Ecophysiological, anatomical, and apigenin changes due to uptake and accumulation of cadmium in Matricaria chamomilla L. flowers in hydroponics.

Cadmium (Cd) is one of the most important heavy metals in the environment which has several effects on the morphology, physiology, and anatomy of plants. It is a mobile heavy metal that can be transferred easily into plants, thus entering into the human food chain. Chamomile (Matricaria chamomilla L.) as an important medicinal plant can uptake and accumulate Cd in its root and aerial organs. In this research, the effects of different concentrations of Cd (90, 180, and 360 µM) were investigated on the growth parameters, anatomical features, and enzymatic antioxidant activities in flowers of chamomile after 7 days of exposure. The content of apigenin, a flavone compound mostly synthesizing in chamomile flowers, was also analyzed after 72 h from Cd treatment. The results showed that all concentrations of Cd reduced the length and biomass of roots and shoots, the diameter of flowers, as well as the number of pollen grains in tubular florets, while increased trichome density on the florets. Cd-treated plants showed an increase in antioxidant enzymes, superoxide dismutase (SOD), and peroxidase (POX) activities. After 7 days of treatment to Cd major concentration, flowers accumulated Cd and enhanced the apigenin production with the increase of Cd contamination in hydroponic solution. This increase of apigenin is most likely due to its antioxidant and sequestering property as a resistance response to Cd excess.

Salycilic Acid Induces Exudation of Crocin and Phenolics in Saffron Suspension-Cultured Cells.

The production of crocin, an uncommon and valuable apocarotenoid with strong biological activity, was obtained in a cell suspension culture of saffron (Crocus sativus L.) established from style-derived calli to obtain an in-vitro system for metabolite production. Salycilic acid (SA) was used at different concentrations to elicit metabolite production, and its effect was analyzed after a 4 days of treatment. HPLC-DAD analysis was used for total crocin quantification while the Folin-Ciocâlteu method was applied for phenolic compounds (PC) content. Interestingly, despite cell growth inhibition, a considerable exudation was observed when the highest SA concentration was applied, leading to a 7-fold enhanced production of crocin and a 4-fold increase of phenolics compared to mock cells. The maximum antioxidant activity of cell extracts was evidenced after SA 0.1 mM elicitation. Water-soluble extracts of saffron cells at concentrations of 1, 0.5, and 0.1 µg mL-1 showed significant inhibitory effects on MDA-MB-231 cancer cell viability. The heterologous vacuolar markers RFP-SYP51, GFPgl133Chi, and AleuRFP, were transiently expressed in protoplasts derived from the saffron cell suspensions, revealing that SA application caused a rapid stress effect, leading to cell death. Cell suspension elicitation with SA on the 7th day of the cell growth cycle and 24 h harvest time was optimized to exploit these cells for the highest increase of metabolite production in saffron cells.

Structural and quantitative changes of starch in seed of Trigonella persica during germination.

Starch, the most abundant carbohydrate reserve in plant seeds, is synthesized and stored in the cotyledons of some plants. In seeds of Trigonella persica (Fabaceae), starch appears during germination and forms granules that are composed of amylose and/or amylopectin. In this study, both quantitative and qualitative traits of starch were evaluated during the germination of T. persica seed. The quantitative assay and microscopic imaging showed that there was a low-amylose starch in the cotyledons and its amount reached the highest at 48 h after imbibition (HAI). According to the SEM images of hydrogels, FT-IR spectra, and analysis of extracted starches, the purity of this starch was decreased during germination. So that the extracted starch from cotyledons of non-germinated seeds (ESCN), with the highest purity and the lowest protein content, was different from all the extracted starches. Therefore, it seems that ESCN was an amylopectin rich type starch, which had low amylose to amylopectin ratio and as waxy starch typically, it can have a cohesive and gummy texture compared with ordinary starch.

Crosstalk among polyamines, phytohormones, hydrogen peroxide, and phenylethanoid glycosides responses in Scrophularia striata to Cd stress.

