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BACKGROUND A wide variety of secondary metabolites are synthesized from primary metabolites by plants which have a vast range in pharmaceutical, food additive and industrial applications. In recent years, the use of elicitors has opened a novel approach for the production of secondary metabolite compounds. Dracocephalum kotschyi is a valuable herb due to pharmaceutical compounds like rosmarinic acid, quercetin and apigenin. In the current study, foliar application of chitosan (0, 100, 400 mg L−1) as an elicitor was used. RESULTS: After chitosan treatment, the amounts of hydrogen peroxide (H2O2) increased and the plant was able to increase the activities of enzymatic (guaiacol peroxidase, catalase and phenylalanine ammonium lyase) and non‐enzymatic (total phenols and flavonoids) defensive metabolites. Also, foliar spray of chitosan promoted nutrient absorption which led to the accumulation of macroelements in the plant. CONCLUSIONS: Chitosan was found to be a very effective elicitor for improving rosmarinic acid and quercetin content (up to 13‐fold). Also, the content of apigenin (anticancer flavonoid) showed 16‐fold enhancement compared to the control. Therefore, the treatment of D. kotschyi leaves with chitosan caused a very large increase in the induction and production of important pharmaceutical compounds such as rosmarinic acid and quercetin. © 2020 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

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]

Contamination of soil and ground water by chromium (Cr), due to its wide industrial use, has become a serious source of concern over the past decade. In this study a glasshouse experiment was conducted to investigate the effects of the mycorrhizal fungus Glomus intraradices on Cr toxicity in maize plants. Half of the plants were inoculated with the arbuscular mycorrhizal fungus (AMF). Cr was supplied in the form of potassium dichromate at 0.00, 0.10, 0.25, and 0.50 mM through irrigation water in a sand culture. At the end of the experiment, it was observed that Cr had significantly decreased the chlorophyll content in the maize leaves. The mycorrhizal plants had greater chlorophyll content than the non-mycorrhizal plants. Moreover, increasing the chromium concentration caused an increase in the malondialdehyde (MDA) content in the shoots and roots of the whole plant; however, the AM plants showed a lower MDA content than the non-AM plants. Cr caused an induction in guaiacol peroxidase (GPX) and ascorbate peroxidase (APX) activity in the roots of the non-mycorrhizal plants but no significant induction was observed in APX activity in Cr-treated AM roots. The activity of GPX in the roots of AM plants was lower than in those of non-AM plants under chromium treatment. Measurements of chromium concentration indicated that Cr mainly accumulated in the roots of the maize plants. The Cr concentration significantly decreased in the shoots through AM symbiosis. [ABSTRACT FROM AUTHOR]

Copyright of Turkish Journal of Biology is the property of Scientific and Technical Research Council of Turkey and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Turkish Journal of Biology is the property of Scientific and Technical Research Council of Turkey and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Turkish Journal of Biology is the property of Scientific and Technical Research Council of Turkey and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

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.

Growth parameters and biochemical changes were studied in roots and leaves of 15 day old maize grown in a nutrient solution containing various copper concentrations (0, 25, 50, 75 and 100 microM). An accumulation of H2O2 was observed in roots and shoots. The leaf chlorophyll a, b and carotenoid contents decreased with increasing Cu concentration. The results demonstrated adverse effects of Cu on N metabolism and plant growth. Cu exposure elevated Cu concentration and decreased Nitrate Reductase (NR) activity in the roots and shoots. However, Cu exposure increased total free amino acid content in the leaves.

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.

High concentrations of heavy metals in the soil have an adverse effect on micro-organisms and microbial processes. Mycorrhizas are among the extracellular strategies to avoid metal toxicity. In the present study, the effect of cadmium on lipid peroxidation and antioxidative enzymes activity of AM (with Glomus veruciforme, G. intraradices and G. etunicatum) and non-AM Wheat plants was investigated. Wheat plants (Triticum aestivum L. cv. Azar2) which have been colonized by above species, were used in this study. They have been exposed to different concentrations of cadmium chloride for 60 days. The test solution contained: 0 (control), 250, 750 and 2500 microm cadmium Toxicity symptoms such as chlorosis and necrosis appeared on the cadmium treated leaves. Activity of detoxifying enzymes Guaiacol peroxidase (GUPX) and Ascorbate peroxidase (APX) of mycorrhizal and non-mycorrhizal plants were increased. Also, the amount of malondialdehyde (MDA) increased in roots and shoots ofmycorrhizal and non-mycorrhizal plants significantly as a result of Cd treatment, but it was more dramatic in mycorrhizal ones.

The effects of zinc toxicity on growth, chlorophyll, total sugar and protein content and mineral content of lettuce plants infected or not by Arbuscular Mycorrhizal (Am) fungus Glomus etunicatum and treated with nutrient solution containing 0, 1.5, 3.5, 5.5, 7.5 mM ZnSO, were studied. The introduction of Zn caused a decrease in the inhibiting effect of zinc on dry weight of roots and shoots of lettuce plant infected by Am in contrary with non-Am plants. This increase observed in dry weight may be due to improvement of Phosphorous uptake by mycorrhizal fungi. The decrease in dry weight of non-Am plants may be because of inhibitory effects of zinc on growth. Chlorophyll and total sugar content decreased in both Am and non-Am plants, which indicate the toxic effect of Zn on photosynthesis and carbohydrate metabolism. Mycorrhizal plants due to changing the translocation of Zn and sequestering in the hypha could elevate the effects of Zn to some extent. Total protein content increased in Am plants, probably due to induction of antioxidant enzymes and some stress proteins but reduced in non-Am plants which maybe caused by toxic effects of Zn on protein synthesis. Alleviating the severe effects of Am fungus observed in this study aroused an interest in considering the role of Am fungi in protection and elevation the sever effects of heavy metals in plants.

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.

Zinc is one of the eight trace elements which are essential for the normal healthy growth and reproduction of crop plants. Plants possess cellular mechanisms that may be involved in the detoxification of heavy metals and thus confer plants a better tolerance against them. Arbuscular mycorrhizal fungi colonization is one of these mechanisms. Here, the effect of mycorrhizal fungus G. etunicatum on Zn toxicity tolerance through enhanced activity of some of antioxidant enzymes has been studied. Treatments were applied in triplicates of two factorial analyses: (a) mycorrhizal and non-mycorrhizal; (b) 5 levels of Zinc (0, 1.5, 3.5, 5.5, 7.5 mM). Zinc was added to modified Hoagland's nutrient solution (with half P concentration). Plants were grown in growth chamber for 10 weeks. Toxicity symptoms such as necrosis and chlorosis appeared on the leaves. Activity of detoxifying enzymes Guaiacol peroxidase (GUPX) and Ascorbate peroxidase (APX) were measured. GPX activity in roots and shoots of mycorrhizal and non-mycorrhizal plants was increased. Also, APX activity increased in roots and shoots ofmycorrhizal and non-mycorrhizal plants. Root length colonization (RLC) was measured by gridline intersect method. Mycorrhizal colonization decreased due to Zinc exposure. The results indicate the probable role of arbuscular mycorrhizal colonization in stress tolerance.

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.