Transcriptome Sequencing Of Cynomorium Songaricum Rupr. And Analysis Of Genes Involved In Catechin Biosynthesis

The accumulation of effective components in medicinal plants is closely related to the regulation of genes. It is helpful to understand the molecular mechanism of secondary metabolism and the expression of genes involved in the pathway by transcriptome analysis. Cynomorium songaricum is widely used in Chinese and Mongolian medicine, but the genomic and transcriptomic data of this species are very limited. In this study, we sequenced the transcriptome of inflorescence and stem of unearthed and earthed C. songaricum using Illumina technology. Then we identified the regulatory genes encoding enzymes involved in catechin metabolism. The main results are as follows:1. A total of 28,932,330,420nt bases were generated and assembled into 51360、 77540、62181、75830 and 86702 unigenes, respectively. These unigenes were annotated to public databases (Nr, NT、Swiss-Prot, KEGG, COG and GO), then we obtained the functional annotation of unigenes. Accordingly, a high-quality and comprehensive transcriptome database of C. songaricum was constructed successfully.2. Differential expression analysis of unigene, the results indicated that the gene expression of stem was higher than in the inflorescence in the two developmental stages of C. songaricum, which may be related to the accumulation of medicinal components during the growth. The gene expression of earthed C.songaricum was higher than in the unearthed C. songaricum probably due to rapid growth, blooming and fruiting.3. High-performance liquid chromatography was used to determine the content of catechin in each sample. Our results indicated that the inflorescence of unearthed C. songaricum accumulated higher catechin than others, followed by in stem. While the content of earthed inflorescence was minimal in all the sample, and the content of the upper and lower parts of earthed stem was higher, but the difference was not significant.4. According to the transcriptome information obtained catechin biosynthesis pathway, we found that a total of 80 unigenes encoding 11 enzymes were assigned to this pathway, and 21 candidate unigenes regulating catechin synthesis were identified by screening.5. Analysis of candidate unigenes expression, we found that the changes of expression of LAR and DFR were similar to the accumulation of catechin. Therefore, LAR and DFR may plays an important role in the regulation of catechin synthesis.