chlorophyll-a and lead-nitrate

Present study was conducted to evaluate the effect of lead tolerant plant growth promoting rhizobacteria (LTPGPR) on growth, physiology, yield, antioxidant activities and lead uptake in sunflower in soil contaminated with lead under pot conditions. Three pre-characterized LTPGP strains (S2 (Pseudomonas gessardii strain BLP141), S5 (Pseudomonas fluorescens A506) and S10 (Pseudomonas fluorescens strain LMG 2189)) were used to inoculate sunflower growing in soil contaminated with different levels (300, 600 and 900 mg kg

Topics: Antioxidants; Ascorbate Peroxidases; Catalase; Chlorophyll; Chlorophyll A; Environmental Pollution; Glutathione Reductase; Helianthus; Lead; Nitrates; Plant Development; Plant Roots; Proline; Pseudomonas; Soil; Soil Microbiology; Soil Pollutants; Superoxide Dismutase

Using model lead compounds Pb(NO3)2 and Pb(CH3CHOO)2, the mechanism and the site of action of Pb2+ ions in the photosynthetic apparatus of spinach chloroplasts were studied. Both compounds inhibited photosynthetic electron transport (PET) through photosystem 1 (PS1) and photosystem 2 (PS2), while Pb(NO3)2 was found to be more effective PET inhibitor. Using EPR spectroscopy the following sites of Pb2+ action in the photosynthetic apparatus were determined: the water-splitting complex and the Z•/D• intermediates on the donor side of PS2 and probably also the ferredoxin on the acceptor side of PS1, because cyclic electron flow in chloroplasts was impaired by treatment with Pb2+ ions. Study of chlorophyll fluorescence in suspension of spinach chloroplasts in the presence of Pb2+ ions confirmed their site of action in PS2. Using fluorescence spectroscopy also formation of complexes between Pb2+ and amino acid residues in photosynthetic proteins was confirmed and constants of complex formation among Pb2+ and aromatic amino acids were calculated for both studied lead compounds.

Topics: Chlorophyll; Chloroplasts; Electron Spin Resonance Spectroscopy; Electron Transport; Ions; Lead; Nitrates; Organometallic Compounds; Photosynthesis; Photosystem I Protein Complex; Photosystem II Protein Complex; Spectrometry, Fluorescence; Spinacia oleracea; Water

Cuttings and seedlings of Jatropha curcas L. were exposed to different regimes of lead (Pb) stress as Pb(NO₃)₂ at 0 (CK), 0.5, 1, 2, 3, and 4 mM kg⁻¹ soil.. The effect of Pb treatment on the root length, tolerance index, photosynthetic pigments, photosynthetic activity, lipid peroxidation, and antioxidant enzyme was studied in a greenhouse pot experiment.. The results showed that root lengths and tolerance index decreased with increase of Pb concentration, but tolerance index of cuttings was always lower than those of the seedlings. For cuttings, Pb treatment had a stimulating effect on chlorophyll content, carotenoid content, and superoxide dismutase (SOD) activity at low concentration and an inhibitory effect at higher concentration. For seedlings, SOD activity increased with increasing Pb concentration. In both seedlings and cuttings, Pb caused inhibition of leaf growth and photosynthesis, and induced the membrane damage which was more obvious in the cuttings. In comparison with the control, the dynamic tendency of catalase and perxidase activities in the leaves of Pb-stressed plants all ascended, and then declined.. The increase in enzyme activities demonstrated that seedlings were more tolerant to Pb stress than cuttings. These results also indicate that the antioxidant system may play an important role in eliminating or alleviating the toxicity of Pb in J. curcas seedlings and cuttings. The accumulation of Pb increased in a concentration-dependent manner; however, its translocation from root to shoot was low. The cuttings accumulated significantly higher Pb in roots than seedlings.

Topics: Biodegradation, Environmental; Biological Transport; Carotenoids; China; Chlorophyll; Drug Resistance; Jatropha; Lead; Malondialdehyde; Nitrates; Oxidative Stress; Oxidoreductases; Photosynthesis; Plant Components, Aerial; Plant Leaves; Plant Roots; Seedlings; Soil Pollutants; Time Factors; Up-Regulation

