Zaibiao Zhu

Variation in concentrations of major bioactive compounds in Prunella vulgaris L. related to plant parts and phenological stages

Prunella vulgaris L. (Labiatae) contains a variety of structurally diverse natural products, primarily rosmarinic acid (RA), ursolic acid (UA) and oleanolic acid (OA), which possess a wide array of biological properties. In the present study, P. vulgaris was harvested at three developmental stages (vegetative, full-flowering and mature-fruiting stages), dissected into stem and leaf tissues and assayed for chemical contents using high performance liquid chromatography. Significant changes in the concentrations of the major secondary metabolites (RA, UA and OA) were observed at the different development stages. The highest concentrations of RA, UA and OA were found at the full-flowering stage (15.83 mg/g dry weight (DW) RA, 1.77 mg/g DW UA and 0.65 mg/g DW OA). Among the different aerial parts of the plant, the concentrations of RA, UA and OA were higher in the leaves than in the stems at the different developmental stages. These results suggest that the full-flowering stage is characterized by the highest concentrations of bioactive compounds. Therefore, this stage may be the optimum point for harvesting P. vulgaris plants. In additional, the leaves of P. vulgaris demonstrated higher RA, UA and OA concentrations than the stems, suggesting higher utilization potential.

A Comparative Proteomic Analysis of Pinellia ternata Leaves Exposed to Heat Stress

Pinellia ternata is an important traditional Chinese medicinal plant. The growth of P. ternata is sensitive to high temperatures. To gain a better understanding of heat stress responses in P. ternata, we performed a comparative proteomic analysis. P. ternata seedlings were subjected to a temperature of 38 °C and samples were collected 24 h after treatment. Increased relative ion leakage and lipid peroxidation suggested that oxidative stress was frequently generated in rice leaves exposed to high temperature. Two-dimensional electrophoresis (2-DE) was used to analyze heat-responsive proteins. More than 600 protein spots were reproducibly detected on each gel; of these spots, 20 were up-regulated, and 7 were down-regulated. A total of 24 proteins and protein species were successfully identified by MALDI-TOF/TOF MS. These proteins and protein species were found to be primarily small heat shock proteins (58%) as well as proteins involved in RNA processing (17%), photosynthesis (13%), chlorophyll biosynthetic processes (4%), protein degradation (4%) and defense (4%). Using 2-DE Western blot analysis, we confirmed the identities of the cytosolic class II small heat shock protein (sHSPs-CII) identified by MS. The expression levels of four different proteins [cytosolic class I small heat shock protein (sHSPs-CI), sHSPs-CII, mitochondrial small heat shock protein (sHSPs-MIT), glycine-rich RNA-binding protein (GRP)] were analyzed at the transcriptional level by quantitative real-time PCR. The mRNA levels of three sHSPs correlated with the corresponding protein levels. However, GRP was down-regulated at the beginning of heat stress but then increased substantially to reach a peak after 24 h of heat stress. Our study provides valuable new insight into the responses of P. ternata to heat stress.

Optimisation of Potassium Chloride Nutrition for Proper Growth, Physiological Development and Bioactive Component Production in Prunella vulgaris L

Prunella vulgaris L. is an important medicinal plant with a variety of pharmacological activities, but limited information is available about its response to potassium chloride (KCl) supplementation. P. vulgaris seedlings were cultured in media with four different KCl levels (0, 1.00, 6.00 and 40.00 mM). Characteristics relating to the growth, foliar potassium, water and chlorophyll content, photosynthesis, transpiration, nitrogen metabolism, bioactive constituent concentrations and yield were determined after three months. The appropriate KCl concentration was 6.00 mM to result in the highest values for dry weight, shoot height, spica and root weight, spica length and number in P. vulgaris. The optimum KCl concentration resulted in a maximum net photosynthetic rate (Pn) that could be associated with the highest chlorophyll content and fully open stomata conductance. A supply of surplus KCl resulted in a higher concentration of foliar potassium and negatively correlated with the biomass. Plants that were treated with the appropriate KCl level showed a greater capacity for nitrate assimilation. The Pn was significantly and positively correlated with nitrate reductase (NR) and glutamine synthetase (GS) activities and was positively correlated with leaf-soluble protein and free amino acid (FAA) contents. Both KCl starvation (0 mM) and high KCl (40.00 mM) led to water loss through a high transpiration rate and low water absorption, respectively, and resulted in increased concentrations of ursolic acid (UA), oleanolic acid (OA) and flavonoids, with the exception of rosmarinic acid (RA). Moreover, the optimum concentration of KCl significantly increased the yields of RA, UA, OA and flavonoids. Our findings suggested that significantly higher plant biomass; chlorophyll content; Pn; stronger nitrogen anabolism; lower RA, UA, OA and flavonoid accumulation; and greater RA, UA, OA and flavonoid yields in P. vulgaris could be expected in the presence of the appropriate KCl concentration (6.00 mM).

