Transcriptome Analysis Of The Transgenic Arabidopsis Thaliana Heterologously Overexpressing 10-HGO Gene From Lithospermum Erythrorhizon

Shikonin and its derivatives are naphthoquinone natural pigments,which are synthesized and accumulated in the roots of boraginaceae plants,such as Lithospermum erythrorrhizon and Onosma paniculatum.They have anti-inflammatory,anti-bacterial and anti-tumor activities.Although the biosynthetic pathway of shikonin and its derivatives has been largely clarified,and a number of related metabolic enzymes have been isolated and cloned,there are still some metabolic steps needs to be explored.Studies have shown that 10-hydroxygeraniol oxidoreductase(10-HGO)plays an important role in the biosynthesis of iridoids.Because the biosynthetic pathway of the iridoid terpene is closely related to the metabolism of phenylpropanoid,so 10-HGO may also be an important regulator of the phenylpropanoid metabolism.Due to the biosynthesis of shikonin also has a phenylpropanoid biosynthesis,and according to the results of the transcriptomics studies in our previous research,we speculate that 10-HGO may also play an important role in regulating the secondary metabolism of Lerythropoietin.The full-length cDNA of 10-HGO gene had been cloned in our laboratory.Because the model plant Arabidopsis has been completed genome-wide sequencing,its primary metabolic pathway and secondary metabolic pathway are similar to the vast majority of other plants',including L.Erythropoietin,so this study intends to investigate the molecular mechanism of 10-HGO-regulated secondary metabolism in L.erythropoietin by overexpressing it in Arabidopsis thaliana.RNA sequencing(RNA-Seq)is a technique for sequencing all mRNAs transcribed by specific cells or tissues at a given time using high-throughput sequencing(HTS)methods.Transcriptome sequencing not only detects the expression of known transcripts,but also predicts new unknown transcripts that allow for the most comprehensive transcript analysis of the species without knowing the genetic or genomic information of a particular species.In this experiment,we used the transcriptome sequencing technique.After analysis of the measured data,it was found that there were 126 differentially expressed genes in the 10-HGO overexpressing group compared with the empty vector control group,among which 71 genes were down-regulated,such as 4-coumarate-CoA ligase,peroxidase,cytochrome P450 704B1,O-methyltransferase family protein,Transcription factor MYB75,etc.;55 genes were up-regulated,such as caffeoyl-CoA O-methyltransferase,mitochondrial Ubiquinol oxidase 3,xyloglucan hydrolase 17,CCT motif family protein,calcium binding protein CML23 and so on.Of the 126 differentially expressed genes,only 114 had GO annotationes,which were annotated to different terms,for example,nine differential expressed genes were annotated into the pollen wall component term and nine differential expressed genes were annotated to the extracellular matrix assembly term,four differential expressed genes were annotated to the pollen biosynthesis process term etc..The overexpression of 10-HGO gene had significant effects on the phenylpropanoid biosynthetic pathway,phenylalanine metabolic pathway,tryptophan metabolism and other metabolic pathways in Arabidopsis thaliana,positive feedback promotes the phenylalanine metabolic pathway and the tryptophan metabolic pathway.These results provide useful information for further study of the specific functions of 10-HGO in the biosynthetic pathway of shikonin and its derivatives.