Plants respond to Cadmium (Cd) as a hazardous heavy metal through various mechanisms depending on their available metabolite resources. In this research, the physiological and signaling pathways mediating the responses to Cd stress in Scrophularia striata seedlings were characterized after they were exposed to different Cd concentrations at different time periods. The results showed that the polyamines (PAs), Abscisic acid (ABA) and hydrogen peroxide (H2O2) contents were significantly enhanced at 48 h. Moreover, the enzyme activity of phenylalanine ammonia-lyase (PAL) and tyrosine ammonia-lyase (TAL) as regulator enzymes in the phenylpropanoid pathway was increased, related to the reinforcement of phenolic compounds such as phenylethanoid glycosides (as a special compound of this plant). This metabolic profiling indicates that the signal transduction of Cd stress increased the activity of different enzymes (PAL and TAL) by regulating the PAs metabolism, the modulation of ABA, and the H2O2 content. As a result, it caused the accumulation of phenolic compounds, especially echinacoside and acteoside, both of which are required to improve the response of Cd stress in S. striata.

Isolation, qualitative and quantitative evaluation of galactomannan during germination of Trigonella persica (Fabaceae) seed.

Galactomannan extracted from Trigonella persica endosperm like to other galactomannans is useful in the medicine and pharmaceutical industry such as drug delivery due to its unique physicochemical properties. As soon as germination takes place, the hydrolysis of galactomannan begins and its structure changes. Evaluation of galactomannan content extracted from the germinating seeds (GEGS) and the non-germinated seeds (GENGS) showed that the amount of galactomannan was highest at 24 h after imbibition and was completely consumed approximately 48 h after imbibition. It seems that galactomannan is used for storage reserve synthesis in the cotyledon during germination. Based on the quantitative assessment, FT-IR, macroscopic and microscopic observations, galactomannan of T. persica seeds have high an M/G ratio (approximately 5:1) and this ratio does not alter during germination. Therefore, changes in galactomannan structure (functional group and band) caused that GEGS have different physicochemical properties than GENGS. Based on the results, GENGS with a high M/G ratio may be suitable for drug delivery system due to some properties such as high viscosity and gelling.

Energy saving and improvement of metabolism of cultured tobacco cells upon exposure to 2-D clinorotation.

Studies have confirmed that on the ground, the plant cells must expend energy to maintain positional homeostasis against gravity. Under microgravity conditions, such energy may be saved for other process such as biosynthesis of beneficial metabolites for growth. This hypothesis was examined on a cell line of tobacco (Nicotiana tabacum cv. Burley 21). The cells were continuously treated with 2-D clinostat for 1 week. Exposure to clinorotation conditions increased biomass and total protein. Total content of soluble sugar also increased which may provide more precursors for Krebs cycle and adenosine triphosphate (ATP) production. In the case of 2-D clinorotation, the expression and activity of glutamate producing enzyme, glutamate dehydrogenase (GDH) increased, whereas the activity of glutamate decarboxylase (GAD) decreased. Regarding the role of GAD in initiation of gamma amino butyric acid (GABA) shunt, it is plausible that under clinorotation condition, the tobacco cells directed their metabolism toward saving energy for Krebs cycling and more production of ATP rather than shifting to side paths such as GABA shunt. Improvement of radical scavenging enzymes activity and increase of the contents of phenolic compounds and certain peroxide neutralizing amino acids, e.g., His, Pro, Ser, and Asp under clinorotation conditions decreased membrane lipid peroxidation and maintained the growth potential of tobacco cells.

Manganese-induced changes in glandular trichomes density and essential oils production of Mentha aquatica L. at different growth stages.

Production and accumulation of essential oils in plants are influenced by intrinsic and environmental factors. Here, we attempted to elucidate the effect of manganese (Mn) supply on the density of glandular trichomes and the production of essential oils in Mentha aquatica (water mint; syn. Mentha hirsuta Huds.) at the different growth stages. To this aim, plants were treated with 100 µM of Mn (supplied as MnSO4·H2O) at early and late vegetative stages of growth. Then, the control and treated plants were harvested, and biochemical, morphological and molecular analyses indicated that Mn supply has affected M. aquatica at the different growth stages. The biomass, Mn accumulation, glandular trichomes density, essential oils yield and expression levels of the genes encoding enzymes involved in terpenoid biosynthesis pathway (1-Deoxy d-xylulose-5-phosphate synthase (Dxs), geranyl diphosphate synthase (Gpps), isopentenyl diphosphate isomerase (Ippi), ß-caryophyllene synthase (Cps), limonene synthase (Ls) and menthofuran synthase (Mfs)) were increased by Mn supply at both growth stages. However, the increased rates of the assayed parameters were varied between the early and late vegetative stages. Moreover, the content and chemical composition of terpenoid components were affected by Mn supply and plant growth stage. There were positive and weak correlations among the study variables under the Mn supply at the different growth stages. Given these findings, we propose that the application of Mn supply at both early and late vegetative stages elevates the growth, density of glandular trichomes and production of essential oils in M. aquatica.

