Accumulation and ultrastructural distribution of copper in Elsholtzia splendens

Copper accumulation and intracellular distribution in Elsholtzia splendens, a native Chinese Cu-tolerant and accu- mulating plant species, was investigated by transmission electron microscope (TEM) and gradient centrifugation techniques. Copper concentrations in roots, stems and leaves of E. splendens increased with increasing Cu levels in solution. After exposure to 500 μmol/L Cu for 8 d, about 1000 mg/kg Cu were accumulated in the stem and 250 mg/kg Cu in the leaf of E. splendens. At 50 μmol/L Cu, no significant toxicity was observed in the chloroplast and mitochondrion within its leaf cells, but separation appeared at the cytoplasm and the cell wall within the root cells. At >250 μmol/L Cu, both root and leaf organelles in E. splendens were damaged heavily by excessive Cu in vivo. Copper subcellular localization in the plant leaf after 8 days’ exposure to 500 μmol/L Cu using gradient centrifugation techniques was found to be decreased in the order: chloroplast>cell wall>soluble fraction>other organelles. The plant root cell wall was found to be the site of highest Cu localization. Increase of Cu exposure time from 8 d to 16 d, increased slightly Cu concentration in cell wall fraction in roots and leaves, while that in the chloroplast fraction decreased in leaves of the plants grown in both 0.25 μmol/L and 500 μmol/L Cu. TEM confirmed that much more Cu localized in cell walls of E. splendens roots and leaves, but also more Cu localized in E. splendens’ chloroplast when the plant is exposed to Cu levels>250 μmol/L, as compared to those in the plant grown in 0.25 μmol/L Cu. Copper treatment at levels>250 μmol/L caused pronounced damage in the leaf chloroplast and root organelles. Copper localization in cell walls and chloroplasts could mainly account for the high detoxification of Cu in E. splendens.

Chelators effect on soil Cu extractability and uptake by Elsholtzia splendens

Phytoremediation is emerging as a potential cost-effective solution for remediation of contaminated soils, and bioavailability of metal in the soil for plant uptake is an important factor for successful phytoremediation. This study aimed at investigating the ability of EDTA and citric acid for enhancing soil bioavailability of Cu and phytoremediation by El-sholtzia splendens in two types of soils contaminated with heavy metals [i.e. mined soil from copper mining area (MS), and paddy soil (PS) polluted by copper refining]. The results showed that addition of 2.5 mmol/kg EDTA significantly increased the H2O extractable Cu concentration from 1.20 to 15.78 mg/kg in MS and from 0.26 to 15.72 mg/kg in PS, and that shoot Cu concentration increased 4-fold and 8-fold as compared to the control. There was no significant difference between the treatment with 5.0 mmol/kg EDTA and that with 2.5 mmol/kg EDTA, probably because that 2.5 mmol/kg EDTA was enough for elevating Cu bioavailability to the maximum level. As compared with the control, citric acid had no marked effect on both soil extractable Cu and shoot Cu concentration or accumulation. The results indicated that EDTA addition can increase the potential and efficiency of Cu phytoextraction by E. splendens in polluted soils.

Science Letters:Gama-aminobiityric acid accumulation in Elsholtzia splendens in response to copper toxicity

A solution with different Cu supply levels was cultured to investigate gama-aminobutyric acid (GABA) accumulation in Elsholtzia splendens, a native Chinese Cu-tolerant and accumulating plant species. Increasing Cu from 0.25 to 500 ?mol/L significantly enhanced levels of GABA and histidine (His), but considerably decreased levels of aspartate (Asp) and glutamate (Glu) in the leaves. The leaf Asp level negatively correlated with leaf Cu level, while leaf GABA level positively correlated with leaf Cu level. The leaf Glu level negatively correlated with leaf GABA level in Elsholtzia splendens. The depletion of leaf Glu may be related to the enhanced synthesis ofleafGABA under Cu stress.

Caffeic acid product from the highly copper-tolerant plant Elsholtzia splendens post-phytoremediation:its extraction,purification,and identification

In the current study,caffeic acid was an important metabolite in the highly copper-tolerant plant Elsholtzia splendens.Preparation and purification of caffeic acid were performed on the dried biomass of the plants by means of sonication/ethanol extraction,followed by purification using a macroporous resin (D101 type) column and silica gel chromatography.The faint-yellow caffeic acid product was yielded with a purity of 98.46%,and it was chemically identified from spectra of Fourier transform infrared spectroscopy (FTIR),proton nuclear magnetic resonance (1 H NMR)/carbon nuclear magnetic resonance (13 C NMR),and electrospray ionization mass spectrometry (ESI-MS).Caffeic acid is a possible product from the post-harvest processing of Elsholtzia splendens biomass.

