-3-acetic acid-amido synthetase GH3.1,reduced the IAA to the optimal concentration in the germination buds.Eucalyptus grandis probable indole-3-acetic acid-amido synthetase GH3.1 was related to leaves extension,less affected by pruned. |
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