Changes in bioactive components related to the harvest time from the spicas of Prunella vulgaris

Context: Prunella vulgaris L. (Labiatae) is a perennial plant common in China and Europe and is rich in rosmarinic acid (RA), ursolic acid (UA), and oleanolic acid (OA). The dried spica of P. vulgaris has been used as traditional medicine in China for over a hundred years. To our best knowledge, no study has been conducted to determine the influence of harvesting time on concentrations of bioactive compounds of P. vulgaris. Objective: In the current study, changes in the bioactive compounds present in spicas were investigated at five harvest times over 2 months. Materials and methods: Plant material were collected at five fixed dates: 5th May, 20th May, 7th June, 15th June, and 25th June and assayed for chemical contents by high-performance liquid chromatography (HPLC). Results: Among the different harvest times, the highest levels of RA (56.81 mg·g−1), UA (2.77 mg·g−1), and OA (0.91 mg·g−1) were found on 5th May, whereas the lowest levels of RA (1.66 mg·g−1), UA (2.27 mg·g−1), and OA (0.43 mg·g−1) were observed on 25th June. Discussion and conclusion: As each medicinal product has its own content requirement for different bioactive components, the optimum harvest time might be determined according to the accumulation dynamics of target compound in dried spicas of P. vulgaris. These results may be useful for determining the optimal harvest time when bioactive components are at the maximum level, which is in early May.

Transcriptome Analysis of Differentially Expressed Genes Provides Insight into Stolon Formation in Tulipa edulis

Tulipa edulis (Miq.) Baker is an important medicinal plant with a variety of anti-cancer properties. The stolon is one of the main asexual reproductive organs of T. edulis and possesses a unique morphology. To explore the molecular mechanism of stolon formation, we performed an RNA-seq analysis of the transcriptomes of stolons at three developmental stages. In the present study, 15.49 Gb of raw data were generated and assembled into 74,006 unigenes, and a total of 2,811 simple sequence repeats were detected in T. edulis. Among the three libraries of stolons at different developmental stages, there were 5,119 differentially expressed genes (DEGs). A functional annotation analysis based on sequence similarity queries of the GO, COG, KEGG databases showed that these DEGs were mainly involved in many physiological and biochemical processes, such as material and energy metabolism, hormone signaling, cell growth, and transcription regulation. In addition, quantitative real-time PCR analysis revealed that the expression patterns of the DEGs were consistent with the transcriptome data, which further supported a role for the DEGs in stolon formation. This study provides novel resources for future genetic and molecular studies in T. edulis.

Effects of different water management options and fertilizer supply on photosynthesis, fluorescence parameters and water use efficiency of Prunella vulgaris seedlings.

BackgroundPrunella vulgaris L. is a medical plant cultivated in sloping, sun-shaded areas in China. Recently, owing to air-environmental stress, especially drought stress strongly inhibits plant growth and development, the appropriate fertilizer supply can alleviate these effects. However, these is little information about their effects on P. vulgaris growing in arid and semi-arid areas with limited water and fertilizer supply.ResultsIn this study, water stress decreased the photosynthetic pigment contents, inhibited photosynthetic efficiency, induced photodamage in photosystem 2 (PS2), and decreased leaf instantaneous WUE (WUEi). The decreased net photosynthetic rate (Pn) under medium drought stress compared with the control might result from stomatal limitations. However, fertilizer supply improved photosynthetic capacity by increasing the photosynthetic pigment contents and enhancing photosynthetic efficiency under water deficit. Moreover, medium fertilization also increased WUEi under the two water conditions, but fertilizer supply did little to alleviate the PS2 photodamage caused by drought stress. Hence, drought stress was the primary limitation in the photosynthetic process of P. vulgaris seedlings, while the photosynthetic characteristics of the seedlings exhibited positive responses to fertilizer supply.ConclusionsAppropriate fertilizer supply is recommended to improve photosynthetic efficiency, enhance WUEi and alleviate photodamage under drought stress.

Physiological characteristics, dry matter, and active component accumulation patterns of Changium smyrnioides in response to a light intensity gradient

Abstract Context: Changium smyrnioides Wolff (Apiaceae) is an endangered medicinal plant with numerous pharmacological uses. Objective: To investigate the effect of light intensity levels on the growth and accumulation of secondary metabolites of C. smyrnioides, cultivated seedlings were subjected to different relative light intensities via sun-shading. Materials and methods: Changium smyrnioides seedlings were subjected to five irradiance treatments (100, 60.54, 44.84, 31.39, and 10.56% sunlight) in glasshouse for 9 months. Enzymatic and non-enzymatic antioxidants with spectrophotometric method, photosynthetic parameters with Li-6400XT, dry matter accumulation and active component contents in the root with spectrophotometric and HPLC method were analyzed. Results: With an increase in relative light intensity levels, activities of enzymatic and non-enzymatic antioxidants, and malondialdehyde (MDA) contents were increased overall, while net photosynthetic rate (Pn) and dry matter accumulation patter first increased and then declined. The highest net photosynthetic rate (30.68 μmol/m2·s) and dry root weight (5.07 g) were achieved under 60.54% sunlight. Lower relative light intensity levels stimulated the accumulation levels of bioactive compounds in the roots so that the highest contents of mannitol (1.35%) and choline (405.58 μg/g) were recorded under 31.39% sunlight, and the highest polysaccharide content (10.80%) were achieved under 44.84% sunlight. With a decrease in the relative light intensity levels, the water-soluble component content increased first and then decreased. Discussion and conclusion: The results revealed that 31.39–60.54% sunlight serve as appropriate relative light intensity conditions for cultivated C. smyrnioides.

