pheophytin-a and phenanthrene

Photosynthesis mediated by chlorophyll metabolism is the basis for plant growth, and also the important regulatory mechanism of carbon pool in cropland ecosystems. Soil organic pollutants induced growth inhibition in crop plants, herein, we conducted an in-depth investigation on the effects of three representative polycyclic aromatic hydrocarbons (PAHs), including phenanthrene (PHE), pyrene (PYR), and benzo[a]pyrene (BaP) on rice (Oryza sativa) growth and photosynthesis. PAHs were absorbed via root uptake and accumulated in leaves, causing the swelling of thylakoids and the increase of osmiophilic granules in chloroplasts. The actual quantum efficiency of PSII was significantly decreased under the stress of PHE, PYR, and BaP by 29.9%, 11.9%, and 24.1% respectively, indicating the inhibition in photon absorption and transfer, which was consistent with the decrease of chlorophyll a (22.3%-32.2% compared to the control) in rice leaves. Twenty-two encoding genes involved in chlorophyll metabolism were determined and the results indicated that the expression of chlorophyll synthetases was downregulated by over 50% whereas the degradation process was promoted. Consequently, the production of carbohydrates and the carbon fixation were inhibited, which revealed by the downregulation of intermediate metabolites in Calvin cycle and the declined carboxylation rate. The disturbed photosynthesis resulted in the decrease of the biomasses of both roots (21.0%-42.7%) and leaves (6.4%-22.1%) under the tested PAH stresses. The findings of this study implied that the photosynthetic inhibition was possibly attributed to the disorder of chlorophyll metabolism, thus providing novel insights into the mechanism of growth inhibition induced by organic pollutants and theoretical basis for the estimation of cropland carbon sequestration potential.

Topics: Chlorophyll; Chlorophyll A; Ecosystem; Environmental Pollutants; Oryza; Photosynthesis; Polycyclic Aromatic Hydrocarbons

The coexistence of polycyclic aromatic hydrocarbons (PAHs) and heavy metals has deleterious effects on environmental quality. Few reports have studied the mechanisms of plant inoculation with Piriformospora indica to remediate PAH-metal co-contaminated soil by analyzing the chemical speciation of the contaminants. This study investigated the influence of the inoculation of Medicago sativa with P. indica to remediate soil co-contaminated with phenanthrene (a kind of PAH) and cadmium (a heavy metal) by analyzing plant growth, physiological parameters and chemical speciation in rhizosphere and nonrhizosphere soils.. The presence of P. indica significantly increased plant tolerance, chlorophyll a, chlorophyll b, maximum quantum efficiency of PSII photochemistry and electron transport rate values in phenanthrene- and/or cadmium-contaminated soil. P. indica inoculation in M. sativa roots increased fluorescein diacetate activities in soils contaminated with phenanthrene, cadmium or both, especially in the nonrhizosphere. The presence of phenanthrene prevented the inoculated plant from accumulating cadmium to some extent, whereas the presence of cadmium did not prevent the degradation of phenanthrene in either the rhizosphere or the nonrhizosphere after P. indica colonization. Although the low bioavailability of cadmium in the rhizosphere restricted its transportation into the stem, P. indica colonization in plants effectively increased cadmium accumulation in roots in soil co-contaminated with cadmium and phenanthrene.. In conclusion, this work provides a theoretical basis for the use of P. indica combined with M. sativa for the remediation of PAH-metal co-contaminated soil.

Topics: Basidiomycota; Biodegradation, Environmental; Biomass; Cadmium; Catechol Oxidase; Chlorophyll; Chlorophyll A; Medicago sativa; Phenanthrenes; Plant Development; Plant Roots; Soil Microbiology; Soil Pollutants

Here, Microcystis aeruginosa (M. aeruginosa) was studied to analyze the effects of 0.5 mg L

Topics: Cell Proliferation; Chlorophyll A; Hydrogen-Ion Concentration; Marine Toxins; Microcystins; Microcystis; Naphthalenes; Phenanthrenes

It is reported that the accumulated polycyclic aromatic hydrocarbons (PAHs) can cause wheat leaf chlorosis, and we identified that carotenoid (Car) and superoxide dismutase (SOD) are the two most active factors in antioxidant system in the previous study. Herein, we applied Car as an exogenous chemical added to alleviate the toxicity triggered by phenanthrene (a model PAH) in wheat seedlings. In the exogenous Car addition groups, we found that the leaf number would grow three, and the relative biomass and the relative root length of 20 mg L

Topics: Antioxidants; Carotenoids; Chlorophyll; Chlorophyll A; Malondialdehyde; Oxidative Stress; Phenanthrenes; Plant Leaves; Seedlings; Soil Pollutants; Superoxide Dismutase; Triticum

The acute effects of three typical polyaromatic hydrocarbons (PAHs): naphthalene (Naph), phenanthrene (Phen) and fluoranthene (Flu) on photochemical activity of photosystem II (PSII) in detached leaves of 3-week-old pea plants were studied. The leaves were exposed in water with PAHs under white light for 0.5-72 h. The activity of PSII was examined by prompt and delayed chlorophyll a (Chl a) fluorescence. The effects of PAHs depended on their concentration and exposure time. This dependency was more significant in the presence of chemical stressors (Triton X-100 or acetone) or under high intensity irradiance. Increased content of PAHs and long-term exposure (24-72 h) led to significant reduction of the maximum photochemical quantum efficiency (Fv/Fm) of PS II, changes in the polyphasic fluorescence induction (OJIP), and to decreasing amplitudes of fast and slow components of delayed Chl a fluorescence. The damage of PSII depended on water solubility of a given type of PAHs, their concentration and exposure time. During short-time exposure the compound with highest water-solubility - naphthalene - revealed the strongest effect. During long-time exposure the compounds with low water-solubility -Phen, Flu-revealed the strongest effect as the corresponding PAH accumulates in the thylakoids especially when the solution is oversaturated containing a solid phase. The reduction of PSII activity at the presence of naphthalene (30 mg L(-1)) was accompanied by transient generation of H2O2 as well as swelling of thylakoids and distortion of cell plasma membranes, which was indicated by electron microscopy images. Distortion of thylakoid membranes due to accumulation of PAHs as well as the development of oxidative stress seems to be the main pathways of PAHs influencing the photochemical activity of PS II.

Topics: Chlorophyll; Chlorophyll A; Fluorenes; Fluorescence; Hydrogen Peroxide; Light; Microscopy, Electron; Naphthalenes; Oxidative Stress; Phenanthrenes; Photosynthesis; Photosystem II Protein Complex; Pisum sativum; Plant Leaves; Polycyclic Aromatic Hydrocarbons; Thylakoids