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Copper is an essential micronutrient for plant growth. It is an important component of proteins. In the present research the effect of copper toxicity on chlorophyll, sugar, protein content and antioxidant enzymes activity in both mycorrhizal and non-mycorrhizal tomato plants were studied. The experiment was performed by using two treatments (mycorrhizal and non-mycorrhizal) and five concentrations of CuSo4 solution added to Hogland nutrient solution . Copper toxicity caused reduction in growth in all treatment (non-AM). It may be due to accumulation of Cu in leaves. Total sugar content in both shoot and roots, the total chlorophyll content in leaves, Protein content in shoots and roots, antioxidant enzyme activity and root colonization were determined.

Silver nanoparticles (AgNPs) have been biosynthesised through the extracts of Ribes khorassanicum fruits, which served as the reducing agents and capping agents. Biosynthesised AgNPs have been found to be ultraviolet–visible (UV–vis) absorption spectra since they have displayed one surface plasmon resonance peak at 438 nm, attesting the formation of spherical NPs. These particles have been characterised by UV–vis, field‐emission scanning electron microscopy, energy‐dispersive X‐ray spectroscopy, X‐ray diffraction, Fourier transform infrared spectroscopy, and transmission electron microscopy analysis. The formation of AgNPs at 1.0 mM concentration of AgNO3 has resulted in NPs that contained mean diameters in a range of 20–40 nm. The green‐synthesised AgNPs have demonstrated high antibacterial effect against pathogenic bacteria (i.e. Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa). Biosynthesising metal NPs through plant extracts can serve as the facile and eco‐friendly alternative for chemical and/or physical methods that are utilised for large‐scale nanometal fabrication in various medical and industrial applications. [ABSTRACT FROM AUTHOR]

Silver nanoparticles (Ag-NPs) were synthesized through a facile and 'green' method, which uses the aqueous shoots extract of Rheum turkestanicum at room temperature. The formation of Ag-NPs was indicated by observing the change in solution color, turning from light brown to dark brown. The synthesized Ag-NPs were characterized with different instrumental tools such as UV-vis, XRD, FESEM, EDAX, FTIR, and TEM. The formation of Ag-NPs at 1.0 mM concentration of silver nitrate resulted in nanoparticles with spherical shapes and a mean diameter of 26 nm. In addition, the biosynthesized Ag-NPs were found to illustrate stronger antibacterial activities against human pathogenic bacteria. From the results and observations, this method can be applied for large-scale preparations of other noble metals regarding various medical and industrial applications. [ABSTRACT FROM AUTHOR]

Objective: Origanum vulgare L. is rarely cultivated in Iran but it is the only species of the Origanum genus growing wild in this country. O.vulgare L. is widely spread all over the country. In this study, parameters of content, composition and antioxidant activity of the essential oils of domestic and wild Iranian Oregano populations were compared with one another. Materials and Methods: The extractions were performed using a clevenger-type apparatus and the essential oils in the Oregano plants were obtained by hydro-distillation and analyzed by GC/MS. Results: The essential oils were obtained in the Oregano field at yield of (0.80%) and the 4 provenance Oregano (ranging from 0.93% to 1.66% v/w). In cultivated plant 22 constituents, representing 94.02% and in 4 provenance plants (O.v-w1--- O.v-w4), 21, 25, 22, 20 constituents, representing 96.55%, 95.66%, 95.8%, 94.48% of the oils, respectively, were identified. The two major constituents of the essential oils, carvacrol ranging from 23.54 to 67.09% and, γ-terpinene ranging from 7.71 to 20.94% were present in relatively equal amounts in all five samples from different localities. Five chemotypes of essential oils were identified. The main chemotype was carvacrol-γ-terpinene. Furthermore, the antioxidant activity of essential oils of O.vulgare using DPPH radical scavenging was determined. All extracts exhibited almost the same pattern of antioxidant activity as ascorbic acid (vit C). Conclusion: Our fmdings demonstrated that the chemical composition of the essential oils of O.vulgare L. varies considering geographical location of collection site, climate and other ecological conditions which suggest both intrinsic/genetic and extrinsic/environmental factors such as: altitude, edaphic, temperature, humidity and climate, may play important roles in determining the oils composition. [ABSTRACT FROM AUTHOR]

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UV-C radiation (220-280 nm) is known to causing damage in some physiological growth parameters such as chlorophyll, carotenoid, protein and sugar contents. In this study, effect of some species of vesicular arbuscular mycorrhizal fungi on tolerance of UV-C radiation in wheat plants was studied. Wheat (Triticum aestivum L. cv. Azar2) plants colonized by three species of mycorrhizae namely Glomus etunicatum, Glomus intraradices and Glomus veruciforme were used in this study. They have been exposed to UV-C (254 nm) light for 7 h (28 days, 15 min each day). We measured total proteins, sugars, chlorophyll a and b and carotenoids. Our study showed that UV-C radiation decreases chlorophylls, carotenoids and sugars contents. But this effect on total proteins content has not been significant. However, mycorrhizal fungi could increase all of these factors in comparison to non-mycorrhizal samples. Therefore, these fungi species can increase above growth factors of wheat plants, apparently.

