Weed Species from Tea Gardens as a Source of Novel Aluminum Hyperaccumulators.

Increased availability of toxic Al3+ is the main constraint limiting plant growth on acid soils. Plants adapted to acid soils, however, tolerate toxic Al3+, and some can accumulate Al in their aerial parts to a significant degree. Studies on Al-tolerant and Al-accumulating species have mainly focused on the vegetation of acid soils distributed as two global belts in the northern and southern hemispheres, while acid soils formed outside these regions have been largely neglected. The acid soils (pH 3.4-4.2) of the tea plantations in the south Caspian region of Northern Iran were surveyed over three seasons at two main locations. Aluminum and other mineral elements (including nutrients) were measured in 499 plant specimens representing 86 species from 43 families. Al accumulation exceeding the criterion for accumulator species (>1000 µg g-1 DW) was found in 36 species belonging to 23 families of herbaceous annual or perennial angiosperms, in addition to three bryophyte species. Besides Al, Fe accumulation (1026-5155 µg g-1 DW) was also observed in the accumulator species that exceeded the critical toxicity concentration, whereas no such accumulation was observed for Mn. The majority of analyzed accumulator plants (64%) were cosmopolitan or pluriregional species, with a considerable rate of Euro-Siberian elements (37%). Our findings, which may contribute to phylogenetic studies of Al accumulators, also suggest suitable accumulator and excluder species for the rehabilitation of acid-eroded soils and introduce new model species for investigating Al accumulation and exclusion mechanisms.

Phenanthrene uptake and translocation by Panicum miliaceum L. tissues: an experimental study in an artificial environment.

Polycyclic aromatic hydrocarbons (PAHs), as priority organic pollutants, are capable of accumulation in plants. Phenanthrene (Phe) is one of the most abundant low-molecular-weight PAH in the environment which is commonly used as a model PAH in many phytoremediation studies and as a representative compound for all PAHs group. This paper highlights the uptake, translocation, and accumulation of Phe by growing proso millet (Panicum miliaceum L.) in a pot experiment, subjected to 500, 1000, 1500, and 2000 ppm of Phe treatment after 15 and 30 days. Phe naturally existed in P. miliaceum and its concentration showed a time-dependent reduction in treated plant tissues as well as in perlites. Phe concentration in shoots was higher than in roots. During the aging process, the uptake of Phe was diminished whereas translocation factor (TF) demonstrated an overall increasing trend among treatments. The shoot concentration factor (SCF) values were higher than those of root concentration factor (RCF) on both days 15 and 30 and the highest values for both parameters were achieved in 500 ppm of Phe. Both RCFs and SCFs generally tended to decrease with the increase of perlite Phe concentrations. These results suggested that Phe tended to transfer to the shoots and be metabolized there. The Phe concentration revealed a significant decline in all levels of treatment on both 15 (84 to 96%) and 30 (76 to 94%) days. Therefore, the presence of P. miliaceum was effective in promoting the phytoremediation of Phe polluted perlites.

Duckweed Potential for the Phytoremediation of Linear Alkylbenzene Sulfonate (LAS): Identification of Some Intermediate Biodegradation Products and Evaluation of Antioxidant System.

Duckweed (Lemna minor L.) has a high potential for wastewater treatment. Here, its capability for bioremoval of linear alkylbenzene sulfonate (LAS) as one of the primary contaminants of water resources was evaluated. The effect of some operational parameters on surfactant removal efficiency was determined. Also, the impact of LAS on several physiological responses of Lemna was investigated. LAS remediation efficiency of L. minor was elevated with increasing LAS concentration, duckweed weight, and temperature. Furthermore, the optimal pH for removal was 7-8.5. The benzenesulfonate ring and five homologs of sulfophenyl carboxylate were identified as intermediates in the LAS degradation pathway. A decrease in relative growth rate and pigment contents was observed by increasing LAS concentration. In contrast, an increase in hydrogen peroxide content and electrolyte leakage indicated oxidative stress by LAS. Induction of enzymatic/non-enzymatic antioxidants was observed during the surfactant remediation process, indicating their role in overcoming free radicals generated under surfactant stress.

Investigation of long-term hazards of chemical weapon agents in the environment of Sardasht area, Iran.

The present study aimed to investigate the persistence and existence of chemical warfare agents (CWAs) and related dissipation products in the environment of Sardasht area, Iran. Three types of environmental samples including water, soil, and native local plant materials were collected and analyzed. Gas chromatography-mass spectrometry in the electron impact ionization mode has been developed for the separation, screening, identification, and qualification of chemicals after the sample preparation methods. The initial results revealed that no trace of related compounds or CWAs was detected in the soil and water samples. However, trace amounts of some degradation products of blistering agents like mustard gas (HD) and lewisite were found in a tree wood from a house subjected to chemical attack as well as in barley samples (a mixture of leaves and root) collected from an agricultural field in the area indicating chronic low exposure to the environment and people. In order to validate the applied extraction procedures, ethylene glycol was spiked to some of the samples including groundwater, surface soil, grape, and alfalfa plants. All the recoveries were in the range of 83.6-107.4% with the relative standard deviations varying from 4.9% to 12.4% (n = 3) successfully.

In vitro study of redroot pigweed effects as weed plant species on leukemia.

