Effects Of EBR On Flavonoid Metabolism Of Ginkgo Biloba And Functional Of Related Genes

Flavonoids are important secondary metabolites of Ginkgo biloba and have important medicinal value.China is rich in ginkgo resources,but the quality of ginkgo is uneven.The contents of flavonoids in Ginkgo biloba leaves are also different,which restricts the development of Ginkgo biloba industry to a certain extent.Therefore,it is of great significance to improve the content of flavonoids.EBR is a new type of plant hormone,which can regulate plant growth and development and secondary metabolism,especially promote the synthesis and accumulation of flavonoids.However,it has not been reported whether EBR has an effect on flavonoid metabolism in Ginkgo biloba leaves.one year gave birth to the west in this study of Ginkgo biloba(half compatriots home department)as the material,after EBR treatment,determination of the ginkgo biloba seedling growth,photosynthetic characteristics and flavonoids compounds content,analyzes the differentially expressed genes,ginkgo leaf extract may be involved in the metabolism of flavonoids MYB transcription factor family,and the transcription factor of candidate gene cloning and functional verification.The results of this study have application value and theoretical significance to the production practice of Ginkgo biloba leaves forest and to reveal the regulation mechanism of EBR on flavonoid compounds.The main results are as follows:(1).The growth and flavonoid content of ginkgo biloba were significantly different between EBR treatments(P < 0.05).EBR treatment at 1.0 mg/L could significantly promote the growth of leaf and seedling height,and the content of flavonoids in leaves,while EBR treatment at medium and high concentrations(1.5 mg/L and 2.0 mg/L)could significantly promote the net photosynthetic rate,stomatal conductance and transpiration rate,and transpiration rate,etc.,had a significant promoting effect,but had no significant effect on the accumulation of flavonoids.(2).The contents of endogenous hormones in ginkgo biloba leaves were significantly different under EBR treatment(P < 0.05),but the variation patterns of different hormones were significantly different.EBR treatment increased the content of GA3 and ZR in ginkgo biloba leaves,but decreased the content of JAME.The accumulation of IAA in leaves was significantly inhibited under medium and low concentrations of EBR(1.5 mg/L and 2.0 mg/L),while the accumulation of BR was significantly inhibited under medium and low concentrations of EBR(0.5 mg/L and 1.0 mg/L).The contents of DHZR,IPA and GA4 in leaves were the highest under EBR3 treatment.Correlation analysis showed that the contents of GA3 and ABA,DHZR and GA4,JAME and BR,BR and IPA,DHZR and IPA in ginkgo biloba leaves were significantly correlated(P < 0.01).(3).After exogenous EBR treatment,2365 genes were induced and differentially expressed in ginkgo biloba leaves.KEGG analysis showed that these genes were enriched in phenylpropanoid biosynthesis pathway,flavonoid biosynthesis pathway,synthesis and degradation of ketone bodies,plant-pathogen interaction,and mutual conversion of pentose and glucuronic acid.Among them,50 genes in phenylpropane biosynthesis and flavonoid biosynthesis pathway were significantly down-regulated(P < 0.05).Transcription factor analysis showed that transcription factor members of MYB family were induced to express the most after treatment with different concentrations of exogenous EBR,and 33 genes were significantly up-regulated(P < 0.05).The expression level analysis and correlation analysis showed that the gene expression levels of GbMYB59(Gb＿06934)and GbMYB23(Gb＿17945)of MYB family transcription factors had the same variation trend with the flavonoid content.GbMYB59 and GbMYB23 were strongly correlated with Gb PAL,Gb C4 H,Gb4CL,GBF3’H and Gb FLS in the flavonoid metabolic pathway(P < 0.05).Therefore,GbMYB59 and GbMYB23 were selected as candidate genes.(4).Two genes GbMYB59 and GbMYB23 were cloned successfully,and they were located in the nucleus.GbMYB59 and GbMYB23 significantly promoted the synthesis of flavonoids in transgenic Tobacco and Arabidopsis.