[Synthesis and regulation of secondary metabolites by microRNA in medicinal plants]

miRNA (microRNA) is a kind of important endogenous non-coding small RNA, which mainly regulates the expression of target gene at the post-transcriptional level by splicing and translation inhibition and it plays an important role in the synthesis of plant secondary metabolites, especially for medicinal plants, the secondary metabolites are mostly active ingredients, which are the basis of medicinal effects. It is of great significance to study the biosynthetic pathways and complex regulatory networks of secondary metabolites of medicinal plants.This review introduces the miRNAs related to the synthesis of secondary metabolites in medicinal plants,which focuses on effects of miRNAs on biosynthesis of terpenoids, alkaloids and flavonoids,aiming to provide new ideas for biosynthesis and regulation of secondary metabolites of medicinal plants.

[Correlative analysis advance of chemical constituents of Polyporus umbellatus and Armillaria mellea]

Medicinal Polyporus umbellatus is the dry sclerotia of P. umbellatus, with the effect of diuresis; Armillaria mellea is a parasitic fungus which can infect plants up to 300 genera, with sedative, anticonvulsant and some other biological activities. As the medicinal value of P. umbellatus and A. mellea is increasingly wide concerned, the market quantity demanded of them is gradually increased and the demand outstrips the supply. The symbiotic A. mellea and P. umbellatus are both the medicinal and edible fungi with diverse activities, including hypoglycemic action, improve immunity and antitumor and so on. The growth of the sclerotia forming from the mycelium of P. umbellatus is related to the infection of the symbiotic A. mellea and their secondary products. In this study, by comparing the chemical constituents of the mycelium and sclerotia of P. umbellatus and A. mellea, we found that they all produced steroids and nitrogen-containing heterocycles. The sclerotia of P. umbellatus and A. mellea also produced triterpenes secondary metabolites. In addition, the mycelium and infected sclerotia of P. umbellatus mainly produced different steroids, and the sclerotia produced some other special secondary metabolites, such as long-chain fatty acids, ceramides, phenol and so on. By analyzing above all kinds of differences, speculated that these may be caused by the infection of the symbiotic A. mellea which mainly produced sesquiterpenes, diterpenes and other secondary metabolites. The contents and types of compounds of P. umbellatus and A. mellea are closely related to their symbiosis and reproduction, therefore, many symbiosis mechanisms should be found by utilizing more molecular biology technology to elucidate this complex symbiotic infection and provide scientific basis for improving the yield and quality of P. umbellatus and A. mellea.

[Transcriptome analysis reveals genes involved in biosynthesis of secondary metabolism in Cornus officinalis]

In order to explore genetic basis for the biosynthesis of secondary metabolism,the transcriptome of Cornus officinalis was sequenced by the new generation of high-throughput sequencing technology,A total of 96 032 unigenes were assembled with an average length of 590.53 bp. Among them, 35 478 unigenes were annotated in the public databases NR,Swissprot,COG,GO,KOG,Pfam and KEGG. Based on the assignment of KEGG pathway, 84 involved in ridoid biosynthesis and 487 unigenes involved in others secondary metabolites biosynthesis were found. Additionally,53 unigenes and 72 unigenes were predicted to have potential functions of cytochome P450 and UDP- glycosyltransferases based on the annotation result, which may encode responsible for secondary metabolites modification. This study was the first comprehensive transcriptome analysis for C. officinalis, and the candidate genes involved in the biosynthesis of secondary metabolites were obtained. The transcriptome data constitutes a much more abundant genetic resource that can be utilized to benefit further molecular biology studies on C. officinalis.