Redroot pigweed is a well-known allelopathic weed worldwide with diverse organic compounds which involving in its allelopathic interactions as well. Preliminary tests of redroot pigweed extract against leukemia and various human phatogenic microorganisms revealed that amaranth extract inhibits the viability and proliferation of NB4 cells in a time- and dose-dependent manner and has an excellent anti-bacterial effect on gram-positive bacteria and Candida fungi. Interestingly, the anti-luekemia effects of redroot pigweed is reported for the first time. Phytochemical analysis of redroot pigweed extract, led to the identification amaranth bioactive compounds that largely were including terpenoid compounds (51.71%) as the main group and Carvacrol (11.33%) was the key compound. Redroot pigweed contains various organic compounds with allelopathic and therapeutic properties and current investigation is a promising revelation for the pharmaceutical importance of this plant.

Phytoremediation potential of Azolla filiculoides for sodium dodecyl benzene sulfonate (SDBS) surfactant considering some physiological responses, effects of operational parameters and biodegradation of surfactant.

In this study, phytoremediation potential of the Azolla filiculoides Lam. was examined for sodium dodecyl benzene sulfonate (SDBS) anionic surfactant. Furthermore, the effect of surfactant treatment on some physiological characteristics of Azolla was studied. The surfactant bioremoval efficiency was studied under variable conditions including treatment time, initial surfactant concentration, Azolla fresh weight, temperature, and pH. Results showed that surfactant removal efficiency of A. filiculoides was significantly enhanced with increasing of temperature, initial surfactant concentration, and amount of Azolla. SDBS led to a reduction in growth rate and total chlorophyll content, but effect index of Azolla increased by higher concentrations of surfactant. In contrast, antioxidant enzymes activities including polyphenol oxidase, ascorbate peroxidase, catalase, and peroxidase, as well as nonenzymatic antioxidants such as total carotenoids and anthocyanin contents significantly increased probably due to the ability of plant to overcome oxidative stress induced by SDBS. An increase in antioxidant activity based on 2, 2-diphenyl-1-picrylhydrazil (DPPH) confirmed this fact. An increase in the amount of hydrogen peroxide and reduction in membrane stability index indicated the induction of oxidative stress. As a result of SDBS biodegradation, 6 homologs of sulfophenyl carboxylates (SPCs) including C2 to C7-SPC and benzenesulfonate ring were identified by liquid chromatography-mass spectroscopy (LC-MS) analysis.

Changes in antioxidants and leaf pigments of safflower (Carthamus tinctorius L.) affected by exogenous spermine under water deficit.

Water deficit is one of the most limiting factors for plant growth and production. Polyamines are osmo-active compounds and have important roles in plant resistance to water limitation. A pot experiment was undertaken in a greenhouse as factorial based on complete randomized block design with three replications to assess the physiological and biochemical responses of safflower to different levels of water supply (100% and 40% field capacity) and spermine (0, 40 and 60 µM). Ascorbate peroxidase and peroxidase activities (POX), malondialdehyde (MDA), hydrogen peroxide (H2O2), anthocyanins, soluble protein, soluble sugars and proline contents in shoots increased, while total phenols, flavonoids, and photosynthetic pigments significantly decreased due to water deficit. Foliar spray of spermine mitigated the adverse effects of water deficit by increasing the catalase, superoxide dismutase, POX activities, soluble proteins and photosynthetic pigments, and by decreasing MDA and H2O2 contents. Spermine could, therefore, play an important role in protecting photosynthetic system and cellular membranes during drought stress in safflower.

Uptake and distribution of phenanthrene and pyrene in roots and shoots of maize (Zea mays L.).

Polycyclic aromatic hydrocarbons as byproducts of carbon-based fuel combustion are an important group of pollutants with wide distribution in the environment. Polycyclic aromatic hydrocarbons are known as toxic compounds for almost all organisms. Different plant species can uptake polycyclic aromatic hydrocarbons by roots and translocate them to various aerial parts. The aim of this study is to investigate the uptake, translocation, and accumulation of pyrene and phenanthrene in maize under controlled conditions. Seeds were cultivated in perlite containing 25, 50, 75, and 100 ppm of phenanthrene and pyrene, and their concentrations in the roots and shoots of the plants were measured using high-performance liquid chromatography technique after 7, 14, and 21 days. The results revealed that phenanthrene naturally existed in maize and its concentration showed a time-dependent decrease in shoots and roots. In contrast, the concentration of pyrene was increased in the roots and reduced in the shoots. Although pyrene had higher uptake than phenanthrene in roots of maize, the translocation factor value for pyrene was lower than for phenanthrene. According to these findings, phenanthrene could be metabolized in maize in the shoot and root tissues, but pyrene had more tendency to be accumulated in roots.

Fluorene and Phenanthrene Uptake and Accumulation by Wheat, Alfalfa and Sunflower from the Contaminated Soil.

Polycyclic Aromatic Hydrocarbons (PAHs) are diverse organic contaminants released into the environment by both natural and anthropogenic activities. These compounds have negative impacts on plants growth and development. Although there are many reports on their existence in different parts of plant, their uptake and translocation pathways and mechanisms are not well understood yet. This paper highlights the uptake, translocation and accumulation of PAHs by wheat, sunflower and alfalfa through an experimental study under controlled conditions. Seeds were cultivated in a soil containing 50 mg/kg of phenanthrene and fluorene and their concentrations in plants roots and shoots were determined using a gas chromatograph after 7 and 14 days. The results showed that phenanthrene and fluorene concentrations in the treated plants were increased over the time. PAHs bioavailability was time and species dependent and generally, phenanthrene uptake and translocation was faster than that of fluorene, probably due to their higher Kow. Fluorene tended to accumulate in roots, but phenanthrene was transported to aerial parts of plants.