title: Molecular, Biochemical and Ultrastructural Changes Induced by Pb Toxicity in Seedlings of Theobroma cacao L.
abstract: Pb is a metal which is highly toxic to plants and animals, including humans. High concentrations of Pb have been observed in beans of T. cacao, as well as in its products. In this work, we evaluated the molecular, biochemical, and ultrastructural alterations in mature leaves and primary roots of seedlings of two progenies of T. cacao, obtained from seed germination in different concentrations of Pb (0, 0.05, 0.1, 0.2, 0.4, 0.8 g L(-1)), in the form of Pb(NO3)2. The progenies resulted from self-fertilization of Catongo and a cross of CCN-10 x SCA-6. The Pb, supplied via seminal, caused alterations in the ultrastructures of the mesophyll cells and in the amount of starch grains in the chloroplasts. The dosage of substances reactive to thiobarbituric acid showed that Pb induced lipid peroxidation. The activity of guaiacol peroxidases and the expression of genes associated to synthetase of phytochelatin, SODcyt and PER increased in response to Pb. In addition, there was alteration in the expression of stress-related proteins. The progeny of CCN-10 x SCA-6 was more tolerant to Pb stress when compared to Catongo, since: (i) it accumulated more Pb in the roots, preventing its translocation to the shoot; (ii) it presented higher activity of peroxidases in the roots, which are enzymes involved in the elimination of excess of reactive oxygen species; and (iii) increased expression of the gene in the phytochelatin biosynthesis route. The results of the proteomic analysis were of paramount importance to differentiate the defense mechanisms used by both progenies of T. cacao.
authors.affiliation: Department of Biological Sciences, State University of Santa Cruz, Campus Soane Nazaré de Andrade, Rodovia Jorge Amado, km 16, 45662-900, Ilhéus, BA, Brazil.
authors.forename: Graciele Santos Monteiro
authors.initials: GS
authors.lastname: Reis
authors.affiliation: Department of Biological Sciences, State University of Santa Cruz, Campus Soane Nazaré de Andrade, Rodovia Jorge Amado, km 16, 45662-900, Ilhéus, BA, Brazil.
authors.forename: Alex-Alan Furtado
authors.initials: AA
authors.lastname: de Almeida
authors.affiliation: Department of Biological Sciences, State University of Santa Cruz, Campus Soane Nazaré de Andrade, Rodovia Jorge Amado, km 16, 45662-900, Ilhéus, BA, Brazil.
authors.forename: Nicolle Moreira
authors.initials: NM
authors.lastname: de Almeida
authors.affiliation: Department of Biological Sciences, State University of Santa Cruz, Campus Soane Nazaré de Andrade, Rodovia Jorge Amado, km 16, 45662-900, Ilhéus, BA, Brazil.
authors.forename: Andressa Vieira
authors.initials: AV
authors.lastname: de Castro
authors.affiliation: Department of Biological Sciences, State University of Santa Cruz, Campus Soane Nazaré de Andrade, Rodovia Jorge Amado, km 16, 45662-900, Ilhéus, BA, Brazil.
authors.forename: Pedro Antonio Oliveira
authors.initials: PA
authors.lastname: Mangabeira
authors.affiliation: Department of Biological Sciences, State University of Santa Cruz, Campus Soane Nazaré de Andrade, Rodovia Jorge Amado, km 16, 45662-900, Ilhéus, BA, Brazil.
authors.forename: Carlos Priminho
authors.initials: CP
authors.lastname: Pirovani
mesh_terms: D002099:Cacao / Q000187:drug effects* / Q000235:genetics / Q000648:ultrastructure*; D002736:Chloroplasts / Q000187:drug effects / Q000235:genetics / Q000648:ultrastructure; D018506:Gene Expression Regulation, Plant / Q000187:drug effects / Q000235:genetics; D007854:Lead / Q000633:toxicity*; D015227:Lipid Peroxidation / Q000187:drug effects / Q000235:genetics; D018384:Oxidative Stress / Q000187:drug effects / Q000235:genetics; D009195:Peroxidase / Q000235:genetics; D054811:Phytochelatins / Q000187:drug effects; D018515:Plant Leaves / Q000187:drug effects / Q000235:genetics / Q000648:ultrastructure; D018517:Plant Roots / Q000187:drug effects / Q000235:genetics / Q000648:ultrastructure; D036226:Seedlings / Q000187:drug effects* / Q000235:genetics / Q000648:ultrastructure*; D057945:Self-Fertilization / Q000187:drug effects / Q000235:genetics; D012989:Soil Pollutants / Q000633:toxicity
chemical_list: D012989:Soil Pollutants; D007854:Lead; D054811:Phytochelatins; C121048:guaiacol peroxidase; D009195:Peroxidase