Changes in primary and secondary metabolites of Mentha aquatica L. exposed to different concentrations of manganese.

This experiment was conducted in order to determine the effects of different concentrations of manganese (Mn) on the levels and correlations of multiple primary and secondary metabolites in Mentha aquatica. With this aim, four levels of Mn concentrations were used as follows: basic Hoagland's solution (control), 40, 80, and 160 µM of Mn supplied as MnSO4.H2O. The results indicated that the biomass and the contents of photosynthetic pigments and soluble carbohydrates were higher in the plants that were treated with the moderate concentrations of Mn (40 and 80 µM) than the control and 160 µM-treated plants. On the other hand, the contents of flavonoids, anthocyanins, malonaldehyde (MDA), hydrogen peroxide (H2O2), and the activities of antioxidant enzymes (total superoxide dismutase (SOD), catalase (CAT), and peroxidase (POX)) were progressively increased with the enhancement of Mn concentration in the nutrient solution. In addition, there were clear differences in the content and chemical composition of essential oils among the control and treatment groups. In this study, 1,8-cineole, menthofuran, and ß-caryophyllene were the most abundant constituents of essential oils in both the control and Mn-treated plants. The correlation analysis between pairs of the primary and secondary metabolites showed that there were positive and negative correlations among the variables when the Mn concentration was increased in the nutrient solution. These findings clearly display a positive effect of Mn up to 80 µM in the nutrient solution on the growth of M. aquatica.

Manganese modulates the physiological and biochemical responses of Mentha aquatica L. to ultraviolet radiation.

Ultraviolet (UV) radiation as an environmental factor alters the physiological and metabolic processes in plants. Manganese (Mn) is an essential element that is required for plant growth and development. This experiment was conducted in order to determine the effects of Mn supply and UV radiation on the physiological and metabolic responses in Mentha aquatica. With this aim, three levels of Mn and UV treatments were used as follows: basic Hoagland's nutrient solution without UV radiation (control), Mn supply (100µM), UV radiation (2h daily), and UV+100µM Mn. After three weeks of treatments, the root and shoot dry weights and the contents of photosynthetic pigments were decreased under UV radiation condition. However, the contents of flavonoids, soluble carbohydrate, anthocyanins, malonaldehyde (MDA), hydrogen peroxide (H2O2), and the activity of antioxidant enzymes (superoxide dismutase, catalase, and peroxidase) were increased. Interestingly, Mn at 100µM concentration decreased the harmful effects of UV radiation on M. aquatica. In addition, the clear differences were observed in the terpene constituents of M. aquatica after the Mn and UV treatments. In this study, 1, 8-cineole, menthofuran and ß-caryophyllene were the most abundant constituents of essential oils in both the control and treated plants. The correlation analysis between pairs of the primary and secondary metabolites showed that there were positive and negative correlations among the variables under the Mn supply and UV radiation conditions. These findings clearly display a positive effect of external Mn up to 100µM in the nutrient solution on the resistant of M. aquatica to UV radiation.

Physiological, biochemical and molecular responses of Mentha aquatica L. to manganese.

Mentha aquatica is an aromatic herb which possesses valuable terpenoids constituents. Here, we intended to evaluate the effects of the different manganese (Mn) concentrations on the physiological, biochemical and molecular responses in M. aquatica. Basic Hoagland's solution (control), 40, 80, and 160 µM of Mn supplied as MnSO4·H2O were applied to the nutrient solution. The results indicated that the different concentrations of Mn differently affected the physiological, biochemical and molecular responses in M. aquatica. The growth parameters (biomass and photosynthetic pigments) and expression levels of ß-caryophyllene synthase (CPS), limonene synthase (Ls), geranyl diphosphate synthase (Gpps), and menthofuran synthase (Mfs) genes were increased at the moderate Mn concentrations (40 and 80 µM) and began to decrease at the higher levels. However, the contents of anthocyanins, flavonoids, malonaldehyde (MDA) and hydrogen peroxide (H2O2), Mn accumulation, activities of antioxidant enzymes, yield of essential oils and the expression levels of 1-Deoxy d-xylulose-5-phosphate synthase (Dxs) and isopentenyl diphosphate isomerase (Ippi) genes were gradually increased with increasing concentration of Mn in the nutrient solution. Also, the content and chemical composition of terpenoid constituents were altered in the Mn-treated plants. Here, we suggest that the application of external Mn in nutrient solution elevates the growth and expression levels of the genes that are involved in the terpenoid biosynthesis pathway in M. aquatica. Nevertheless, the extent and stability of these growth and gene expression elevation are varied among the different Mn treatments.