An endophytic fungus was tested in rice (Oryza sativa L.) exposed to four levels of lead (Pb) stress (0, 50, 100 and 200 μM) to assess effects on plant growth, photosynthesis and antioxidant enzyme activity. Under Pb stress conditions, endophyte-infected seedlings had greater shoot length but lower root length compared to non-infected controls, and endophyte-infected seedlings had greater dry weight in the 50 and 100 μM Pb treatments. Under Pb stress conditions, chlorophyll and carotenoid levels were significantly higher in the endophyte-infected seedlings. Net photosynthetic rate, transpiration rate and water use efficiency were significantly higher in endophyte-infected seedlings in the 50 and 100 μM Pb treatments. In addition, chlorophyll fluorescence parameters Fv/Fm and Fv/Fo were higher in the infected seedlings compared to the non-infected seedlings under Pb stress. Malondialdehyde accumulation was induced by Pb stress, and it was present in higher concentration in non-infected seedlings under higher concentrations of Pb (100 and 200 μM). Antioxidant activity was either higher or unchanged in the infected seedlings due to responses to the different Pb concentrations. These results suggest that the endophytic fungus improved rice growth under moderate Pb levels by enhancing photosynthesis and antioxidant activity relative to non-infected rice.

Topics: Antioxidants; Biomass; Carotenoids; Chenopodiaceae; Chlorophyll; Culture Media; Endophytes; Lead; Malondialdehyde; Nitrates; Oryza; Photosynthesis; Plant Leaves; Spectrometry, Fluorescence

This study investigated antioxidative response and proline metabolism in two wheat cultivars (Tritium aestivum Xihan 2 (Xihan) and Ningchun 4 (Ningchun)) under Pb(NO(3))(2) stress. The constitutive H(2)O(2) scavenging enzyme activities and proline content in the leaves of drought-tolerant Xihan are higher than those in drought-sensitive Ningchun. Higher Pb concentration reduced chlorophyll content in both cultivars, but Ningchun was more sensitive to lead toxicity than Xihan. The higher activities of antioxidant enzyme and the significant proline accumulation provide protection for two wheat cultivars against lead toxicity, resulting in unaltered MDA content. Analysis of enzyme activities showed that the accumulation of proline induced by lead stress is due to the increases of OAT and GK activities in Xihan seedlings, and to the increase of GK activity in Ningchun leaves. Therefore, the different mechanism of proline metabolism was associated with increased proline levels in two wheat cultivars when exposed to lead stress.

Topics: Antioxidants; Catalase; Chlorophyll; Hydrogen Peroxide; Lead; Lipid Peroxidation; Malondialdehyde; Nitrates; Oxidative Stress; Plant Leaves; Proline; Seedlings; Soil Pollutants; Superoxide Dismutase; Triticum

To elucidate the deleterious effects of excess lead on radish (Raphanus sativus) cv. Jaunpuri plants were grown in refined sand in complete nutrient solution for 30 days. On the 31st day lead nitrate was superimposed at 0.1 and 0.5mM to radish for 65 days. A set of plants in complete nutrient solution was maintained as control for the same period without lead. Excess Pb at 0.5mM showed growth depression with interveinal chlorosis on young leaves at apex. Excess Pb reduced the fresh and dry weight pronouncedly at d 65. Lead accumulation reduced the concentration of chlorophyll, iron, sulphur (in tops), Hill reaction activity and catalase activity whereas increased the concentration of phosphorus, sulphur (in roots) and activity of peroxidase, acid phosphatase and ribonuclease in leaves of radish.

Topics: Acid Phosphatase; Biological Transport; Chlorophyll; Iron; Lead; Nitrates; Peroxidase; Phosphorus; Plant Leaves; Plant Proteins; Raphanus; Ribonucleases; Sulfur

Lead is a heavy metal which is believed to be toxic when present in excessive amount. Excess Pb in Triticum sativum and Lens esculanta alters several physiological and biochemical processes in both species. Seed germination of both species grown on soaked filter paper with Pb (NO3)2 was highly inhibited (about 60% at 20 mM Pb (NO3)2). Results obtained from measurement of lead content in the roots and shoots of both species indicated that most of the lead accumulated in the roots of both species with a lower degree within the shoots. Lead uptake by both species whether grown in perlite medium or on filter paper soaked with Pb (NO3)2, was correlated with lead concentration. These results indicate a passive process of lead translocation. These results also show that lead inhibits the growth of both plant species, but root growth inhibition was more pronounced than shoot growth inhibition at different lead concentration. Total chlorophyll content was found to be decreased in both species after treatment with Pb (NO3)2. Total protein content in the seedlings, as our results have indicated, was found to be increased with increasing lead concentration in both species.

Topics: Chlorophyll; Fabaceae; Lead; Nitrates; Plant Development; Plant Proteins; Plants; Plants, Medicinal; Seeds; Species Specificity; Triticum