Illumina Sequencing Reveals Conserved and Novel MicroRNAs of Dendrobium nobile Protocorm Involved in Synthesizing Dendrobine, a Potential Nanodrug.

Emergency of nanoparticulate drug delivery systems has improved the target, bioavailability, and curative effect of traditional Chinese medicine (TCM). However, the application of nano-preparation has been limited owing to the low content of active ingredients in part TCM. MicroRNAs (miRNAs) regulate plant growth, development, and response to environmental stresses at post-transcriptional regulation level by cleavage or translational inhibition. The molecular functions of miRNAs playing a role in synthesizing active comportments at medicinal plants have been widely researched. Dendrobium nobile is a perennial herb in the orchidaceae family. D. nobile protocorm can produce plant-specific metabolites at a short period. Therefore, it is a good substitute for producing metabolites. To understand the functions of miRNAs in D. nobile protocorm, Illumina sequencing of D. nobile protocorm (Dnp), D. officinale protocorm (Dcp), and D. nobile leaf (Dnl) were carried out. A total of 439, 412, and 432 miRNAs were identified from Dnp, Dcp, and Dnl, respectively. Some specific miRNAs were identified among them. Through combing GO and KEGG function annotation, miRNAs mainly involved metabolic pathways, plant hormone signal transduction, biological regulation, and protein binding. Acetyl-CoA acetyltransferase (AACT), mevalonate kinase (MK), 1-deoxy-D-xylulose 5-phosphate reductoisomerase (DXR), and 2-C-methyl-D-erythritol 4-phosphate cytidylyltransferase (HDS), synthesizing basic precursor isoprene pyrophosphate (IPP) in terpenoid backbone biosynthesis pathway, were predicted as potential targets of 6 different miRNAs. Twenty-six miRNAs participated in auxin, cytokinin, abscisic acid, jasmonic acid, and salicylic acid signal transduction pathway. This report provided valuable candidate genes in Dnp involved in terpenoid biosynthesis and plant hormone signal transduction pathway. At the same time, it can help accelerate the use of dendrobine into nano preparation.

[Karyotype analysis and its systematic implications of Pterocypsela formosana and P. elata].

Pterocypsela is a very important traditional Chinese medicine from the tribe Cichorieae of Asteraceae. Mitotic chromosome numbers and karyotypes are reported for P. formosana and P. elata from Hunan and Hubei province, China. The former is new and the latter provide confirmation of previous reference. All P. taxa are diploidy with 2n = 18 and their basic number is tentatively suggested as x = 9. Karyotype of Pterocypsela is 2A and P. formosana with a karyotype formula of 2n = 2x = 18 = 4m + 14sm, and 2n = 2x = 18 = 2m + 8sm +8st for P. elata. It is the first time to report the AI value for Pterocypsela in this paper. Cytological data of chromosomal numbers and karyotypes were used to discuss the close relationships of the Pterocypsela genus and the taxonomy of the medicinal plants.