Magnesium and manganese affect photosynthesis, essential oil composition and phenolic compounds of Tanacetum parthenium.

The accumulation of plant defense metabolites is closely associated with the concentration of nutrient elements, yet data related to the interactive effects of two nutrients on the deployment of phenolics and terpenoids are scare. In the present study, the interaction between magnesium (Mg) and manganese (Mn) on nutrient uptake, photosynthesis, oxidative status and the accumulation of phenolics and terpenoids in the leaves of feverfew plants grown at different concentrations of Mg and Mn was investigated. Nutrient uptake and photosynthesis were associated with the amount of applied Mg but could be modified by the concentration of Mn. Phenolic biosynthetic enzymes and individual phenolics were not only induced by Mg, but their levels were also dependent on the Mn supply. Additionally, the proportion of monoterpenes was enhanced by a deficiency of Mg rather than an excess of Mn. Deprivation of Mg also decreased the proportion of sesquiterpenes in the essential oil. Therefore, it appears that a high Mg and a low Mn supply lead to a marked shift from monoterpene to sesquiterpene production. Phenolic compounds also differentially accumulated under varying Mg and Mn concentrations. These results suggest a profound effect of the combined supply of Mg and Mn on the biosynthesis of terpenes and phenolics.

Magnesium and manganese interactively modulate parthenolide accumulation and the antioxidant defense system in the leaves of Tanacetum parthenium.

A balanced nutrient supply is a critical factor affecting accumulation of terpenoids in plants, yet data related to the interactive effects of two essential nutrients for the biosynthesis of sesquiterpenes are scarce. Here, the interactional effects between magnesium (Mg) and manganese (Mn) on plant growth, oxidative status, parthenolide accumulation and expression of key genes involved in parthenolide biosynthesis including 1-deoxy-d-xylulose-5-phosphate reductoisomerase (DXR), hydroxy-2-methyl-2-(E)-butenyl-4-diphosphate reductase (HDR), 3-hydroxy-3-methylglutarylcoenzyme A reductase (HMGR), germacrene A synthase (GAS), germacrene A oxidase (GAO), costunolide synthase (COS) and parthenolide synthase (PTS) in the leaves of feverfew plants grown at different Mn and Mn levels were assessed. Plant growth and leaf pigment concentrations were associated with the amount of applied Mg but could be modified by the Mn level. Deprivation and the addition of both Mg and Mn induce oxidative stress. Mg supply also alleviated the adverse effects of Mn excess on plant growth and oxidative status. In addition, parthenolide biosynthesis decreased under deprivation of Mg or Mn, but the addition of Mn up to 50µM under 2mM Mg supply considerably increased its accumulation. The parthenolide accumulation trend might reflect the up-regulation of terpenoid-related genes and enzyme activities as well as the oxidative status of feverfew leaves. Our data suggest a profound effect of the combined supply of Mg and Mn on parthenolide biosynthesis through the activation of terpene synthases, which concomitantly modulate by oxidative status.

Effect of lead treatment on medicarpin accumulation and on the gene expression of key enzymes involved in medicarpin biosynthesis in Medicago sativa L.