Chloroplast ultrastructure, photosynthesis and accumulation of secondary metabolites in Glechoma longituba in response to irradiance

Glechoma longituba (Nakai) Kupr. is a perennial shade plant with pharmaceutical importance. The aim of this study was to investigate the effects of light intensity on the growth, photosynthesis, and accumulation of secondary metabolites in G. longituba grown under six different light environments. The high light intensity decreased the leaf size, specific leaf area, and aboveground dry mass, the number of grana per chloroplast, the number of lamella per granum, the thickness of the grana, the apparent quantum efficiency, the chlorophyll (Chl) content, the concentrations of ursolic and oleanolic acid. The high light increased the stomatal density, the stoma size, the number of chloroplast per a cell, the chloroplast size, the dark respiration rate, the light saturation point, the light compensation point, and the Chl a/b ratio. With the reduction in the light intensity, the light-saturated net photosynthetic rate, the aerial dry mass per plant, and the yields of ursolic and oleanolic acid decreased after an initial increase, peaking at 16 and 33% of sunlight levels. Overall, the 16 and 33% irradiance levels were the most efficient in improving the yields and qualities of the medicinal plant. The lower light demand and growth characteristics suggest that G. longituba is an extremely shade-tolerant plant and that appropriate light intensity management might be feasible to obtain higher yields of secondary metabolites in agricultural management.

Effects of ammonium to nitrate ratio on growth, nitrogen metabolism, photosynthetic efficiency and bioactive phytochemical production of Prunella vulgaris.

Abstract Context: Prunella vulgaris L (Labiatae) is commonly used as a traditional medicinal herb in some Asian and Europe countries. To date, few studies have been conducted to determine the influence of  − N/ − N ratio on growth, physiological development, and bioactive phytochemical accumulation in hydroponically grown P. vulgaris. Objective: The current study was conducted to evaluate the effect of five  − N/ − N ratios on growth, nitrogen metabolism, photosynthetic efficiency, and bioactive phytochemical production in P. vulgaris. Materials and methods: Hydroponically cultivated P. vulgaris were fertilized with five  − N/ − N ratios in a greenhouse for 85 d. Dried weight of root, stem, leaf and spica, leaf area, photosynthetic efficiency, activities of nitrate reductase (NR), glutamine synthetase (GS), and the concentrations of N, soluble protein, and free amino acids in the leaves, as well as the contents of rosmarinic acid (RA), ursolic acid (UA), and oleanolic acid (OA) in the spicas were measured. Results: Both  − N and  − N as the sole source of nitrogen had inhibitory effects on P. vulgaris growth. P. vulgaris fertilized with the 25/75 ( − N/NO3 − N) ratio had the highest leaf area, photosynthetic rate, and chlorophyll content. The 25/75 (/) ratio increased the spica biomass by 1828%, nitrate-reductase (NR) activity by 98%, and soluble protein concentration by 29.45% compared with the 100/0 (/) treatment. Additionally, 25  − N/75 NO3 − N resulted in the highest contents of RA and total flavonoids as well as relatively high contents of UA and OA; therefore, this ratio had the highest yield of RA, UA, OA, and total flavonoids in spicas. Discussion and conclusion: The use of 25  − N/75  − N is recommended to improve biomass production and medicinal quality of P. vulgaris.

Variation in contents of major bioactive compounds in Glechoma longituba related to harvesting time and geographic distribution

Glechoma longituba (Nakai) Kupr. (Labiatae) is an important medicinal plant with various pharmacological activities. Current study was carried out to establish the variation pattern in the contents of ethanol-soluble extractive, total flavonoids, ursolic acid (UA) and oleanolic acid (OA) in G. longituba in relation to harvesting time and geographical origin. G. longituba was harvested at one month interval during ontogenetic development phases and twenty-nine populations were collected from different distribution areas in China. The results showed that the contents of ethanol-soluble extractive, total flavonoids, UA and OA in G. longituba were related to harvesting time and distribution origin. The optimum harvesting time should be in mid-April in terms of the contents of ethanol-soluble extractive and total flavonoids, and be in mid-August or in mid-March in terms of the contents of UA and OA. Populations of G. longituba showed remarkable differences in chemical composition depending on the provenance of plants. And the differences among 29 populations are likely to be genetically controlled since all populations were grown under uniform conditions. Our results on seasonal and environmental factors will be useful for commercial producers of G. longituba in determining the optimum harvesting time and the most appropriate plants for germplasm evaluation and breeding.