Responses of photosystem to long-term light stress in a typically shade-tolerant species Panax notoginseng.

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 (C i) and net photosynthesis rate (P n) had opposite trends. The maximum photo-oxidation P 700 + (P m) was greatly reduced in 29.8% full sunlight (FL) plants; The maximum quantum yield of photosystem II (F v/F m) 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 (V J) and the ratio of variable fluorescent F K occupying the F J-F O amplitude (W k) were significantly increased in 0.2% FL plants. However, the increase in W k was lower than the increase in V J. 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.

[Effects of light intensity on photosynthetic capacity and light energy allocation in Panax notoginseng.] / å ‰å¼ºå¯¹ä¸‰ä¸ƒå ‰åˆèƒ½åŠ›åŠèƒ½é‡åˆ†é çš„å½±å“.

To explore the effects of light intensity on photosynthetic characteristics and light adaptation of the shade-demanding species Panax notoginseng, the responses of photosynthesis to photosynthetic photon flux density, CO2 and sunflecks in the two-year-old Panax notoginseng were investigated under different levels of light intensity (29.8%, 9.6%, 5.0%, 1.4% and 0.2% of full sunlight). Meanwhile, chlorophyll a fluorescence parameter and light energy partitioning were also recorded and calculated in the responsive process. P. notoginseng grown under 29.8% full sunlight (FL) had a lower apparent quantum yield (AQY), potential photochemical quantum yield (Fv/Fm) and potential photochemical activity (Fv/Fo), however, it had a higher maximum net photosynthetic rate (Pn max), maximum electron transport rate (Jmax), F/Fm', electron transport rate (ETR), photochemical quenching (qP) and the proportion of light energy allocated to photochemistry dissipation (ΦPS2), but the non-photochemical quenching (NPQ) was not the highest. There were no significant differences in Pn max, light compensation point (LCP), light saturation point (LSP), dark respiration rate (Rd) among 9.6%FL and 5.0% FL treatments, but these treatments had relatively higher values of NPQ, AQY, carboxylation efficiency (CE), maximum carboxylation rate (Vc max), Fv/Fm and Fv/Fo. In addition, the Pn max, CE, Vc max, Jmax, ETR,F/Fm', qP, NPQ and ΦPSII decreased with the decrease in light intensity from 5.0%FL to 0.2%FL, and the proportion of light energy allocated to fluorescent dissipation (Φf,d) were increased. Under 500 µmol·m-2·s-1 light-flecks inducting, the ΦPSⅡof P. notoginseng increased slowly with the extension of time except for the treatment of less than 5.0%FL, and under the circumstance of 1.4%FL and 0.2%FL, ΦPSⅡreached significantly a perfect result, moreover, Φf,dincreased rapidly. These results suggested that the enhancement in photosynthetic electron transport to use the light energy and the moderate photoinhibition of PS2 might avoid the irreversible oxidative damage of photosynthetic organization in P. notoginseng under high levels of light intensity. Moderate shading was beneficial to maintain its higher non-photochemical quenching ability. However, its photosynthetic capacity depressed and the proportion of light energy allocated to non-photochemical pathway increased obviously in excessive shading, and it easily caused a light oxidative damage.

Transcriptome analysis of Panax vietnamensis var. fuscidicus discovers putative ocotillol-type ginsenosides biosynthesis genes and genetic markers.

BACKGROUND: P. 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. RESULTS: To 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). CONCLUSIONS: The 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.

Determination of multiple elements in samples of the medicinal plant Marsdenia tenacissima and estimation of geographic origin via pattern recognition techniques.

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.

[FTIR fingerprint spectrograms of traditional Chinese medicine Marsdenia tenacissima].

In this paper, Fourier transform infrared spectroscopy fingerprint analysis of Marsdenia tenacissima samples was used to develop a reliable method of tracing the geographical origins. Forty-eight samples from four provinces of China were analyzed by FTIR. We analyzed and characterized the fingerprints in both the full spectrum peaks and characteristic peaks, then the principal component analysis and the cluster analysis were carried out. The results of fingerprint analysis, correlation analysis, principal component analysis and cluster analysis can identify the geographic origins correctly, which verified and supplemented each other; the identification results and the actual location showed a high degree of consistency, namely the lower the space distance, the greater the similarity of different samples. These results revealed the obvious superiority and practical value in comparison to the more tedious and time-consuming wet chemistry method normally used. Using appropriate metrology methods can trace the geographical source correctly. The M. tenacissima materials from the region of Maguan should be considered as genuine medicinal materials taking into account the good quality.