title: Modulation of Pb-induced stress in Prosopis shoots through an interconnected network of signaling molecules, phenolic compounds and amino acids.
abstract: Lead (Pb) is a hazardous heavy metal present in the environment which elicits oxidative stress in plants. To characterize the physiological and biochemical basis of Pb tolerance, Prosopis farcta seedlings were exposed to Hoagland's solutions at six different Pb concentrations (0, 80, 160, 320, 400 and 480 μM) for different periods of time. As expected, application of Pb significantly increased hydrogen peroxide (H2O2) content. In response, P. farcta deployed the antioxidative defence mechanisms with significantly higher activities of superoxide dismutase (SOD), enzymes related to H2O2 removal, and also the increases in proline as a solute marker of stress. Increases were observed in nitric oxide (NO) production which could also act in triggering defense functions to detoxify Pb. Enhanced phenylalanine ammonia-lyase (PAL) activity at early days of exposure to Pb was correlated with increases in phenolic compounds. Significant increases in phenolic acids and flavonoids; daidzein, vitexin, ferulic acid and salicylic acid were observed with Pb treatment. Furthermore, the stress effects were followed by changes in free amino acid content and composition. Aspartic acid and glycine content was increased but glutamic acid significantly decreased. It is likely that stress signal transduction by NO and H2O2 mediated defence responses to Pb by coordination of antioxidative system and metabolic pathways of phenylpropanoid and amino acids.
authors.affiliation: Department of Plant Biology, Faculty of Biological Sciences, Tarbiat Modares University, Tehran, Iran.
authors.forename: Somaieh
authors.initials: S
authors.lastname: Zafari
authors.affiliation: Department of Plant Biology, Faculty of Biological Sciences, Tarbiat Modares University, Tehran, Iran. Electronic address: msharifi@modares.ac.ir.
authors.forename: Mohsen
authors.initials: M
authors.lastname: Sharifi
authors.affiliation: Department of Biology, Faculty of Basic Sciences, University of Mazandaran, Babolsar, Iran.
authors.forename: Najmeh
authors.initials: N
authors.lastname: Ahmadian Chashmi
authors.affiliation: Aberystwyth University, Institute of Biological, Environmental and Rural Sciences, Aberystwyth, Wales, SY23 3DA, UK.
authors.forename: Luis A J
authors.initials: LA
authors.lastname: Mur
mesh_terms: D000596:Amino Acids / Q000378:metabolism*; D006861:Hydrogen Peroxide / Q000378:metabolism*; D007854:Lead / Q000633:toxicity*; D009569:Nitric Oxide / Q000378:metabolism; D010636:Phenols / Q000378:metabolism*; D010650:Phenylalanine Ammonia-Lyase / Q000378:metabolism; D018520:Plant Shoots / Q000187:drug effects* / Q000378:metabolism*; D029862:Prosopis / Q000187:drug effects* / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects
chemical_list: D000596:Amino Acids; D010636:Phenols; D007854:Lead; D009569:Nitric Oxide; D006861:Hydrogen Peroxide; D010650:Phenylalanine Ammonia-Lyase
keywords: Amino acids; Enzymatic antioxidant; Lead; Nitric oxide; Phenolic acids; Phenylalanine ammonia-lyase