Soil pollution by heavy metals has become a critical environmental concern due to its potential adverse ecological effects. In this study we have investigated the effect of arbuscular mycorrhizal fungus (Glomus veruciforme) on some physiological growth parameters, such as chlorophyll content, amount of total soluble sugar and total protein of wheat plants (Triticum aestivum L. cv. Azar2) and we compared these factors in mycorrhizal (AM) and non-mycorrhizal (non-AM) plants. The content of chlorophyll in the absence of Cd in AM-plants was higher than non-AM plants. In the presence of mycorrhiza the content of chlorophyll a and b was decreased by increase in Cd concentration in both AM and non-AM plants. Furthermore, the amount of total soluble sugars and total proteins of shoots and roots have been increased in parallel to exogenous Cd concentration. In roots of AM-plants, the increase of soluble sugars was more dramatic in the presence of 2500 microm, but in the roots of non-AM plants this increase was step-by-step. The increase of total soluble sugars was gradually and significant in shoots of both AM and non-AM plants. The content of total proteins in shoots was raised with the increased level ofCd treatment, gradually and non-significantly.

Maize seedlings treated with various concentrations (25-100 microM) of copper for 15 days. A progressive decrease of root length and biomass with increasing Cu in nutrient solution was observed. The roots accumulated significantly higher amounts of Cu than the above ground parts. Accumulation of copper resulted in more active lipid peroxidation in both roots and shoots, which was attributed to copper-induced additional oxidative stress. Activities of APX (ascorbate peroxidase), GPX (guaiacol peroxidase), GR (glutathione reductase) and CAT(catalase) were higher in both roots and shoots in response to copper accumulation. Changes in lipid peroxidation and antioxidant enzyme activities suggest that oxidative damage may be involved in copper toxicity.

Soil microorganisms have been shown to possess several mechanisms capable of altering metal bioavailability for uptake into roots. In addition, root mycorrhizal associations have been shown to affect the rate of metal uptake. There is evidence that exposure of plants to excess concentrations of heavy metals such as Cu results in oxidative injury. In this study, effect of arbuscular mycorrhizal fungus Glomus etunicatum on tolerance of Cu toxicity in tomato plants was studied. In order to prepare seedling medium, we used washed and sterilized sand and agricultural soil. Tomato seeds were surface sterilized and planted in two pots. One filled just with sterilized sand (for non-mycorrhizal treatments) and the other filled with sterilized sand mixed with G. intraradices mycorrhizal inoculum. We were certain about complete colonization after 4 weeks, so we transferred three seedlings to each main pot. Plants grew in growth chamber for nine weeks. During growth period plants received modified Hoagland's solution (with half P content) with Cu concentration of 0, 1.5, 3.5, 5.5, 7.5 mM CuSO4 in triplicates. Antioxidant enzymes activity, Ascorbate Peroxidase (APX) and Guaiacol Peroxidase (GPX) and Root Length Colonization (RLC) percentage in mycorrhizal and non-mycorrhizal plants were measured. APX activity in mycorrhizal shoots increased but there was no significant correspondent increase in roots of these plants. GPX activity in mycorrhizal roots increased but there was no significant correspondent increase in shoots of these plants. Activity of this enzyme in roots and shoots of mycorrhizal plantshigher than non-mycorrhizal plants. Estimation of root length colonizatinon by gridline intersect method, increase in Cu concentration, colonization percentage decreased significantly. The data show the possible role of mycorrhiza in plant protection against Cu toxicity.

In acid soils worldwide cadmium toxicity is a major factor limiting plant growth. The harmful effect of cadmium is initially expressed as a reduction in growth followed by several other secondary responses. In this study, some of the toxic effects of Cd(+2) like induction of oxidative stress were investigated. The effect of metal ion on the root growth was considered in maize plants. Maize (Zea mays L.) seeds were sterilized with 2.5% sodium hypochlorite solution for 15 min and washed thoroughly with distilled water. These seeds then germinated in petri dish (20 cm) containing distilled water at 37 degrees C in the dark. After a 1 day incubation, uniformly germinated seeds were selected and transferred to Petri dishes (9.0 cm) containing filter paper moistened with 10 mL of distilled water. Each Petri dish contained 12 germinated seeds. Each treatment was replicated 4 times. The germinated seeds were allowed to grow at 27 degrees C in darkness and 5 mL of test solution was added to each Petri dish in the second day. The test solution contained 0, 0.25, 0.5, 0.75, 1, 3 and 5 mM CdCl2. Cadmium treatments, increased GPX and APX activities in root in the presence of 0.25, 0.5, 0.75 mM concentrations, but their activities were constant in 1, 3 and 5 mM. Increased concentrations of CdCl2 from 0.25 to 5 mM decreased root length progressively. However, no reduction of shoot length by CdCl2 was observed.