ABSTRACT
In order to study the biosynthesis pathway of esculentoside A, the Illumina HiSeq 4000 highthroughput sequencing method was used to analyze the transcriptome of Phytolacca americana seedlings. The 9.60 Gb clean data were obtained after the transcriptome of P. americana assembled by Trinity software. The total 63 957 unigenes were obtained after assembly and the average length was 988.82 bp, among them 24 517 unigenes (38.33%) were annotated in the public databases Nr, Swiss-Prot, COG, KOG, Pfam, GO and KEGG. According to the assignment of KEGG pathway, 53 unigenes were involved in terpenoid backbone biosynthesis and 8 unigenes involved in triterpenoid biosynthesis. Additionally, there were 417 unigenes assigned to other secondary metabolic pathways in P. americana. The post-modification enzyme genes involved in the esculentoside A biosynthesis were also analyzed in the transcriptome of P. americana. The results indicated that 130 unigenes may have the function of CYP450 which was involved in oxidation/hydroxylation modification of P. americana secondary metabolites. Furthermore, 46 unigenes had the function of glycosyltransferase UGT. The transcriptome data of P. americana laid a foundation for studying the biosynthesis pathway of esculentoside A and other secondary metabolites, and also provided theoretical basis for formation of medicinal materials quality.
ABSTRACT
Lepidium apetalum was used as an experimental material in this study. By analyzing the tran-scriptome data of L. apetalum and application of the specific primers, cDNA of cinnamate-4-hydroxylase (C4H) gene was isolated from L. apetalum and named as LaC4H (GenBank accession No. KX064050). Meanwhile, the bioinformatic analysis, prokaryotic expression, purification, tissue-specific expression analysis and expres-sion analysis after methyl jasmonate (MeJA) treatment were carried out. The results indicated that: ① The open reading frame (ORF) of LaC4H was 1 518 bp, which encoded a protein of 505 amino acid residues, with a predicted molecular mass of 57.73 kD. ② Bioinformatic analysis showed that LaC4H protein contained the conserved sequences of cytochrome P450 (CYP450) and 5 substrate recognition sites (SRSs) of CYP73A1, therefore LaC4H protein was a member of CYP450 superfamily. The phylogenetic analysis indicated that LaC4H protein showed the highest homology with C4H protein from cruciferous plants (such as AtC4H from Arabidopsis thaliana). ③ Through the construction of the prokaryotic expression vector pET-32a-LaC4H, the recombinant LaC4H protein was successfully expressed in E. coli BL21 (DE3) cells and the recombinant LaC4H protein was purified by Ni2+ affinity chromatography. ④ Real-time PCR analysis indicated that LaC4H was expressed in a high transcript level in stems, lower levels in leaves and flowers, the lowest level in roots. After MeJA treatment, the expression level of LaC4H in leaves was increased significantly to reach the highest level at 48 h. Furthermore, the expression levels of LaC4H were positively correlated with the flavonoids contents in leaves. The results of this study provide the fundamental information on LaC4H gene in the flavonoids biosyn-thesis pathway of L. apetalum.
ABSTRACT
Jasmonic acid carboxyl methyltransferase (JMT), a key enzyme for jasmonate (JA) biosynthesis, catalyzes the methylation of JA to form MeJA. To characterize the function of JMT, a plasmid pGEX-4T-SmJMT1 harboring JMT1 (SmJMT1) gene from Salvia miltiorrhiza was successfully transformed into E.coli BL21 (DE3) for protein expression. The recombination SmJMT1 was separated using SDS-PAGE and the size of expressed SmJMT1 protein was consistent with the prediction. The bacterial growth conditions were determined for optimal expression, which include growth temperature, incubation time, IPTG concentrations and culture density. The optimal growth conditions for SmJMT1 were that the bacterial cultures were grown to an A600 of 0.8, and induced with IPTG at a final concentration of 0.4 mmol·L-1, and then incubated for 8 h at 20℃. The expression of SmJMT1 in E.coli was confirmed by Western blotting, and mass spectrometry analysis of methyltransferase family. The successful expression and purification of JMT in this study provide the basis for more study of JA biosynthetic pathway and JA-regulated secondary metabolism of medicinal plants.