Apigenin-7-O-β-D-glycoside isolation from the highly copper-tolerant plant Elsholtzia splendens

Elsholtzia splendens （Lamiaceae） is a copper-tolerant plant species growing on copper deposits in the south of China. Chromatographic separation of n-BuOH extracts from the flowering aerial biomass afforded apigenin- 7-O-β-D-glycoside, using macroporous resin, SephadexTM LH-20 gel, polyamide resin as well as preparative high- performance liquid chromatography （P-HPLC） columns. Chemical structure was elucidated using HPLC/ESI-MS （electrospray ionization-mass spectrometry）, Fourier transform infrared （FTIR）, and 1D- and 2D-nuclear magnetic resonance （NMR）. Apigenin-7-O-β-D-glycoside could be the post-harvesting product from E. splendens biomass.

Uptake, Distribution and Accumulation of Copper in Two Ecotypes of Elsholtzia

Two ecotypes of Elsholtzia, Elsholtzia splendens and E. argyi, are dominantplants growing on Cu and Pb-Zn smelters, respectively. Samples of the two ecotypes and thecorresponding soils from fields of a copper mining area and a Pb-Zn mining area ofZhejiang Province,China, were analyzed to investigate Cu or Zn tolerance of these two ecotypes. Effects of nine Culevels (0, 5, 10, 20, 40, 80, 160, 240 and 320 mg Cu L^(-1) as CuSO_4 centre dot 5H_O) on growth anduptake, translocation and accumulation of Cu in these two ecotypes were examined in a solutionculture experiment. The experimental results showed that dry weights (DW) of shoots and roots weredepressed, and growth of E. splendens was less depressed than that of E. argyi when treated with>= 5mg Cu L^(-1). Concentrations of Cu in shoots of E. splendens and E. argyi exceeded 1000 mg kg^(-1)DW at >= 40 mg Cu L^(-1). The maximum Cu accumulated in the shoots of Cu-treated E. splendens and E.argyi reached 101 and 142 mu g plant^(-1). Furthermore, analysis of plant samples from the fieldsshowed that these two ecotypes can tolerant excess heavy metals and produced high dry matter, and E.splendens can accumulate 11.7 mg Cu plant^(-1) grown on the Cu smelter. Therefore, E. splendens andE.argyi could be good plants for phytoremediation.

“Co-culture Engineering”for Enhanced Phytoremediation of Metal Contaminated Soils

A co-culture of two plant materials, Astragalus sinicus L., a leguminous plant with concomitant nodules, and Elsholtzia splendens Naki-a Cu accumulator, along with treatments of a chelating agent (EDTA), root excretions (citric acid), and a control with E. splendens only were used to compare the mobility of heavy metals in chelating agents with a co-culture and to determine the potential for co-culture phytoremediation in heavy metal contaminated soils. The root uptake for Cu, Zn, and Pb in all treatments was significantly greater (P ＜ 0.05) than that of the control treatment. However with translocation in the shoots, only Cu, Zn, and Pb in plants grown with the EDTA treatment and Zn in plants cocropped with the A. sinicus treatment increased significantly (P ＜ 0.05). In addition, when a co-culture in soils with heavy and moderate contamination was compared, for roots in moderately contaminated soils only Zn concentration was significantly less (P ＜ 0.05) than that of heavily contaminated soils, however, Cu, Zn, and Pb concentrations of shoots were all significantly lower (P ＜ 0.05). Overall, this 'co-culture engineering' could be as effective as or even more effective than chelating agents, thereby preventing plant metal toxicity and metal leaching in soils as was usually observed in chelate-enhanced phytoremediation.

海州香薷挥发油成分的分析

采用 GC/MS/DS 分析了江苏连云港海州山产海州香薷 Elsholtzia splendens Nakai.ex F.Maekawa.挥发油成分,分离并鉴定了以香薷酮 Elsholtzia ketone.(85.27%)、去氢香薷酮 dehydro elsh-oltzione(2.00%)、β-石竹烯β-Caryophyllene(2.20%)、γ-榄香烯γ-element(1.54%)、3-辛醇3-Octanol(1.36%)、优葛缕酮 Eucarvone(1.04%)、波旁烯 Bourbonene(0.75%)、γ-木罗烯γ-muurolene(0.88%)、为主的37个成分。