Lead (Pb) is the most common heavy metal contaminant in the environment. The present study was undertaken to determine the effect of Pb treatment on medicarpin production and accumulation in Medicago sativa L. To this aim, 7- and 30-day-old plants were treated with 0, 120, 240, 500, and 1,000 µM Pb during 10 days. The content of medicarpin was determined by HPLC, and the extent of medicarpin production was deduced from the result of semiquantitative RT-PCR performed on PAL, CHS, and VR genes. HPLC results indicated that medicarpin concentration has been reduced in the roots, while its exudation to the culture medium has been increased. RT-PCR results indicated that the transcript levels of PAL, CHS, and VR genes have not been affected following Pb stress in seedlings. At the vegetative stage, transcript levels of PAL and CHS genes have been reduced in the roots. However, the transcript level of VR gene increased at 120 and 240 µM Pb, while it decreased at higher concentrations. In the shoot, the transcript levels of PAL, CHS, and VR genes were increased following increased concentration of lead in the medium. Overall, q-PCR results suggest that medicarpin biosynthesis has been induced in the shoots and reduced in the roots of the plants treated with a toxic concentration of Pb.

Exogenously applied calcium alleviates cadmium toxicity in Matricaria chamomilla L. plants.

Cadmium (Cd) toxicity in plants leads to serious disturbances of physiological processes, such as inhibition of chlorophyll synthesis, oxidative injury to the plant cells and water and nutrient uptake. Response of Matricaria chamomilla L. to calcium chloride (CaCl(2)) enrichment in growth medium for reducing Cd toxicity were studied in this study. Hydroponically cultured seedlings were treated with 0, 0.1, 1, and 5 mM CaCl(2), under 0, 120, and 180 µM CdCl(2) conditions, respectively. The study included measurements pertaining to physiological attributes such as growth parameters, Cd concentration and translocation, oxidative stress, and accumulation of phenolics. Addition of CaCl(2) to growth media decreased the Cd concentration, activity of antioxidant enzymes, and reactive oxygen species accumulation in the plants treated with different CdCl(2), but increased the growth parameters. Malondialdehyde and total phenolics in shoots and roots were not much affected when plants were treated only with different CaCl(2) levels, but it showed a rapid increase when the plants were exposed to 120 and 180 CdCl(2) levels. CaCl(2) amendment also ameliorated the CdCl(2)-induced stress by reducing oxidative injury. The beneficial effects of CaCl(2) in ameliorating CdCl(2) toxicity can be attributed to the Ca-induced reduction of Cd concentration, by reducing the cell-surface negativity and competing for Cd(2+) ion influx, activity enhancement of antioxidant enzymes, and biomass accumulation.

Analysis of vascular development in the hydra sterol biosynthetic mutants of Arabidopsis.

BACKGROUND: The control of vascular tissue development in plants is influenced by diverse hormonal signals, but their interactions during this process are not well understood. Wild-type sterol profiles are essential for growth, tissue patterning and signalling processes in plant development, and are required for regulated vascular patterning. METHODOLOGY/PRINCIPAL FINDINGS: Here we investigate the roles of sterols in vascular tissue development, through an analysis of the Arabidopsis mutants hydra1 and fackel/hydra2, which are defective in the enzymes sterol isomerase and sterol C-14 reductase respectively. We show that defective vascular patterning in the shoot is associated with ectopic cell divisions. Expression of the auxin-regulated AtHB8 homeobox gene is disrupted in mutant embryos and seedlings, associated with variably incomplete vascular strand formation and duplication of the longitudinal axis. Misexpression of the auxin reporter proIAA2ratioGUS and mislocalization of PIN proteins occurs in the mutants. Introduction of the ethylene-insensitive ein2 mutation partially rescues defective cell division, localization of PIN proteins, and vascular strand development. CONCLUSIONS: The results support a model in which sterols are required for correct auxin and ethylene crosstalk to regulate PIN localization, auxin distribution and AtHB8 expression, necessary for correct vascular development.

Stomatal observations in dicotyledons.

Since 1998, research into more than 470 plant species from some 65 families, found growing in a unique protected area of Irano-Torany, has examined diverse aspects of their anatomical and structural features and has studied the ecological implications of these finding for each species. The present paper, as a part of this research, focuses on the stomatal characters of 326 species from 36 families of dicotyledons, the majority of which are herbaceous species. The stomatal density, guard cell lengths on the adaxial and abaxial leaf epidermis and the stomatal type in each family is described and the relationship between stomatal density and guard cell size is reviewed. The stomatal characteristics presented here are a valuable research resource, allowing; I) the identification of basic stomatal types in these plants, II) the facilitation of their taxonomic classification and III) constitution of a baseline data set against which to monitor and evaluate environmental changes at these sites of international conservation interest.