Selection of reference genes for quantitative real-time PCR in Morinda officinalis / 中草药

Objective: To select the appropriate reference genes for calibrating the quantitative real-time PCR detection of gene expression in different tissues and leaves with different treatments of Morinda officinalis. Methods: With different groups and different processing leaves of M. officinalis as materials, 10 internal genes, including GAPDH, CYP, TUA, Actin and so on, were selected as candidate genes according to the M. officinalis transcriptome data. The expression stability of internal reference genes was analyzed by using real-time fluorescence quantification technique combined with software such as geNorm, NormFinder and BestKeeper, so as to select stable reference genes in different tissues and leaves of M. officinalis with different treatments. Finally, appropriate internal reference genes were selected to analyze the relative expression levels of DXS and DXR genes in different tissues and leaves with different treatments. Results: Internal reference genes GAPDH and UBQ were the most stable in different tissues of M. officinalis, the double internal reference combination of GAPDH + UBQ can more accurately analyze the relative expression levels of target genes in different tissues of M. officinalis, while the most stable reference genes in leaves with different treatments were GAPDH and Actin; The selection of the double reference combination of GAPDH + Actin can ensure the reliability of the target gene expression results. In different tissues of M. officinalis, the relative expression of DXS target gene was in sequence of root < stem < leaf, while the relative expression of DXR was stem < root < leaf. The relative expression levels of DXS and DXR genes in leaves with different treatments were increased compared with those untreated leaves (CK). Conclusion: The selected stable internal reference genes lay a foundation for the subsequent study on the expression of related genes of M. officinalis. Using the combination of two stable internal references to homogenize the target genes is conducive to improving the accuracy of the analysis of the expression of target genes.

Cloning and analysis of the DXR gene and its promoter in Morinda officinalis / 药学学报

The objective of this research was to clone 1-deoxy-D-xylulose 5-phosphate reductoisomerase gene (MoDXR) and its promoter sequence from Morinda officinalis and carry out bioinformatic analysis, cis-acting elements analysis, and prokaryotic expression. On the basis of the MoDXR gene sequence obtained from the M. officinalis transcriptome and with NCBI-ORFfinder analysis, a pair of specific primers were designed, and used for RT-PCR amplification. The promoter region sequence at the 5′ end of MoDXR gene was isolated by the genome walking technique. Localization of MoDXR was carried out by subcellular analysis. The prokaryotic expression plasmid pET-28a-MoDXR was constructed and transfected into Escherichia coli BL21(DE3) chemically-competent cells; the recombiant plasmid expressed fusion protein after the induction by IPTG. The full-length cDNA of MoDXR was 2 015 bp,and open reading frame (ORF) size was 1 425 bp, and it encoded 474 amino acid residues and had a molecular mass of 51.27 kD. Sequence comparison with BlastP to the NCBI database revealed that MoDXR had high sequence similarity with many other DXRs, such as Coffea arabica DXR (CaDXR) and Rauvolfia verticillata DXR (RvDXR). A phylogenetic tree revealed that MoDXR had its closest relationship with DXR from Coffea arabica and Gardenia jasminoides. The subcellular localization revealed that MoDXR protein was located on the chloroplast. Plantcare analysis indicated that the promoter region sequence of MoDXR was 1 493 bp, covering multiple light, stress, and hormone-responsive cis-regulatory elements; protein electrophoresis showed that the expressed protein was the anticipated size. This research lays the foundation for further purification and structural and functional characterization of the MoDXR protein.

Identification and analysis of the R2R3-MYB transcription factor based on a transcriptome database in Morinda officinalis / 药学学报

In order to explore MYB transcription factors related to developmental processes and secondary metabolism in Morinda officinalis, we analyzed MoMYB expression based on transcriptome data from three tissues (root, stem and leaf). We used this analysis to provide a theoretical foundation for regulating the metabolism of M. officinalis. RNA-seq data along with the five databases including PFAM and plantTFDB and others were used to screen and classify MoMYB, including GO functional annotation and classification, subcellular localization, signal peptide prediction, conserved motif discovery, and comparative phylogenetic analysis. RT-qPCR was carried out to detect tissue-specific expression differences of MoMYB genes. According to transcriptome data, 109 MoMYB sequences were identified and divided into four classes, containing 51 sequences related to R2R3-MYB. Subcellular localization analysis indicated that a majority of sequences were located in nucleus. Blast2GO analysis showed that 109 MoMYB sequences were classified into three major functional ontologies including molecular function (112), biological processes (76) and cellular components (239). The R2-MYB conserved motif of 51 R2R3-MYB sequences possessed three significantly conserved tryptophan residues, whereas a phenylalanine replaced the first tryptophan in R3-MYB. The results of multiple sequence alignment and phylogenetic analysis revealed that the R2R3-MYB was distributed in all subgroups, apart from the S10, S19 and S21 subgroups. RT-qPCR indicated that several R2R3-MYB genes were differentially expressed among the three tissues, and this finding was consistent with transcriptome data. The 109 MoMYB sequences were annotated and divided into different classes, which lays the foundation for further study on MYB transcriptional factors in M. officinalis.