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Polygonatum sibiricum polysaccharides (PSPs) are used to improve immunity, alleviate dryness, promote the secretion of fluids, and quench thirst. However, the PSP biosynthetic pathway is largely unknown. Understanding the genetic background will help delineate that pathway at the molecular level so that researchers can develop better conservation strategies. After comparing the PSP contents among several different P. sibiricum germplasms, we selected two groups with the largest contrasts in contents and subjected them to HiSeq2500 transcriptome sequencing to identify the candidate genes involved in PSP biosynthesis. In all, 20 kinds of enzyme-encoding genes were related to PSP biosynthesis. The polysaccharide content was positively correlated with the expression patterns of β-fructofuranosidase ( sacA ), fructokinase ( scrK ), UDP-glucose 4-epimerase ( GALE ), Mannose-1-phosphate guanylyltransferase ( GMPP ), and UDP-glucose 6-dehydrogenase ( UGDH ), but negatively correlated with the expression of Hexokinase ( HK ). Through qRT-PCR validation and comprehensive analysis, we determined that sacA , HK , and GMPP are key genes for enzymes within the PSP metabolic pathway in P. sibiricum. Our results provide a public transcriptome dataset for this species and an outline of pathways for the production of polysaccharides in medicinal plants. They also present more information about the PSP biosynthesis pathway at the molecular level in P. sibiricum and lay the foundation for subsequent research of gene functions., Competing Interests: The authors declare no conflict of interest.

The dried root of Gentiana macrophylla is a well-known traditional Chinese herbal medicine for treating jaundice, hepatitis, and stomachic and choleretic ailments. However, natural sources are now in short supply. A lack of information about its genetic background has been a great hindrance to producing its active constituents via genetic engineering. We performed RNA-seq to obtain 42,918 unigenes (average length = 667 bp) in its transcriptome. Of these, 32,141 (74.89 %) were annotated and 2,339 unigenes were assigned to secondary-metabolite pathways. In all, 114 putative unigenes involved in secoiridoid biosynthesis were identified in our transcriptome library. A Blast X search against the Arabidopsis gene regulatory information server showed that 4,413 unigenes are homologous to transcription factor genes from Arabidopsis. Organ-specific genes and candidate gene expression profiles were also investigated with digital gene expression technology. Quantitative PCR was used to verify the expression patterns of several novel transcripts involved in secoiridoid biosynthesis. Our results not only enrich the gene resource but will also benefit research into the molecular genetics and functional genomics of this species.

Background: Hypericum perforatum L. (St. John's wort) is a medicinal plant with pharmacological properties that are antidepressant, anti-inflammatory, antiviral, anti-cancer, and antibacterial. Its major active metabolites are hypericins, hyperforins, and melatonin. However, little genetic information is available for this species, especially that concerning the biosynthetic pathways for active ingredients., Methodology/principal Findings: Using de novo transcriptome analysis, we obtained 59,184 unigenes covering the entire life cycle of these plants. In all, 40,813 unigenes (68.86%) were annotated and 2,359 were assigned to secondary metabolic pathways. Among them, 260 unigenes are involved in the production of hypericin, hyperforin, and melatonin. Another 2,291 unigenes are classified as potential Type III polyketide synthase. Our BlastX search against the AGRIS database reveals 1,772 unigenes that are homologous to 47 known Arabidopsis transcription factor families. Further analysis shows that 10.61% (6,277) of these unigenes contain 7,643 SSRs., Conclusion: We have identified a set of putative genes involved in several secondary metabolism pathways, especially those related to the synthesis of its active ingredients. Our results will serve as an important platform for public information about gene expression, genomics, and functional genomics in H. perforatum.

Jasmonic acid (JA) carboxyl methyltransferase (JMT), a key enzyme in jasmonate-regulated plant responses, may be involved in plant defense and development by methylating JA to MeJA, thus influencing the concentrations of MeJA in plant. In this study, we isolated the JMT gene from Salvia miltiorrhiza, an important medicinal plant widely used to treat cardiovascular disease. We present a genetic manipulation strategy to enhance the production of phenolic acids by overexpresion SmJMT in S. miltiorrhiza. Global transcriptomic analysis using RNA sequencing showed that the expression levels of genes involved in the biosynthesis pathway of phenolic acids and MeJA were upregulated in the overexpression lines. In addition, the levels of endogenous MeJA, and the accumulation of rosmarinic acid (RA) and salvianolic acid (Sal B), as well as the concentrations of total phenolics and total flavonoids in transgenic lines, were significantly elevated compared with the untransformed control. Our results demonstrate that overexpression of SmJMT promotes the production of phenolic acids through simultaneously activating genes encoding key enzymes involved in the biosynthesis pathway of phenolic acids and enhancing the endogenous MeJA levels in S. miltiorrhiza. [ABSTRACT FROM AUTHOR]