BackgroundP. vietnamensis var. fuscidiscus, called “Yesanqi” in Chinese, is a new variety of P. vietnamensis, which was first found in Jinping County, the southern part of Yunnan Province, China. Compared with other Panax plants, this species contains higher content of ocotillol-type saponin, majonoside R2. Despite the pharmacological importance of ocotillol-type saponins, little is known about their biosynthesis in plants. Hence, P. vietnamensis var. fuscidiscus is a suitable medicinal herbal plant species to study biosynthesis of ocotillol-type saponins. In addition, the available genomic information of this important herbal plant is lacking.ResultsTo investigate the P. vietnamensis var. fuscidiscus transcriptome, Illumina HiSeq™ 2000 sequencing platform was employed. We produced 114,703,210 clean reads, assembled into 126,758 unigenes, with an average length of 1,304 bp and N50 of 2,108 bp. Among these 126,758 unigenes, 85,214 unigenes (67.23%) were annotated based on the information available from the public databases. The transcripts encoding the known enzymes involved in triterpenoid saponins biosynthesis were identified in our Illumina dataset. A full-length cDNA of three Squalene epoxidase (SE) genes were obtained using reverse transcription PCR (RT-PCR) and the expression patterns of ten unigenes were analyzed by reverse transcription quantitative real-time PCR (RT-qPCR). Furthermore, 15 candidate cytochrome P450 genes and 17 candidate UDP-glycosyltransferase genes most likely to involve in triterpenoid saponins biosynthesis pathway were discovered from transcriptome sequencing of P. vietnamensis var. fuscidiscus. We further analyzed the data and found 21,320 simple sequence repeats (SSRs), 30 primer pairs for SSRs were randomly selected for validation of the amplification and polymorphism in 13 P. vietnamensis var. fuscidiscus accessions. Meanwhile, five major triterpene saponins in roots of P. vietnamensis var. fuscidicus were determined using high performance liquid chromatography (HPLC) and evaporative light scattering detector (ELSD).ConclusionsThe genomic resources generated from P. vietnamensis var. fuscidiscus provide new insights into the identification of putative genes involved in triterpenoid saponins biosynthesis pathway. This will facilitate our understanding of the biosynthesis of triterpenoid saponins at molecular level. The SSR markers identified and developed in this study show genetic diversity for this important crop and will contribute to marker-assisted breeding for P. vietnamensis var. fuscidiscus.Electronic supplementary materialThe online version of this article (doi:10.1186/s12864-015-1332-8) contains supplementary material, which is available to authorized users.

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Multi-element analysis of the medicinal plant Marsdenia tenacissima was used to develop a reliable method of tracing the geographical source of the samples. The concentrations of 27 elements in 128 samples from 4 provinces in China were analyzed by inductively coupled plasma-atomic emission spectroscopy. Pattern recognition techniques, viz. principal component analysis (PCA), cluster analysis (CA), stepwise linear discriminant analysis (SLDA) and k-nearest neighbor analysis (KNN), were used for this purpose. It was verified that 21 elements in the M. tenacissima samples from different regions showed significant differences (P < 0.05). The PCA explained 87.36 % of the variance with the first seven principal component variables, and a score plot produced from the largest three principal components showed that the source area of most samples could be correctly distinguished. The CA showed that samples were separated into three clusters. The SLDA produced an overall correct classification rate of 87.5 % and a cross-validation rate of 85.2 %. The KNN analysis performed ideally, with an average identification rate of 100 % for the training set and 93.33 % for the test set. These results laid the foundation for the application of multi-element analysis combined with pattern recognition techniques for tracing the geographical origin of samples of medicinal plants.

Photosynthetic adaptive strategies vary with the growth irradiance. The potential photosynthetic adaptive strategies of shade-tolerant species Panax notoginseng (Burkill) F. H. Chen to long-term high light and low light remains unclear. Photosynthetic performance, photosynthesis-related pigments, leaves anatomical characteristics and antioxidant enzyme activities were comparatively determined in P. notoginseng grown under different light regimes. The thickness of the upper epidermis, palisade tissue, and lower epidermis were declined with increasing growth irradiance. Low-light-grown leaves were declined in transpiration rate (Tr) and stomatal conductance (Cond), but intercellular CO2 concentration (Ci) and net photosynthesis rate (Pn) had opposite trends. The maximum photo-oxidation P700+ (Pm) was greatly reduced in 29.8% full sunlight (FL) plants; The maximum quantum yield of photosystem II (Fv/Fm) in 0.2% FL plants was significantly lowest. Electron transport, thermal dissipation, and the effective quantum yield of PSI [Y(I)] and PSII [Y(II)] were declined in low-light-grown plants compared with high-light-grown P. notoginseng. The minimum value of non-regulated energy dissipation of PSII [Y(NO)] was recorded in 0.2% FL P. notoginseng. OJIP kinetic curve showed that relative variable fluorescence at J-phase (VJ) and the ratio of variable fluorescent FK occupying the FJ-FO amplitude (Wk) were significantly increased in 0.2% FL plants. However, the increase in Wk was lower than the increase in VJ. In conclusion, PSI photoinhibition is the underlying sensitivity of the typically shade-tolerant species P. notoginseng to high light, and the photodamage to PSII acceptor side might cause the typically shade-tolerant plants to be unsuitable for long-term low light stress.