Effects Of Naphthylacetic Acid And Paclobutrazol On The Synthesis And Accumulation Of Flavonoids And Terpenoids In Ginkgo Biloba L. Leaves

Ginkgo biloba leaves have high medicinal value,among which the most active ingredients are flavonoids and terpenoids.Naphthalene acetate（NAA）and paclobutrazole（PBZ）are two widely used plant growth regulators,which have important regulatory effects on plant growth,development,secondary metabolism and other physiological processes.How to improve the content of flavonoids and terpenoids in Ginkgo biloba leaves has always been an important research topic.It is of great significance to explore the effects of growth regulators on the content of secondary metabolites in Ginkgo biloba leaves.Aiming at this problem,this paper adopts the field and pot experiment method,NAA and PBZ processing was studied under the growth,leaf of flavonoids and terpenoids compounds,endogenous hormones,chlorophyll and the change of primary metabolites.Combined with the transcriptome sequencing analysis,we found differentially expressed genes in flavonoids and terpenoids synthesis.This study laid a foundation for improving the medicinal value of Ginkgo biloba leaves and the spraying methods of NAA and PBZ.The main results are as follows:1.NAA treatment had a certain promotion effect on the growth and chlorophyll content of new shoot of Ginkgo biloba.After treatment for 20 days,the length of new shoots of Ginkgo biloba significantly increased,and the chlorophyll content significantly increased.However,PBZ treatment inhibited the growth and the content of chlorophyll.Only 150 mg/L treatment partially increased the content of chlorophyll.2.Suitable concentrations of NAA and PBZ can increase the contents of flavonoids and terpenoids in Ginkgo biloba leaves.Compared with the control,5 mg/L NAA and 50 mg/L PBZ treatments increased the content of flavonoids in Ginkgo biloba leaves by 19.4%and 31.7%,respectively.And the content of terpenoids increased by 13.5%and 39.3%,respectively.3.The appropriate concentration of NAA treatment can increase the content of soluble sugar and soluble protein in Ginkgo biloba leaves.After 5 mg/L NAA treatment for 15 days,the soluble sugar content in Ginkgo biloba leaves increased by 37.5%compared with the control.After treatment with 20 mg/L NAA for 5 days,the soluble protein content of Ginkgo biloba leaves increased by 16.8%.However,different concentrations of PBZ treatment overall increase contents of soluble sugar and soluble protein in Ginkgo biloba leaves.Especially the treatment of100 mg/L,which had a significant effect.4.NAA and PBZ treatments significantly affected the contents of various hormones in Ginkgo biloba leaves.5 mg/L and 10 mg/L NAA treatments significantly decreased the content of IAA in Ginkgo biloba leaves.The content of IAA in Ginkgo biloba leaves treated with all concentrations of PBZ showed a trend of first decreasing and then increasing.NAA and PBZ treatments decreased GA₃content in Ginkgo biloba leaves in general,while ABA content showed a trend of first decreasing and then increasing.The ZR content in Ginkgo biloba leaves was decreased by PBZ treatment,while the ZR content in Ginkgo biloba leaves was firstly decreased and then increased by NAA treatment.5.The appropriate concentration of NAA and PBZ treatment can improve the antioxidant activity of flavonoids in Ginkgo biloba leaves,such as 5 mg/L NAA and 50 mg/L PBZ treatment.The NAA＿CK transcriptome differential gene analysis showed that the expression levels of two POD and one SOD gene were significantly up-regulated,and the expression levels of three POD genes were significantly down-regulated.The PBZ＿CK transcriptome analysis showed that the expression levels of 5 POD and 1 SOD genes were significantly up-regulated,and the expression levels of 3 POD genes were significantly down-regulated.6.Transcriptome sequencing results showed that 1002 differential genes were detected in the NAA＿CK contrast group,among which 634 were up-regulated and 368 were down-regulated.There were 923 differential genes detected in PBZ＿CK control group,335 of which were up-regulated and 588 of which were down-regulated.The KEGG pathway analysis of the NAA＿CK and PBZ＿CK contrast groups showed that 2 and 4 differential genes were enriched in the flavonoid synthesis pathway.10 and 18 differential genes were enriched in the phenylpropane biosynthesis pathway.11 and 12 differential genes were enriched in the terpenoid biosynthesis related pathway.In conclusion,appropriate treatment of NAA and PBZ can improve the contents of flavonoids and terpenoids in Ginkgo biloba leaves,which is related to the gene expression that affects the synthesis of secondary metabolites after treatment of the two hormones.Under the current experimental conditions,the appropriate spraying method is:spray 5 mg/L NAA once 15days before leaf picking or 50 mg/L PBZ once 10 days before leaf picking.